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Google digs into wallet for geothermal energy to invest in enhanced geothermal system start-ups--AltaRock and Potter Drilling--and gives grant to study the potential of renewable geothermal energy.

Google is investing $10 million in "enhanced" geothermal systems--essentially technology for tapping underground heat--which it says is one of most promising forms of renewable energy.

Through its philanthropic arm, the Internet giant will invest in two geothermal technology start-up companies and give a university grant to study the potential of geothermal resources.

Heat underfoot: a Google Earth representation of geothermal resources. Click the image for a larger view. Google Earth

The move is part of's RE<C (shorthand for Renewable Energy Less than Coal), an initiative with the goal of producing one gigawatt of electricity--larger than a typical coal-fired power plant--through renewable sources.

Google has invested in solar thermal companies eSolar and BrightSource Energy as well as wind company Makini Power. It has also installed a large 1.6-megawatt solar array, established a plug-in hybrid station at its headquarters, and spearheaded energy-efficient computing programs like Climate Savers.

The latest investments are meant to spur development of geothermal, which a Massachusetts of Institute of Technology study last year found was underutilized. Like fossil fuel power plants, geothermal plants can supply electricity during peak times, while wind and solar have limitations in this regard.

Mixing water and hot rocks
The two companies Google is investing in--AltaRock Energy and Potter Drilling--focus specifically on so-called enhanced geothermal technology.

Typically, geothermal plants, which are in the Western U.S., tap into existing wells of hot water or steam thousands of feet underground. The retrieved hot water or steam turns a steam turbine to make electricity.

Enhanced geothermal technology pumps water underground to crack hot rocks. The heated water or steam is captured to turn a turbine and then pumped back down underground.

The U.S. Department of Energy says that these advanced techniques can dramatically increase geothermal potential--by 40 times.

"EGS (enhanced geothermal systems) could be the 'killer app' of the energy world. It has the potential to deliver vast quantities of power 24/7 and be captured nearly anywhere on the planet. And it would be a perfect complement to intermittent sources like solar and wind," Dan Reicher, director of climate and energy initiatives for, said in a statement.

Google is putting $6.25 million into AltaRock Energy, part of a larger $26.5 million second round of investment. First round investors included high-profile green-tech venture capital firms Khosla Ventures and Kleiner Perkins Caufield & Byers.

AltaRock Energy is looking to develop a cost-effective method for pumping water underground and recuperating it. It plans to launch a pilot project and is targeting utilities in Western U.S. states that have renewable energy mandates. will also invest $4 million in two separate "tranches" into Potter Drilling, which is making drilling products designed for hard-rock environments like granite. The technology can also be used for carbon capture and storage and nuclear waste storage.

Meanwhile, Southern Methodist University's Geothermal Lab will get a $489,521 grant to study the size and distribution of geothermal energy resources in North America.

While geothermal power plants are now in the Western U.S., the MIT study found that large-scale geothermal power production can be done in some parts of the Eastern U.S.

In an FAQ, said that development of enhanced geothermal systems means that renewable energy "could conceivably be deployed almost anywhere, and is essentially limitless in supply."

Reicher said enhanced geothermal system technology "hasn't received the attention it merits." is pressing for policies and commercial investment to better encourage EGS development.

Google is also said to have been in discussions with Israeli geothermal company Ormat Technologies.

For a discussion about's geothermal investment and the growing interest in clean tech, see the Daily Debrief video.