DEPARTMENT OF PLANNING AND NATURAL RESOURCES
VIRGIN ISLANDS ENERGY OFFICE
45 ESTATE MARS HILL
FREDERIKSTED, VIRGIN ISLANDS 00840 -
TELEPHONE 340 773-1082 STX FAX 340 772-0063
340 774-3320 STT FAX 340 714-9531
Geothermal energy is the natural heat of the earth stored deep below the earth's
surface. The energy is found near areas where volcanic activity has taken place,
either recently or many years ago. It can be in the form of steam, hot liquid, or hot
dry rock. Wells drilled deep into the ground bring steam and hot water to the
In areas where geothermal steam or hot fluids are thought to be within economic
reach of drilling equipment, wells are drilled to bring the steam or hot fluids to the
surface. The steam, or steam produced by the fluids in a heat exchange process, is
used to drive a turbine generator to make electricity. Modern technology allows
spent geothermal fluids and non-condensable gases to be reinjected back into the
ground, eliminating surface disposal and air pollution.
Geological, geochemical, and geophysical techniques are used to locate geothermal
Drilling for geothermal resources has been adapted from the oil industry. Improved
drill bits, slim hole drilling, advanced instruments, and other drilling technologies
are under development.
Geothermal hot water near the Earth's surface can be used directly for heating
buildings and as a heat supply for a variety of commercial and industrial uses.
Geothermal direct use is particularly favored for greenhouses and aquaculture.
Geothermal Heat Pumps
GEOTHERMAL HEAT PUMP Geothermal heat pumps, or ground-source heat pumps, use
the relatively constant temperature of soil or surface water as
a heat source and sink for a heat pump which provides
heating and cooling for buildings.
Closed Horizontal Loop
Underground reservoirs of hot water or steam, heated by an upwelling of magma,
can be tapped for electrical power
Power Lines Generating Plant
Advanced Technologies Production Well
Advanced technologies will help Injecion wel
manage geothermal resources for
maximum power production, improve
plant-operating efficiencies, and Geothemal Reservoir
develop new resources such as hot dry
rock, geopressured brines, and
ADVANTAGES AND DISADVANTAGES
Geothermal energy can be used instead of fossil fuels to
produce electricity. Replacing fossil fuels will reduce the
amount of air pollutants that can cause acid rain and contribute
to global warming.
Direct-use geothermal heat and some of its mineral by-products
have been successfully demonstrated in aiding agricultural
production; drying lumber, fruits and vegetables; assisting
certain manufacturing processes; and for art purposes.
During normal operations, stringent permit conditions, state-of-
the-art abatement systems, and process design should virtually
eliminate unpleasant odors and mitigate noise impacts from
new geothermal facilities.
The exploration and development of geothermal resources can
be permitted within conservation, agricultural, rural, and urban
residential areas where some residents may not want
geothermal activities to occur.
Geothermal wells are sometimes vented for a few hours to clear
the well and pipelines resulting in a temporary release of steam
and abated gases. Such events can be noisy for a short time.
Some continuous low-level noise is also generated during
normal power plants.
Geothermal Energy Program: www.eren.doe.gov/geothermal/
Geothermal Education Office: www.geothermal.marin.org