Study highlights potential of geothermal energy to decarbonize electricity

Enhanced geothermal systems (EGS) are man-made or enriched reservoirs in the Earth’s subsurface, from which heat can be extracted to produce geothermal energy. The energy produced by these reservoirs could serve as an alternative source of electricity, helping to mitigate carbon emissions.

Until now, EGS have been primarily considered as potentially stable and reliable sources of electricity, capable of operating consistently over time. However, these geothermal reservoirs could also store energy for longer before converting it into electricity, rather than converting it entirely at one point.

Researchers from Princeton University’s ZERO Lab and EGS developer Fervo Energy recently conducted a study exploring the potential impact of flexible use of EGS and the storage of the energy they generate on continued long-term efforts to decarbonize electricity generation. The results of their project were published in Natural energy.

“This paper is the result of a collaboration between my research group at Princeton, the ZERO Lab, and Fervo Energy, an enhanced geothermal systems technology startup,” Wilson Ricks, co-author of the paper, told Tech Xplore . “The project aimed to explore the potential benefits of flexible operations both for EGS as an industry and for the decarbonized electricity networks in which it could participate.”

The idea that EGS could be operated flexibly has been around for decades and was first demonstrated in the 1990s. Yet climate change and ongoing efforts to decarbonize power systems have reignited interest for this idea, ultimately prompting Ricks and colleagues to conduct their study.

“The recent resurgence in EGS development and the growing need for flexibility and energy storage in power systems using large amounts of wind and solar power has prompted us to look further into the benefits of this approach” , explained Ricks.

“My co-authors and I first performed detailed simulations of EGS reservoirs undergoing flexible operations. We used them to develop an accurate representation of flexible EGS in GenX, the power system planning model open source that ZERO Lab develops and maintains.”

GenX is an optimization model developed by researchers at the Massachusetts Institute of Technology (MIT) and Princeton’s ZERO Lab, designed to make predictions about electricity demand, production and storage. The model works by identifying the least cost configurations for the power system given a set of available technologies and various physical and policy constraints.

As part of their study, Ricks and colleagues specifically used GenX to explore the impact of flexible EGS operation on the long-term deployment of geothermal energy in the Western United States. Additionally, they sought to determine whether these flexible operations could reduce the costs of decarbonized electricity systems in the same region.

“We tried to represent the available geothermal resource base in as much detail as possible, mapping availability at different temperatures and depths in the region,” Ricks said. “We also incorporated additional details such as local hourly variability in air temperature, which impacts the production power of some geothermal plants.”

The analyzes carried out by this team of researchers suggest that EGS could be a much more useful resource than expected for decarbonizing electricity. The flexible operation of these systems and the storage of energy in the reservoirs was found to significantly increase their contribution to decarbonization efforts, significantly reducing the costs of supplying wholesale electricity.

“By providing both clean, firm generation and long-duration energy storage, EGS could act as an all-in-one complement to cheap but intermittent wind and solar power,” Ricks said. “Our results also suggest that EGS R&D efforts should focus as much on increasing the ‘value’ of the technology through flexible operation as on reducing its cost.”

Overall, the work of this team of researchers suggests that moving to flexible operation of EGS and introducing long-term geothermal energy storage in reservoirs could be beneficial in reducing the cost of electricity in the western United States, and potentially other regions as well. global. This study could inform future research efforts and policy development, potentially contributing to new investments in geothermal energy systems.

“We now plan to continue exploring how EGS could play a role in electricity decarbonization, including outlining potential pathways from emerging technology status to large-scale deployment,” Ricks added.

“On the engineering side, the basic principles of flexible operation were successfully demonstrated at the Fervo pilot project site in Nevada last spring, and further demonstration and risk reduction work is planned .”

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