Feasibility and techno-economic analysis of combining water tower energy storage with geothermal energy systems

Abstract

In some enhanced geothermal systems (EGS), pumps must provide hydraulic pressure in excess of 2000 psi to re-inject the geothermal brine into the reservoir. The parasitic load used to power the injector pumps is significant. Total parasitic load in geothermal plants can range from 15% to 45% of the plant electricity output (Chagnon-Lessard et al., 2020). The thesis hypothesizes that integrating a system of water towers with geothermal systems could provide useful energy storage and reduce overall pumping power costs. This conceptual system would utilize an elevated tank or reservoir to store water during times of low power demand. The stored potential energy could be dispatched by discharging the water from the elevated tank to provide hydraulic pressure to help inject fluid into a geothermal system. Reducing the power required to run the injection pumps could significantly boost the power output of the system during discharge of the stored energy when electricity costs are highest.