Geothermal: Renewable Energy Stealth Candidate

by Erik Larson | November 3, 2008 at 09:10 am

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The current investment in Geothermal energy is dwarfed by what's being put into wind and solar, but this is changing thanks to high energy prices, social pressure for clean, renewable energy sources, and breakthroughs in technology. The amount of heat trapped in the Earth's first 6 miles of crust is said to be more than 50,000 times the the heat energy contained in all the world's oil and natural gas supplies. The problem has been extracting it, and the huge upfront costs; once facilities are in place, electricity can be produced cleanly and silently for 4-7 cents/kwh, competitive with wind, and much cheaper than today's solar prices (which are dropping fast). A new technique called Enhanced Geothermal Systems (EGS) promises to lower costs and make it possible to develop geothermal in new places; traditional technology involves tapping hot water/steam resources already underground, EGS pumps water underground to be heated, and extracts the steam, returning it underground after it's turned the turbines.

"There's no smoke. Very little noise," said Paul Thomsen, director of policy and business management for Ormat Technologies Inc., which owns the operation. "People don't even know it's here."

Geothermal energy may be the most prolific renewable fuel source that most people have never heard of. Although the supply is virtually limitless, the massive upfront costs required to extract it have long rendered geothermal a novelty. But that's changing fast as this old-line industry buzzes with activity after decades of stagnation.

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Some say the key to harnessing this energy source on a massive scale lies with a technology known as enhanced geothermal systems, or EGS for short. The idea is to engineer the necessary conditions by pumping water into the Earth's crust and fracturing the hot rocks below. Heat from the Earth warms the water, whose resulting steam is channeled back to the surface, powering turbines to create electricity. The water is then pumped back underground.

Though still in its infancy, EGS has the potential to open up much of the planet to geothermal development. Tiny plants are already online in France and Germany. More than 30 EGS firms are engaged in exploration and development in Australia.