Geothermal energy, heat energy derived below the earth’s surface, could be a dependable source of renewable energy. Depending on the temperature of the underground reservoir, the heat energy available can be used in a wide variety of applications including electricity generation or district heating and cooling. Opportunities for tapping its potential are expanding as new technology approaches, like use of directional drilling and pressurized water, continue to emerge.
Although conventional geothermal power production is limited to near-surface activity in naturally occurring hydrothermal systems, technological advances in enhanced geothermal systems (EGS) are enabling heat extraction in locations that were once considered uneconomical or impossible to tap.
Understanding the subsurface is key to effectively and efficiently developing geothermal resources. That’s where NETL’s fossil energy expertise and distinctive geologic-geostatistical capabilities come into play. Custom models developed by NETL scientists are enabling an unprecedented “look” at geothermal systems and opening windows of opportunity. NETL research is playing a key role in geothermal projects across the nation that could someday have a positive effect on the energy future of millions of Americans.
Newberry Volcano, Oregon
In central Oregon, the Newberry Volcano represents a potential resource for geothermal energy with temperatures exceeding The Geysers of California—currently the world’s largest producer of geothermal power. The volcano displays favorable heat flow and natural rock permeability that are crucial to the production of EGS energy. Its proximity to population centers, power transmission lines, and water supply all make the Newberry Volcano a promising location for developing EGS.
Interest in developing the Newberry Volcano’s geothermal potential led to many datasets on the volcano’s subsurface, but industry decision-makers have lacked an effective way to analyze all the data collected. For example, in exploring resources like the Newberry Volcano, researchers must take into account all information and data related to safety to reliably explore its resource potential. To do that, they need a platform to integrate historical data for comparison with new findings.
NETL researchers created two three-dimensional computer models of the Newberry subsurface. A geologic model integrates geological observations and interpretations, and provides a synthesis of knowledge to date. A geophysical model provides researchers with a specific interpretation of Newberry’s subsurface based on various geophysical data sets.
Using the team’s models, researchers are able to visualize subsurface geology layer-by-layer and study important features such as heat capacity, porosity, and permeability. By viewing side-by-side comparisons, researchers can identify correlations that will help reduce subsurface uncertainty and provide a clearer understanding of how geologic features are arranged, thereby improving predictions for potential EGS sites.
Research to establish EGS at Newberry Volcano is ongoing. This September 2017, an international group of geoscience experts, including those from NETL, will meet to develop a proposal for the EGS site at Newberry Volcano.
City of Wells, Nevada
In the City of Wells, Nevada, spatial and subsurface analytical tools developed by NETL are being used to synthesize datasets and assess opportunities for deep direct-use of geothermal energy.
Wells is located a short drive away from Elko, Nevada—a city which has proven to be a success story in geothermal energy. Since 1979, Elko’s central business district and industrial park have relied on geothermal-derived heat. Now Wells, which shares many geologic similarities with its neighbor, is hoping to tap into the same abundant, renewable energy resource.
Representatives from Elko and Wells are working with scientists from NETL and Lawrence Berkeley National Lab to better understand the region’s geothermal resources, using geologic data collected from the early 1980s through 2017. The NETL team is leading development of subsurface geologic models for Wells’ geothermal resource.
The models will help researchers provide an updated resource assessment—information which will allow Wells to evaluate the viability of establishing its own district heating system, including geothermal production wells and piping infrastructure to heat existing downtown buildings.
Although most of our nation’s geothermal sources are located in the western states, NETL’s geologic-geostatistical capabilities are helping to unearth potential hot spots in the eastern states as well.
In Pittsburgh, Pennsylvania, researchers are using NETL-developed geologic models to determine if geothermal exploitation may be a viable, economic option to help fuel the city—including a brownfield site that is getting a fresh start. The work is part of NETL’s memorandum of understanding with the city to develop advanced energy technologies that will help Pittsburgh earn designations as both a “center for innovation in energy” and an “eco-district.”
NETL’s ongoing assessment indicates that Pittsburgh is a strong candidate for deep direct-use (DDU) geothermal energy. DDU systems are an emerging technology area that draws on lower temperature geothermal resources. DDU is deployable at large scale, maximizes system efficiencies and return on investment, and can create greater opportunities for geothermal resource development throughout the United States.
DDU applications are best suited to large, commercial operations. Because of their higher temperature gradients, geothermal resources in the U.S. western states are more accessible and not as deep as those in the eastern states. While geothermal gradients in the vicinity of Pittsburgh appear to be lower than would normally be considered economically viable, NETL is looking at ways newer technologies and approaches could make even marginal geothermal resources competitive with existing energy sources, such as natural gas. NETL is currently assessing whether an opportunity exists to transition from natural gas to geothermal energy as much-needed infrastructure upgrades occur.
One area of the city that shows great potential for geothermal development is Almono, a brownfield area located along the Monongahela River that was once the site of steel production facilities. The Almono development features all new homes and businesses, and NETL’s preliminary analysis indicates that the area could be a candidate for onsite renewable energy via DDU heating.
If pursued, DDU of geothermal energy could be a valuable component in cleaning up and safely reusing the brownfield site—helping transform the Almono district from an area of environmental concern to vital community powered by renewable, reliable energy sourced, in part, from deep underground.
Camp Dawson, West Virginia
In Preston County, West Virginia, NETL applied its geologic, geostatistical, and energy conversion capabilities to investigate the geothermal potential for Camp Dawson, a state-owned, federally funded West Virginia Army National Guard training facility. NETL recently completed an initial feasibility study of the geothermal and natural gas resources beneath Camp Dawson and the opportunities for using these resources for space heating and generation of electricity. Camp Dawson is located within a geothermal warm spot (relative to other areas in the eastern United States) previously identified by other researchers. Such a deep geothermal resource should be suitable for direct-use applications, such as facility heating and industrial processes in manufacturing.
The NETL study concluded that Camp Dawson hosts a range of potential geothermal opportunities. While natural gas currently offers the lowest costs and the lowest risks, the lifespan of a natural gas-based system would be relatively short if electricity is generated. Geothermal energy, on the other hand, would be practical for district heating over a long lifespan—effectively hedging against natural gas price increases—but would cost more compared to systems using purchased natural gas at current gas prices.
Additional research is needed for reducing the costs of geothermal wells, which account for most of the cost of direct-use geothermal systems. Ultimately this project has the potential to benefit the nation by helping to launch a geothermal industry in the eastern United States.