Hot Rocks, Cool Technology: Greener Than Wind or Solar, Geothermal Energy Gets Little Attention-Even Though, as Nick Schulz Writes, It Could Provide 2,000 Times Our Current Power Needs

Article excerpt

A PROMISING, BUT LARGELY unrecognized, source of clean, renewable energy is right beneath your feet. It's geothermal energy, which comes from the super-hot rocks just under the Earth's crust. The United States is the global leader in geothermal, which provides about the same amount of power as the combined output of wind and solar energy, says MIT geophysicist M. Nail Toksoz. That's not much, but it could be a great deal more. Right now, geothermal gets little attention-from environmentalists, traditional energy companies, or governments.

This lack of attention is all the more surprising since geothermal is a greener source of power than either solar or wind. But if several intrepid scientists and engineers are right, advanced-technology geothermal will get the respect it now lacks.

The idea is simple--tapping underground heat to generate electricity. The Earth's core emits enormous amounts of heat, which, when combined with water--either naturally in hydrothermal reservoirs, or artificially--creates the steam needed to turn a turbine and produce electricity.

The idea isn't new. Geothermal electricity was first generated in 1904 in Larderello, Italy, in a part of Tuscany called Valle del Diavolo--Valley of the Devil, known for boiling liquids that rise to the surface. Italian engineers slapped an electricity generator on top of their Hades, and the first geothermal installation was born. Today, Iceland generates 15 to 20 percent of its electricity this way.

The problem for large-scale development of geothermal energy is that the planet's underground heat is not evenly distributed. In the U.S., for example, hot rocks are closer to the surface in Western states such as California, Utah, and Nevada than elsewhere. The largest and best-known U.S. geothermal installation is located at The Geysers,just north of San Francisco. Run by the Calpine Corporation, this field generates more electricity than any other in the world: 850 megawatts--enough to provide power for a million households.

In the 1970s, scientists affiliated with the Los Alamos National Laboratory wondered if they could tap heat located far deeper underground. If so, they figured, geothermal energy could be harnessed just about anywhere. They established the technological foundation for what they called Hot Dry Rock heat extraction and patented the idea in 1974.

Under this process (also known as Enhanced Geothermal Systems or "EGS"), wells are drilled into burning subterranean rock, which can be miles below the surface. Water is pumped down at high pressure, creating a reservoir amid the cracks and fissures in the rock. The water is returned to the surface, where hydrothermal energy is extracted to create electricity. The water is then recirculated. According to a paper from Los Alamos scientists, "In this closed-loop process, nothing is released to the environment except heat, and no long-term wastes accumulate." Unlike with fossil fuels, no C[O.sub.2] or other greenhouse gases are produced.

And the ecological advantages geothermal enjoys over other alternatives are considerable. …