Nearly Forgotten, Geothermal Could Erupt

A report from an interdisciplinary panel of scientists and engineers released yesterday says that heat from geothermal resources could supply a substantial portion of the energy countries such as the United States will need in the future, at competitive rates and with little environmental impact. The study, organized by the Massachusetts Institute of Technology, examines the viability of new technology to scale up geothermal mining to levels of commercial production not discussed widely for decades, according to a news announcement from MIT.

Sponsored by the U.S. Department of Energy, the 400-plus page study, "The Future of Geothermal Energy: Impact of Enhanced Geothermal Systems (EGS) on the United States in the 21st Century", outlines a plan to use new techniques to efficiently convert the heat from steam or boiling water trapped in the Earth's crust into electricity. It is the first study in some 30 years to take a new look at geothermal, an energy resource that has been largely ignored, in recent times, according to its 18-member panel.

Going back to the 1960s, geothermal energy was considered a potentially limitless source of future power generation. While its promise never matched its initial expectations, for economic and technical reasons, it has become a component of the overall energy marketplace (creating about 8000 megawatts worldwide per year), with the U.S. leading the world in mining it to produce power. However, existing plants to date have focused on high-grade geothermal systems primarily located in the western U.S. The authors of the new MIT study say that they have taken a more ambitious look at the resource and evaluated 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 chief panelist Jefferson W. Tester, 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."

With plants in operation for about a century (the first built in 1904 in Larderello, Italy), geothermal power seems to be something of a late bloomer in the commercial sector. The MIT researchers aim to rectify this situation in the U.S., though, in light of current global developments. 'Recent national focus on the value of increasing our supply of indigenous, renewable energy underscores the need for reevaluating all alternatives, particularly those that are large and well distributed nationally,' they write in the study's preface. 'One such option that is often ignored is geothermal energy, produced from both conventional hydrothermal and enhanced (or engineered) geothermal systems.'

The panelists state in their announcement:

The study shows that drilling several wells to reach hot rock and connecting them to a fractured rock region that has been stimulated to let water flow through it creates a heat-exchanger that can produce large amounts of hot water or steam to run electric generators at the surface. Unlike conventional fossil-fuel power plants that burn coal, natural gas or oil, no fuel would be required. And unlike wind and solar systems, a geothermal plant works night and day, offering a non-interruptible source of electric power.

The study notes that its aim was to investigate whether the implementation of new technologies, such as EGS, could result in the inexpensive and environmentally responsible production of as much as 100 000 megawatts of base-load electric generating capacity in the U.S. in the year 2050. In its conclusion, the panelists state that such a goal is achievable with research, development, demonstration, and deployment funding over the next five decades of approximately US $600 to $900 million, with an absorbed cost of $200 to $350 million.


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