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Geothermal
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in the West
On Aug. 9, the Department of Energy (DOE) teamed up with private industry
to rally for geothermal energy. Their joint efforts “move us one step closer
to our goal of providing 10 percent of the electricity needs of the western
states with geothermal resources by 2020,” says Secretary of Energy Bill
Richardson, who, along with Sen. Harry Reid (D-Nev.), made the announcement. |
Crops surround this
plant in Imperial Valley, Calif. High mineral contents of some southern
California geothermal
reservoirs provide salable by-products like silica and zinc.
Photo courtesy of the
Geothermal Education Office. |
Twenty-one companies plan to expand geothermal activities in California,
New Mexico, Nevada and Utah. The DOE will fund $3.5 million for one year
to increase research and development in small-scale geothermal electric
power plants, enhanced geothermal systems technology and geothermal resource
exploration.
In January, the DOE launched an initiative, GeoPowering the West, to
expand the production of geothermal activities in 19 western states. Other
goals of the initiative include supplying geothermal electricity to at
least 7 million homes by 2010 and doubling to eight the number of states
with geothermal electric power facilities. “Clean, reliable and renewable
energy sources such as geothermal energy can become a significant contributor
to the energy mix in the West,” Richardson says. Especially, he adds, at
a time when parts of the region are experiencing power shortages.
The country currently houses 69 working geothermal electric power plants
at 18 different sites, providing more than 2,700 megawatts (MW) of power
— the equivalent of three large coal-fired or nuclear power plants and
enough to provide electricity to 3.5 million homes. John Lund, Director
of the Geoheat Center at the Oregon Institute of Technology, calculated
the effects of using electricity and direct heat from geothermal resources
rather than conventional coal-fired plants. “Each year the United States
saves 22 million tons of carbon dioxide, 6 million tons of carbon, 41.5
million barrels of oil and 200 thousand tons of sulfur dioxide.” he says.
Geothermal resources come in five forms: hydrothermal fluids, hot dry rock,
geopressured brines, magma and ambient ground heat. Of these five, only
hydrothermal fluids have been developed commercially for power generation.
The state and temperature of water in a reservoir determines what type
of power plant can be built.
Flash-steam power plants built in the 1980s tapped into reservoirs of
water with temperatures greater than 182 degrees Celsius. The hot water
flows up through wells in the ground under its own pressure. As it flows
upward, the pressure decreases and some of the hot water “flashes” into
steam. The Geysers in northern California, which uses steam piped directly
from wells, produces the world’s largest single source of geothermal power.
A third type, known as a binary cycle power plant, operates on water
at lower temperatures of about 107 degrees Celsius to 182 degrees Celsius.
These plants use the heat from the hot water to boil a fluid, usually an
organic compound with a low boiling point.
Generating electricity from geothermal power has some challenges. “It
is hard to compete with the cheap price of natural gas,” says engineer
Manuel Nathenson of the USGS in Menlo Park, Calif. Unlike oil, which is
expensive, and coal, with its environmental issues, natural gas is a plentiful
resource that only needs a slight scrubbing to be considered a clean fuel.
“Natural gas as a way to heat your house is very convenient,” Nathenson
says.
But its value may become questionable in the future, he adds. “With
the run up in oil prices the whole energy economics begins to change.”
If the high oil and gas prices stick, competing energy sources may follow.
“If the price of natural gas comes up then the price of geothermal may
become more competitive.”
Nathan Morris
AGI/AIPG Geoscience Policy Intern
