A significant long-term opportunity for widespread power production from new geothermal sources lies in Enhanced Geothermal Systems (EGS), where innovative technology development and deployment could facilitate access to 100+ GW of energy, exponentially more than today's current geothermal capacity. With EGS, we can tap otherwise inaccessible resources in areas that lack traditional geothermal systems.
One of the Geothermal Technologies Office (GTO)'s major long-term goals is to realize this potential through commercial, cost-competitive, EGS-based electricity generation in the U.S. In pursuit of this goal, GTO actively engages in research and development (R&D) and field demonstrations to validate cutting-edge analysis, improve performance, and ultimately reduce costs.
While advanced EGS technologies are still young and under development, EGS has been successfully realized on a pilot scale in Europe and now at three DOE-funded demonstration projects in the U.S. Two more EGS demonstrations are on track to deliver results by 2014.
Location: Churchill County, Nevada
Partner: Ormat Technologies
DOE Funding: $5.4 million
In April 2013, as part of the Obama Administration's all-of-the-above energy strategy, DOE recognized the nation's first commercial EGS project to supply electricity to the grid. Leveraging $5.4 million in DOE funding matched by $2.6 million in industry investment, Nevada-based Ormat Technologies increased power output by 38% within an operating geothermal field at Desert Peak, Nevada, generating an additional 1.7 MW of power.
Extending the life of unproductive wells using new technologies is one example of these innovations. With an increased injection rate up to 1500 gpm, the well stimulation at Desert Peak establishes new revenue, greater resource reserve, and production certainty, which boosts investor confidence. The Desert Peak success demonstrates that EGS technologies are within reach right now.
"We're very pleased to have partnered with Ormat Technologies to achieve the first commercial EGS success in the United States," stated Doug Hollett, Director of DOE's Geothermal Technologies Office. "Desert Peak is an example of our federal role to push the boundaries and do what has not been done before."
EGS projects capture power from intensely hot rocks, buried thousands of feet below the surface, that lack the permeability or fluid saturation found in naturally occurring geothermal systems. EGS technologies utilize directional drilling and pressurized water to enhance flow paths in the subsurface rock and create new reservoirs, capturing energy from resources that were once considered uneconomical or unrecoverable. With the support of research and development investments across the Energy Department's renewable energy and oil and gas portfolios, American companies like Ormat Technologies are now taking advantage of this untapped resource.
Location: Bend, Oregon
Partner: AltaRock Energy, Inc.
DOE Funding: $21.4 million
AltaRock's EGS demonstration project at Newberry Volcano near Bend, Oregon, represents a key step in geothermal energy development, demonstrating that an engineered geothermal reservoir can be developed at a greenfield site. Preliminary results from the AltaRock Energy EGS demonstration suggest that the project successfully created three separate zones of fluid flow from a single well where none existed before—a first-of-its-kind achievement. AltaRock completed reservoir stimulation in January 2013, and data are being analyzed to confirm this significant technical milestone.
The concept behind heat extraction from EGS is similar to that of a radiator, in which cold water circulates through a very hot substrate—in this case, cracks in hot rocks more than 6,000 feet below the surface that are created or extended via fluid injection. The heated water is brought to the surface, converted to electricity, and then re-injected at depth. Unlike conventional geothermal energy extraction, which relies on locating basins of heated water, EGS technology creates reservoirs to tap the energy found in the subsurface.
The AltaRock project represents the largest cost share in the GTO, with a DOE commitment of $21.4 million toward the $44 million demonstration total. Newberry marks a critical achievement in lowering the cost of geothermal development. As the generation capacity of geothermal wells improves, costly drilling can be minimized, dramatically reducing project costs.
Location: Middletown, California
Partner: Lawrence Berkeley National Lab
DOE Funding: $6 million
The Geysers represents the nation's first sustained EGS demonstration success, following a year-long stimulation along the outer edges of an operating geothermal field. Using cost share from the Geothermal Technologies Office, Calpine Corporation's EGS demonstration in Middletown, California completed stimulation at an abandoned well in the largest geothermal complex in the world. The new and distinct reservoir that was created has successfully yielded enough steam to produce 5 MW of electricity. Because of existing infrastructure, this EGS reservoir demonstrates that stimulating hot rock on the margins of existing hydrothermal fields can secure higher productivity at low cost.
Location: Raft River, Idaho
Partner: University of Utah
DOE Funding: $8.6 million
At the Raft River geothermal field in Idaho, the University of Utah is developing and demonstrating the techniques required to create and sustain EGS reservoirs, including thermal and hydraulic stimulation, with the ultimate goal of improving the overall performance and output of the field. The University of Utah successfully completed well rework operations at US Geothermal's Raft River field in March 2012. This sets the stage for the thermal and hydraulic stimulation of the target well and ultimately, demonstration of the technical viability of EGS technology at this site. Like Bradys field, the Raft River demonstration will encourage future EGS well stimulations to improve the flow characteristics of sub-commercial wells to the levels of commercial production. Phase II demonstration activities are underway.
Location: Churchill County, Nevada
Partner: Ormat Technologies
DOE Funding: $4.5 million
At the Bradys field EGS demonstration site in Nevada, Ormat is working to improve well injectivity to commercial levels and to ensure a robust hydraulic connection between the well and the producing field. To this end, Ormat for planned stimulation, and hydraulic stimulation of the target well using EGS technology is underway. The project's success would encourage future utilization of EGS well stimulations to improve flow to commercial production levels, yielding clean, domestic, baseload geothermal energy. DOE has partnered with the Bureau of Land Management to collaborate on environmental permitting efforts.