'Heat Mining' as energy source

MIT-led panel backs 'heat mining' as key U.S. energy source

A comprehensive new MIT-led study of the potential for geothermal energy within the United States has found that mining the huge amounts of heat that reside as stored thermal energy in the Earth's hard rock crust could supply a substantial portion of the electricity the United States will need in the future, probably at competitive prices and with minimal environmental impact.

An 18-member panel led by MIT prepared the 400-plus page study, titled "The Future of Geothermal Energy." Sponsored by the U.S. Department of Energy, it is the first study in some 30 years to take a new look at geothermal, an energy resource that has been largely ignored.

The goal of the study was to assess the feasibility, potential environmental impacts and economic viability of using enhanced geothermal system (EGS) technology to greatly increase the fraction of the U.S. geothermal resource that could be recovered commercially.

Although geothermal energy is produced commercially today and the United States is the world's biggest producer, existing U.S. plants have focused on the high-grade geothermal systems primarily located in isolated regions of the west. This new study takes a more ambitious look at this resource and evaluates its potential for much larger-scale deployment.

"We've determined that heat mining can be economical in the short term, based on a global analysis of existing geothermal systems, an assessment of the total U.S. resource and continuing improvements in deep-drilling and reservoir stimulation technology," said panel head Jefferson W. Tester, the H. P. Meissner Professor of Chemical Engineering at MIT.

"EGS technology has already been proven to work in the few areas where underground heat has been successfully extracted. And further technological improvements can be expected," he said....

In its report, the panel recommends that:

• More detailed and site-specific assessments of the U.S. geothermal energy resource should be conducted.

• Field trials running three to five years at several sites should be done to demonstrate commercial-scale engineered geothermal systems.

• The shallow, extra-hot, high-grade deposits in the west should be explored and tested first.

• Other geothermal resources such as co-produced hot water associated with oil and gas production and geopressured resources should also be pursued as short-term options.

• On a longer time scale, deeper, lower-grade geothermal deposits should be explored and tested.

• Local and national policies should be enacted that encourage geothermal development.

• A multiyear research program exploring subsurface science and geothermal drilling and energy conversion should be started, backed by constant analysis of results.