New research from SMU’s Geothermal Laboratory, funded by a grant from Google.org, documents significant geothermal resources across the United States capable of producing more than three million megawatts of green power – 10 times the installed capacity of coal power plants today. Sophisticated mapping produced from the research is viewable via Google Earth at www.google.org/egs. Image: Google Earth, SMU Geothermal Laboratory |
New
research from Southern Methodist University’s Geothermal Laboratory, funded by a grant from
Google.org, documents significant geothermal resources across the United
States capable of producing more than three million megawatts of green
power—10 times the installed capacity of coal power plants today.
Sophisticated mapping produced from the research, viewable via Google Earth at http://www.google.org/egs/,
demonstrates that vast reserves of this green, renewable source of
power generated from the Earth’s heat are realistically accessible using
current technology.
The
results of the new research, from SMU Hamilton Professor of Geophysics
David Blackwell and Geothermal Lab Coordinator Maria Richards, 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. The estimated amounts and locations of heat stored in
the Earth’s crust included in this study are based on nearly 35,000 data
sites—approximately twice the number used for Blackwell and Richards’
2004 Geothermal Map of North America, leading to improved detail and
contouring at a regional level.
Based
on the additional data, primarily drawn from oil and gas drilling,
larger local variations can be seen in temperatures at depth,
highlighting more detail for potential power sites than was previously
evident in the eastern portion of the U.S. For example, eastern West
Virginia has been identified as part of a larger Appalachian trend of
higher heat flow and temperature.
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 north of San Francisco is
home to more than a dozen large power plants that have been tapping
naturally occurring steam reservoirs to produce electricity for more
than 40 years.
However,
newer technologies and drilling methods can now 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 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
is scheduled to release a paper with details of the results of the
research to the Geothermal Resources Council in October 2011.
Blackwell
and Richards first produced the 2004 Geothermal Map of North America
using oil and gas industry data from the central U.S. 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 that concluded
geothermal energy had the potential to supply a substantial portion of
the future U.S. electricity needs, likely at competitive prices and with
minimal environmental impact. SMU’s 2004 map has been the national
standard for evaluating heat flow, temperature and thermal conductivity
for potential geothermal energy projects.
In
this newest SMU estimate of resource potential, researchers used
additional temperature data and in-depth geological analysis for the
resulting heat flow maps to create the updated temperature-at-depth maps
from 3.5 km to 9.5 km (11,500 to 31,000 feet). This update revealed
that some conditions in the eastern two-thirds of the U.S. are actually
hotter than some areas in the western portion of the country, an area
long-recognized for heat-producing tectonic activity. 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% of the ‘theoretical potential’ of stored geothermal heat in the
U.S., 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.
Areas
of particular geothermal interest include the Appalachian trend
(Western Pennsylvania, West Virginia, to northern Louisiana), the
aquifer heated area of South Dakota, and the areas of radioactive
basement granites beneath sediments such as those found in northern
Illinois and northern Louisiana. The Gulf Coast continues to be outlined
as 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.
SMU’s
Geothermal Laboratory in Dedman College of Humanities and Sciences
conducted this research through funding provided by Google.org, which is
dedicated to using the power of information and innovation to advance
breakthrough technologies in clean energy.
Editor’s
Note: To explore the new Enhanced Geothermal Systems maps built on
SMU’s research via Google Earth, download the latest version of Google
Earth at http://www.google.com/earth/ and then download and open the file at http://www.google.org/egs/downloads/EGSPotential.kmz.
