Geothermal aquifers show green energy promise but require quality monitoring

Tokyo, Japan (SPX) Dec 23, 2024 - The aquifer thermal energy storage (ATES) system, a renewable energy innovation leveraging geothermal heat, is gaining traction as a method to cut fuel use and reduce carbon dioxide emissions. By storing heat underground in aquifers and using groundwater as a medium, the system provides an efficient solution for heating and cooling buildings depending on seasonal demands.

Primarily adopted across Europe, the ATES system is poised for broader implementation in Japan. However, ensuring the system's efficiency necessitates routine inspections.

Researchers from the Osaka Metropolitan University Urban Resilience Research Center, led by Specially Appointed Professor Harue Masuda, uncovered challenges in maintaining these systems. Their study focused on a facility in Osaka, where clogging occurred in the ATES well due to air inadvertently entering the system through an open vent. This introduced oxygen into the plumbing pipes, creating an environment where iron oxyhydroxide accumulated, leading to clogging, leaks, and the mixing of groundwater between two separate aquifers at different depths. Remarkably, natural microbial activity eventually cleared the clog and restored groundwater flow.

The incident underscores the importance of pre-operational water quality assessments and ongoing monitoring for long-term functionality of the ATES system.

"The results of this research show that geochemical analysis of groundwater, which has not been emphasized in the engineering field until now, is effective and essential for the stable, widespread use of the ATES system," said Professor Masuda. "We believe that by proposing a method for monitoring water quality as a guideline, we can establish the ATES system as a technology that can be used for the long term."

Research Report:Natural recovery from Fe-oxyhydroxide clogging of a geothermal well in Osaka, Japan