Energy futureDOE, partners test commercial geothermal technology in Nevada
Geothermal energy attracts more and more attention, and for good reason: One cubic kilometer of hot granite at 250 degrees centigrade has the stored energy equivalent of 40 million barrels of oil
One of the more intriguing, and promising, alternative energy sources is Hot Fractured Rock (HFR), or geothermal, energy. U.S. Department of Energy (DOE) has embarked on a project with a number of partners to test Enhanced Geothermal Systems (EGS) technologies at a commercial geothermal power facility near Reno, Nevada. EGS technology enhances the permeability of underground strata, typically by injecting water into the strata at high pressure. The concept was initially developed to create geothermal reservoirs in hot underground strata where no water existed — a technology called “hot dry rock” — but has since been extended as a means of enhancing the performance of existing geothermal reservoirs. Under the DOE project, EGS technology will be tested in a well at the 11-megawatt Desert Peak facility, which is owned by Reno, Nevada-based Ormat Technologies. The well is currently not able to produce commercially useful quantities of hot geothermal fluid, but with the help of EGS, the site is thought to have the potential to produce 50 megawatts of power or more.
DOE, Ormat, and GeothermEx are leading the research and development project, with the participation of the University of Utah, TerraTek, Pinnacle Technologies, the U.S. Geological Survey, and three of DOE’s national laboratories: Idaho National Laboratory, Lawrence Berkeley National Laboratory, and Sandia National Laboratory. DOE is providing $1.6 million to support the project. In addition to the current work on the subcommercial well, the project participants are planning to use the EGS facilities at Desert Peak as a potential test site for future technology developments.
Meanwhile, an application of EGS in a true hot dry rock application in Australia is continuing to make progress (see 28 January 2008 HSDW story). Geodynamics announced on 5 February that the company has completed its production well, called Habanero 3. Any day now, the company should be starting a circulation test by injecting water into Habanero 1 and removing the heated geothermal water from Habanero 3. The test should give the company an indication of the potential power production of the artificially created geothermal reservoir.
HFR technology
Geodynamics published a useful white paper on geothermal energy and climate change. An important point to keep in mind: One cubic kilometer of hot granite at 250 degrees centigrade has the stored energy equivalent of 40 million barrels of oil.
Hot Fractured Rock (HFR) geothermal energy relies on existing technologies and engineering processes, and is the only known source of renewable energy with a capacity to carry large base loads. The concept behind HFR geothermal energy is relatively simple. Heat is generated by special high heat producing granites located three km or more below the Earth’s surface. The heat inside these granites is trapped by overlying rocks which act as an insulating blanket. The heat is extracted from these granites by circulating water through them in an engineered, artificial reservoir or underground heat exchanger. HFR geothermal energy relies on existing technologies and engineering processes such as drilling and hydraulic fracturing, techniques used by the oil and gas industry. Standard geothermal power stations convert the extracted heat into electricity. HFR geothermal energy is environmentally clean and does not produce greenhouse gases. It has been classified as renewable energy by national and international authorities.
