Google.org-Funded U.S. Study Finds 'Hot Pockets' of Geothermal Energy Coast-to-Coast

West Virginia has always been known as coal country, but now an alternative energy sector is heating up in that region. Significantly high temperatures have been discovered beneath the Earth’s crust in the southeastern United States, indicating a generous source of previously untapped geothermal energy.

A three-year research project, executed by Dallas-based Southern Methodist University’s Geothermal Laboratory and funded by a $10 million grant from Google (News - Alert).org, documents substantial geothermal resources across the United States; capable of producing more than 3 million megawatts (MW) of green power —10 times the installed capacity of coal power plants today.

The study, led by Principal Investigator and Hamilton Professor of Geophysics David Blackwell, Ph.D., used tens of thousands of new thermal data points to create the most data rich perspective on US geothermal resources to date. The full results can be seen in the updated Google Earth layer on U.S. Geothermal Resources and in SMU’s paper to be presented at the Geothermal Resources Council Annual Meeting this week in San Diego.

The SMU research team—which also includes Lab Coordinator Maria Richards; and Zachary Frone, Joseph Batir, Ryan Dingwall, Andrés Ruzo, and Mitchell Williams —has been developing entirely new pictures of the Earth's geothermal resources.

They started by aggregating thousands of new Bottom Hole Temperature (BHT) readings from oil, gas, and water wells in previously under-sampled regions of the United States to create updated temperature-at-depth maps from 3.5 kilometers to 9.5 kilometers (11,500 to 31,000 feet). For example, The 2004 Geothermal Map of North America used only five heat flow points to inform its geothermal estimates for West Virginia, compared to the additional 1,455 BHT points in the updated version. In addition, the team has improved estimates of heat flow through the Earth's crust with better regional lithologic (e.g., from the study of rocks) data.

The results of the new research confirm and refine locations for resources capable of supporting large-scale commercial geothermal energy production under a wide range of geologic conditions, including significant areas in the eastern two-thirds of the United States. Areas of particular geothermal interest include the Appalachian trend (Western Pennsylvania, West Virginia, to northern Louisiana); the aquifer (underground area of porous rock) heated area of South Dakota; and the areas of radioactive basement granites beneath sediments such as those found in northern Illinois and northern Louisiana. In addition, the Gulf Coast continues to be a huge resource area and a promising sedimentary basin for development. The Raton Basin in southeastern Colorado possesses extremely high temperatures and is being evaluated by the State of Colorado along with an area energy company

Conventional U.S. geothermal production has been restricted largely to the western third of the country in geographically unique and tectonically active locations.  For instance, The Geysers Field — a complex of 22 geothermal power plants, drawing steam from more than 350 wells, located in the Mayacamas Mountains 72 miles north of San Francisco —has tapped naturally occurring steam reservoirs to produce electricity for more than 40 years.

However, today, newer technologies and drilling methods can be used to develop resources in a wider range of geologic conditions, allowing reliable production of clean energy at temperatures as low as 100�C (212�F) – and in regions not previously considered suitable for geothermal energy production. Preliminary data released from the SMU study in October 2010 revealed the existence of a geothermal resource under the state of West Virginia equivalent to the state’s existing (primarily coal-based) power supply.

"Once again, SMU continues its pioneering work in demonstrating the tremendous potential of geothermal resources,” said Karl Gawell, executive director of the Washington, D.C.-based Geothermal Energy Association. “Both Google and the SMU researchers are fundamentally changing the way we look at how we can use the heat of the Earth to meet our energy needs, and by doing so are making significant contributions to enhancing our national security and environmental quality."

“This assessment of geothermal potential will only improve with time,” said Blackwell.  “Our study assumes that we tap only a small fraction of the available stored heat in the Earth’s crust, and our capabilities to capture that heat are expected to grow substantially as we improve upon the energy conversion and exploitation factors through technological advances and improved techniques.”

Blackwell and Richards first produced the 2004 Geothermal Map of North America using oil and gas industry data from the central United States.  Blackwell and the 2004 map played a significant role in a 2006 Future of Geothermal Energy study sponsored by the U.S. Department of Energy, which concluded that geothermal energy had the potential to supply a substantial portion of future U.S. electricity needs—likely at competitive prices and with minimal environmental impact. To date, SMU’s 2004 map has been the national standard for evaluating heat flow, temperature, and thermal conductivity for potential geothermal energy projects.

In determining the potential for geothermal production, the new SMU study considers the practical considerations of drilling, and limits the analysis to the heat available in the top 6.5 km (21,500 ft.) of crust for predicting megawatts of available power. This approach incorporates a newly proposed international standard for estimating geothermal resource potential that considers added practical limitations of development, such as the inaccessibility of large urban areas and national parks.  Known as the “technical potential’” value, it assumes producers tap only 14 percent of the ‘theoretical potential’ of stored geothermal heat nationwide, using currently available technology.

Three recent technological developments already have sparked geothermal development in areas with little or no tectonic activity or volcanism:

1.     Low Temperature Hydrothermal – Energy is produced from areas with naturally occurring high fluid volumes at temperatures ranging from less than boiling to 150°C (300°F). This application is currently producing energy in Alaska, Oregon, Idaho and Utah.

2.     Geopressure and Coproduced Fluids Geothermal – Oil and/or natural gas are produced together with electricity generated from hot geothermal fluids drawn from the same well. Systems are installed or being installed in Wyoming, North Dakota, Utah, Louisiana, Mississippi and Texas.

3.     Enhanced Geothermal Systems (EGS) – Areas with low fluid content, but high temperatures of more than 150°C (300°F), are “enhanced” with injection of fluid and other reservoir engineering techniques. EGS resources are typically deeper than hydrothermal and represent the largest share of total geothermal resources capable of supporting larger capacity power plants.

A key goal in the SMU resource assessment was to aid in evaluating these nonconventional geothermal resources on a regional to sub-regional basis.