RE-Powering America's Land:
Geothermal Technologies
Siting Renewable Energy on Potentially Contaminated Land and Mine Sites
A geothermalpower plant in Mammoth Lakes, CA
How much geothermal potential exists
on contaminated sites?
Flash power plant -173 sites
Resource temperature >149°C (SOOT) Well depth < 4.5 km
Distance to transmission lines < 10 miles Acreage >10 acres
Distance to graded roads < 25 miles
Binary power plant - 474 sites
Resource temperature > 93°C (200°F) Well depth < 3 km
Distance to transmission lines< 10miles Acreage >10 acres
Distance to graded roads < 25 miles
Geothermal heat pump -9,112 sites
All sites are considered viable for geothermal heat pumps,
though sites with near surface temperatures of 10°C (50°F) to
24°C(75°F) are preferred.
What is the RE-Powering America's Land initiative?
Demand for renewable energy is increasing in the United States.Through
its RE-Powering America's Land: Siting Renewable Energy on Potentially
Contaminated Land and Mine Sites initiative, the U.S. Environmental
Protection Agency (EPA) identified more than 11,000 EPA tracked sites
and nearly 15 million acres that have potential for developing solar, wind,
biomass and geothermal facilities. Using potentially contaminated land and
mine sites to develop renewable energy facilities can preserve greenfields;
provide developers with access to existing infrastructure; create jobs; and
enable potentially contaminated property to return to a productive and
sustainable use.
What is geothermal energy?
Geothermal energy is extracted from
heat stored in the earth. This heat
comes from the original formation
of the planet, radioactive decay of
minerals, tectonic activity and solar
energy absorbed at the surface.
Geothermal facilities use this heat
to generate electricity. Three types
of geothermal production were
evaluated for this study:
• Flash power plant - Uses geothermal reservoirs of water with very high
temperatures that flow up through wells in the ground under its own
pressure. As it flows upward, the pressure decreases and some of the hot
water boils into steam. The steam is then separated from the water and
used to power a turbine that generates electricity.
• Binary power plant - Uses the heat from lower temperature geothermal
resources to boil a working fluid, usually an organic compound with a low
boiling point. The working fluid is vaporized in a heat exchanger and used
to turn a turbine that generates electricity.
• Geothermal heat pump -The upper 10 feet of the earth maintains a nearly
constant temperature between 50° and 60°F (10°-16°C). Geothermal heat
pumps take advantage of this resource to heat and cool buildings using
significantly less energy.
What are some examples of geothermal facilities being
successfully sited on contaminated land?
Some formerly contaminated sites are using geothermal heat pumps. The
Green Institute in Minneapolis, Minnesota, a former brownfield site, uses a
geothermal heat pump to regulate the building's temperature. According to an article posted by the National Renewable Energy
Laboratory (NREL) entitled Geothermal Developers Remain Optimistic, there is increased interest in geothermal energy production.
Installed geothermal power generation capacity increased by approximately 4% since 2007.
EPA tmckedsites with geothermal binary power plant potential
Estimating total technical potential
Geothermal technical potential for EPA tracked sites:
more than 3,200 MW
Market potential -The portion of the
economic potential that could be achieved
given current costs, policies and
technical constraints.
Economic potential - The portion of the
technical potential that is economically
viable, but requires additional policies to
break down market barriers.
Technical potential - Potential that is
technically possible, without consideration •
of cost or practical feasibility.
For more information on geothermal technologies, visit:
www.nrel.gov/learning/re_geothermal.html
For more information, visit www.epa.gov/renewableenergyland or contact cleanenergy@epa.gov
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