Geothermal Heat Exchange Technology Evaluated as a Potential Solution for Grid Support and Sustainable Cooling in Hawaii

A new study conducted under the U.S. Department of Energy’s Energy Technology Innovation Partnership Project (ETIPP) has identified geothermal heat exchanger (GHE) systems as a potential solution to help reduce cooling demand and ease pressure on Hawaii’s electricity grid.

The research was carried out through a collaboration between the University of Hawaii at Manoa’s Hawaii Groundwater and Geothermal Resources Center and scientists from Lawrence Berkeley National Laboratory. The ETIPP program, managed by the National Laboratory of the Rockies (formerly NREL), provides remote and island communities up to two years of technical assistance to design more affordable, resilient energy systems.

Hawaii joined the initiative in 2022 to explore geothermal applications suitable for the state’s volcanic geology and high cooling demand. The newly released report evaluates the feasibility of shallow ground heat exchangers across Oahu, as well as a detailed site assessment at the University of Hawaii at Manoa’s Stan Sheriff Center.

Unlike high-temperature geothermal systems that require deep drilling to produce electricity, low-temperature geothermal technologies use subsurface temperature stability for heating and cooling. “Low-temperature geothermal systems such as GHEs can significantly reduce building cooling loads and relieve pressure on the electric grid,” said Christine Doughty, staff scientist at Lawrence Berkeley National Laboratory.

Nicole Lautze, director of the Hawaii Groundwater and Geothermal Resources Center, noted that both high- and low-temperature geothermal systems may serve Hawaii’s long-term clean energy goals.

Findings and Deployment Conditions

The report analyzed open-loop and closed-loop geothermal system designs. Open-loop systems use groundwater flow to transfer heat, while closed-loop systems use sealed pipe networks to exchange heat with the earth.

Given Hawaii’s limited need for heating and heavy reliance on air conditioning, the study found that sufficient groundwater flow is critical to prevent long-term heat buildup beneath the surface. Areas with restricted aquifers or protected watersheds were deemed less suitable, while several coastal zones demonstrated higher deployment potential.

Using GIS datasets with factors such as elevation, geology, soil permeability, and land-use restrictions, researchers developed detailed favorability maps for GHE installation across Oahu.

Site-Specific Assessment for the Stan Sheriff Center

A hydrogeologic model was applied to evaluate the potential for a closed-loop cooling system at the Stan Sheriff Center, one of the university’s highest-demand facilities. Simulations showed that without groundwater movement, heat buildup would degrade system performance within one year, increasing chiller reliance between years two and six. However, when modeled with groundwater circulation, the geothermal cooling system remained viable for at least a decade.

The analysis suggests that financial mechanisms such as low-interest loans could improve the economic feasibility of GHE deployment. The study also noted the potential of seawater cooling systems, pointing to the existing installation at the Natural Energy Laboratory of Hawaii as a reference model.

Next Steps

The ETIPP report recommends continued research and funding support to further assess geothermal cooling applications across Hawaii. The findings could contribute to reduced grid strain, improved energy affordability, and progress toward the state’s broader clean energy commitments.

“This project has laid the groundwork for future grant proposals to assess geothermal heat exchangers across the University of Hawaii campus and throughout the state,” Lautze said.

ETIPP will continue working with participating communities nationwide to evaluate geothermal and other clean energy options based on regional needs and conditions.