Electrical & Thermal Energy Storage in Geothermal Plants

Geothermal energy is one of America’s best choices as a low-cost renewable energy resource for power generation. By adding energy storage capability to geothermal resources, the power produced/offset can be dispatched as necessary based on changing grid conditions, further expanding the usage and utility of geothermal energy. The proposed energy storage system for capture of both electrical energy (in a non-battery system) and low-temperature thermal energy (≤ 150oC) would be an ideal extension to the capabilities of existing geothermal power-plants. Deployment of advanced geothermal energy storage contributes to grid reliability, flexibility, resilience and security, and also supports DOE’s Grid Modernization Initiative. Geothermal plants have both electrical energy and thermal energy. The electrical energy produced in geothermal plants cannot be stored cost-effectively by battery-based systems. Low-temperature heat emitted from geothermal plants also cannot currently be stored and converted to power efficiently. This project will use osmotic solutions to store both electrical and thermal energy, to produce power on demand in high-pressure hydro-turbines. During the storage cycle, high concentration osmotic solutions are produced from electrical and thermal energy. During the generation cycle, the osmotic energy is converted to hydraulic energy to produce power from hydro-turbines on demand. Nrgtek has already developed the technology for conversion of low-temperature energy to hydro-electric power, using thermolytic polymers with high osmotic potential. In Phase I, we will further optimize these osmotic polymers, and also develop technology for regeneration of high osmotic-potential ionic solutions, using a process called Continuous Electro Deionization (CEDI), to store surplus electrical energy as concentrated ionic solutions. Integration of both systems will enable storage of both thermal and electrical energy for on-demand power production in hydro-turbines. Long-duration energy storage for geothermal, industrial and renewable energy applications, wherever electrical and low-temperature thermal energy is available. Non-geothermal applications include industrial CHP and WHP systems, solar-thermal plants, CO2 capture and conventional power-plants, with attendant carbon credits.