Emergy evaluation of water
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Title: Emergy evaluation of water
Physical Description: xvi, 248 leaves : ill. ; 29 cm.
Language: English
Creator: Buenfil, Andrés A., 1971- ( Dissertant )
Brown, Mark T. ( Thesis advisor )
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2001
Copyright Date: 2001
 Subjects
Subjects / Keywords: Environmental Engineering Sciences thesis, Ph. D   ( lcsh )
Dissertations, Academic -- Environmental Engineering Sciences -- UF   ( lcsh )
emergy
water value
Genre: bibliography   ( marcgt )
theses   ( marcgt )
non-fiction   ( marcgt )
 Notes
Abstract: To better understand the values of water within different contexts and spatial scales, the emergy inputs to water were evaluated and compared at four scales: 1) global, 2) regional (the state of Florida), 3) local (water supply utilities), and 4) small-scale (home water purification). Emergy (spelled with an "m") represents all the previous work of one kind required to generate a product or provide a service. Since water can be found at all stages of the global hierarchy of biogeochemical processes, it has many emergy values and transformities. Transformities of water indicate the convergence of energy and materials that are required to produce the water. Global water storages were evaluated using the total emergy driving the geobiochemical processes of the biosphere and storage turnover times. Transformities for these water storages varied between 3.54 E3 sej/J (water vapor) and 1.05 E6 sej/J (glaciers). Calculated transformities for global water flows ranged from 3.96 E3 sej/J (precipitation) to 9.55 E5 sej/J (ice melt). Regional transformities of water resources reflected specific conditions of the landscape. The mean transformities for water in estuaries, rivers, lakes, wetlands and deep groundwater storages in Florida were calculated at 3.19 E4, 4.26E4, 5.64 E4, 7.09 E4 and 1.66 E5 sej/J, respectively. Eight local water supply utilities in Florida were evaluated to determine the emergy cost of producing potable water. Potable water transformities ranged from 1.39 E5 (West Palm Beach plant) to 1.39 E6 (Stock Island reverse osmosis plant). Five home water purification processes were evaluated to compare the emergy costs of producing potable water just for drinking, yielding transformities between 5.19 E6 (filtered water) and 3.16 E7 sej/J (bottled water). To test theories of the appropriate use of water to maximize economic vitality, a computer model of a generalized regional production function was simulated. Using Florida as a case study, maximum total production occurred when the economic/urban sector, the agricultural sector, and the environment received approximately 25, 30, and 45%, respectively, of the fresh water remaining after evapotranspiration. Since the calculated transformities for potable water are equivalent in magnitude to gasoline and electricity, the use of potable water should correspond with its high value. Therefore, measures need to be taken at local and regional levels to use potable water more appropriately.
Subject: KEYWORDS: emergy analysis, water, value, public supply, potable water, Florida, drinking water, water allocation, transformity, hydrologic cycle
Statement of Responsibility: by Andrés A. Buenfil.
Thesis: Thesis (Ph. D.)--University of Florida, 2001.
Bibliography: Includes bibliographical references (leaves 239-247).
Additional Physical Form: Also available on the World Wide Web; Adobe Acrobat Reader required to view and print PDF file.
General Note: Printout.
General Note: Vita.
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Source Institution: University of Florida
Holding Location: University of Florida
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Resource Identifier: oclc - 49232307
alephbibnum - 002765925
notis - ANP3964
System ID: UF00100834:00001

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EMERGY EVALUATION OF WATER


By

ANDRES A. BUENFIL















A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY

UNIVERSITY OF FLORIDA


2001




























I dedicate this work to my grandparents Joan and Abe Friedman, as well as to Jacinto,
David, Alberto and Ciltalli; but most especially to my mother, Roberta D. Friedman, my
first teacher.















ACKNOWLEDGMENTS

I am very grateful to M.T. Brown and H.T. Odum for their support, advice, and

mentoring. Both have inspired me to try to understand and experience this fascinating

world. I thank C.L. Montague, D.P. Spangler, P.A. Chadik and C.F. Kiker for their

supervision and participation in this dissertation. I also thank the staff and faculty of the

Environmental Engineering Sciences Department as well as all the students and staff of

the Center for Wetlands for their help during my graduate studies. Financial support for

my doctorate research was provided by the U.S. Department of Education and the

Environmental Engineering Sciences Department through their Graduate Assistance in

Areas of National Need (GAANN) Fellowship program. I thank the University of

Florida GAANN program directors, J.M.M. Anderson and J.M. Andino, for their

encouragement and assistance through the Fellowship.
















TABLE OF CONTENTS

page

A C K N O W L E D G M E N T S ....................................................................... .....................iii

LIST OF TABLES ................ .................. ............... ............... ........... viii

LIST OF FIGURES ..................................................... .......... ....... ........ xii

A B S T R A C T .................................................................................................x v

IN T R O D U C T IO N ......................................... .................... .. .... ........ .. ............ 1

State ent of the P problem .................................................................... ...................... 1
R ev iew of th e L iteratu re .............................................................. ....................... ....... 2
E m ergy V alues of W ater ................................................... ...................... .............. 2
Chemical potential energy of water. ............................................. ................. 2
G eopotential energy of w ater. ....................................................................... .... 4
Nutrients and dissolved solids in water ............... .................................... 5
Waste assimilation capacity of water. ............. ................................ ..............6
Econom ic V alues of W ater ........................................................... ........... 7
Potable w after supply. ................................................. ........ .. ........ .. 7
Treated w astew after ................................ ........... ............ .................... 9
A gricu ltu ral w after. ................. ...... .................. ..... ................... ........ ................. 11
W aste assim ilation values. ............................................... ........... .............. 12
Water used for recreation and aesthetic purposes. ........................................... 13
Sum m ary of W ater V alues .......................................................... .............. 13
P lan of Study ........... ............ .......................................... . ................. 16

M E T H O D S .......................... .. ......... ... .. .................................................... 18

Em ergy Synthesis M ethodology .............. .......................................................... 18
E energy Sy stem s D iagram s ........................................................................................ 18
Emergy Tables ................ ......... ............. .................... 21
E m ergy Indices .......................................................................................................... 22
E m ergy invest ent ratio (E IR ). ................................................................. .... 23
Emergy yield ratio (EYR). ............ ................. ..... .............. 24
Percent renewable em ergy (% R). ....................................................... ................ 24
Emergy benefit to the purchaser (EBP) ............. .............................. ..........25
Em -dollars per volum e (Em $/m 3). ............. ..................................................... 25
Emergy-per-unit and transformity............................................................... 26

iv









Emergy Evaluation of Global Water Storages and Flows....................... .............. 26
Emergy Evaluation of Regional Waters Using Florida as a Case Study ................... 27
Surface Water .............. .. ...... ............... ............. ...... .......... 27
Ground after ....................................... ....... ... .. .. ... .......... 28
Emergy Evaluation of Potable Water Supply Alternatives........................................... 31
Surface (Lake) Water Source: West Palm Beach's Water Treatment Plant............ 34
Surface Water Source: Hillsborough River Water Treatment Plant, Tampa............ 34
Groundwater Source: Murphree Water Treatment Plant, Gainesville .................... 35
W ater Conservation as a Source: Tampa Bay........................................................ 39
Brackish Water Source: City of Dunedin Reverse Osmosis Treatment Facility. ..... 39
Seawater Source: Reverse Osmosis Desalination, Tampa Bay............................ 40
Surficial Groundwater Source: Transported Via Aqueduct, Florida Keys. .............. 43
Seawater Source: Reverse Osmosis Desalination, Stock Island ............. ...............43
Water Distribution System: Gainesville Regional Utility ....................... ........47
Emergy Evaluation of Small Scale Water Purification Alternatives ................................ 47
Groundwater Source: Home Filtration.............................................. .............48
Groundwater Source: Boiling Water ............................ ......................... 50
Salty Water Source: Advanced Solar Distillation
(Humidification-Dehumidification Cycle)........... ............... ............... 50
Salty W ater Source: Traditional Solar Distillation. ............. .................................. 53
Tap Water Source: Purified Bottled Water. ....................................................... 53
Computer Simulation of W ater Allocation .............................................. ............. 56
Analysis and D iagram m ing ........................................................ .............. 56
Structure of the M odel ............. .......... ........................... ............. 56
Computer Simulation ........................................................ .............. 59
Sensitivity A nalysis.................................................... .. .. ............ .. .............. 59

R E S U L T S .......................................................................................................................... 6 1

G lobal W ater R sources ............................. ...................... ..... ...................... 61
Emergy Evaluation of Regional Water Flows and Storages ............. ...............66
Potable W ater Supply Alternatives Evaluated ......................... ....................... ..... 78
Surface (Lake) Water Source: West Palm Beach's Water Treatment Plant.............. 78
Surface Water Source: Hillsborough River Water Treatment Plant, Tampa............ 81
Groundwater Source: Murphree Water Treatment Plant, Gainesville ..................... 81
W ater Conservation as a Source: Tampa Bay........................................................ 82
Brackish water source: City of Dunedin Reverse Osmosis Treatment Facility........ 89
Seawater Source: Reverse Osmosis Desalination, Tampa Bay............................. 89
Surficial Groundwater Source: Transported Via Aqueduct, Florida Keys .............. 90
Seawater Source: Reverse Osmosis Desalination, Stock Island. ........................... 97
Water Supply Distribution System: Gainesville Regional Utility. ...........................97
Summary of Potable Water Supply values ............... .................................... 102
Small Scale Water Purification Alternatives Evaluated ................ ........ ........... 108
Groundwater Source: Home Filtration................. ............................................. 108
G round ater Source: B oiling W ater ................................................................. ... 111
Salty Water Source: Advanced Solar Distillation
(Humidification-Dehumidification Cycle) .................................. ................. 111









Salty Water Source: Traditional Solar Distillation. ............................................. 116
Tap or Spring Water Source: Bottled Water. ................................ .............. 116
Summary of Small Scale Water Purification Values. ........................................... 117
Comparison of Potable Water Alternatives ............... .................................... 128
Simulation of Water Allocation in Florida ............... ..................................... 130
O u tp u t ............................................................................ .............. 13 0
Sensitivity A analysis .................. ................................... ...... .. ........ .. 132

D ISC U S SIO N ........................................................... ........ ...... 138

S u m m ary ......................................................................... 13 8
Principal Conclusions of this Study .................................... .......................... ........ 139
Discussion of Principal Conclusions.................................................................... 139
W after Has Different Values. ... ............................................... .............. 139
Factors affecting the value of water......................... ..................................... ... 141
Comparison of potable water alternatives evaluated................ .... .......... 143
Ranking of potable w ater system s ................................................ ............. 148
Large scale vs. small scale potable water systems. ...................................... 149
Potable water systems self organize to maximize empower by using
high quality w ater sources ....................................................... ..... ......... 150
Much of the Emergy of Public Supply Water is Wasted. .............. ............... 150
Enforce stronger water conservation measures .......................................... 153
Emergy evaluations can complement economic analyses for determining
the most appropriate water supply alternatives............................. ............... 153
Regional Production is Maximized when Water Resources are Used in the
U rban E conom y... ............... ................. ............ .......... ............. .................. 155
Environmental Impacts ........................................ 157
Suggestions for Further Research ......................................................................... 158
Evaluation of Other Potable Water Alternatives............................ .............. 158
Evaluation of Other Policies for the Appropriate Use of Public Supply ............... 158
Dual piping ......................................................................... ..... ...................... 159
Increase of w after rates ......... ................. ................... ................. .............. 160

GLOSSARY ................. ................................................. ......... 161

APPENDICES

A SYMBOLS OF ENERGY LANGUAGE USED TO REPRESENT SYSTEMS ...... 164

B FOOTNOTES OF EM ERGY TABLES........................................... .................... 165

C ASSET CALCULATION S ............................... .. .................................... 208

D T R A N SF O R M IT IE S ........................................................................ .................... 222

E COEFFICIENTS AND REFERENCES FOR THE WATER

A L L O C A T IO N M O D E L ............................................................................................ 226









F ENVIRONMENTAL IMPACTS OF POTABLE WATER PRODUCTION ........... 229

L IST O F R E FE R E N C E S ................................................................................................ 239

B IO G R A PH IC A L SK E T C H ........................................................................................... 248
















LIST OF TABLES


Table Page

1 Potable water supply component costs ........................................ .............. 8

2 M monthly w ater charges ......................... ....... ..................................... 9

3 Monthly wastewater disposal charges .......................................................... 10

4 Comparative values of water...................................... ........ ................ 14

5 Tabular format of emergy evaluation tables used in this study......................... 22

6 Public supply alternatives evaluated with emergy synthesis. ............................ 32

7 Small scale water purification alternatives evaluated. ........................................ 48

8 Distribution and emergy values of global water storage. ............. ................. 63

9 Distribution and emergy values of global water flows. ...................................... 64

10 Emergy evaluation of Florida's intertidal water ................................................ 67

11 Emergy evaluation of Florida's river and stream water............... .................. 68

12 Emergy evaluation of Florida's lake water ..................................................... 69

13 Emergy evaluation of Florida's wetland (freshwater marshes & swamps) water. 70

14 Summary of emergy evaluation of Florida's surface water resources ............... 71

15 Emergy evaluation of fresh groundwater from Florida's Surficial aquifer ......... 72

16 Emergy evaluation of fresh groundwater from the Sand and Gravel aquifer
sy ste m .................. .............................. .... ................ 7 3

17 Emergy evaluation of fresh groundwater from the Biscayne aquifer system ...... 74

18 Emergy evaluation of fresh groundwater from the Intermediate aquifer ............ 75

19 Emergy evaluation of fresh groundwater from the Floridan Aquifer system. ...... 76









20 Summary of emergy evaluation of Florida's groundwater resources ................... 77

21 Emergy evaluation of the drinking water produced at the City of West Palm
Beach W ater Treatment Facility .............. ................................... ........ 80

22 Emergy indices and ratios for the drinking water produced at the City of West
Palm Beach W ater Treatment Facility. .......................................... .... 80

23 Emergy evaluation of the drinking water produced at the Hillsborough River
W ater Treatm ent Plant ........................................... .................. ...... 84

24 Emergy indices and ratios for the drinking water produced at the Hillsborough
River W ater Treatment Plant...................... ........................... 84

25 Emergy evaluation of the drinking water produced at the Murphree Water
Treatm ent Plant ............................ .... ... ..... .... ........ .. ........ .. 86

26 Emergy indices and ratios for the drinking water produced at the Murphree
W ater Treatm ent Plant. ........................................ .................. ...... 86

27 Emergy evaluation of Tampa Bay's water conservation/management plan.......... 88

28 Emergy indices and ratios for the drinking water saved by Tampa Bay's water
conservation program ................ ................. .................... .............. 88

29 Emergy evaluation of the drinking water produced at the City of Dunedin
Reverse Osmosis W ater Treatment Facility ........................... .............. 92

30 Emergy indices and ratios for the drinking water produced at the City of
Dunedin RO W ater Treatment Facility. ........................................ ..... 92

31 Emergy evaluation of drinking water to be produced by RO desalination in
Tam pa B ay ..................... ................ ............................... 94

32 Emergy indices and ratios for Tampa Bay's desalination plant. ....................... 94

33 Emergy evaluation of the drinking water produced and distributed through the
aqueduct system of the Florida Keys Aqueduct Authority ..................... 96

34 Emergy indices and ratios for the drinking water produced and delivered by the
Florida Keys Aqueduct Authority. .............. ............................ ....... ....... 96

35 Emergy evaluation of the drinking water produced from a reverse osmosis
water treatment plant in Stock Island.............. .... ................ 99

36 Emergy indices and ratios for the drinking water produced by Stock Island's
R O facility. ...................................................... ............. 99









37 Emergy evaluation of a 25 mgd drinking water distribution system in
G ainesville ........................................ ......... 100

38 Summary of the emergy evaluations of public supply alternatives. .................... 103

39 Emergy evaluation of the drinking water produced with a home filter ............. 110

40 Emergy indices and ratios for the drinking water produced with a home filter.... 110

41 Emergy evaluation of the boiling water to make it potable ............................. 113

42 Emergy indices and ratios for boiling water to make it potable.......................... 113

43 Emergy evaluation of potable water produced by solar desalination with a 2.0
m2 solar distiller using a humidification-dehumidification cycle ............ 115

44 Emergy indices and ratios for the potable water produced with a solar distiller
containing a humidification-dehumidification cycle................................ 115

45 Emergy evaluation of potable water produced by desalination using a 1.0 m2
solar distiller ....... ......... .. ......... ................ .............. 119

46 Emergy indices and ratios for the potable water produced by desalination using
a 1.0 m 2 solar distiller ............................................ ... ........... ...... .... 119

47 Emergy evaluation of bottled water .......................................................... 122

48 Emergy indices and ratios of bottled water................. .................. 122

49 Summary of the emergy evaluation of small scale water purification
alternatives. .................... ................ ............................... 123

50 Comparison of emergy values of potable water (home-consumed)...................... 129

B-l Notes for the emergy evaluation of the drinking water produced at the City of
W est Palm Beach W ater Treatment Plant.............................................. 166

B-2 Notes for the emergy evaluation of the drinking water produced at the
Hillsborough River W ater Treatment Plant ............................................ 169

B-3 Notes for the emergy evaluation of the drinking water produced at the
Murphree Water Treatment Plant............................ 172

B-4 Notes for the emergy evaluation of the drinking saved by Tampa Bay Water's
W ater Conservation Program .................................................................. 174

B-5 Notes for the emergy evaluation of the drinking water produced at the City of
Dunedin Reverse Osmosis Water Treatment Facility ............................ 179









B-6 Notes for the emergy evaluation of the drinking water to be produced in
Tampa Bay by desalinating water using reverse osmosis.......................... 182

B-7 Notes for the emergy evaluation of the drinking water produced and delivered
by the Florida Keys Aqueduct Authority ................................................ 185

B-8 Notes for the emergy evaluation of the drinking water produced at the Reverse
Osmosis Desalination plant in Stock Island......................... ............ 188

B-9 Notes for the emergy evaluation of filtered water ................. ...... ............ 191

B-10 Notes for the emergy evaluation of boiled water ............................................. 193

B-11 Notes for the emergy evaluation of the potable water produced with a solar
desalination with a humidification-dehumidification cycle.................... 196

B-12 Notes for the emergy evaluation of the potable water produced by
desalination using a 1.0 m 2 solar distiller............................................. 200

B-13 Notes for the emergy evaluation of the purified bottled water ......................... 204

C-l West Palm Beach Water Treatment Plant assets.......................................... 209

C-2 Murphree Water Treatment Plant assets. .................................. .............. 212

C-3 Florida K eys A queduct Authority assets............................................................. 215

C-4 Gainesville Regional Utility water distribution system assets..........................219

D-l Transformities, emergy per mass and emergy per volume used in the study..... 223

D-2 Summary of water transformities calculated in this study............................... 225

E-l Flows and calibration values for the simulation of water allocation in Florida.. 227

F-l Emergy evaluation of environmental impacts resulting from the production of
potable water. .............. .................................... 230

F-2 Emergy evaluation of environmental impacts resulting from the small scale
production of potable w ater .......................... ........... ............. .............. 236
















LIST OF FIGURES


Figure Page

1 A generic systems diagram of the production of potable water for public supply... 20

2 Diagram illustrating the definition of the emergy indices used. The letters
on the pathways refer to flows of emergy per unit time............................ 23

3 Sequence of aquifer system s in Florida ......................................... ..... ......... 30

4 Approximate location of the public supply systems analyzed ............................ 33

5 Schematic of the production of drinking water at the City of West Palm Beach
W ater T reatm ent P lant. ................................................................................. 36

6 Schematic of the production of drinking water at the Hillsborough River Water
Treatment Plant ................ ...................................... ...... ............ .. 37

7 Schematic of the production of potable water at the Murphree Water Treatment
P la n t ....................................................................... 3 8

8 Schematic of the production process of potable water at the City of Dunedin
Reverse Osmosis W ater Treatment Facility............... .............. ............ 41

9 Schematic of the reverse osmosis desalination facility being built in Tampa Bay.. 42

10 Schematic of the production and transportation of potable water by the Florida
K eys A queduct A uthority...................................................... .... .............. 45

11 Schematic of Stock Island's RO facility............................... ............. 46

12 Schematic of the production of purified water with a home filter ...................... 49

13 Schematic diagram of boiling water........ ......................................... 51

14 Schematic diagram of an advanced solar distillation process containing a
humidification-dehumidification cycle. .............................. ............ .. 52

15 Schematic of a traditional solar distiller................ ......................... ............ 54

16 Schematic of the production of purified bottled water.............. ...... ......... 55









17 Model of water allocation for maximizing the total production of Florida. ............ 60

18 The global hydrologic cycle ............................................................................ ....65

19 Energy systems diagram of the water production by the City of West
Palm Beach................................... ........................... ........... 79

20 Energy systems diagrams of the Hillsborough River Water Treatment Plant ......... 83

21 Energy systems diagram of Tampa Bay's water conservation program................. 85

22 Energy systems diagram for the Murphree Water Treatment Plant......................... 87

23 Energy systems diagram for the City of Dunedin Reverse Osmosis Water
Treatm ent Facility. ...... ................................ ...... ............. ............. 91

24 Energy systems diagram of Tampa Bay's RO desalination plant ........................ 93

25 Energy systems diagram of the water production and transportation process
by the Florida Keys Aqueduct Authority. ........................................ 95

26 Energy systems diagram of Stock Island's reverse osmosis desalination plat. ........ 98

27 Emergy Signature of the Public Water Supply Alternatives Evaluated................. 104

28 Transformities for water source and finished (potable) water for the public water
supply alternatives evaluated .............. ...... ........................................ 105

29 Comparison of the public supply systems evaluated using several emergy
indices and ratios...................................... .................. ......... .. 106

30 Energy systems diagram of the production of purified water with a home filter..... 109

31 Energy systems diagram of boiling groundwater...................................... 112

32 Systems diagram of potable water produced by solar distillation with a
humidification/dehumidification cycle. .............................................. 114

33 Systems diagram of potable water produced by solar distillation............................ 118

34 Systems diagram of the production of purified bottled water................................ 120

35 Systems diagram of the production of purified bottled water using spring
water from the Floridan aquifer as a source............................................... 121

36 Emergy signature of the small scale water purification alternatives evaluated. ...... 124

37 Transformities for water source and finished (potable) water for the small scale
water systems evaluated ... ............................... .............. 125









38 Comparison of the small scale water purification systems evaluated using
several emergy indices and ratios.... ...................... .............. 126

39 Graphs of simulation results of the model in Figure 17....................... .............. 133

40 Three-dimensional view of the model output ................... .................... 134

41 Results of sensitivity analysis based on total fuels, goods and services
imported by the regional economy............................... ............. .......... 136

42 Results of sensitivity analysis based on the distribution of total fuels, goods and
services imported by the regional economy............................................ 137

43 Concentration and upgrading of water for human use. ............. ............... 140

44 Water value as a function of several key parameters........................................ 141

45 Diagram of the level of water treatment as a function of annual benefits and
costs of adding an additional step in the treatment process. ....................... 142















Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy

EMERGY EVALUATION OF WATER


By

Andres A. Buenfil

August, 2001


Chair: Mark T. Brown, Ph.D.
Major Department: Environmental Engineering Sciences

To better understand the values of water within different contexts and spatial

scales, the emergy inputs to water were evaluated and compared at four scales: 1) global,

2) regional (the state of Florida), 3) local (water supply utilities), and 4) small-scale

(home water purification). Emergy (spelled with an "m") represents all the previous

work of one kind required to generate a product or provide a service.

Since water can be found at all stages of the global hierarchy of biogeochemical

processes, it has many emergy values and transformities. Transformities of water

indicate the convergence of energy and materials that are required to produce the water.

Global water storage were evaluated using the total emergy driving the geobiochemical

processes of the biosphere and storage turnover times. Transformities for these water

storage varied between 3.54 E3 sej/J (water vapor) and 1.05 E6 sej/J (glaciers).









Calculated transformities for global water flows ranged from 3.96 E3 sej/J (precipitation)

to 9.55 E5 sej/J (ice melt).

Regional transformities of water resources reflected specific conditions of the

landscape. The mean transformities for water in estuaries, rivers, lakes, wetlands and

deep groundwater storage in Florida were calculated at 3.19 E4, 4.26E4, 5.64 E4, 7.09

E4 and 1.66 E5 sej/J, respectively.

Eight local water supply utilities in Florida were evaluated to determine the

emergy cost of producing potable water. Potable water transformities ranged from

1.39 E5 (West Palm Beach plant) to 1.39 E6 (Stock Island reverse osmosis plant). Five

home water purification processes were evaluated to compare the emergy costs of

producing potable water just for drinking, yielding transformities between 5.19 E6

(filtered water) and 3.16 E7 sej/J (bottled water).

To test theories of the appropriate use of water to maximize economic vitality, a

computer model of a generalized regional production function was simulated. Using

Florida as a case study, maximum total production occurred when the economic/urban

sector, the agricultural sector, and the environment received approximately 25, 30, and

45%, respectively, of the fresh water remaining after evapotranspiration.

Since the calculated transformities for potable water are equivalent in magnitude

to gasoline and electricity, the use of potable water should correspond with its high value.

Therefore, measures need to be taken at local and regional levels to use potable water

more appropriately.















INTRODUCTION


Statement of the Problem

Water is essential for life. Water is a fundamental resource that is necessary to

most processes of the biosphere. It is required as an input where its chemical and

physical properties are used to dilute, cool, carry, react or physically drive processes. In

addition, it is required as a sink for many processes, carrying away wastes and by-

products that would other wise build up to lethal quantities in local environments. One of

its values lies in this versatility. Water is valued for its chemical potential and for its

physical potential energy. In essence, it is valued for its quality and for its quantity.

Water has a cycle, driven by solar, tidal and geologic energies. It flows from one place to

another and changes state from one time to another. In so doing it carries materials and

energy. Another of its values lies in its ability to carry substances, and in the value of the

substances it carries.

Increasingly, as quantity and quality of water resources decline, the following

questions are posed by citizens and policy makers. What are the values of water? What

are the best uses of present water resources? How can scarce water be allocated to best

maximize its use and economic vitality? As adequate supplies of fresh water decrease

due to the rapid growth of populations and the economies, there is a pressing need to

answer these questions to decide what is the most appropriate use and allocation of water

resources for the welfare of both humans and the environment. To answer these






2


questions, the emergy contributions of water at different levels of the global and regional

hydrological cycle were evaluated. Emergy (spelled with an "m") puts all products of

nature, technology, and the economy on a common basis of the prior work required and

embodied in the water. In addition, a simulation model of a generalized regional

production function was used to explore theories of water allocation for maximizing

empower.



Review of the Literature

Emergy Values of Water

Different aspects of water have been evaluated in previous emergy studies (Odum

et al., 1987a; Odum et al., 1987b; Green, 1992; Brown and McClanahan, 1992; Doherty

et al., 1993; Odum and Arding, 1991; Odum, 1996; Romitelli, 1997; Brandt-Williams,

1999; Howington, 1999). These aspects of water include 1) chemical potential energy, 2)

geopotential energy, 3) nutrients, suspended solids and dissolved solids present in water,

and 4) the capacity of water to assimilate wastes.


1) Chemical potential energy of water.

Odum et al. (1987b) calculated the emergy-based dollar (Em$) value of water

resources used for irrigation in Texas by using the chemical potential energy of water.

The calculated values for rain, river, and groundwater were 0.035, 0.091 and 0.25

Em$/m3, respectively. In addition, Odum et al. (1987b) valued agricultural water and

municipal drinking waters at 0.44 and 1.16 Em$/m3, respectively. These values were 11

and 1.5 times greater than their corresponding market values at the time of calculation

(Odum et al., 1987b). The chemical potential energy of water was used to measure the









energy input of fresh water to fisheries by Odum et al. (1987b), Odum and Arding

(1991), and Brown et al. (1991). Green (1992) calculated the emergy value of water and

its economic contribution to the Bay of Banderas, between the states of Jalisco and

Nayarit, in Mexico. The author calculated the emdollar values of several water types,

including rainfall (0.027 Em$/m3), water used in fisheries (0.06 Em$/m3), river water

(0.072 Em$/m3), irrigation water (0.11 Em$/m3), groundwater (0.27 Em$/m3), urban use

water (0.64 Em$/m3), raw wastewater (1.55 Em$/m3), and treated wastewater (2.54

Em$/m3). Odum (1996) calculated the emdollar value of water stored in the Santa Fe

Swamp in Florida at 6.0 million Em$ or 0.1 Em$/m3. The average global value of river

water was estimated at 0.12 Em$/m3 (Odum, 1996). In an evaluation of alternative ways

of supplying freshwater to Windhoek, the capital of Namibia, the value of the water from

the Kavango River that discharges to the Okavango Delta was estimated at 0.01 Em$/m3

(Buenfil, 2000). Using the chemical potential of rain relative to seawater, Odum (1996)

calculated the "free" contribution of rain to the economy of the United States in 268.0 E9

Em$ or 0.032 Em$/m3 for 1983. Odum (1996) estimated the average global values of

oceanic precipitation and rain on land at 0.018 and 0.045 Em$/m3, respectively. In 1989

the chemical potential energy of rainfall in Ecuador was valued at 19.1 E9 U.S. Em$ or

0.042 Em$/m3 (Odum and Arding, 1991). Brown and McClanahan (1992) estimated the

chemical potential contribution of rain to the economy of Thailand in 1984 at 30.7 E9

U.S. Em$ or 0.032 Em$/m3. In the same study, the authors valued the water used in the

production of low-energy rice in Thailand at 760 E12 solar em-joules per year (sej/yr) per

hectare of cultivation land, which was nearly 37% of the emergy yield of the rice

produced. In a study of environmental alternatives in Martin County, Florida, Engel et al.









(1995) estimated the annual value of retaining local freshwater in the county in 0.15

Em$/m3. Furthermore, when this value was matched with the emergy investment ratio

(EIR) of Martin County (1.4) and the EIR of Florida (7.0), the freshwater was worth 0.36

and 1.20 Em$/m3 per year, respectively (Engel et al., 1995). Tilley (1999) reported the

chemical potential value of groundwater in North Carolina in 0.62 Em$/m3 for 1992. The

average value of groundwater in the U.S. (1983) was estimated at 0.07 Em$/m3 (Odum,

1996). Brandt-Williams (1999) valued the water from two lakes in central Florida in 0.22

Em$/m3 (Newnan's Lake) and 0.063 Em$/m3 (Lake Weir).


2) Geopotential energy of water.

The value of the geopotential energy of water has also been examined in a number

of emergy studies. Brown and McClanahan (1992) calculated the geopotential emergy of

the Mekong River between Thailand and Laos (average flow of 17,000 m3/sec) at 2.18 E9

sej/m3 or 0.001 Em$/m3 for 1984. In an emergy evaluation of the United States, Odum

(1996) estimated that the geopotential energy of rain falling in the U.S. was worth

approximately 234.2 billion Em$ or 0.028 Em$/m3 for 1983. The geopotential energy of

rainfall in Ecuador was valued at 14.6 E9 U.S. Em$ or 0.032 Em$/m3 for 1989 (Odum

and Arding, 1991). Doherty et al. (1993) reported the geopotential value of rain in Papua

New Guinea at 1.5 E9 U.S. Em$ or 0.001 Em$/m3 for 1987. Tilley (1999) calculated the

geopotential value of rain in North Carolina in 0.006 Em$/m3 for 1992. Romitelli (1997)

used the geopotential energy of rivers in the Ribeira de Iguape River Basin, between

Curitiba and Sao Paulo in Brazil, and the Coweeta Basin, between Tennessee and North

Carolina in the U.S., to calculate the value of river water. Geopotential values increased

as water flowed downstream to the lowest elevation of the basins. Geopotential river









water values in the Ribeira watershed ranged from 1.9 El1 sej/m3 (0.023 Em$/m3) for the

Eta sub-basin to 2.2 E12 sej/m3 (0.26 Em$/m3) for the Betari sub-basin. Values in the

Coweeta River Basin averaged 2.86 El 1 sej/m3 or approximately 0.29 Em$/m3

(Romitelli, 1997).


3) Nutrients, suspended solids and dissolved solids present in water.

The value of water has also been calculated based on the nutrients or sediments

present in water. In an evaluation of the Mississippi River Basin, Odum et al. (1987a)

estimated the macroeconomic emergy value of the sediments carried by the Mississippi

River at 1.05 billion Em$/yr or 0.002 Em$/m3. In this study, the authors also estimated

the contribution of river water for the formation of coastal wetlands by evaluating the

suspended sediments and organic matter carried by the river. Odum and Arding (1991)

calculated the value of the organic load present in Rio Chone, a coastal river in Ecuador,

by using the chemical oxygen demand of the river water. With an average flow rate of

3,650 m3/sec, the value of the organic load in the river was calculated at 8.63 E9 U.S.

Em$/yr or 0.075 Em$/m3. Howington (1999) calculated the emergy per volume of river

water in the Catatumbo Drainage Basin between Colombia and Venezuela by using river

sediment and nutrient concentrations. Using sediment concentrations, water in this basin

was estimated at 1.4 El1 sej/m3 (0.02 Em$/m3) for first order streams (Howington,

1999). The value of river water based on nutrient concentrations averaged 1.0 E9 sej/m3

(0.0001 Em$/m3) and 5.0 E9 sej/m3 (0.0007 Em$/m3) for the respective total

phosphorous and total nitrogen present in the water (Howington, 1999). Brandt-Williams

(1999) included the total phosphorous of watershed runoff to calculate the emergy of

water in Newnan's Lake and Lake Weir in central Florida. Total phosphorous accounted









for approximately 23% of the value of water in Newnan's Lake (3.44 El1 sej/m3 or 0.22

Em$/m3) and 4.4% of the value of water in Lake Weir (9.75 E10 sej/m3 or 0.063

Em$/m3).


4) Waste assimilation capacity of water.

Water values based on waste assimilation have also been estimated with emergy

synthesis. Mitsch (1976) evaluated several disposal alternatives for secondarily treated

wastewater effluent by comparing the changes in emergy flows caused by different

disposal systems (a cypress dome, a lake system, and a tertiary treatment plant). The

value of water for waste assimilation was measured by the amount of production the

nutrient-rich effluent supported relative to the amount of outside emergy required for

treating the wastewater. Nelson (1998) calculated the emergy value of highly treated

wastewater effluent from the advanced wastewater treatment plant at the University of

Florida in Gainesville. This treated effluent was valued in 2.32 E14 sej/m3 or 170.1

Em$/m3. Although high, this value is still less than what Nelson (1998) calculated for

wastewater treated with a package sewage system in Yucatan, Mexico, which was

reported at 3.38 E14 sej/ m3 or 174.4 Em$/m3. In both cases about 99% of this value of

treated wastewater came from the raw sewage itself (Nelson, 1998). The value of raw

sewage is very high since it was assumed to be equal to all the emergy needed to support

an average person divided by the per-capita wastewater production in either Florida or

Yucatan (Nelson, 1998).









Economic Values of Water

Economic values of water are normally synonymous to consumer surplus plus

producer surplus (Howe, 1971; Gibbons, 1986; Achttienribbe, 1998; Sunding, 2000).

Many economic studies have calculated the value of different types of water by using the

marginal value of water based on existing or inferred market prices (Gibbons, 1986;

Payton et al., 1990; Griffin, 1990; Kulshreshtha and Tewari, 1991) or the economic cost

of production (Guttman and Clark, 1978; Clark et al., 1984; Proefke, 1984; South Florida

Water Management District (SFWMD), 1992; Howe et al., 1994). These studies can be

divided into evaluations of 1) potable water supply, 2) treated wastewater, 3) agricultural

water, 4) water used for waste assimilation, and 5) water used for recreational and

aesthetic purposes.


1) Potable water supply.

Total cost of potable water supply is basically a function of the water source

quality, the type of treatment, and the flow rate of water treated. The lower the quality of

the water source and the higher the level of treatment, the higher the costs of treatment.

However, because of economies of scale, the larger the volume of water treated, the

lower the cost per unit volume of water supply (Guttman and Clark, 1978; Fernald and

Purdum, 1998). Table 1 shows some common potable water supply systems in Florida

with their corresponding costs of treatment and delivery. Instead of developing new

capital-intensive water treatment facilities, cities often explore expanding current

facilities or opening new wells to increase production. For instance, marginal values for

water supply augmentation for 221 communities in Texas were estimated to range from

zero to 0.33 $/m3 (Griffin, 1990). Although groundwater and surface waters are











traditionally used as sources of drinking water, scarcity and overpopulation in certain


regions have promoted the use of other water source alternatives. For example, the city


of San Diego is planning to construct a facility to process sewage to make it drinkable at


an anticipated cost of approximately 0.53 $/m3, which is less expensive than seawater


desalination (Chapman, 2000).




Table 1. Potable water supply component costs (adapted from SFWMD, 1992).


Type of treatment $/1000 gal $/1000 gal
(water source) capital cost O&M for
for treatment treatment
Disinfection only (high quality groundwater)
30 mgd 0.12 0.05
10 mgd 0.14 0.05
1 mgd 0.24 0.06
Wastewater reuse (effluent wastewater)
30 mgd 0.25 0.17
10 mgd 0.43 0.21
1 mgd 0.91 0.57
Coagulation & Filtration (surface water)
30 mgd 0.54 0.21
10 mgd 0.66 0.29
1mgd 1.24 0.70
Lime softening (groundwater)
30 mgd 0.41 0.35
10 mgd 0.57 0.42
1mgd 1.26 0.85
Membrane softening (groundwater)
30 mgd 0.59 0.52
10 mgd 0.95 0.60
1mgd 2.25 1.01
Reverse Osmosis (groundwater)
30 mgd 0.60 0.72
10 mgd 0.97 0.78
1 mgd 2.36 0.93

O&M = operation and maintenance
mgd = million gallons per day
mi = mile (1 mile = 1.6 km)

(Divide $/1000 gal by 3.785 to obtain $/m3)


$/1000 gal $/1000 gal $/1000 gal $/1000 gal
capital cost for O&M for 10-mi pipe Total system
water source water source









Table 2 shows average drinking water costs paid by different public supply user

sectors in the United States and Florida. The apparent decrease in cost as more water is

used (e.g., industrial vs. residential use) is not due to the actual price charged per volume

of water, but due to the total cost of water supply service. All consumer classes pay

relatively the same fixed charges for water service but residential users typically consume

less water than other classes. Thus, when the water bill is averaged over total water use,

the fixed charges spread over the volume used results in the apparent decrease in cost of

higher users. The actual charge per unit volume may be constant or increasing as more

water is used (Ayres Associates, 1997; Femald and Purdum, 1998; Stone & Webster,

1999).


Table 2. Monthly water charges (adapted from Fernald and Purdum, 1998).

Monthly water charges
Residential Commercial Light industrial Industrial
water consumption bill (7,000 gal)* (22,000 gal) (374,000 gal) (11.2 E6 gal)
avg. cost ($/1000 gal) in the U.S. (a) 1.76 1.48 1.25 1.10
avg. cost ($/1000 gal) in the U.S. (b) 2.21 1.96 1.71 1.54
avg. cost ($/1000 gal) in Florida (a) 1.28 1.06 1.00 1.01
avg. cost ($/1000 gal) in Florida (b) 2.36 2.05 2.05 2.06

(a) 1992 Ernst and Young National Water and Wastewater Rate Survey
(b) 1998 Raftelis Environmental Consulting Group National Water and Wastewater Survey
* 7,480 gal for (b)

(Divide $/1000 gal by 3.785 to obtain $/m3)



2) Treated wastewater.

The same factors that affect the economic value of drinking water, like economies

of scale, used capacity and level of treatment, also affect the cost of wastewater treatment

and disposal. In addition, the cost of effluent disposal increases from low-cost disposal

methods, such as percolation ponds and surface water discharge, to high-cost disposal









methods such as reuse. Table 3 shows some wastewater economic values in the United

States and Florida. These values are based on the average fees charged by utilities to

different wastewater-producing classes. Higher wastewater producers, like industries,

pay less per unit volume of wastewater produced since the fixed service fees are spread

over the volume of wastewater produced.


Table 3. Monthly wastewater disposal charges (adapted from Fernald and Purdum, 1998).

Monthly wastewater charges
Residential Commercial Light industrial Industrial
wastewater effluent bill (7,000 gal)* (22,000 gal) (374,000 gal) (11.2 E6 gal)
avg. cost ($/1000 gal) in the U.S. (a) 1.97 1.75 1.64 1.60
avg. cost ($/1000 gal) in the U.S. (b) 2.53 2.40 2.21 2.18
avg. cost ($/1000 gal) in Florida (a) 2.57 2.31 2.24 2.20
avg. cost ($/1000 gal) in Florida (b) 4.17 3.93 3.89 3.81

(a) 1992 Ernst and Young National Water and Wastewater Rate Survey
(b) 1998 Raftelis Environmental Consulting Group National Water and Wastewater Survey
* 7,480 gal for (b)

(Divide $/1000 gal by 3.785 to obtain $/m3)



The values above represent the money households or business paid utilities to

collect and treat their wastewater. Thus, these values include the administration services

in addition to the cost of collection, treatment and disposal by the local utilities.

However, other studies show that the value of just treating wastewater can be

significantly lower. For instance, Payton et al. (1990) calculated the value of treated

wastewater in 0.009 $/m3. Raw wastewater also has an economic value. Gibbons (1986)

estimated that the economic value of raw wastewater ranges from 0.0002 to 0.006 $/m3.









3) Agricultural water.

The cost of irrigation water is a function of permitting, pumping depth, treatment,

withdrawal impact avoidance, mitigation, transmission, distribution and disposal

requirements (Fernald and Purdum, 1998). Generally, the further away the water has to

be transmitted and distributed, the higher the cost of irrigation. Water requirements and

irrigation costs are unique for different crops and vary according to site location, resulting

in a wide range of irrigation demands. For example, to produce one kg of potatoes it is

necessary to use 500 to 1,500 L of water and to yield one kg of rice the water

requirements often range from 1,900 to 5,000 L (Gleick, 2000). High and low sides of

these ranges depend on specific factors, such as climate, irrigation methods, types of

seeds and the technology used. Thus, depending on the combination of all these factors,

the economic value of agricultural water may vary substantially. Kulshreshtha and

Tewari (1991) calculated the water value for irrigation in the south Saskatchewan

irrigation district, Canada, to be approximately 0.077 $/m3. Using hedonic price analysis,

Faux and Perry (1999) estimated that the value of irrigation water in Malheur County,

Oregon, ranges from 0.008 $/m3 for the least productive lands to 0.037 $/m3 for the most

productive lands. Gibbons (1986) estimated the range of irrigation water to vary from

0.01 to 0.093 $/m3. In this study Gibbons also estimated that the value of water used in

fisheries ranged between 0.018 and 0.15 $/m3. Marginal pumping costs also vary

depending on the agricultural region since different electric, fuel, wages, and services

cost will affect the transmission and distribution of water. For example, mean marginal

pumping costs for agricultural water in the U.S. were valued at 0.016, 0.013 and 0.019

$/m3 for the Northwest, Central plains, and Southwest, respectively (Moore et al., 1994).









4) Waste assimilation values.

Water also has a value associated with the dilution and assimilation of

wastewater. Normally, marginal values can be estimated for treatment and dilution of a

number of pollutants including biological oxygen demand (BOD), total dissolved solids

(TDS), nitrogen, phosphorous, water-born pathogens and heavy metals. The value of

water for waste assimilation is usually based on additional waste treatment costs forgone

(Lynne, 1991). Thus, the cost of waste assimilation and dilution is a function of the

treatment level required and is specific to each type of pollutant removed or diluted.

Kneese (1964) was among the first to conduct benefit-cost analyses of water pollution

control, thus indirectly comparing the value of water with and without pollution. Using

construction and operational costs, Boyle (1981) determined the economic costs of

wetland effluent application systems in Waldo, Florida. The author estimated the costs of

these wetland application systems to be 0.11 $/m3 for wetland discharge, 0.28 $/m3 for

advanced physical/chemical treatment and 0.17 $/m3 for spray irrigation systems. Boyle

also estimated the costs of effluent disposal to a cypress dome and a cypress strand in

Orlando, Florida. These values were estimated to be 0.19 and 0.06 $/m3, respectively

(Boyle, 1981). Gibbons (1986) calculated the marginal values of wastewater treatment

forgone by the initial assimilation capacity of rivers. This waste assimilation capacity

ranged from 0.0004 $/m3 for the Pacific Northwest to 0.006 $/m3 in the upper Arkansas-

White-Red river basin. In a study of the Colorado River Basin, Payton et al. (1990) used

treatment costs forgone to calculate the value of water for dilution of TDS. The authors

valued the Colorado River's capacity to dilute TDS in 0.008 $/m3.









5) Water used for recreation and aesthetic purposes.

Several methodologies have been used to estimate the value of water for

recreation and aesthetic purposes (Howe, 1971; Gibbons, 1986; Johnson and Adams,

1988; Lant and Mullens, 1991). Recreational water values have been estimated using

entrance fees, travel costs, contingent valuation (questionnaires and consumer surveys),

hedonic pricing, or taking the water value as a portion of the total value of the

recreational site. Gibbons (1986) estimated maximum marginal values of water for

fishing (0.013 $/m3), shoreline recreation (0.008 $/m3), and rafting (0.005 $/m3) during

low flows of the Colorado River. Gibbons (1986) also estimated values for fish hatchery

water in California's Trinity River (0.019 $/m3) and the value for spawning water in

California's Toulumne River (0.032 $/m3). In addition, Gibbons (1986) calculated the

water value for recreational fish and wildlife in the Charles River, Massachusetts (0.021

$/m3), as well as the average wetland water value for fishing, waterfowl, hunting and

recreation in Michigan coastal regions (0.48 $/m3). Johnson and Adams (1988)

concluded that the marginal value of increasing summer water flows to enhance

recreational steelhead fishing in the John Day River, Oregon, was worth approximately

0.002 $/m3.



Summary of Water Values

Table 4 summarizes the emergy and economic water values reported above. The

table is divided into water types and water values are listed in ascending order. Overall,

water values increase with increasing upgrading and concentration for human use (e.g.,

from rain to public supply). In addition, emergy values are generally higher than

economic values for the same type of water.











Table 4. Comparative values of water. Legend: (a) geopotential energy of water, (b)
chemical potential energy of fresh water relative to seawater, (c) phosphorous in river
water, (d) nitrogen in river water, (e) sediments present in the water (f) sediments in first
order streams, and (g) organic load.

Water type & location Em$/m3 $/m3 source


Rain
Papua New Guinea (a)
North Carolina (a)
Global average (oceanic rain) (b)
Bay of Banderas, Mexico (b)
U.S. (a)
Thailand (b)
U.S. (b)
Ecuador(a)
Texas (b)
Ecuador(b)
Global average (rain on land) (b)

River & River Basin Waters
Catatumbo Basin, Colombia/Venezuela (c)
Catatumbo Basin, Colombia/Venezuela (d)
Mekong River, Thailand/Laos (a)
Mississippi River (e)
Recreational steelhead fishing, John Day River, Oregon
Water rafting, Colorado River, U.S.
Shore recreation, Colorado River, U.S.
Kavango River, Namibia/Angola (b)
Fishing, Colorado River, U.S.
Fish hatchery water, Trinity River, California
Catatumbo Basin, Colombia/Venezuela (f)
Recreational fishing, Charles River, Massachusetts
Eta River sub-basin, Brazil (a)
Spawning water for rec. fishing, Toulumne River, CA
Bay of Banderas, Mexico (b)
Rio Chone, Ecuador (g)
Texas (b)
Global average (b)
Betari River sub-basin, Brazil (a)
Coweeta River basin, North Carolina (a)

Lake water
Lake Weir, Florida (b)
Martin County, Florida (b)
Newnan's Lake, Florida (b)

Wetland water
Santa Fe Swamp, Florida (b)
Value for fishing & recreation, Michigan

Groundwater
U.S. (b)
Bay of Banderas, Mexico (b)
Texas (b)
North Carolina (b)


0.001
0.006
0.018
0.027
0.028
0.032
0.032
0.032
0.035
0.042
0.045


0.0001
0.0007
0.001
0.002


0.010


0.020

0.023

0. 072
0.075
0.091
0.12
0.26
0.29


0.063
0.15
0.22


0.10




0.07
0.27
0.25
0.62


(Doherty et al., 1993)
(Tilley, 1999)
(Odum, 1996)
(Green, 1992)
(Odum, 1996)
(Brown and McClanahan, 1992)
(Odum, 1996)
(Odum and Arding, 1991)
(Odum et al., 1978b)
(Odum and Arding, 1991)
(Odum, 1996)


(Howington, 1999)
(Howington, 1999)
(Brown and McClanahan, 1992)
(Odum et al., 1987a)
0.002 (Johnson and Adams, 1988)
0.005 (Gibbons, 1986)
0.008 (Gibbons, 1986)
(Buenfil, 2000)
0.013 (Gibbons, 1986)
0.019 (Gibbons, 1986)
(Howington, 1999)
0.021 (Gibbons, 1986)
(Romitelli, 1997)
0.030 (Gibbons, 1986)
(Green, 1992)
(Odum and Arding, 1991)
(Odum et al., 1978b)
(Odum, 1996)
(Romitelli, 1997)
(Romitelli, 1997)


(Brandt-Williams, 1999)
(Engel et al., 1995)
(Brandt-Williams, 1999)


(Odum, 1996)
0.48 (Gibbons, 1986)


(Odum, 1996)
(Green, 1992)
(Odum et al., 1978b)
(Tilley, 1999)











Table 4--continued.

Water type & location
Agricultural/irrigation water
Malheur County, Oregon
Central Plains, U.S.
Northwest U.S.
Southwest U.S.
Water for fisheries, Bay of Banderas, Mexico (b)
South Saskatchewan irrigation district, Canada
U.S.
Water for fisheries, U.S.
Bay of Banderas, Mexico (b)
Texas (b)

Raw wastewater
Bay of Banderas, Mexico (b)

Waste assimilation by river waters
Pacific Northwest, U.S.
Upper Arkansas-White-Red river basin, U.S.
Colorado River, U.S.


Treated wastewater
Wetland application, Waldo, Florida
30-mgd Wastewater reuse system, Florida
Spray irrigation systems, Waldo, Florida
Advanced physical/chemical treatment, Florida
1-mgd Wastewater reuse system, Florida
Industrial, U.S.
Light industrial, U.S.
Commercial, U.S.
Residential, U.S. .
Bay of Banderas, Mexico (b)
Industrial, Florida
Light industrial, Florida
Commercial, Florida
Residential, Florida
University of Florida (b)
Package sewage system, Yucatan, Mexico (b)

Potable water supply
Water supply augmentation, Texas
30-mgd Disinfection (high quality groundwater), FL
30-mgd Lime softening treatment plant (gw), FL
30-mgd Coagulation/Filtration (surface water), FL
1-mgd Disinfection (high quality groundwater), FL
30-mgd Membrane softening treatment plant (gw), FL
Highly treated wastewater, San Diego, CA
30-mgd RO treatment plant (groundwater), Florida
Bay of Banderas, Mexico (b)
1-mgd Coagulation/Filtration (surface water), FL
1-mgd Lime softening treatment plant (gw), FL
1-mgd RO treatment plant (groundwater), Florida
1-mgd Membrane softening treatment plant (gw), FL
Texas (b)


Em$/m3 $/m3 source


0.008 (Faux and Perry, 1999)
0.013 (Moore et al., 1994)
0.016 (Moore et al., 1994)
0.019 (Moore et al., 1994)
0.06 (Green, 1992)
0.077 Kulshreshtha (1991)
0.01 to 0.093 (Gibbons, 1986)
0.018 to 0.15 (Gibbons, 1986)
0.11 (Green, 1992)
0.44 (Odum et al., 1978b)


0.0004
0.006
0.008


0.11
0.14
0.17
0.28
0.57
2.18
2.21
2.40
2.53


170.1
174.1


0 to 0.33
0.12
0.26
0.28
0.32
0.35
0.53
0.41


(Green, 1992)


(Gibbons, 1986)
(Gibbons, 1986)
(Payton et al., 1990)


(Boyle, 1981)
(SFWMD, 1992)
(Boyle, 1976)
(Boyle, 1976)
(SFWMD, 1992)
(Raftelis, 1998)
(Raftelis, 1998)
(Raftelis, 1998)
(Raftelis, 1998)
(Green, 1992)
(Raftelis, 1998)
(Raftelis, 1998)
(Raftelis, 1998)
(Raftelis, 1998)
(Nelson, 1998)
(Nelson, 1998)


(Griffin, 1990)
(SFWMD, 1992)
(SFWMD, 1992)
(SFWMD, 1992)
(SFWMD, 1992)
(SFWMD, 1992)
(Chapman, 2000)
(SFWMD, 1992)
(Green, 1992)
(SFWMD, 1992)
(SFWMD, 1992)
(SFWMD, 1992)
(SFWMD, 1992)
(Odum et al., 1978b)










Plan of Study

To answer the questions raised in the statement of the problem (e.g., what are the

values of water and what is the best allocation of water resources?), the emergy inputs to

water were evaluated and compared at four scales: 1) global, 2) regional, 3) local

(community-level), and 4) small-scale (household-level). In addition, the state of Florida

was used as a case study for investigating the value and best allocation of water

resources.

Transformities of global storage of water (e.g., oceans, groundwater, lakes,

atmospheric water and biological water) were calculated using the global empower base,

9.44 E24 sej/yr (Odum, 1996), and storage replacement times. Transformities of global

water flows (e.g., rain, runoff and infiltration) were calculated by dividing the global

empower base by the chemical energy of the volumetric flow. Em-dollar per cubic meter

(Em$/m3) values were calculated using the global emergy-per-dollar ratio, 2.0 E12 sej/$

(Odum, 1996), the global empower (9.44 E24 sej/yr) and the flow rates (in m3/yr) of each

water resource.

The state of Florida was used as a case study to evaluate regional water storage

in Florida, such as rain, surface water, and groundwater. Transformities of water

reservoirs (wetlands, lakes and five aquifer systems) were calculated using storage

turnover times and the emergy required to generate the water volume of each storage

(i.e., the emergy of rain falling on the storage's drainage or recharge area). Emergy per

cubic meter (sej/m3) values were calculated by dividing the empower (sej/yr) of each

water storage by its volumetric flow rate (m3/yr). Em-dollar/m3 values were calculated

by dividing the sej/m3 by the 2000 U.S. emergy-per-dollar ratio (9.1 E11 sej/$).









Seven public water supply utilities in Florida, ranging from surface water

treatment to seawater desalination with reverse osmosis, were evaluated with emergy

synthesis to investigate the value of local potable water and compare treatment

alternatives. In addition, a water conservation program in Tampa and a drinking water

distribution system in Gainesville were evaluated. To evaluate small-scale drinking

water production (i.e., water used just for drinking), five water purification schemes,

ranging from filtering to boiling water, were analyzed. The emergy cost of each potable

water system was calculated by adding the emergy of all the inputs needed to produce the

finished water (e.g., raw water, materials, energy, technology and human services).

Transformities and Em$/m3 of each type of potable water were computed.

A water allocation model was simulated using Excel spreadsheets to explore the

appropriate use of water to maximize total productivity. Using statewide data from

Florida and two productive functions, the effect of varying water resource allocation

among urban, agricultural and environmental sectors on total state production was

explored.















METHODS

Emergy evaluations of global and regional hydrologic systems as well as potable

water alternatives were conducted leading to suggestions concerning values, appropriate

allocation, and potential metrics for public policy decision making regarding the best use

of water resources. The general methodology employed was a "top-down" systems

approach using both emergy synthesis and simulation modeling. First the general

methodology of emergy synthesis is given, then specific methods are presented for each

facet of the evaluation of water and, finally, methods used to develop and simulate the

model of water allocation are provided. Odum (1996) provides further explanation of

emergy concepts and evaluation methodology.



Emergy Synthesis Methodology

Energy Systems Diagrams

In order to identify the fundamental components and energy pathways required

for water resources and the production of potable water, energy systems diagrams

(Odum, 1994) were drawn for water resources and potable water alternative. Systems

diagrams included the principal variables, sources, processes, components and energy

flows of the water system studied. Flows crossing the system boundary (inputs) were

evaluated. The procedure used for drawing systems diagrams was the following.

First, the boundary of the water system in question was defined and represented

by drawing a rectangular box to separate the components and production processes within









the system from the driving sources outside the system. The boundaries of potable water

treatment facilities were defined as the physical property of the facility and were drawn

inside a larger boundary representing the local environment. A generic systems diagram

of a water treatment plant is given in Figure 1. The water treatment boundary is

illustrated with the darkest rectangular box (right side). The inputs and outputs of this

boundary (darkest box) were evaluated in the emergy tables. Second, the principal

energy sources or forcing functions (e.g., materials, electricity, and services) were listed

and drawn outside the system boundary. Third, the principal units and interactions

necessary for the water production processes were drawn inside the diagram using the

appropriate symbols (definitions of symbols are given in Appendix A). These symbols

were arranged inside the diagram according to their place in the energy hierarchy (Odum,

1994). Fourth, lines representing water, energy and material flows were used to connect

the symbols and processes inside the boundary. Finally, when appropriate, monetary

flows--represented by dashed lines--were drawn to inventory the exchange of money for

water (consumer side) and for human services and resources (production side).

The left side of Figure 1 was drawn to show where the water source comes from.

The environmental system providing the water source was not included in the emergy

evaluations of potable water alternatives. The purpose of showing this environmental

side in the diagrams was to illustrate the larger support system, from nature, required for

the production of drinking water.












































Water source system

B=biomass; P=price; E=environment
WTP=Water Treatment Plant


surface water
& groundwater
outflow


Figure 1. A generic systems diagram of the production of potable water for public supply.









Emergy Tables

The systems diagrams served as the blue print for developing the emergy

evaluation tables. For potable water evaluations, each major input of material, energy,

goods and services crossing the water treatment boundary (darkest box in the right side of

the diagram) became a row in the emergy evaluation table. The input numbers used for

the public supply evaluations were generally obtained from the water treatment facilities.

The physical plant infrastructure of these facilities was evaluated and included as an

annualized input to the process by dividing the value of the infrastructure by its average

replacement time. Input quantities of materials and energy flows for the evaluation tables

of global and regional water resources as well as the small-scale water purification

systems were generally obtained from the literature.

As illustrated in Table 5, all emergy tables included the following seven columns:

1) Note, to document the source of data and calculations for each row in the table; 2)

Item, to name or describe the item being evaluated; 3) Unit, to provide the unit of each

item; 4) Energy Data, to show the value of the item with units given in column 3; 5)

Emergy-per-unit, to be used as a "conversion factor" to yield values in solar emergy

units; 6) Solar Emergy, to list the emergy value for a specific item, which was obtained

by multiplying columns 4 and 5; and 7) Emergy/m3, to show the emergy necessary to

produce a cubic meter of water.

Inputs of the potable water systems were grouped into Renewable Resources

(inputs obtained "free" from nature) and Purchased & Operational Inputs (those that

were either purchased or processed by the human economy). The section Emergyper

unit of water was provided to summarize the total emergy of water per unit of










measurement (e.g., m3, g, J). Transformities (sej/J) were provided with and without

human services to facilitate future emergy studies.





Table 5. Tabular format of emergy evaluation tables used in this study.

Energy Emergy Solar Emergy (sej)
Note Item Unit Data per unit Emergy per m3
(unit/year) (sej/unit) (El8 sej/yr) (E10)
RENEWABLE RESOURCES
1 Water J A B AxB (AxB)/m3


PURCHASED & OPERATIONAL INPUTS
2 Operating & Maintenance $
3 Electricity J

5 Plant Assets kg
Yield (Y) = Total emergy of drinking water:

EMERGY PER UNIT OF POTABLE WATER
6 Potable water produced m3
7 Potable water produced J
8 Potable water produced g
9 Drinking water with-out services J


D CxD (C xD) / m3



sum 1 sum 2 sum 3


sum 1 / M
sum 1 /N

(sum 1 services) / P


Emergy Indices

Several emergy indices and ratios were used to analyze and compare different

water resources and technologies for producing potable water. Figure 2 illustrates the

definition and way of calculating these emergy indices. The letters on the pathways refer

to flows of emergy per unit time (usually one year). The meaning and application of the

emergy indices are explained below.









energy, fuels, goods


Emergy Indices:
Purchased inputs (F) = P+S
Emergy Yield (Y) = R+N+F
Emergy Investment Ratio (EIR) = F/(R+N)
Emergy Yield Ratio (EYR) = Y/F
% Renewable = R/Y x 100
Emergy Benefit to the Purchaser (EBP) = (emergy of Y)/(emergy of $ paid for Y)
Em$/m3 = (Y / m3 of Y) / (sej/$)
Transformity of Y = (emergy of Y)/(energy of Y)


Figure 2. Diagram illustrating the definition of the emergy indices used. The letters on
the pathways refer to flows of emergy per unit time (sej/yr).



1) Emergy investment ratio (EIR).

The EIR represents the purchased emergy feedback from the economy (F) divided

by the free emergy inputs from the environment (R+N). This ratio measures the intensity

of a production process. If the EIR of the proposed development is greater than the









regional EIR, the project may be too emergy-intensive and negatively affect the

environment. To be economical in the long-term, the process should have a ratio similar

to the region's EIR. If the EIR of the production process is higher than that of the region,

the opportunity costs will be higher and the process may not compete in the long run. On

the other hand, EIRs that are lower than the regional average will have lower opportunity

costs since much of the useful work is coming free from nature. However, operating

below the regional EIR indicates that the environmental emergy is not being fully

matched with economic emergy and the system may be operating below its development

potential. Consequently, development processes tend to self-organize towards an

optimum matching of the EIR in relation to the intensity of regional economic activity

supported by the environment.


2) Emergy yield ratio (EYR).

The EYR of a process is the emergy of the output (Y) divided by the emergy of

all inputs coming from the human economy (F). This ratio indicates if the process can be

economically competitive and measures the net contribution of the product to the

economy beyond its own generation. The higher the EYR, the greater the net benefit to

society.


3) Percent renewable emergy (%R).

The percent renewable emergy is obtained by dividing the renewable emergy of a

product (R) by the emergy yield of the product (Y) and multiplying this by 100.

Renewable emergy includes sunlight, wind, rain, and most forms of water. The larger the

%R, the more sustainable the production process is in the long run.









4) Emergy benefit to the purchaser (EBP).

The EBP represents the emergy in a product divided by the buying power of the

money paid for such product (in terms of emergy). Since the environment is not paid

with money for its services to the human economy, the emergy of environmental

resources contributes more real wealth than the emergy embodied in the money paid for

these resources. Thus, this ratio indicates how much more emergy is delivered in a

product to the purchaser relative to the buying power of the payment. The higher the

EBP the more the purchaser benefits; yet, at the expense of the environment.


5) Em-dollars per volume (Em$/m3).

Em-dollars (Em$) are emergy-based monetary values of a good or service.

Similarly to $/m3, Em$/m3 represent the cost of producing one cubic meter of water. The

Em$/m3 for a specific year are calculated by dividing the emergy per volume (sej/m3) of

water by the emergy-per-dollar ratio (sej/$) of the country were the water is produced.

For global water resources, the sej/m3 is divided by the global sej/$ ratio. Emergy-per-

dollar ratios used in this study were calculated by dividing the annual empower (sej/yr) of

the U.S. economy by its gross national product ($/yr) for the year of evaluation.

Similarly, the global sej/$ ratio was calculated by dividing the global empower base by

the global gross economic product.

Odum (1996) gives U.S. sej/$ ratios from 1947 to 1993. These values decline

from 25.4 E12 sej/$ in 1947 to 1.37 E12 sej/$ in 1993 (Odum, 1996). Since the sej/$

ratio decreased more rapidly during the 1983-1993 decade, a 2000 sej/$ ratio was

estimated from decreasing the sej/$ ratio by 5.7% per year, which represents the average

sej/$ decrease between 1983 to 1993. The projected sej/$ ratio for 2000 (i.e., 9.1 Ell









sej/$) was used to calculate the Em$ values of the regional (Florida) water resources and

all the potable water alternatives. Since the global sej/$ ratio remained fairly constant at

2.0 E12 sej/U.S.$ during the 1980's (Odum, 1996), this value was assumed to remain

constant for 2000.


6) Emergy-per-unit and transformity.

The emergy-per-unit and transformity of a commodity indicates its place in the

energy hierarchy and the efficiency of producing such commodity. Emergy-per-unit

(e.g., sej/m3, sej/g and sej/$) and transformities (sej/J) are calculated by dividing the

emergy yield of a product (Y) by the corresponding unit of the product (e.g., m3, g, $ or

J). For any commodity or resource (e.g., potable water), the lower the emergy-per-unit or

transformity, the greater the efficiency of the production process.




Emergy Evaluation of Global Water Storages and Flows

The emergy values of global water storage were calculated by assuming that

these storage are co-products of the global empower base (9.44 E24 sej/yr). The global

empower base (9.44 E24 sej/yr) represents the annual emergy flowing to Earth and was

calculated by Odum (1996) by summing the annual emergy of the sun (3.93 E24 sej/yr),

tide (1.44 E24 sej/yr), and deep heat (4.07 E24 sej/yr). Emergy per volume (sej/m3) of

global water storage were calculated by dividing the empower base by the annual

average volumetric flow of each water storage. Volumetric flow rates were calculated by

dividing the volume in each water storage by its replacement time. Similarly, global

water flows were assumed to be co-products of the global empower base. Emergy per

volume of global water flows were calculated also by dividing the empower base by the









annual volumetric flow of each global water flux. Emergy per volume values were used

to calculate emergy-per-mass (sej/g), transformities (sej/J), and Em-dollar (Em$/m3)

values. For example, emergy per mass (sej/g) values were calculated by dividing the

emergy per volume (sej/m3) by the density of fresh water (1 E6 g/m3).

Transformities for several types of global precipitation were calculated by

dividing the global empower base by the volumetric flow rate of each type of

precipitation. The volumetric flux of tropical rainfall was estimated by multiplying the

average rainfall between latitudes 23.50 N and 23.50 S by the total surface area between

the same latitudes. The volumetric flow rate of temperate rain was assumed to be the

difference between the global precipitation and the estimated tropical precipitation.

Tropical and temperate precipitation on land were estimated by using the corresponding

land surface areas. For example, the land between latitudes 23.50 N and 23.50 S were

used to calculate the tropical rain on land, whereas the land outside these latitudes was

used to calculate the temperate rain flux on land.



Emergy Evaluation of Regional Waters Using Florida as a Case Study

The water resources of Florida (major storage and flows) were evaluated. Each

category of water (estuaries, rivers, lakes, wetlands and groundwater) was evaluated as a

storage. Detailed methods including calculations and assumptions are given for each in

the following sections.



Surface Water

To calculate the emergy of surface waters, maps and statistical data (Femald and

Purdum, 1998) of the Florida watershed (which includes portions of Georgia and









Alabama) were used to proportion rainfall into river watersheds, lake watersheds, and

wetland watersheds. The percent of total Florida watershed assigned to each type of

surface water feature was estimated from the data on individual river, lake and wetland

watersheds and visually from maps. Of the total area, approximately 55% was estimated

to be river watershed, 15% was lake watershed, and 30% was wetland watershed.

The transformity of rain in Florida was assumed to be equivalent to the average

global precipitation on land. The emergy of the total rainfall (sej/year) over the

watershed for each surface water storage type multiplied by the turnover time of the

storage (in years) resulted in the total emergy required for river, lake and wetland

storage. The emergy of intertidal water (i.e., water in estuaries, salt marshes and

mangrove ecosystems) was assumed to be equal to the emergy of river water. Tidal

emergy was not added to the emergy of intertidal water since this is already included in

the rain used to calculate the transformity of river water. Transformities for each surface

water storage were then calculated by dividing the total emergy required by the chemical

potential energy of each storage.



Groundwater

Emergy of groundwater storage was calculated for the main aquifers in Florida

using rainfall and turnover times. The aquifers evaluated included the Surficial, Sand and

Gravel, Biscayne, Intermediate, and Floridan. Emergy input to each aquifer was

calculated as the emergy of rainfall on the recharge area.

Figure 3 shows the three principal groundwater storage making up the Florida

aquifer system. The surficial aquifer overlays the intermediate and Floridan aquifers.

The Biscayne aquifer because of its shallow depth and unconfined characteristics is






29


considered surficial, as is the sand and gravel aquifer in the western portion of Florida's

panhandle. The recharge areas of each aquifer were estimated from data and maps in

Femald and Purdum (1998) and Miller (1990). The annual emergy in rain falling on each

recharge area was multiplied by the calculated turnover time of each aquifer to obtain

total emergy required for the aquifer storage. Turnover times were calculated by dividing

the total volume of each aquifer by its recharge rate (in volume/time). Transformities

were then calculated by dividing the total emergy required by the energy of the storage.
















/
sand and gravel aquifer


Biscayne
aquifer
/


Floridan
aquifer system


/ increasing
depth


Figure 3. Sequence of aquifer systems in Florida (adapted from Miller, 1990).


surficial









Emergy Evaluation of Potable Water Supply Alternatives

A list of the public supply systems evaluated is given in Table 6. The

approximate location of these public utilities is shown in Figure 4. For each public

supply system the emergy value of finished water was calculated by adding the principal

emergy inputs required to produce potable water. Using the systems diagram in

Figure las a guide, the inputs included the following: 1) a water source (surface water,

groundwater or salty water); 2) money paid to humans for their work and services (e.g.,

fees, wages, design and development costs, construction costs, operation and

maintenance costs, chemical costs and power costs); 3) energy (e.g., fuels and

electricity); 4) chemicals and supplies; and 5) assets and infrastructure materials (e.g.,

steel and concrete). Annual inputs were multiplied by their corresponding transformity

(calculated separately) to convert them to emergy. Useful lifetimes of assets and

treatment plants infrastructure were use as turnover times to annualize the emergy of

plant assets. The assets of most public supply systems were assumed to have an average

useful lifetime of 30 years.

The evaluations done for different plants had dollar costs for different years. The

sej/$ ratio for the year in which the treatment system was evaluated was used to calculate

the emergy input of human services and other economic costs for producing potable

water. For example, if the year of evaluation was 1995, then a 1995 sej/$ ratio was used

to evaluate annual flows of human services, or if the plant costs were in 1990 dollars then

the ratio for 1990 was used. Emergy-dollar ratios for different years were obtained from

Odum (1996). Since sej/$ ratios incorporate depreciation, monetary flows were not

discounted with depreciation interest rates as commonly done in economic analyses. The











process description and main characteristics of the public supply systems evaluated are

presented below.




Table 6. Public supply alternatives evaluated with emergy synthesis.


plant name


1) City of West Palm
Beach Water
Treatment Plant


2) Hillsborough River
Water Treatment Plant


3) Murphree Water
Treatment Plant


4) Tampa Bay Water
conservation program


5)City of Dunedin RO
Facility


6) Tampa Bay
Desalination Plant


7) Florida Keys
Aqueduct Authority


8) Seawater
Desalination Facility


type of treatment


Coagulation
flocculation
& settling


Coagulation
flocculation
& settling


Lime softening



Water conservation


Reverse Osmosis



Reverse Osmosis


Lime softening



Reverse Osmosis


location


West Palm
Beach



Tampa


Gainesville



Tampa Bay



Dunedin



Tampa


From Florida
City to Key West


Stock Island
(near Key West)


water source


surface water
(lake water)



surface water
(river water)


groundwater
(Floridan aquifer)


potable water
(saved)


brackish
groundwater


seawater


groundwater
(Biscayne aquifer)


seawater


mgd = million gallons per day
RO = reverse osmosis


production


28.0 mgd or
1.2 m3/sec



62.0 mgd or
2.7 m3/sec


21.0 mgd or
0.92 m3/sec


25.0 mgd or
1.1 m3/sec
(saved)

5.6 mgd or
0.25 m3/sec


25.0 mgd or
1.1 m3/sec


15.0 mgd or
0.66 m3/sec


3.0 mgd or
0.13 m3/sec









































Figure 4. Approximate location of the public supply systems analyzed: 1) City of West
Palm Beach Water Treatment Plant, 2) Hillsborough River Water Treatment Plant in
Tampa; 3) Murphree Water Treatment Plant in Gainesville; 4) Tampa Bay Water's water
conservation program; 5) City of Dunedin Reverse Osmosis Water Treatment Plant; 6)
Tampa Bay desalination Plant; 7) Florida Keys Aqueduct Authority from Florida City
(7*) to Key West; and 8) Stock Island desalination Plant next to Key West.









1) Surface (Lake) Water Source: West Palm Beach's Water Treatment Plant.

In 1999 (year of evaluation) the City of West Palm Beach Water Treatment Plant

produced 28.0 mgd (1.23 m3/sec) of drinking water from two lakes that get their water

from a water catchment area south of Lake Okeechobee in south Florida. Figure 5

illustrates a schematic of the production of drinking water by this facility. The treatment

process includes lime softening, flocculation, coagulation, clarification, filtration,

fluorination, and disinfection by chloramination. The sludge from the settling basins and

the backwash water from the filters is sent to a settling tank. The water from the top of

this tank is recycled back to the treatment process. The settled sludge is air-dried on land

next to the facility and then taken off-site for disposal. After treatment the finished water

is stored and then sent to the distribution system.



2) Surface Water Source: Hillsborough River Water Treatment Plant, Tampa.

Figure 6 shows a schematic of the production of drinking water at the

Hillsborough River Water Treatment Plant in Tampa, Florida. In 1996 this surface water

treatment facility produced, on average, 62 mgd (2.72 m3/sec) of potable water. The

Hillsborough River has high concentrations of tannins and humic acids, which come from

the slow decomposition of organic matter in the headwaters of the river (the Green

Swamp) and along the river. In addition, the river has high concentrations of suspended

and dissolved solids. Consequently, the treatment includes the removal of turbidity and

dissolved solids by coagulation and settling, and the removal of suspended solids by

filtration. Because of high concentrations of organic compounds in the river, post-

disinfection is carried out with chloramines (chlorine and ammonia) to prevent the

formation of trihalomethanes and other harmful disinfection by-products. After









disinfection the finished water is stored in an underground clear well and then sent to the

distribution system.



3) Groundwater Source: Murphree Water Treatment Plant, Gainesville.

Figure 7 shows a schematic of the Murphree Water Treatment Plant, which

supplies most of Gainesville's drinking water. In 1994 the plant produced about 21 mgd

or 0.92 m3/sec. The schematic illustrates the principal unit operations and processes

required for the production of this potable water. Since groundwater from the Floridan

aquifer in this region is of very high quality, the treatment scheme consists primarily of

calcium hardness removal and disinfection with chlorine. Calcium ions are removed by

adding quicklime, which raises the pH and precipitates the calcium ions as calcium

carbonate (CaCO3). Just before entering the clarifiers, chlorine (C12) is added to the

water to oxidize hydrogen sulfide (H2S). After settling the CaCO3 in the plant's clarifiers,

the water is filtered to remove additional particles and then disinfected with chlorine.

The finished water is then stored and pumped to the distribution system.











powder activated
carbon I
I ferric sulfate


lime


Cl + NH3


rapid
mixing


flocculation-
coagulation


water recycling


backwash settling


chlorine


sludge dewatering


fluoride an




:: :::::: s::a: e::: :
.............i


to the distribution
system


high pressure
pump station


Figure 5. Schematic of the production of drinking water at the City of West Palm Beach Water Treatment Plant.


C02










polymer


dam


Figure 6. Schematic of the production of drinking water at the Hillsborough River Water Treatment Plant in Tampa, Florida.













quicklime


reactor-clarifiers
(CaCO3 settling)


high service
pump station


Figure 7. Schematic of the production of potable water at the Murphree Water Treatment Plant in Gainesville, Florida.









4) Water Conservation as a Source: Tampa Bay.

For comparative purposes, a water conservation program in Tampa was evaluated.

A water management/conservation plan developed by Tampa Bay Water is expected to

save approximately 24.4 mgd (1.07 m3/sec) of potable water in the Bay area between

2000 and 2030. Tampa Bay Water (TBW) is in charge of supplying potable water to

Pasco, Pinellas and Hillsborough County including the cities of Tampa, St. Petersburg

and New Port Richey. Because of rapid population growth and limited fresh water

resources in the region, TBW developed this demand management/conservation program

by using best management practices and implementing several water conservation

measures. These measures include the use of educational campaigns to increase the

efficiency of water use and the implementation of economic incentives, such as rebates,

to install water-saving devices (rain sensor shut-off units). The water conservation

program also promotes replacing conventional fixtures with more efficient ones (low-

volume toilets and low-flow showerheads), purchasing water-saving appliances (low-

volume dishwashers), and reducing the use of potable water for irrigation (xeriscaping

gardens and using reclaimed water).


5) Brackish Water Source: City of Dunedin Reverse Osmosis Treatment Facility.

In 1996 the City of Dunedin Reverse Osmosis (RO) Water Treatment Facility

produced 5.6 mgd (0.25 m3/sec) of drinking water from a blend of fresh [350 parts per

million (ppm) of total dissolved solids (TDS)] and brackish (1,100 ppm of TDS)

groundwater. The percentages of fresh and brackish groundwater used for the production

of potable water in 1996 were 90% and 10%, respectively. A schematic of the treatment

process is given in Figure 8. First, potassium permanganate is added to the raw water to









oxidize iron and hydrogen sulfide (H2S). After this, the water is pre-treated in a pressure

filter (Greensand filter). Some of the exiting water goes through a 20 micron filter and

the rest is fed with sulfuric acid and an antiscalant before entering a 5 micron filter. The

water leaving the 5 micron filter goes through the RO membranes and is blended with the

water exiting the 20 micron filter. The blended water is then degasified (to remove

residual H2S and CO2), chlorinated, and fluorinated before pumped to the distribution

system. The concentrate (reject brine) leaving the RO membranes, which represent about

17% of the water entering the membranes, is dosed with sodium hydroxide for pH control

and then disposed to the city's sewer system.


6) Seawater Source: Reverse Osmosis Desalination, Tampa Bay.

A reverse osmosis desalination plant is under construction in Tampa Bay, Florida.

When completed in 2003, the facility will produce 25 mgd (1.1 m3/sec) from salty water

discharged from the cooling system of an adjacent power plant. A schematic for Tampa

Bay's RO desalination process is given in Figure 9. As depicted in the schematic, the

water source will be taken from the discharge of Tampa Electric's Big Bend Power

Station's cooling towers. The cooling water flows from Tampa Bay through an inlet

canal and is discharged back to the bay. After intake from this canal, the water source

will be screened and dosed with sulfuric acid and an antiscalant to prevent the

precipitation of minerals on the surface of the filters and RO membranes. Next, the water

will be filtered and then forced through the RO modules. The permeate (fresh water) will

be sent to a drawback tank and then degasified to remove H2S and CO2. The pH will be

neutralized and the water disinfected with chlorine before connected to the distribution

system. Finally, the concentrate and backwashed water will be flushed to the Bay via the

exiting side of the power plant's discharge canal.














brackish
groundwater
supply


high service pumps to
distribution system


Figure 8. Schematic of the production process of potable water at the City of Dunedin Reverse Osmosis Water Treatment Facility.















intake canal


cartridge
filters RO membrane
pressure modules
S pumps Z


../sulfuric .-.- anti-scal
-.- N .-.- sulfuric
: .. ":* acid



Tampa
Bay intake from
Big Bend
the power plant's
Power Plant
S* cooling water





discharge canal




to o
distribution



high service
storage tanks
pumps


permeate


fluori(


caustic
soda


product u iavv U
transfer pumps degasifier tank
transfer pumps


Figure 9. Schematic of the reverse osmosis desalination facility being built in Tampa Bay.


A r-1 a kr -


ant


c*^1









7) Surficial Groundwater Source: Transported Via Aqueduct, Florida Keys.

Figure 10 shows a schematic of the production and transportation of potable water

by the Florida Keys Aqueduct Authority (FKAA). The aqueduct system delivered, on

average, 15 mgd (0.66 m3/sec) of potable water throughout the Florida Keys in 1996.

Groundwater from the Biscayne aquifer is pumped near Florida City, southwest of

Miami. Quicklime is added to the water to precipitate calcium and magnesium ions.

Then the water is filtered to remove suspended solids and other contaminants. After

disinfection with chlorine, the water is sent through a 210 km-long transmission pipeline

ranging from 36 to 18 inches (92 to 46 cm) in diameter (Malgrat and Doughtry, 1996).

This pipeline extends from Florida City to Key West along U.S. Highway 1. This section

of the highway has 43 bridges (Malgrat and Doughtry, 1996), which "subsidize" the

pipeline infrastructure. To provide the adequate pressure for the distribution system, the

FKAA counts with 25 storage tanks (ranging from 1.9 E3 to 18.9 E3 m3) and 42 pumps

(ranging from 10.6 to 70.7 BTU/sec) (Malgrat and Doughtry, 1996).



8) Seawater Source: Reverse Osmosis Desalination, Stock Island (Adjacent to Key
West).

A reverse osmosis desalination facility operated throughout the 1970's and early

1980's in Stock Island and supplied approximately 3.0 mgd (0.13 m3/sec) of potable

water to Key West. This facility was shut down after less expensive drinking water was

available with the construction of the Florida Keys aqueduct. A schematic of the RO

desalination process that operated in Stock Island, Florida, is given in Figure 11.

Seawater was pumped from shallow wells on a small peninsula within the island and then

filtered to remove larger particles and some corrosive elements. After this, high-pressure









pumps were used to force the water through the RO membranes to separate the salts from

the feed water. The concentrate was returned to the sea via an adjacent ship channel

under permission of the Environmental Protection Agency and the Florida Department of

Environmental Protection. The permeate (drinking water) was sent to a drawback tank

which provided freshwater back to the RO membranes to prevent possible damage to the

permeators in case of a power failure. After the drawback tank the fresh water was

passed through a degasifier to strip off H2S and CO2. After the degasifier the fresh water

entered a clear well where soda ash was added to raise the pH and then the water was sent

to a ground storage tank where it was disinfected with chlorine. Finally, the finished

water was pumped to Key West's distribution system.













shallow wells


quicklime


reactor-clarifiers
(CaCO3 settling)


CO2 chlorine


transfer pump stations aqueduct
storage reservoirs transfer pump stations


Figure 10. Schematic of the production and transportation of potable water by the Florida Keys Aqueduct Authority.














reject concentrate to disposal


high service
pumps


Figure 11. Schematic of Stock Island's RO facility that desalinated water for Key West, Florida, in the 1970's.









Water Distribution System: Gainesville Regional Utility.

Generally the distribution systems were not included in the evaluation of potable

supply alternatives. So that the emergy required for the water yield was the sum of the

inputs to the process, excluding distribution. The aqueduct in the Florida Keys however,

was included in the evaluation for that water supply alternative, since the aqueduct is an

integral part of the production process (the distribution system throughout the keys that

distributes water to consumers was not included, however). A separate evaluation was

conducted for a distribution system to give perspective to the additional costs of

distribution so that comparisons with other consumer devices for potable water could be

made.

The emergy required for distribution of potable water was evaluated using the

system in Gainesville Florida. Inputs to the system included: pipe materials, electricity,

goods, and services. The annualized emergy costs (sej/year) of the distribution system

were divided by the annual flow rate (m3/year) to obtain sej/m3 of delivered water. For

comparison with other consumer operated and small-scale potable water supply options,

the emergy of distribution was added to emergy of production.



Emergy Evaluation of Small Scale Water Purification Alternatives

Several consumer oriented potable water alternatives were evaluated for

comparison with the large scale public utilities. Table 7 lists the alternatives that were

evaluated, and each alternative is described briefly below.









Table 7. Small scale water purification alternatives evaluated.

type of treatment location water source production


1) Home filter


2) Water boiling


3) Solar distillation *
with a humidification-
dehumidification cycle

4) Solar distillation **


Florida


Florida


Florida



Florida


groundwater


groundwater


salty water



salty water


10.0 gal/day or
37.9 L/day

2.0 gal/day or
7.6 L/day

4.3 gal/day or
16.3 L/day


0.8 gal/day or
3.0 L/day


5) Bottled water: Ocala, Ocala's tap water 13.5 E3 gal
microfiltration/RO/ Florida (from the or 51.1 m3/
ozonation Floridan aquifer)

* production flows are per 2.0 m2 of solar collector surface area.
** production flows are per 1.0 m2 of effective evaporating surface area.


/day
day


1) Groundwater Source: Home Filtration.

Figure 12 illustrates a schematic diagram of a home filter that produces 10 gal/day

(37.9 L/day) of purified water. The schematic shows how either water coming from

public supply or private wells are fed through the filter system, which is commonly

placed under the kitchen sink. Only the second option (private well) was evaluated. The

filter system consist of: 1) a reverse osmosis membrane for removing any water-born

pathogens, 2) a micron filter for removing small solids, and 3) a carbon filter for

absorbing unpleasant tastes and odors. After filtration the water is stored in a 2.5 gal (9.5

L) reservoir tank, which is connected to the kitchen faucet. A valve in the faucet is used

to switch between filtered or regular water.


















water source: 1) potable water from public supply


or 2) private well
(this water source was used
for the emergy evaluation)


Figure 12. Schematic of the production of purified water with a home filter.









2) Groundwater Source: Boiling Water.

A schematic diagram of the process of boiling water in an average home in

Florida is given in Figure 13. The daily volume of boiled water used for evaluation was

2.0 gal (7.6 L). First water from a kitchen sink is added to a pot. Then the pot is covered

and placed on a range (stove), and the stove turned on. Finally, after ten minutes of

vigorous boiling the range is tuned off and the water left to cool.



3) Salty Water Source: Advanced Solar Distillation (Humidification-Dehumidification
Cycle).

The schematic of a solar distillation system that produces approximately 4.0

gal/day (15.0 L/day) of drinking water with a 2.0 m2 solar collector is given in Figure 15.

This distillation process integrates a humidification-dehumidification cycle to increase

the water production capacity. The purpose of this cycle is to use the latent heat of

condensation to preheat the seawater going into the solar collector. The preheated

seawater passes through the solar collector where the water is further heated but not

condensed. Then this water passes through a humidifier where some water evaporates

and the rest leaves the system. Cool air blows through the humidifier and carries the

water vapor to the condenser. The water vapor is then condensed as the hot moist air

flows through the condenser. The fresh water is collected at the bottom of the condenser

unit but the now cold dry air moves to the humidifier to close the cycle. Since this

distiller works by condensing water vapor in the air moving through the system and not

directly condensing seawater inside a distiller, large flows of seawater are required to

operate this system.


















water source: 1) potable water from public supply


or 2) private well
(this water source was used
for the emergy evaluation)


I m


Figure 13. Schematic diagram of boiling water.















estuary or
salty lagoon


reflector


salty water


brine


Legend:
1-condenser
2-condenser water inlet
3-condenser water outlet
4-humidifier
5-humidifier water inlet
6-humidifier water outlet
7-cold air at the bottom of the unit
8-hot air at the top of the unit


Figure 14. Schematic diagram of an advanced solar distillation process containing a humidification-dehumidification cycle.


desalinated
water









4) Salty Water Source: Traditional Solar Distillation.

Figure 15 shows a schematic diagram of a common solar distillation unit that

produces approximately 0.8 gal/day (3.0 L/day) of drinking water per m2 of effective

evaporating area. Salty water is hand-delivered to the distiller as required. Inside the

distiller, the seawater slowly evaporates and condenses on the glass of the unit. The

condensed (distilled) water is collected and the excess saltwater recycled or discarded.

The main structure of the unit is made of fiberglass and covered with a one cm-thick

glass. A jute cloth is used inside the distiller to act as a humidifier to increase the rate of

evaporation. To maximize evaporation efficiency, the outer glass has to be cleaned once

a week.



5) Tap Water Source: Purified Bottled Water.

In 1999 Culligan Co. in Ocala, Florida, sold roughly 2,700 five-gallon (18.9 L)

bottles of purified water every day. A schematic of the bottling and delivery process is

illustrated in Figure 16. The already potable water from the city of Ocala is softened and

then passed through a carbon filter to remove any bad taste and odors (e.g., chlorine).

After this, the water is fed through an RO filter and the brine is sent to the city's sewer

system. The treated water is stored in a storage tank and then passed through another

carbon filter. After this, the water is disinfected with ozone and radiated with ultraviolet

light to kill any pathogens still remaining. Then, the water is re-filtered and re-ozonated

before being bottled into sterilized 5-gallon plastic jugs. Finally, the water bottles are

road-delivered to consumers.



















estuary or
salty lagoon


Figure 15. Schematic of a traditional solar distiller.














concentrate to Ocala's
sewer system


I- water softener

water source: potable water
from Ocala City air
air



ozone
electricity generator
Harmsco filter I


carbon filter


pressure pumps


electricity


4


Figure 16. Schematic of the production of purified bottled water in Ocala, Florida.










Computer Simulation of Water Allocation

The main purpose of this model was to explore what allocation of water, among

the natural, agricultural, and urban sectors, maximizes total regional production. The

state of Florida was used as a case study (i.e., the region) for this water allocation

simulation.


Analysis and Diagramming

Systems diagrams were drawn to understand the relation between Florida's water

resources, the environment, agriculture, and the urban economy. After several revisions,

one diagram was selected to define the simulation equations, which are implicit in

systems language (Odum, 1994). The system diagram used for the simulation is given in

Figure 17.


Structure of the Model

The model relates production in three sectors of the economy (urban, agricultural

and environmental) to availability of purchased goods, fuels and services and the

allocation of water. A systems diagram of the simulation model is given in Figure 17.

Each sector has its own production function. In the urban sector, production is a function

of imported fuels, goods and services to the urban economy (FF*Si) and available water

allocated to this sector (AW*Fu). Production in the agricultural sector is a function of

sunlight (R), imported fuels goods and services for agriculture (FF*S2) and available

water for the agricultural sector (AW*FA). Environmental production is a function of

sunlight (R) and available water to the environment (Fe). Here the fraction of regional

available water (AW) is not multiplied by the fraction of water allocated to the









environment (Fe) since AW is based on environmental production (Pe), which is a

function of Fe. Purchased fuels goods and services (FF) result from the sale of exports

from each of the sectors. Thus ultimately, the "health" of the regional economy is largely

determined by its export base. The greater the exports, the greater the imports.

The model generates production curves for each sector, and for the regional economy.

Each sector has a production function that generates an index of total product from that

sector. The regional product is calculated in two ways: as a product function of the three

sectors and as an empower function (addition of empowers from each of the sectors).

Sector production functions used a simple product of each of the inputs as follows:


Pu = k3*(FF*Si)*(AW*Fu) (1)
Pa = k4*R*(FF*S2)*(AW*Fa) (2)
Pe = k5*R*Fe (3)
and:
R = J / [1 + (k2*AW*Fa*FF*S2+ ki*Fe)] (4)
FF = kio*Pu + kll*Pa + k12*Pe (5)
Fe + Fa + Fu = 1 (6)
AW = k6*Pe (7)

where:

Pu = Total production from the urban sector.
Pa = Total production from the agricultural sector.
Pe = Total production from the environment.
R = Remainder of insolation (solar energy not directly
converted by plants to a higher form of energy)
Fu = Fraction of total renewable freshwater used in the
urban sector.
Fa = Fraction of total renewable fresh water used in the
agricultural and forestry sectors.
Fe = Fraction of total renewable fresh water used in the
environment (including estuaries and coastal ecosystems)
AW = Available water (renewable fresh surface and ground
water)
FF = Total purchased goods, energy and services used in
regional economy
Si = Fraction of purchased goods, energy and services from









the economy used in the urban sector.
S2 = Fraction of purchased goods, energy and services from
the economy used in the agricultural sector.
ki-k6, k10-k12 = coefficients

The regional macro economic production function (an Index of Regional

Production) was calculated as the product of the three sectors as follows:


TP = k14*(Pe*Pa*Pu) (8)


One can think of TP as regional gross economic product where the factors of

production are the output from each of the sectors. Output from each sector is calibrated

in physical units of material (g/yr) and the production indices include internal cycling.

The available water (AW) factor relates the production in the urban and agricultural

sectors to the amount of water captured and made available by the environment. As more

water is used in the urban sector the environment is impacted, decreasing the overall

availability of regional freshwater resources.

The second regional function is an index of regional Empower and is the sum of

the emergy output from each sector as follows:


TMP = (Pe*te)+(Pa*ta)+(Pu*tu) (9)

where:
te = transformity of environmental production (sej/J of biomass)
ta = transformity of agricultural production (sej/J of crops)
tu = transformity of urban production (sej/J)


This function is an index of total empower of the regional economy. Since

emergies are additive, not multiplicative, the index is a summation of emergy outputs

from each sector obtained by multiplying output of each sector by an average

transformity for that sector.









Simulation of the regional model was done to evaluate allocation of water

between sectors of the economy. The hypothesis was that there should be some

allocation scheme that maximizes total product as well as a scheme that maximizes

empower. An open question was whether the same allocation scheme would maximize

both total regional production and empower. The model was simulated in quasi-steady

state where the allocation of water was varied between each of the sectors. The

allocation of available water in the region was varied from 0% to 100% for each of the

sectors and production under each scenario was calculated using the production

functions. A table of coefficients, notes, and references for the models is included in

Appendix E.



Computer Simulation

Excel spreadsheets were used to calibrate, program and simulate the model. A

simulation graph plotted the changes in productivity (Pu, Pa, Pe, TP and TMP) as a

function of the fraction of renewable water allocated to the urban sector (Fu).



Sensitivity Analysis

The effects of changing FF and its distribution between the urban and agricultural

sectors on the model's output was explored as part of the sensitivity analysis. Changes in

kio where used to trigger changes in FF, whereas different combinations of S1 and S2

(always summing 1) were used to represent changes in the distribution of FF between

these two sectors.















FF = klO*Pu + kll*Pa + kl2*Pa


total
productivity:
TP=kl5*(Pe*Pa*Pu)
TMP=kl6*(Pu*tu+Pa*ta+Pe*te)


t_=transformity; F_=fraction of water used heat sink
AW = available water (renewable fresh surface water & ground water)
# includes industry, manufacturing, construction, tourism, and other services.


Figure 17. Model of water allocation for maximizing the total production of Florida.















RESULTS

Emergy evaluations and simulation modeling of the values of water are given in

the following sections. First the results of global and regional evaluations of the main

flows and storage of water are provided, then the results of evaluations of 8 potable

water supply alternatives and 5 small scale, consumer oriented systems, are presented.

Finally, simulation results of the computer model developed to test theories of water

allocation that maximize regional production are given.



Global Water Resources

Emergy evaluations of the main storage and flows of water in the biosphere are

summarized in Tables 8 and 9, respectively. The storage of water in Table 8 are

arranged by increasing transformity, which is the result of increasing turnover times.

Atmospheric water vapor has the lowest transformity, while polar ice and glaciers,

because of their long turnover times, have the highest transformity. Since seawater is

considered the "ground state" it has no chemical potential energy and therefore its

transformity is zero. The energy for fresh water is calculated as the chemical potential

relative to seawater. An average transformity for all fresh water in the biosphere is given

in the last row of the table as the weighted average of all transformities. The weighted

average is relatively high as a result of the large portion of biosphere water that is in polar

ice and glaciers. Transformities for these water storage varied between 3.54 E3 sej/J for

water vapor in clouds and 1.05 E6 sej/J for polar ice and glaciers.









In Table 9, the flows of water in the biosphere are listed in ascending order of

transformity. Several different types of rainfall were calculated. These data represent

global averages. Rainfall in any particular location could have higher or lower

transformities based on the conditions of a particular area. The transformity of global

surface runoff (5.79 E4 sej/J) is about 3 times the transformity of average rainfall on land

(1.82 E4 sej/J) while global recharge (2.27 E5 sej/J) is more than 12 times that of rainfall

on land. As the flow rates decrease transformities increase. The transformity of tropical

rain on land (3.19 E4 sej/J) is about 3.8 times greater than that of tropical rain on both

land and water (8.43 E3 sej/J). Similarly, the transformity of temperate rain on land (2.43

E4 sej/J) is approximately 3.3 times greater than the transformity of temperate rain on

both land and water (7.46 E3 sej/J).

Figure 18 summarizes the principal storage and flows of the global hydrologic

cycle. This diagram includes storage turnover times, volumes and transformities (except

oceans and salty lakes) as well as the rates and transformities of water flows.
















Table 8. Distribution and energy values of global water storage.

average (a) % of water reserve Emergy (b) Emergy (c) Transformity (d) Em-dollars (e) Total Em$ (f)
water stock replacement volume (a) of total water of fresh water per mass per volume (chem. potential) per volume of water storage
time (yrs) (x1000 km3) (sej/g) (sej/m3) (sej/J) (Em$/m3) (trillion Em$)
World ocean 3,278 1,370,000 97.3
Saline lakes* 25 104 0.007
water vapor in clouds 0.00015 0.08 0.00001 0.0002 1.75E+04 1.75E+10 3.54E+03 0.01 0.001
Atmospheric vapor 0.026 14 0.001 0.04 1.77E+04 1.77E+10 3.59E+03 0.01 0.12
Soil & subsoil water 0.77 67 0.005 0.18 1.08E+05 1.08E+11 2.19E+04 0.05 3.6
Freshwater lakes 3 125 0.009 0.33 2.27E+05 2.27E+11 4.59E+04 0.11 14.2
Biological water 0.05 2.1 0.0002 0.006 2.44E+05 2.44E+11 4.94E+04 0.12 0.26
Rivers and streams 0.04 1.2 0.0001 0.003 3.23E+05 3.23E+11 6.54E+04 0.16 0.19
Wetland water 1 11.5 0.001 0.03 8.21E+05 8.21E+11 1.66E+05 0.41 4.7
Fresh groundwater 994 8,350 0.59 22.2 1.12E+06 1.12E+12 2.27E+05 0.56 4,692
Polar ice and glaciers 16,000 29,000 2.06 77.2 5.21E+06 5.21E+12 1.05E+06 2.60 75,520
Total freshwater resources 12,571 37,571 100 3.16E+06 3.16E+12 6.39E+05 1.58 59,335
It was assumed that all global water storage are co-products of the global empower base (9.44 E24 sej/yr).
* emergy and transformity are 0.0 since salt water is considered the ground state.


(a) From Wetzel (1975; p. 1), except:
1) replacement times: oceans from Suomi (1992); biological water replacement times were assumed to be 20 days; wetland replacement time was assumed to be one year; the groundwater
replacement time was calculated by dividing the groundwater reservoir (8.35 E6 km3) by 8,400 km3/yr, the annual renewable groundwater flow. This flow was estimated assuming that 8%
of the global precipitation on land infiltrates the ground: 105,000 km3/yr *0.08 = 8,400 km3/yr. The replacement time for total water reserves represents the weighted average of
all storage replacement times. Similarly, the replacement time of total fresh water reserves represents the weighted average of all fresh water replacement times.
2) volumes: groundwater (up to a depth of 4,000 m) from van der Leeden (1975); wetland water from Gleick (1993); and biological water from Anthes (1997; p. 46).
(b) sej/g = (9.44 E24 sej/yr)(turn over time) / [(km3)(1 E9 m3/km3)(1E6 g/m3)]
(c) sej/m3 =(sej/g)(1 E6 g/m )
(d) Water carries different available energies (e.g. Gibbs free energy of its chemical potential, geopotential, thermal gradient potential) from which transformities can be calculated (Odum, 1994).
In this table, transformities were calculated using the chemical potential energy of fresh water (10 ppm) relative to seawater (35,000 ppm), with a Gibbs free energy of 4.94 J/g.
Thus, sej/J = (sej/g) / (4.94 J/g). Since transformities were calculated using the chemical potential energy of freshwater relative to ocean water, the transformities of saline waters
(e.g. ocean water) do not have chemical potential energy and, thus, their chemical potential energy-transformity is zero.
(e) Em$/m 3 (sej/m ) divided by 2.0 E12 sej/$, which is the world emergy per dollar ratio; sej/$ from Odum (1996; p. 201)
(f) Em$ (9.44 E24 sej/yr)(replacement time in yrs)/(2.0 E12 sej/$)











Table 9. Distribution and energy values of global water flows.

annual (a) Emergy (b) Emergy (c) Transformity (d) Em-dollars (e)
water flow flow rate per mass per volume (chem. potential) per volume
Note (E3 km3/yr) (sej/g) (sej/m3) (sej/J) (Em$/m3)
1 Evaporation 483 1.95E+04 1.95E+10 3.96E+03 0.01
2 from oceans 418 2.26E+04 2.26E+10 4.57E+03 0.01
3 from land areas* 65 1.45E+05 1.45E+11 2.94E+04 0.07
4 Precipitation 483 1.95E+04 1.95E+10 3.96E+03 0.01
5 to oceans 378 2.50E+04 2.50E+10 5.06E+03 0.01
6 Temperate rain 256 3.68E+04 3.68E+10 7.46E+03 0.02
7 Tropical rain 227 4.16E+04 4.16E+10 8.43E+03 0.02
8 to land** 105 8.99E+04 8.99E+10 1.82E+04 0.04
9 Temperate rain on land ** 79 1.20E+05 1.20E+11 2.43E+04 0.06
10 Tropical rain on land 60 1.57E+05 1.57E+11 3.19E+04 0.08
11 Surface runofftooceans 33.0 2.86E+05 2.86E+11 5.79E+04 0.14
12 Global groundwater recharge 8.4 1.12E+06 1.12E+12 2.27E+05 0.56
13 Ice melt 2.0 4.72E+06 4.72E+12 9.55E+05 2.36
It was assumed that all global water flows are co-products of the global empower base (9.44 E24 sej/yr).
* includes plant transpiration
** including frozen land

(a) Annual flow rates for notes 1, 2, 3, 4, 5, 8, 12 and 13 were obtained from Suomi (1992; p.20)
6) The volumetric flow rate of temperate rain was assumed to be the difference between global precipitation
(483 E3 m3/yr) and tropical rainfall (227 E3 km3/yr), which estimation is described below.
7) The volumetric flux of tropical rainfall was estimated by using 1.26 m/yr of precipitation over the tropical
surface are of the world (1.8 E8 km2). The 1.26 m/yr was estimated from a global average rainfall map
given in Hammond Atlas of the World (1999; p.31). The tropical surface are was calculated by multiplying
the total surface area of the world (5.1 E8 km2) by 0.354, which represents the ratio of tropical surface area
(between latitudes 23.50 N and 23.50 S) to non-tropical area (23.50 N to 900 N plus 23.50 S to 900 S).
9) The flow rate of temperate rain on land was estimated by multiplying the avg. global temperate
precipitation (0.78 m/yr) by the temperate (i.e. non-tropical) land area of the world (10.13 km2).
The global temperate precipitation was estimated by dividing the temperate rain (256 E3 km3/yr) by the
difference between the world's surface area (5.1 E8 km2) and the tropical area (1.8 E8 km2). The
temperate land area (10.13 km2) was estimated from subtracting the tropical land area (4.76 E7 km2) from the
total world land area (14.89 E7 km2). Land areas were obtained from Hammond Atlas of the World (1999).
10) Tropical rain on land was estimated using 1.26 m/yr for tropical precipitation and the tropical
land area of the world (4.76 E7 km2). This area was estimated by summing the area of all countries within
latitudes 23.50 N and 23.50 S using maps and country areas given in Hammond Atlas of the World (1999).
11) The global groundwater recharge was estimated by assuming that 8% of land precipitation infiltrates the
ground and accumulates as groundwater.

(b) sej/g = (9.44 E24 sej/yr) / [(km3/yr)(1 E9 m3/km3)(1E6 g/m3)]
(c) sej/m3 = (sej/g)(1 E6 g/m3)
(d) transformities were calculated using the chemical potential energy of fresh water (10 ppm) relative
to seawater (35,000 ppm), with a Gibbs free energy of 4.94 J/g: sej/J = (sej/g) / (4.94 J/g)
(e) Em$/m3 = (sej/m3) divided by 2.0 E12 sej/$, which is the world emergy per dollar ratio; sej/$
from Odum (1996; p. 201)










































= sum of volumes & ** = prorated turnover time:
lake water (125 E3 km3, t=3 yr, 45.9 E3 sej/J), river water (1.2 E3 km3, t=0.04 yr, 65.4 E3 sej/J),
wetland water (11.5 E3 km3, t=l yr, 166.0 E3 sej/J), and biological water (2.1 E3 km3, t=0.05 yr, 49.4 E4 sej/J).

Figure 18. The global hydrologic cycle. Reservoirs include volume (km3), average replacement time (t) and transformities (bold
numbers). Global water flows are given in km3/yr and bold numbers represent water transformities in E3 sej/J.










Emergy Evaluation of Regional Water Flows and Storages

The emergy evaluation of intertidal water (estuaries) and river water in Florida are

given in Tables 10 and 11, respectively. The most important numbers in these and the

rest of the emergy tables consist of the water transformity and total sej/m3 values. The

sej/yr values shown in Table 11 represent the emergy of all the river water flowing

through Florida every year. The sej/m3 values indicate the average emergy per volume of

river water in Florida. The emergy of river water was used as the input to intertidal

water. Tables 12 and 13 show the results from the emergy evaluations for lake-pond and

wetland waters, respectively. Table 14 summarizes the results from the emergy

evaluations of Florida's surface water resources.

Florida groundwater resources are typically divided into three aquifer systems: 1)

the surficial, including the Sand and Gravel and the Biscayne aquifers; 2) the

Intermediate; and 3) the deep (i.e., the Floridan) aquifer. Results of the emergy

evaluation of surficial groundwater are given in Table 15. Table 16 and 17 show the

results of the emergy evaluation of groundwater from Sand and Gravel and the Biscayne

aquifers in northwestern and southeastern Florida, respectively. Both of these aquifers

are also surficial systems but were evaluated separately because of their importance as

regional water sources. The evaluation in Table 15 does not include the water from these

two aquifers. Tables 18 and 19 show the results from the emergy evaluations of

groundwater from the Intermediate and the Floridan aquifer systems, respectively. Table

20 summarizes the results of the emergy evaluations of Florida's groundwater resources.











Table 10. Emergy evaluation of Florida's intertidal water (water from estuaries, salt
marshes and mangrove ecosystems).

Energy Emergy Solar Emergy (sej)
Note Item Unit Data per unit Emergy per m
Unit/yr (sej/unit) (E18 sej/yr) (E10)
RENEWABLE RESOURCES
1 Emergy of all FL rivers sej 1.69E+22 16,910 4.50

ENERGY PER UNIT OF INTERTIDAL WATER IN FLORIDA
2 Intertidal water g 3.83E+17 44,159 16,910 4.50
3 Intertidal water m3 3.75E+11 4.50E+10 16,910 4.50
4 Chem. energy of intertidal water J 5.30E+17 31,917 16,910 4.50

Notes
1 Since tidal emergy is already included in the rain used to calculate the transformity of river water,
no tidal emergy is added to the emergy of intertidal water.
Emergy of Florida's river water (based on rain fallen on total river/stream drainage area), sej


Emergy of major FL rivers:


2 Area of intertidal waters (Gulf coast)
Area of intertidal waters (East coast)
Total area of intertidal waters:
Avg. depth of intertidal waters
Average vol. of FL intertidal waters:
Turnover time of estuarine water:
Annual volume of intertidal water:
Annual mass of intertidal water:
Emergy of intertidal water:
Emergy/mass of intertidal water:

3 Annual volume of intertidal water:
Emergy of intertidal water:
Emergy/volume of intertidal water:

4 Avg. TDS of FL estuarine water:
Avg. Gibbs free energy water:

Chem. energy of intertidal water:
Emergy of intertidal water:
Transformity of FL intertidal water:


sej/yr 1.69E+22 (Table 11)


km
km2
km2
m
m
yr
m3/yr
g/yr
sej/yr
sej/g

m3/yr
sej/yr
sej/m3


12,000
2,400
14,400
1.5
2.16E+10
0.06
3.75E+11
3.83E+17
1.69E+22
4.42E+04

3.75E+11
1.69E+22
4.50E+10


(Livingston, 1990; p. 550)
20% of Gulf area (est. from Livingston, 1990)
(Gulf coast area + East coast area)
assumed
(km2) (1000 m/km)2(m)
3 weeks, assumed
(m3)/(yr)
(m3/yr)(1.02 E6 g/m3)
from note 1
(sej/yr) / (g/yr)

i. i '1.02E6 g/m3)
from note 1
(sej/yr) / (m3/yr)


ppm 25,000 assumed
J/g 1.38 [(8.33 J/mol/K)(290 K)/(18 g/mol)]
In [(1E6 TDS in ppm)/(965,000)]
J/yr 5.30E+17 (g/yr)(J/g)
sej/yr 1.69E+22 from note 1
sej/J 31,917 (sej/yr) / (J/yr)











Table 11. Emergy evaluation of Florida's river and stream water.

Energy Emergy Solar Emergy (sej)
Note Item Unit Data per unit Emergy per m
Unit/yr (sej/unit) (E18 sej/yr) (E10)
RENEWABLE RESOURCES
1 Rainfall on river watershed: J 9.29E+17 18,200 16,910 20.31

ENERGY PER UNIT OF RIVER WATER IN FLORIDA
2 River water: g 8.33E+16 203,113 16,910 20.31
3 River water: m3 8.33E+10 2.03E+11 16,910 20.31
4 Chemical pot. energy of river water: J 3.97E+17 42,586 16,910 20.31


Notes
1 Florida's drainage area:


Effective drainage river drainage A:
Annual rainfall on drainage area:
Rainfall on effective drainage area:
Chem. potential energy of rainfall:
Transformity:

2 Avg. flow of major rivers in FL:
Avg. flow of major rivers in FL:
Annual mass of river water:
Emergy per mass of river water:

3 Avg. annual flow of river water:
Emergy/volume of river water:

4 Prorated hardness of major FL rivers:
Avg. dissolved solids (TDS) of FL rivers:
Avg. Gibbs free energy of FL's rivers:

Chem. Potential energy of FL river water:
Transformity (chem. pot.) of river water:


.2
mi

.2
mi
in/yr
gal/yr
J/yr
sej/J

m3/sec
m3/yr
g/yr
sej/g


98,000 measured from Femald and Purdum (1998; p.66)
includes all of FL and parts of GA and AL
53,900 est. from maps in Femald and Purdum (1998; p. 67)
53 (Fernald and Purdum, 1998)
4.97E+13 (mi2)(1,610 m/mi)2(in/yr)(0.0254 m/in)(264.2gal/m3)
9.29E+17 (gal/yr)(1E6 g/m3)(4.94 J I 2. .4.2 gal/m3)
18,200 chemical energy, rain on land (Table 9)


2,640
8.33E+10
8.3E+16
2.0E+05


(Nordlie, 1990; p.398)
(m3/sec)(3,600 sec/hr)(24 hr/day)(365 day/yr)
(m3/yr)(1 E6 g/m3)
(sej/yr from line 1) / (g/yr)


m3/yr 8.33E+10 (g/yr)/(l E6 g/m3)
sej/m3 2.03E+11 (sej/yr from line 1) / (m3/yr)

ppm 62 (Nordlie, 1990; p.399)
ppm 89 (assuming hardness = 70% of TDS)
J/g 4.77 [(8.33 J/mol/K)(290 K)/(18 g/mol)]
In [(1E6 TDS in ppm)/(965,000)]
J/yr 3.97E+17 (g/yr)(J/g)
sej/J 42,586 (sej/yr from line 1) / (J/yr)











Table 12. Emergy evaluation of Florida's lake water.


Energy Emergy Solar Emergy (sej)
Note Item Unit Data per unit Emergy per m
Unit/yr (sej/unit) (El8 sej/yr) (E10)
RENEWABLE RESOURCES
1 Rainfall on lake's drainage area: J 2.53E+17 18,200 4,612 26.87

EMERGY PER UNIT OF LAKE WATER IN FLORIDA
2 Lake water g 1.72E+16 268,653 4,612 26.87
3 Lake water m3 1.72E+10 2.69E+11 4,612 26.87
4 Chemical energy of lake water J 8.17E+16 56,427 4,612 26.87


Notes
1 Florida's drainage area:


Lake's drainage area:
Annual rainfall on lake drainage area:
Annual rainfall on lake drainage area:
Chem. potential energy of rainfall:
Transformity:

2 Tot. area of lakes > 0.4 ha in Florida:
Avg. depth of Florida lakes
Average volume of Florida lakes:
Mean residence time of Florida lakes:
Annual volume of lake water:
Annual mass of lake water:
Emergy per mass of lake water:

3 Annual volume of lake water:
Emergy per volume of lake water:


mi2 98,000 measured from Femald and Purdum (1998; p.66)
includes all of FL and parts of GA and AL
mi2 14,700 estimated from Fernald and Purdum (1998; p. 67)
in/yr 53 (Femald and Purdum, 1998)
gal/yr 1.36E+13 (mi2)(1,610 m/mi)2(in/yr)(0.0254 m/in)(264.2 gal/m3)
J/yr 2.53E+17 (gal/yr)(1E6 g/m3)(4.94 .i ,-1. .4.2 gal/m3)
sej/J 18,200 chemical energy, rain on land (Table 9)


km2
m
3
m
yr
m3/yr
g/yr
sej/g

m3/yr
sej/m3


4 Avg. dissolved solids (TDS) of FL lakes: ppm
Avg. Gibbs free energy of FL's lake water: J/g

Chem. Potential energy of FL lake water: J/yr
Transformity (chem. pot.) of lake water: sej/J


9,270 (Brenner et al., 1990; p. 364)
5.0 estimated from (Brenner et al., 1990; p. 365)
4.64E+10 (km2)(1000 m/km)2(m)
2.7 (Brenner et al., 1990; p. 372)
1.72E+10 (m3)/(yr)
1.72E+16 (m3/yr)(1 E6 g/m3)
2.7E+05 (sej/yr from line 1) / (g/yr)

1.72E+10 (g/yr)/(1 E6 g/m3)
2.69E+11 (sej/yr from line 1) / (m3/yr)

151 (Brenner et al., 1990; p. 378)
4.76 [(8.33 J/mol/ K .*' K)/(18 g/mol)]
In [(1E6 TDS in ppm)/(965,000)]
8.17E+16 (g/yr)(J/g)
56,427 (sej/yr from line 1) / (J/yr)







70


Table 13. Emergy evaluation of Florida's wetland (freshwater marshes & swamps) water.

Energy Emergy Solar Emergy (sej)
Note Item Unit Data per unit Emergy per m
Unit/yr (sej/unit) (El8 sej/yr) (E10)
RENEWABLE RESOURCES
1 Rainfall on wetland drainage area: J 5.07E+17 18,200 9,224 33.76

EMERGY PER UNIT OF WETLAND WATER IN FLORIDA
2 Wetland water: g 2.73E+16 337,584 9,224 33.76
3 Wetland water: m3 2.73E+10 3.38E+11 9,224 33.76
4 Chemical pot. energy of wetland water: J 1.30E+17 70,905 9,224 33.76


Notes
1 Florida's drainage area:

Wetland drainage area:
Rainfall on wetland drainage area:
Rainfall on wetland drainage area:
Chem. potential energy of rainfall:
Transformity:


mi2 98,000


.2
mi
in/yr
gal/yr
J/yr
sej/J


2 Surface A of freshwater wetlands in FL: mi
Avg. depth of Florida wetlands: m
Average volume of Florida wetlands: m
Mean residence time of Florida wetlands: yr
Annual value of wetland water: m3/yr
Annual mass of wetland water: g/yr
Emergy per mass of wetland water: sej/g

3 Annual value of wetland water: m3/yr
Emergy/volume of wetland water: sej/m3


4 Avg.diss. solids (TDS) of FL wetlands: ppm
Avg. Gibbs free energy of wetland water: J/g

Chem. potential energy of wetland water: J/yr
sej/J (chem. pot.) of wetland water: sej/J


29,400
53
2.71E+13
5.07E+17
18,200

10,541
0.5
1.37E+10
0.5
2.73E+10
2.73E+16
3.4E+05


measured from Fernald and Purdum (1998; p.66)
includes all of FL and parts of GA and AL
estimated from Fernald and Purdum (1998; p. 67)
(Femald and Purdum, 1998)
(mi2)(1,610 m/mi)2(in/yr)(0.0254 m/in)(264.2gal/m3)
(gal/yr)(1E6 g/m3)(4.94 .i ,I. -- .4.2 gal/m3)
chemical energy, rain on land (Table 9)


(Fernald and Purdum, 1998; p. 3)
assumed
(mi2)(1,610 m/mi)2(m)
assumed
(m3)/(yr)
(m3/yr)(1 E6 g/m3)
(sej/yr from line 1) / (g/yr)


2.73E+10 (g/yr)/(1 E6 g/m3)
3.38E+11 (sej/yr from line 1) / (m3yr)

151 assuming the same as lakes (Brenner et al., 1990; p. 378)
4.76 [(8.33 J/mol/ K .*' K)/(18 g/mol)]
In [(1E6 TDS in ppm)/(965,000)]
1.30E+17 (g/yr)(J/g)
70,905 (sej/yr from line 1) / (J/yr)










Table 14. Summary of emergy evaluation of Florida's surface water resources.


Fresh surface


volume (a) (b) (c) sej/m ((
Surface water type (E9 m3) sej/J sej/g (xElO
Intertidal* 21.6 31,917 44,159 4.50
River 8.3 42,586 203,113 20.31
Lake 46.4 56,427 268,653 26.87
Wetland 13.7 70,905 337,584 33.76
Total: 76.3
Fresh surface water average #: 57,630 219,136 21.93


water values
d) Em$/yr (e)
) (xE9)
18.58
18.58
5.07
10.14
42.23


* Includes waters on shallow bays, estuaries, salt marshes, mangroves and salty lagoons.
# Average values were weighted to represent the proportion of the volume for each surface water type.
To avoid double counting, the prorated average does not include the transformity of intertidal water
since this is based on the emergy of river water.

(a) volume from tables 10, 11, 12 and 13.
(b) sej/J from tables 10, 11, 12 and 13.
(c) sej/g = (sej/J)(4.94 J/g)
(d) sej/m3 = (sej/g)(1 E6 g/m3)
(e) Em$/yr (year 2000) = (m3/yr)(sej/m3)/(9. 1 E11 sej/$)
(f) Em$/m3 (year 2000) = (sej/m3)/(9.1 E11 sej/$)


Em$/m3 (f)
year 2000
0.05
0.22
0.30
0.37

0.24











Table 15. Emergy evaluation of fresh groundwater from Florida's Surficial aquifer
system.


Energy Emergy Solar Emergy (sej)
Note Item Unit Data per unit Emergy per m
Unit/yr (sej/unit) (El8 sej/yr) (xElO)
RENEWABLE RESOURCES
1 Rainfall on rechargeable aquifer area: J 8.20E+17 18,200 14,917 20.97

EMERGY/UNIT OF FRESH GROUNDWATER FROM THE SURFICIAL AQUIFER
2 Surficial groundwater: g 7.11E+16 209,732 14,917 20.97
3 Surficial groundwater: m3 7.11E+10 2.10E+11 14,917 20.97
4 Surficial groundwater: J 3.37E+17 44,300 14,917 20.97


Notes
1 Recharge A of the Surficial aquifer:
Annual rainfall on rechargeable area:
Annual flux of rainfall on recharge A:
Chem. potential energy of rainfall:
Transformity:


2 Surface A overlaying the aquifer:
Porosity fraction of aquifer:
Avg. aquifer thickness:
Land volume of aquifer:
Volume of water in the aquifer:
Average recharge rate:
Recharge area:
Turn-over time:
Annual mass of groundwater:
Emergy per mass of groundwater:


3 Total m3/yr of groundwater:
Emergy/volume of groundwater:

4 Avg. total dissolved solids (TDS):
Gibbs free energy of Biscayne gw:


Chem. potential energy of gw:
Transformity of surficial groundwater:


.2
mi
in/yr
gal/yr
J/yr
sej/J

.2
mi

ft
3
m
3
m
ft/yr
.2
mi
yrs
g/yr
sej/g


45,000
56
4.38E+13
8.20E+17
18,200


60,000
0.11
70
5.02E+12
5.71E+11
2.0
45,000
8.0
7.1E+16
2.1E+05


assumed to be 75% of aquifer surface area
(Femald and Purdum, 1998; p.17)
(mi2)(1,610 m/mi)2(in/yr)(0.0254m/in)(264.2gal/m3)
(gal/yr)(1E6 g/m3)(4.94 .J ,, .4.2 gal/m3)
chemical energy, rain on land (Table 9)


(Measured from Miller, 1990; p6)
(0.65)(Avg. sand and limestone porosity) (Odum, 1996)
Inferred from Miller (1990; p.6)
(mi2)(ft)(5,280 ft/mi)2(0.305 m/ft)3
(land .from Femald and Purdum (1998
Estimated from Femald and Purdum (1998)
Estimated from Femald and Purdum (1998)
(m3) / [(ft/yr)(mi2)(1 m / 3.28 ft)(1,610 m/mi)2]
(m3)(1 E6 g/m3) / (yrs)
(sej/yr from line 1) / (g/yr)


m3/yr 7.11E+10 (g/yr)/(l E6 g/m3)
sej/m3 2.10E+11 (sej/yr from line 1) / (m3yr)


ppm 350 (Femald and Purdum, 1998; p. 54)
J/g 4.73 [(8.33 J/mol/ K ,,' *" I K)/(18 g/mol)]
In [(1E6 TDS in ppm)/(965,000)]
J/yr 3.37E+17 (m3)(J/g)(1E6 g/m3)/(yrs)
sej/J 44,300 (sej/yr from line 1) / (J/yr)











Table 16. Emergy evaluation of fresh groundwater from the Sand and Gravel aquifer
system in NW Florida.

Energy Emergy Solar Emergy (sej)
Note Item Unit Data per unit Emergy per m
Unit/yr (sej/unit) (E18 sej/yr) (xE10)
RENEWABLE RESOURCES
1 Rainfall on rechargeable aquifer area: J 8.66E+16 18,200 1,576 22.47

EMERGY/UNIT of FRESH GROUNDWATER from the SAND & GRAVEL AQUIFER
2 Sand & Gravel groundwater: g 7.01E+15 224,712 1,576 22.47
3 Sand & Gravel groundwater: m3 7.01E+09 2.25E+11 1,576 22.47
4 Sand & Gravel groundwater: J 3.35E+16 47,103 1,576 22.47


Notes
1 Recharge A of the Sand & G. aquifer:
Annual rainfall on rechargeable area:
Annual flux of rainfall on recharge A:
Chem. potential energy of rainfall:
Transformity:

2 Porosity fraction of Sand & G. aquifer:
Land volume of aquifer:
Volume of water in the aquifer:
Average recharge rate:
Recharge area:
Turn-over time:
Annual mass of Sand & Gravel gw:
Emergy/mass of Sand & Gravel gw:

3 Total m3/yr of Sand & Gravel gw:
Emergy/volume of Sand & Gravel gw:

4 Avg. total dissolved solids (TDS):


mi2 4,225
in/yr 63
gal/yr 4.63E+12
J/yr 8.66E+16
sej/J 18,200


3
m
3
m
ft/yr
.2
mi
yrs
g/yr
sej/g

m3/yi
sej/m


Gibbs free energy of Sand & Gravel gw: J/g

Chem. Potential energy of S&G gw: J/yr
Transformity of Sand & Gravel gw: sej/J


0.13
2.50E+12
3.26E+11
2.1
4,225
46.4
7.0E+15
2.2E+05


assumed to be 65% of aquifer surface area
(Femald and Purdum, 1998; p.17)
(mi2)(1,610 m/mi)2(in/yr)(0.0254 m/in)(264.2gal/m3)
i_..1' (1E6 g/m3)(4.94 .i 2- .4.2 gal/m3)
chemical energy, rain on land (Table 9)

(0.65)(Avg. sand porosity) (Odum, 1996)
calculated from Miller (1990; p7)
(land l..in.',; |. ,., il1
Estimated from Femald and Purdum (1998)
assumed to be 65% of aquifer surface area
(m3 [H1 ;i I2)(1 m/3.28 ft)(1,610 m/mi)2]
(m3)(1 E6 g/m3) / (yrs)
(sej/yr from line 1) / (g/yr)


S7.0E+09 .. l E6 g/m3)
2.2E+11 (sej/yr from line 1) / (m3/yr)

80 (Femald and Purdum, 1998; p. 54)
4.77 [(8.33 J/mol/ K)(290 K)/(18 g/mol)]
In [(1E6 TDS in ppm)/(965,000)]
3.35E+16 (m3)(J/g)(1E6 g/m3)/(yrs)
47,103 (sej/yr from line 1) / (J/yr)







74



Table 17. Emergy evaluation of fresh groundwater from the Biscayne aquifer system in
South Florida.


Energy Emergy Solar Emergy (sej)
Note Item Unit Data per unit Emergy per m
Unit/yr (sej/unit) (El8 sej/yr) (xEl0)
RENEWABLE RESOURCES
1 Rainfall on rechargeable aquifer area: J 3.71E+16 18,200 675 28.46

EMERGY/UNIT OF FRESH GROUNDWATER FROM THE BISCAYNE AQUIFER
2 Groundwater from the Biscayne: g 2.37E+15 284,636 675 28.46
3 Groundwater from the Biscayne: m3 2.37E+09 2.85E+11 675 28.46
4 Groundwater from the Biscayne: J 1.12E+16 60,206 675 28.46


Notes
1 Recharge area of the Biscayne aquifer:
Annual rainfall on rechargeable area:
Annual flux of rainfall on recharge A:
Chem. potential energy of rainfall:
Transformity:


2 Surface A overlaying the Biscayne aquifer:
Porosity fraction of aquifer:
Aquifer thickness:
Volume of the Biscayne groundwater:
Average recharge rate:
Recharge area:
Turn-over time:
Annual mass of fresh Biscayne gw:
Emergy per mass of Biscayne gw:

3 Total volume/yr of Biscayne gw:
Emergy per volume of Biscayne gw:

4 Avg. total dissolved solids (TDS):
Gibbs free energy of Biscayne gw:

Chem. Potential energy of Biscayne gw:
Transformity of Biscayne groundwater:


.2
mi
in/yr
gal/yr
J/yr
sej/J

.2
mi

ft
3
m
ft/yr
.2
mi
yrs
g/yr
sej/g

m3/yr
sej/m3


2,000
57
1.98E+12
3.71E+16
18,200


3,200
0.1
175
2.21E+10
1.5
2,000
9.3
2.4E+15
2.8E+05


(Femald and Purdum, 1984; p.37-38)
(Fernald and Purdum, 1998; p. 17)
(mi2)(1,610 m/mi)2(in/yr)(0.0254 m/in)(264.2gal/m3)
(gal/yr)(1E6 g/m3)(4.94 .i ,, -. .4.2 gal/m3)
chemical energy, rain on land (Table 9)


(Femald and Purdum, 1984; pp. 37-38)
Estimated based on avg. limestone porosity
wedge shaped -(Fernald and Purdum, 1984; p. 37)
[(mi)( 1,610 m/mi)2][(ft/ 2)(1 m/3.28 ft)](porosity)
(Femald and Purdum, 1984; p. 37)
(Femald and Purdum, 1984; p. 38)
(m3) / [(ft/yr)(mi2)(1 m/3.28 ft)(1,610 m/mi)2]
(m3)(1 E6 g/m3) / (yrs)
(sej/yr from line 1) / (g/yr)


2.4E+09 (g/yr)/(1 E6 g/m3)
2.8E+11 (sej/yr from line 1) / (gal/yr)


ppm 400 (Femald and Purdum, 1998; p. 54)
J/g 4.73 [(8.33 J/mol/ K,' '** K)/(18 g/mol)]
In [(1E6 TDS in ppm)/(965,000)]
J/yr 1.12E+16 (m3)(J/g)(1E6 g/m3)/(yrs)
sej/J 60,206 (sej/yr from line 1) / (J/yr)











Table 18. Emergy evaluation of fresh groundwater from the Intermediate aquifer in
western Florida.

Energy Emergy Solar Emergy (sej)
Note Item Unit Data per unit Emergy per m
Unit/yr (sej/unit) (El8 sej/yr) (xE10)
RENEWABLE RESOURCES
1 Rainfall on rechargeable aquifer area: J 7.32E+16 18,200 1,332 53.50

EMERGY/UNIT of FRESH GROUNDWATER from the INTERMEDIATE AQUIFER
2 Groundwater from the Intermediate: g 2.49E+15 535,030 1,332 53.50
3 Groundwater from the Intermediate: m3 2.49E+09 5.35E+11 1,332 53.50
4 Groundwater from the Intermediate: J 1.18E+16 113,170 1,332 53.50


Notes
1 Recharge A of the aquifer:
Annual rainfall on rechargeable area:
Annual flux of rainfall on recharge A:
Chem. potential energy of rainfall:
Transformity:

2 Surface A overlaying the aquifer:
Porosity fraction of aquifer:
Land volume of aquifer:
Volume of water in the aquifer:
Average recharge rate:
Recharge area:
Turn-over time:
Annual mass of groundwater:
Emergy per mass of groundwater:


2
mi
in/yr
gal/yr
J/yr
sej/J


4,500
50
3.91E+12
7.32E+16
18,200


mi2 9,000
0.065
m3 2.85E+12
m3 1.85E+11
ft/yr 0.7
mi2 4,500
yrs 74.3
g/yr 2.5E+15
sej/g 5.4E+05


assumed to be 50% of aquifer surface area
(Femald and Purdum, 1998; p.17)
(mi2)(1,610 m/mi)2(in/yr)(0.0254 m/in)(264.2gal/m3)
(gal/yr)(1E6 g/m3)(4.94 .i -' .4.2 gal/m3)
chemical energy, rain on land (Table 9)

(Measured from Miller, 1990; pl1)
(0.65)(Avg. limestone porosity) (Odum, 1996)
(Calculated from Miller, 1990; pl 1)
(land ls .', ,.. i l i
Estimated from Femald and Purdum (1998)
Estimated from Femald and Purdum (1998)
(m3) / [(ft/yr)(mi2)(1 m/3.28 ft)(1,610 m/mi)2]
(m3)(1 E6 g/m3) / (yrs)
(sej/yr from line 1) / (g/yr)


3 Total m3/yr of groundwater: m3/yi
Emergy per volume of groundwater: sej/m

4 Avg. total dissolved solids (TDS): ppm
Gibbs free energy of intermediate gw: J/g

Chem. potential energy of groundwater: J/yr
Transformity of groundwater: sej/J


2.49E+09 (g/yr)/(1 E6 g/m3)
5.35E+11 (sej/yr from line 1) / (m3/yr)


400 (Fernald and Purdum, 1998; p. 54)
4.73 [(8.33 J/mol/ K ,*' I K)/(18 g/mol)]
In [(1E6 TDS in ppm)/(965,000)]
1.18E+16 (m3)(J/g)(1E6 g/m3)/(yrs)
113,170 (sej/yr from line 1) / (J/yr)


3











Table 19. Emergy evaluation of fresh groundwater from the Floridan aquifer system.

Energy Emergy Solar Emergy (sej)
Note Item Unit Data per unit Emergy per m
Unit/yr (sej/unit) (El8 sej/yr) (E10)
RENEWABLE RESOURCES
1 Rainfall on rechargeable aquifer area: J 7.6E+17 18,200 13,923 77.46

EMERGY/UNIT OF FRESH GROUNDWATER FROM THE FLORIDAN AQUIFER
2 Fresh Floridan groundwater g 1.80E+16 774,594 13,923 77.46
3 FreshFloridan groundwater m3 1.80E+10 7.75E+11 13,923 77.46
4 Fresh Floridan groundwater J 8.39E+16 166,010 13,923 77.46


Notes
1 Recharge area of the Floridan aquifer:
Avg. annual rainfall on rechargeable A:
Annual flux of rainfall on recharge A:
Chem. potential energy of rainfall:
Transformity:

2 Volume of fresh groundwater in FL:
% of this gw that is in the Floirdan:
Vol. of fresh gw in the Florida aquifer:
Avg. recharge rate of aquifer in rech. A:
Replacement time of Floridan fresh gw:
Annual mass of fresh Floridan gw:
Emergy per mass of fresh Floridan gw:

3 Total m3/yr of fresh Floridan gw:
Emergy per volume of fresh Floridan gw:


mi
in/yr
gal/yr
J/yr
sej/J

gal
%
gal
in/yr
yrs
g/yr
sej/g

m3/yr
sej/m3


4 Avg. dissolved solids in upper Floridan: ppm
Gibbs free energy of upper Floridan gw: J/g

Chem. Pot energy of fresh Floridan gw: J/yr
Transformity of fresh Floridan gw: sej/J


42,000
56
4.09E+13
7.65E+17
18,200

1.0E+15
75
7.5E+14
6.50
158
1.8E+16
7.7E+05


(Estimated from Fernald and Purdum, 1998; p.53).
(Femald and Purdum, 1998; p. 17).
(mi2)(1,610 m/mi)2(in/yr)(0.0254 m/in)(264.2 gal/m3)
(gal/yr)(1E6 g/m3)(4.94 .i ,, .- .4.2 gal/m3)
chemical energy, rain on land (Table 9)

(Fernald and Purdum, 1998; p. 38)
estimated from Miller (1990)
(g.,I ,,"../100)
(calc. from data in Fernald and Purdum, 1998, p53)
gal/[(mi2)(1,610 m/mi)2(in/yr)(0.0254m/in)(264.2gal/m3)]
(gal)(1000 g/L)(3.785 L/gal) / (yrs)
(sej/yr from line 1) / (g/yr)


1.8E+10 (g/yr)/(1 E6 g/m3)
7.7E+11 (sej/yr from line 1) / (m3/yr)

250 (Femald and Purdum, 1998, p. 54)
4.67 [( 8.33 J in. K.. i,',5 K)/(18 g/mole)]
[ln (1000,000 ppm / 965,000)]
8.4E+16 (g/yr)(J/g)
166,010 (sej/yr from line 1) / (gal/yr)










Table 20. Summary of emergy evaluation of Florida's groundwater resources.

Fresh groundwater values
volume (a) avg. withdrawal % of total (c) (d) sej/m3 (e) Em$/yr Em$ (g)
Aquifer (E9 m3) (m3/sec) (b) withdrawal sej/J sej/g (xE10) (xE9) (f) perm3
Surficial 571 28.5 18.0 44,300 209,732 20.97 16.39 0.23
Sand & gravel 326 5.5 3.5 47,103 224,712 22.47 1.73 0.25
Biscayne 22 39.4 24.9 60,206 284,636 28.46 0.74 0.31
Intermediate 185 11.0 6.9 113,170 535,030 53.50 1.46 0.59
Floridan 2,839 107.8 68.1 166,010 774,594 77.46 15.30 0.85
Total: 3,046 158.2 100.0 17.50
Weighted average *: 145,580 681,398 68.14 0.75

Average values were weighted to represent the proportion of groundwater withdrawn from each aquifer
e.g. 145,580 was obtained by the sum of each (% of total withdrawal)*(sej/J)

(a) volume from Tables 15, 16, 17, 18, and 19.
(b) Total fresh water withdrawals in 1995 (Marella, 1999)
(c) sej/J from Tables 15, 16, 17, 18 and 19.
(d) sej/g = (sej/J)(4.94 J/g)
(e) sej/m3 = (sej/g)(1 E6 g/m3)
(f) Em$/yr (year 2000) = (m3/yr)(sej/m3)/(9.1 E11 sej/$)
(g) Em$/m3 (year 2000) = (sej/m3)/(9.1 E11 sej/$)

The last 3 columns represent the emergy values of the fresh groundwater in the aquifers, and
not for the water withdrawn.










Potable Water Supply Alternatives Evaluated

A brief description of the water supply alternatives and the results for each

evaluation is presented below. All the notes that document the emergy tables below are

given in Appendix B.



1) Surface (Lake) Water Source: West Palm Beach's Water Treatment Plant.

Figure 19 illustrates a systems diagram for the production of drinking water by

the City of West Palm Beach Water Treatment Plant. The plant's water source comes

from two lakes (Lake Mangonia and Clear Lake) that get their water from a water

catchment area south of Lake Okeechobee in south Florida. This diagram illustrates the

principal inputs required for the production of drinking water in West Palm Beach. The

numbers on the diagram correspond to the input rows in the emergy evaluation table of

potable water produced by the facility.

The emergy evaluation of this drinking water is given in Table 21. Of special

importance in this table are the transformity (1.39 E5 sej/J), the emergy yield (2.66 E19

sej/yr) and the total emergy per volume (0.69 E12 sej/m3). Lake water represented the

greatest emergy input for producing this drinking water followed by the emergy of

chemicals used in the treatment process. Several emergy indices and ratios for the

drinking water produced at the West Palm Beach plant are given in Table 22.











































B=Biomass; P=price
WPB = West Palm Beach
E=watershed environment


Figure 19. Energy systems diagram of the water production by the City of West Palm Beach.











Table 21. Emergy evaluation of the drinking water produced at the City
Beach Water Treatment Facility, Florida (28 mgd or 1.23 m3/sec).


of West Palm


Energy Emergy Solar Emergy (sej)
3
Note Item Unit Data per unit Emergy per m
(unit/year) (sej/unit) (El8 sej/yr) (E10)
RENEWABLE RESOURCES
1 Surface water J 1.94E+14 5.64E+04 10.96 28.25

PURCHASED & OPERATIONAL INPUTS
2 Operating & Maintenance $ 2.42E+06 9.60E+11 2.32 5.98
3 Electricity J 3.00E+13 1.60E+05 4.79 12.35
4 Fuels J 5.32E+12 6.60E+04 0.35 0.90
5 Chemicals ($) $ 1.30E+06 9.60E+11 1.25 3.22
6 Chemicals (kg) kg 5.09E+06 1.00E+12 5.09 13.12
7 Plant construction & upgrading $ 8.13E+05 9.60E+11 0.78 2.01
8 Plant Assets (concrete) kg 7.82E+05 1.23E+12 0.96 2.48
9 Plant Assets (steel & iron) kg 4.62E+04 1.80E+12 0.08 0.21
Yield (Y) = Total emergy of drinking water (not including distribution): 26.59 68.52

EMERGY PER UNIT OF POTABLE WATER (not including distribution):
10 Drinking water produced m3 3.88E+07 6.85E+11 26.59 68.52
11 Drinking water produced $ 1.13E+07 2.36E+12 26.59 68.52
12 Drinking water produced J 1.92E+14 1.39E+05 26.59 68.52
13 Drinking water produced g 3.88E+13 6.85E+05 26.59 68.52
14 Drinking water with-out services J 1.92E+14 1.27E+05 24.27 62.54


Table 22. Emergy indices and ratios for the drinking water produced at the City of West
Palm Beach Water Treatment Facility.

Note Name of Index Short expression Quantity
15 Emergy Investment Ratio (EIR) (P + S)/(N + R) 1.43
16 Emergy Yield Ratio (EYR) Y/(P + S) 1.70
17 % Renewable emergy 100 x (R/Y) 41.2
18 Emergy Benefit to the Purchaser (EBP) in 1999 Em$/$ 2.46
19 2000 Em-dollar value of potable water per m3 Em$/m3 0.75
20 Transformity of potable water sej/J 1.39E+05
21 Emergy per m3 of potable water sej/m3 6.85E+11


Footnotes to tables 21 and 22 in Appendix B.









2) Surface Water Source: Hillsborough River Water Treatment Plant, Tampa.

Figure 20 shows the systems diagrams of the Hillsborough River Water

Treatment Plant, the principal drinking water source for the city of Tampa, Florida. The

diagram illustrates the main environmental and economic components required to

produce drinking water by this facility.

Table 23 shows the results of the emergy evaluation for the production of

drinking water at the Hillsborough River plant. The numbers of the items listed in the

table correspond to the numbers shown in Figure 20. The calculated transformity,

emergy yield and emergy per volume of this drinking water were 1.87 E5 sej/J, 7.86 E19

sej/yr and 0.92 E12 sej/m3, respectively. The emergy of the chemicals used in the

treatment process had the highest emergy contribution for the production of drinking

water followed by the emergy of river water. Several emergy indices and ratios for the

drinking water produced by this water treatment plant are given in Table 24.



3) Groundwater Source: Murphree Water Treatment Plant, Gainesville.

A systems diagram of the Murphree groundwater treatment plant that supplies

most of Gainesville's drinking water is given in Figure 21. The diagram illustrates the

flows of groundwater, chemicals, energy, materials and services necessary to produce

drinking water in Gainesville.

Table 25 shows the results of the emergy evaluation of the water produced by the

facility. The calculated transformity, emergy yield, and total emergy per volume were

2.95 E5 sej/J, 4.22 E19 sej/yr and 1.46 E12 sej/m3, respectively. The emergy of

groundwater had the highest contribution to the total emergetic value of this drinking









water followed by electricity. Several emergy indices and ratios for the drinking water

produced at the Murphree plant are given in Table 26.



4) Water Conservation as a Source: Tampa Bay.

A systems diagram of the water conservation program developed by Tampa Bay

Water (TBW) is given in Figure 22. The potable water (A) entering the left side of the

interaction symbol is divided by the energy flows entering the top of the symbol (B). The

water demand or output of the water conservation program (C) is proportional to (A/B).

Thus, the water demand (C) equals k(A/B), where k represents a transformation

coefficient. Therefore, as more energy, goods, and services (e.g., B) are assigned to the

water conservation program, the lower the demand for potable water (C).

Table 27 shows the emergy evaluation for TBW's water demand

management/conservation program. The transformity, emergy yield and emergy per

volume of water saved with the conservation program were 3.06 E5 sej/J, 5.09 E19 sej/yr

and 1.51 E12 sej/m3, respectively. The actual potable water saved represented the

greatest emergy input of the conservation program. The second most important emergy

input were water-efficient appliances installed in place of conventional appliances.

Emergy indices for the water saved by this water conservation program are given in

Table 28.












































water source system | drinking water production system

B=biomass; P=price
E=Hillsborough River watershed environment Heat sink
HRWTP=Hillsborough River Water Treatment Plant

Figure 20. Energy systems diagrams of the Hillsborough River Water Treatment Plant, Tampa, Florida. oo
W*











Table 23. Emergy evaluation of the drinking water produced at the Hillsborough River
Water Treatment Plant, Tampa, Florida (62 mgd or 2.72 m3/sec).

Energy Emergy Solar Emergy (sej)
Note Item Unit Data per unit Emergy per m
(unit/yr) (sej/unit) (El8 sej/yr) (E10)
RENEWABLE RESOURCES
1 Surface (river) water used J 4.5E+14 4.26E+04 19.2 22.51

PURCHASED & OPERATIONAL INPUTS
2 Operation & maintenance $ 3.9E+06 1.15E+12 4.5 5.29
3 Labor and services $ 3.7E+06 1.15E+12 4.2 4.97
4 Electricity J 8.7E+13 1.60E+05 13.9 16.28
5 Fuels (oil) J 6.2E+12 6.60E+04 0.4 0.48
6 Chemicals ($) $ 4.0E+06 1.15E+12 4.6 5.38
7 Chemicals (kg) kg 2.8E+07 1.00E+12 28.0 32.90
8 Depreciation & purchased assets $ 9.9E+05 1.15E+12 1.1 1.34
9 Plant Assets (concrete) kg 2.0E+06 1.23E+12 2.4 2.84
10 Plant Assets (steel & iron) kg 1.5E+05 1.80E+12 0.3 0.32
Yield (Y) = Total emergy of drinking water (not including distribution): 78.6 92.29

EMERGY PER UNIT OF POTABLE WATER (not including distribution):
11 Potable water produced m3 8.5E+07 9.2E+11 78.6 92.29
12 Potable water produced $ 2.7E+07 2.9E+12 78.6 92.29
13 Potable water produced J 4.2E+14 1.87E+05 78.6 92.29
14 Potable water produced g 8.5E+13 9.2E+05 78.6 92.29
15 Drinking water with-out services J 4.2E+14 1.7E+05 69.8 82.03


Table 24. Emergy indices and ratios for the drinking water produced at the Hillsborough
River Water Treatment Plant in Tampa.

Note Name of Index Short expression Quantity
16 Emergy Investment Ratio (EIR) (P + S)/(N + R) 3.10
17 Emergy Yield Ratio (EYR) Y/(P + S) 1.32
18 % Renewable emergy 100 x (R/Y) 24.39
19 Ratio of Emergy Benefit to the Purchaser (EBP) in 1996 Em$/$ 2.53
20 2000 Em-dollar value of potable water per m3 Em$/m3 1.01
21 Transformity of potable water sej/J 1.87E+05
22 Emergy per m3 of potable water sej/m3 9.23E+11


Footnotes to tables 23 and 24 in Appendix B.




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