SOLUTIONS
Natural & Enhanced Geothermal Power
Geothermal energy, heat emanating from the planet’s interior, is an inexhaustible, essentially limitless, carbon-neutral resource. It is estimated to be equivalent to 42 million megawatts of power. To generate electricity from geothermal resources, wells are drilled into the natural hot water or superheated steam of a geothermal reservoir, a long way below the groundwater table. The wells bring geothermal liquid to the surface, where it is converted at a power plant into electricity (steps 1-6 in the illustration above). Alternatively, direct-use applications utilize geothermal heat for space heating or industrial processes. Direct use traces back to Roman times.
In 2000, 21 countries generated 8660MW of electricity from natural geothermal power sources. The U.S. has geothermal power in Alaska, California, Hawaii, Nevada and Utah. In Iceland, 87% of heating and 17% of electricity comes from geothermal sources. Indonesia and Mexico generate 2000MW and 953MW respectively. New Zealand has major developments in its Rotorua region. China operates several plants in Tibet, and makes direct use of its extensive low-temperature resources. By 2010, it is estimated that 13500MW will be generated in 40 countries.
Enhanced Geothermal Systems (EGS), mining deep geothermal heat to produce electricity, is under development in France, Switzerland and Australia. A recent review by the Massachusetts Institute of Technology, MIT, found this technology could be applied essentially anywhere, since advances in oil drilling technology now permit drilling as much as 6 miles down into solid rock. Power plants inject water down one such well, passing it through crevices in hot rock, and then extracting steam through another well. Drilling is currently 60% of the cost of commissioning a 1000MW EGS plant, but research would dramatically reduce this. MIT states that EGS plants could produce 100,000MW in the U.S. by 2050; equivalent to 200 large coal-burning plants.