Research is critical to unlocking superhot geothermal energy. DOE’s proposed program could help achieve its potential.
The U.S. Department of Energy’s Advanced Research Projects Agency – Energy (ARPA-E) office has taken an important step toward accelerating the development of superhot rock (SHR) geothermal energy by exploring a program focused on the advancement of geothermal systems that operate in harsh, high-temperature environments. If approved, the program could have a meaningful impact on the energy system by helping to accelerate the timeline to commercialization of superhot rock energy.
ARPA-E has solicited recommendations from the public to support the planning of the SHR program to inform the possible formulation of future research programs, and asked for clarification of R&D needed. CATF responded with insights gathered from our time speaking to technology leaders across the geothermal sector, the Bridging the Gaps series, and our expertise in climate and energy policy. CATF’s response identifies areas for research and development that can help bring superhot rock geothermal systems to commercial scale.
Why a superhot rock geothermal research and development program?
Making SHR a reality will require technology advancements from geothermal and fossil technologies that exist today. And through its exploration of an SHR program, ARPA-E is homing in on exactly this. If ARPA-E proceeds with an SHR research program, there could be huge advancements in SHR technology, which would be good for energy resilience and decarbonization. By taking on targeted R&D for SHR, ARPA-E could ensure that the scope of geothermal widens beyond small hydrothermally active pockets of the world and that its power potential increases significantly. Targeted investments in R&D, which were noted as a key priority in CATF’s SHR Policy Brief, could make this not-so-far-out technology a reality.
Following ARPA-E’s announcement that it is exploring an SHR program, global momentum has also ramped up: the agency held an event at the beginning of October to gather more insight on R&D needs; CATF held a SHR summit at the end of October to build a technology roadmap; and countries like Iceland, New Zealand, and Japan are setting the stage for their own work on the subject.
CATF’s response: Key technology gaps that ARPA-E’s superhot rock program should address
- Drilling and well design. Well construction has been the failure point of nearly all past SHR demonstration projects. Testing and advancement of existing casing and cement materials are necessary to improve well performance and longevity. We recommend ARPA-E supports lab testing and alteration of the materials that exist today. In addition to well performance and longevity, advancement of drill bit technologies and high-temperature sensing equipment will be necessary in accessing the resource in more locations.
- Innovative materials for extreme conditions. In addition to testing and alteration of existing materials, R&D into the use of novel well completion materials and methods is also important. Although the testing and iteration of existing equipment is useful for accessing SHR today, exploration of novel materials (such as cements) and approaches could bring down cost in the long run.
- Reservoir creation and management for enhanced geothermal systems (EGS) methods. This topic is likely the least mature out of any technology vertical in SHR. For SHR systems to be effective, ensuring that a reservoir can be enhanced or created, and then maintained over the full life of the well, is essential to building a productive SHR system as a whole. This includes the advancement of SHR methods that may include the use of packers, proppants, sliding sleeves, and explosives, or the exploration of alternative methods like thermal shock and hydroshearing. In addition to a specific focus on advancement of equipment, gaining more precise control over the subsurface environment is important. CATF suggests that ARPA-E also directs efforts toward creating more robust models for permeability management and seismicity mitigation.
- Surface power generation systems. Enhancing the replicability and reducing the cost of the power plant design options that exist today is the “name-of-the-game” for improvements in surface equipment. The full heat conversion system for SHR is not available off-the-shelf due to lack of demand, and thus, SHR power plants would need to be custom-built, limiting cost reductions and increasing time to realize first projects and later-on scalability. CATF recommends the development of power plant models specific to SHR’s unique demands, which would help streamline the process of building power systems that can efficiently convert superhot energy to electricity. CATF also recommends the exploration of power plant design and equipment that can be repeatable enough and useable for the variety of SHR fluid conditions expected.
- Consideration of facilities and expertise built for other sectors. ARPA-E should consider the opportunity to leverage its program to support research groups in related fields with similar high-temperature material needs like nuclear and aerospace industries and collaborate with the oil and gas sector.
CATF has also explored methods, challenges, and pathways forward for SHR geothermal through the Bridging the Gaps series. This collection of reports, authored by leading experts, dives into areas such as site characterization, drilling, heat extraction, well construction, and power production, and provides an in-depth analysis of the technology challenges for each. These reports are intended to guide the development of SHR from concept to commercial viability. The work is ongoing, and the website will continue to be updated as we publish additional resources.
As we look to the future, CATF is committed to collaborating with the broader community of technology and policy experts to unlock the full potential of geothermal energy as a climate solution in an age of rapidly rising energy demand. With the right investments, superhot rock geothermal energy could emerge as a powerful solution to bolster U.S. energy security and provide reliable, clean energy for the future.
