In this article, we explore how advanced geothermal systems are shaping the future of clean energy, offering scalable and reliable solutions even in regions without traditional geothermal resources. We'll examine recent breakthroughs in Enhanced and Closed-Loop Geothermal Systems, the surge in global investment, and the key technical and operational challenges that must be addressed.
We will analyse the following factors:
- Geothermal Revolution
- Evolution of Geothermal Systems
- Surface geothermal systems for EGS and AGS
- Advancements and Challenges in Geothermal Systems
- Global Trends and Adoption of EGS
- Overcoming Barriers and the Future of Geothermal Energy
1. Geothermal Revolution: Unlocking New Potential
The shift toward next-generation geothermal energy is redefining what's possible in the world of sustainable power. Traditionally, geothermal development has relied on either shallow ground-source heat pumps or high-temperature hydrothermal reservoirs resources that are often limited by geography and geology. This has posed a barrier, especially for industrial applications and large-scale power generation.
Today, however, innovative breakthroughs are opening the door to advanced geothermal systems that are no longer bound by natural reservoir availability. By leveraging technologies developed in the oil and gas sector such as directional drilling, hydraulic fracturing, and well insulation researchers and developers are pioneering reservoir-independent solutions like Enhanced Geothermal Systems (EGS) and Closed-Loop Geothermal Systems (CLGS).
The integration of next-generation geothermal energy is transforming the energy landscape, particularly in areas where geothermal resources were once inaccessible.
2. Evolution of Geothermal Systems
Enhanced Geothermal Systems (EGS) and advanced geothermal systems (AGS) are transforming how and where geothermal energy can be harnessed, making it possible to tap into heat sources even in areas without naturally occurring reservoirs. With continued technology improvements and reductions in project costs, geothermal could meet up to 15% of global electricity demand growth to 2050.
What is an enhanced geothermal system?
EGS technologies work by enhancing or creating permeability in hot rock formations, typically through advanced drilling techniques and targeted stimulation methods. Hydraulic stimulation is one of the most used approaches, injecting high-pressure fluids into deep wells to create or open fractures within the rock. Other techniques, such as thermal stimulation (using cold fluids to induce thermal cracking) and chemical stimulation (using specific compounds to dissolve minerals and open pathways), further increase rock permeability and heat extraction efficiency.
These engineered fractures allow fluids to circulate through the subsurface, absorb heat, and bring it to the surface for electricity generation or direct use. EGS expands the reach of geothermal energy to high-temperature regions that lack sufficient fluid volumes or natural permeability areas once dismissed as "hot dry rock" zones. Today, major projects such as the Utah FORGE initiative and Fervo Energy's Cape Station in the U.S., along with Switzerland's Haute-Sorne project, are pushing the boundaries of what EGS can achieve, with promising potential for high-output, low-carbon power generation.
In Europe, an example of an EGS project is being developed in Cornwall, UK, at the United Downs site, Geothermal Engineering Ltd. (GEL) is the developing company, in partnership with Exergy International as technology provider for the power plant. This project marks the first integrated deep geothermal initiative in the UK, with a capacity of 3 MWe of baseload renewable electricity and up to 10 MWth of zero-carbon heat, expected to be operational by the end of 2024.
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Another frontier of new generation technologies is represented by, advanced geothermal systems often referred to as closed-loop geothermal systems (CLGS). These systems circulate a working fluid through sealed, underground loops that extract heat via conduction from the surrounding rock, without direct interaction with the subsurface. Though still emerging, projects like Eavor-Lite in Canada and GreenFire Energy's GreenLoop in California have demonstrated the technical feasibility of CLGS solutions, while Eavor's upcoming plant in Geretsried, Germany aims to scale these systems commercially.
3. Binary cycle systems: a key technology for EGS and AGS
EGS and AGS subsurface technologies can be efficiently utilized through binary cycle power plants for electricity generation and large heat pumps for direct heating applications. Binary cycle systems are particularly well-suited for next-generation geothermal reservoirs due to their high efficiency in harnessing low- to medium-enthalpy resources, operational flexibility, and lower maintenance requirements. These characteristics make them an ideal match for the evolving demands of EGS and AGS developments.
Binary-cycle power plants are closed-loop systems with no emissions to the atmosphere, making them a highly sustainable option. Unlike flash power plants, the geothermal fluid in binary systems never comes into direct contact with the turbine or generator. Instead, the geothermal fluid transfers its heat to a secondary organic working fluid via a heat exchanger. This secondary fluid, with a lower boiling point, vaporizes and drives the turbine to generate electricity. Afterward, it is condensed and repressurized to repeat the cycle, while the cooled geothermal fluid is reinjected into the reservoir. This closed-loop process enhances environmental safety and long-term system reliability, aligning well with the technical and sustainability goals of advanced geothermal projects.
4. Advancements and Challenges in Geothermal Systems
Recent breakthroughs in Enhanced Geothermal Systems (EGS) technology, including the use of horizontal wells and multistage stimulation techniques, have significantly improved reservoir volumes, heat transfer areas, and flow rates, as demonstrated in 2023 at Fervo's Project Red in Nevada. Despite these advancements, EGS remains technically challenging, with technical difficulties related to:
- Managing water losses
- Maintaining well integrity
- Ensuring consistent high flow rates and production temperatures
Additionally, the stimulation process implies some impact on environment:
- Significant water usage
- Risks connected to induced seismicity, which has led to social opposition and regulatory restrictions in some areas
In contrast, Closed-Loop Geothermal Systems (CLGS) offer the advantage of
- Minimal site-specific requirements, enabling them to be deployed nearly anywhere
- Avoiding the risks associated with reservoir stimulation, including induced seismicity
However, CLGS face their own set of challenges, particularly the need for much longer drilling distances to create sufficient heat transfer areas, leading to higher costs and more complex downhole completions. Moreover, maintaining stable production temperatures over time remains a hurdle that requires improved designs and operating strategies.
While EGS projects involve risks tied to site-specific characteristics, CLGS challenges are more related to engineering and operational factors that need to be addressed for better cost-efficiency and performance.
5. Global Trends and Adoption of EGS
Enhanced Geothermal Systems (EGS) are rapidly emerging as a cornerstone for sustainable energy solutions, with global investments steadily increasing to drive technological advancements and scalability. Since 2017, investment in next-generation geothermal technologies has surged from negligible amounts to over USD 420 million annually by 2023, with expectations for continued growth as global interest in geothermal intensifies. This trend is backed by both private and public sector contributions, with countries like the United States, Canada, and Germany providing substantial public funding to accelerate the development of EGS and Advanced Geothermal Systems (AGS). Key investments are being made by venture capital firms, oil and gas companies, and innovative startups, with pioneering companies such as Fervo and Eavor raising over USD 700 million since 2021, representing more than 60% of the total early-stage geothermal investment. Global market opportunities for next-generation geothermal systems are concentrated in regions with high energy demand, including China, the U.S., India, Southeast Asia, Europe, and Japan.
