A three-year project supported by Google.org, the company's philanthropic arm, gives a clearer picture of geothermal energy in the United States. In short, there's a lot of it, especially if enhanced geothermal systems or other advanced technologies are used.
The study conducted by SMU Geothermal Laboratory incorporated tens of thousands of new thermal data points to create the most data rich perspective on U.S. geothermal resources to date, according to a Google.org's blog. The study aimed to measure the potential of enhanced geothermal systems (ESG) in the continental United States. UPDATE: Several astute readers noticed the legend in the geothermal map was incorrect. I've replaced it with a corrected version.
The project estimates that "technical potential" for the continental U.S. exceeds 2,980,295 megawatts using EGS and other advanced geothermal technologies such as low temperature hydrothermal, according to Google.org. To put that into perspective, currently there is 9,000 MW of traditional geothermal generating capacity installed in 24 countries around the world. The United States, the world's largest geothermal energy producer, has about 2,800 MW of installed capacity, which generates enough electricity to power roughly 2.8 million homes.
For the full results, check out the updated Google Earth layer. The new map shows EGS potential for depths from 3 kilometers to 6.5 kilometers and excludes inaccessible zones including national parks and protected lands.
What is EGS?
Traditional geothermal energy involves locating and then drilling into naturally occurring pockets of hot water and steam. The amount of power that can be produced is dependent on the temperature and size of these pockets. Geothermal power isn't a primary energy source largely because these "pockets" are limited and dispersed widely across the United States.
EGS takes the basic concept of geothermal energy and uses technology to tap into the heat located under the Earth's crust and replicate the naturally occurring water pockets. Theoretically, EGS can be developed anywhere there is hot rock -- meaning any rock above 150 degree Celsius. The process involves fracturing hot rock and then circulating water through an underground system, which creates steam to drive a turbine and produce electricity. The water is then re-injected back into the rock, where the closed-loop cycle begins again.
Google's geothermal investments
Right now, drilling deep into hot rock is expensive and most EGS is done in shallow, high temperature areas. But as drilling technology improves it could become economical enough to reach deeper resources and produce energy on a commercial scale. Google.org has spent nearly $11 million to help advance EGS, including a $4 million investment into Potter Drilling to develop breakthrough hard rock drilling technologies and $6.25 million into AltaRock Energy.
Check out this Google.org created animation of the 50 megawatt Habanero EGS system under development in Australia.
Photo: SMU Geothermal Laboratory via Google.org