As the global energy landscape rapidly shifts toward sustainable development, geothermal energy is gaining renewed attention as a clean and renewable ecological resource. Unlike solar and wind, geothermal energy offers the unique advantage of stable, weather-independent output, making it a crucial player in the transition to a low-carbon energy system. In Europe and North America, where climate targets are tightening and environmental awareness is deepening, the race to develop next-generation geothermal technologies is becoming a major scientific and policy priority.
Traditional geothermal energy extraction relies on three natural factors: underground heat, fluid, and geological fractures. These conditions, however, occur together only in specific geological settings, limiting conventional geothermal to select locations worldwide. Enhanced Geothermal Systems (EGS) have emerged as a revolutionary solution to this problem. EGS technology can unlock vast reservoirs of heat trapped within low-permeability rock deep beneath the Earth’s surface—areas that were previously considered inaccessible for energy production.
EGS does not require naturally occurring fluid or fractures. Instead, it uses engineered stimulation techniques to create or open fracture networks, allowing fluid to circulate and transport heat to the surface. A key example of this innovation is the Utah FORGE project, supported by the U.S. Department of Energy. By adapting advanced methods from the oil and gas sector, such as multi-stage hydraulic fracturing and horizontal drilling, researchers have successfully established deep fracture networks in hot, impermeable rock, proving the viability of EGS in real-world conditions.
The National Renewable Energy Laboratory (NREL) plays a vital role in advancing EGS through subsurface characterization, reservoir modeling, and techno-economic analysis. These efforts aim to optimize fracture development, guide strategic drilling decisions, and ultimately reduce the costs and risks of EGS deployment. In partnership with Cornell University, NREL is developing geothermal reservoir models and running simulations to assess the feasibility of campus-wide geothermal heating. This project could drastically cut fossil fuel use and set a new benchmark for low-carbon district energy systems.
In addition to mechanical stimulation, NREL is working with Utah FORGE to explore chemical stimulation techniques. These methods, which involve injecting specially designed chemical agents to improve rock permeability, offer an alternative—or a complement—to traditional hydraulic fracturing. Such innovations could reduce costs, minimize water use, and lower the risk of induced seismicity, making EGS more adaptable for global application.
Beyond EGS, closed-loop geothermal systems (CLG) are also gaining traction as a safe, scalable, and geographically flexible approach to geothermal energy. Unlike EGS, CLG systems do not rely on existing underground fluids or fractures. Instead, they operate as sealed heat exchange systems, circulating fluid through closed-loop pipes drilled into hot rock formations. Heat is transferred to the surface without fluid loss or subsurface interaction, making CLG inherently low-risk and suitable for deployment in urban and geologically complex areas.
Several CLG designs are currently under development, featuring a variety of well geometries and heat transfer fluids. For instance, some companies are experimenting with spiral-shaped horizontal wells to increase surface contact with hot rock and boost heat extraction efficiency. NREL contributes to these efforts through design optimization, field testing, and cost-performance modeling to help bring CLG systems to commercial scale.
Deep geothermal development represents more than just an energy innovation—it’s a strategic pathway toward ecological sustainability. Unlike wind or solar, which face challenges related to intermittency and energy storage, geothermal energy provides reliable baseload power and can integrate seamlessly with smart grids, carbon capture systems, and district heating networks.
In Europe, Iceland stands out as a global model of geothermal utilization, with nearly all buildings in Reykjavik powered by geothermal heating. Germany, France, and other European countries are also scaling up deep geothermal pilot projects through subsidies and research incentives. With continued advances in drilling technology, improved thermal transfer efficiency, and growing policy support, geothermal energy is poised to play an even larger role in the global clean energy transition.
Next-generation geothermal technologies like EGS and CLG are not only unlocking new energy potential but also reshaping the investment landscape for clean energy. These innovations offer scalable, low-emission alternatives to fossil fuels—especially important in highly regulated Western markets. As technical maturity improves, geothermal systems could one day deliver on the promise of “geothermal anywhere,” transforming the way we power homes, cities, and entire nations with sustainable heat from beneath our feet.