Tapping the Power in Hot Rocks

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So-called geothermal power has been around for more than a century. What will it take to heat up this energy source?

David Biello reports

On September 25, 1960, the first turbine at the world's largest geothermal power plant started spinning. Using the steam created by hot rocks deep beneath California, The Geysers power plant has been pumping out 6 million megawatt-hours of power a year ever since—and it remains the world's largest such geothermal power plant 50 years later.

Geothermal power has a lot of advantages: no CO2 emissions, renewable if used correctly and constantly available. Unlike other renewables, such as the wind or sun, the Earth's heat never stops. Scientists estimate that geothermal alone could supply 2,000 times the amount of energy used by the U.S. annually.

That's why the U.S. Department of Energy is investing at least $35 million in a bid to expand its use. As is Google. And countries from Indonesia to Guatemala are also looking to expand its use. Australian companies have even begun drilling wells for new, entirely man-made geothermal power plants.

But The Geysers remains the world's largest such power plant for two simple reasons: cost and risk. Drilling a well to the depths required is expensive, time-consuming and there is no guarantee of success. Perhaps the best way to expand geothermal is to pair it with another industry that likes to poke holes deep beneath the Earth: oil and gas.

After all, the world could use more CO2-free forms of energy generation and this one's just a few kilometers beneath our feet.

—David Biello

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http://www.scientificamerican.com/article.cfm?id=geothermal-drilling-earthquakes