Small Business Research in Geothermal Energy

The OG SBIR portfolio continued to grow in FY24 with 17 active projects (10 Phase I projects and 7 Phase II projects). Two projects were added with Phase I selections on the Advanced Exploration Methods topic area in 2024, as well as another Phase I topic area (Inhibition of Mineral Scaling). This growing portfolio means growing opportunities for DOE to partner with small businesses in advancing geothermal technologies. In FY25, OG topics include low-impact drilling systems and site assessments for geothermal heat pumps, geothermal heating and cooling in protected agriculture, and high-temperature elastomers for enhanced geothermal systems.

The Twin Cities-based startup Darcy Solutions’ SBIR-funded project, “Advanced Geothermal Heat Pump System for Bi-Directional Energy Storage” tested innovative ground source heat pump (GSHP) technology to allow for thermal energy storage in shallow reservoirs. This technology, termed advective GSHP, fundamentally changes the way heat is transferred with the shallow subsurface. Darcy Solutions’ technology advances are being implemented in Rochester, Minnesota, as part of a OG-managed Congressionally Directed Spending project to construct a downtown district energy system supplying heating and cooling for 2.3 million square feet of undeveloped property and 750,000 square feet of city-owned facilities. 

This topic focused on advancing technical systems for geothermal heating and cooling through collaborative efforts involving multiple small businesses. Applications were submitted under three subtopics: 

• Low-impact drilling systems for geothermal heat pumps (GHPs): Support the research, development, and demonstration of advanced drilling systems for GHPs, with a focus on compact, automated, and robotic technologies. 
• Rapid site assessments for GHPs: Support development of advanced tools for rapid site assessment and screening of GHP installation locations that address market barriers like site assessment, heat exchanger sizing, and permitting to accelerate GHP adoption. 
• Geothermal heating and cooling for protected agriculture: Create affordable, scalable geothermal heating solutions for greenhouses and other controlled farming environments to support year-round food production. 

This topic focused on improving elastomeric materials used in harsh downhole geothermal environments, particularly in enhanced geothermal systems (EGS) development and high temperatures (over 250°C for long-term use and 300°C for short-term use, up to 375°C for superhot systems). OG sought applications focused on improving elastomeric materials specifically for use in geothermal wells, including for use in seals, o-rings, zonal isolation devices, pumps, valves, motors, and wellbore monitoring tools.

Mineral scaling in geothermal systems can cause challenges within the reservoir, wellbores, and surface equipment associated with geothermal energy production. Several methods currently exist to mitigate scaling issues but can require shutdown of wells or surface equipment and/or are administered on an intermittent basis, reducing their effectiveness. OG sought projects to develop advanced methods to inhibit mineral scale from geothermal brines that improve on the current state-of-the-art in terms of effectiveness, efficiency, cost, and environmental considerations.

Data are essential to improving the cost and accuracy of geothermal exploration. High-value datasets can help justify funding in exploratory drilling, one of the higher risk phases of geothermal development. The primary research objective for this SBIR/STTR topic was to demonstrate significant improvements in survey cost, efficiency, speed, and/or scale compared to current practice for several commonly used methods to indicate potential high-temperature geothermal reservoirs. Projects also needed to supply needed data to validate ongoing resource assessment efforts and support development of a geothermal resource playbook. 

This subtopic focused on accuracy of flow data measurements from individual geothermal production wells, especially in high-temperature conditions (> 390°F or approximately 200°C). Traditionally, power plant optimization relies on bulk flow data from multiple wells, which does not provide detailed insights into individual well performance. Accurate, continuous, real-time data on flow rates, temperatures, liquid/vapor fractions, and chemical composition from individual wells would significantly enhance understanding and management of geothermal reservoirs. By fully characterizing multiphase flow systems, these projects were intended to enable operators to monitor changes in specific wells or reservoir zones, thereby improving overall efficiency and stability. 

This sedimentary systems topic area aimed to enhance the precision of flow data measurements from individual production wells, which is vital for generating electricity from geothermal energy. Accurate flow data are necessary for optimizing the efficiency and reliability of geothermal power plants. Focusing on innovative methods to measure flow data accurately is key to advancing geothermal energy production.

With this topic, OG aimed to develop integrated, long-term monitoring tools and data analysis techniques for actively producing geothermal reservoirs by focusing on measuring previously unmeasured field parameters or improving the accuracy, durability, and cost-effectiveness of current measurements. Addressing technological gaps and uncertainties is crucial for acquiring high-quality data and ensuring the economic viability of long-term geothermal energy production. Key areas include real-time data acquisition, uncertainty quantification, reservoir boundary definition, physical property tracking, and demonstrating long-term reservoir stability.