Geothermal Energy Production Waste Scales
Using geothermal energy requires drilling deep holes (boreholes) and inserting pipes for pumping high-temperature fluids from the ground. The rocks that contain the high-temperature fluids may also contain minerals, which tend to form a scale inside the pipes and production equipment. If the rocks also contain radionuclides, such as radium, the mineral scale, production sludges, and waste water will contain TENORM [ie. Technologically Enhanced Naturally-Ocurring Radioactive Materials] .
Geothermal energy currently makes a relatively minor contribution to total U.S. energy production. The primary geothermal development sites in the U.S. are the Geysers, in Sonoma County in northern California, and the Imperial Valley in southern California. The only significant TENORM wastes from geothermal power production are the solid wastes originating from the treatment of spent brines such as in Imperial Valley.The hot saline fluids from geothermal reservoirs in that area may have a dissolved solids content approaching 30 percent by weight. The estimated annual generation rate of geothermal energy production waste is 54 thousand metric tons.
Because of unsuitable physical characteristics, solid geothermal wastes are not reused, but disposed of in solid waste landfills.
A few facilities are also considering process of these wastes to extract valuable minerals (gold, sliver, and platinum).
The table below shows the estimated average activity in geothermal wastes, based on data from southern California geothermal power production facilities:
Geothermal Energy Waste Scales Radiation Level
low average high
10 132 254 [pCi/g]
0.37 4.9 9.4 [Bq/g]
370 4,900 9,400 [Bq/kg]
Radiation in TENORM Summary Table http://www.epa.gov/radiation/tenorm/sources_table.htm
One curie of radioactive material will have 37 billion atomic transformations (disintegrations) in one second.
Calpine Geysers Announce Five-Year Geothermal Energy Deal
by Staff Writers
San Jose CA (SPX) Jun 08, 2007
Calpine Corporation, the nation's largest renewable, geothermal power provider, has announced the launch of a five-year, multi-million dollar green power program designed to increase power production by up to 80 megawatts at the company's Geysers geothermal operations in northern California.
The program includes a new, two-year multi-rig drilling program to expand steam production and identify new sources of geothermal power and also to rebuild eight older geothermal turbines to make them even more energy-efficient.
May added that Calpine anticipates spending $200 million to initiate the repowering and exploration phase of the program and would consider further development at The Geysers if Calpine is able to enter into long term power sales contracts.
Located about 100 miles north of San Francisco, The Geysers is the single-largest geothermal operation in the world, with Calpine's portfolio of units there generating 725 megawattsof renewable energy. It is one of California's most beneficial domestic energy resources, representing about 25 percent of the state's renewable energy production.
Geothermal power plants take advantage of a natural, clean energy source -- heat from the earth's interior -- to produce electricity. Because these plants do not burn fossil fuel, they have an inherent environmental advantage.
Calpine owns 19 of the 21 geothermal units at The Geysers and a vast network of steam fields, making Calpine California's largest renewable energy provider. Unlike other renewable energy resources like wind and solar, geothermal power plants continuously generate electricity so Calpine's geothermal units run with near-perfect (97%) availability 24-hours a day, seven days a week. Because they interconnect with five separate major transmission lines, they can deliver electricity throughout California.
Calpine will be tapping production and exploratory wells -- some as deep as 11,000 feet -- to expand steam production and to identify new sources of geothermal power.To further enhance production, the company is committing to rebuild many of its older facilities for higher efficiencies and to sustain clean, reliable geothermal generation for decades to come.
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