SBIR-STTR Award

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.

Geothermal energy is one of America’s best choices as a lowcost renewable energy resource for power generation. Adding energy storage capability to geothermal resources enables the power produced/offset to be dispatched as necessary based on changing grid conditions, expanding the usage and utility of geothermal energy. The proposed energy storage system for capture of both electrical energy in a nonbattery system and lowtemperature thermal energy ? 150oC would be an ideal extension to the capabilities of existing geothermal powerplants. Deployment of flexible power production and storage of geothermal energy storage contributes to grid reliability, flexibility, resilience and security, and the DOE’s Grid Modernization Initiative. The Phase I project successfully demonstrated flexible power generation, as well as thermal and electrical energy storage. Thermal energy was stored in concentrated osmotic polymeric solutions, while electrical energy was stored in concentrated ionic solutions. These solutions produced flexible power generation in a Pressure Retarded Forward Osmosis PRFO system, converting their osmotic potential to hydraulic pressure on dilution with water across membranes. The system essentially works as a miniaturized hydroelectric plant, when combined with a hydroturbine. In Phase I, special osmotic polymers were developed, used in the power generation, and re converted back to their concentrated form by utilizing thermal energy. The ionic polymers were re converted back to their concentrated by using electrical energy in a modified electrodialysis CEDI system. In addition, special polymers were developed which are capable of CO2 absorption 250 g CO2 absorbed per ml of solvent and decarbonization of geothermal plants, as well as low boilingpoint osmotic polymers 30oC which can be used for both osmotic power production and additional power production in an Organic Rankine Cycle ORC engine. In the proposed Phase II project, the osmotic engine from Phase I will be coupled with an ORC engine for additional power production in series, increasing the total power generated, and adding to the thermal storage capability. Additionally, a steam electrolysis system will be developed, using the lowtemperature exhaust steam ? 125oC from a geothermal powerplant steam turbine effluent to create “green hydrogen”. This green hydrogen will also serve as an electrical energy storage medium. Both systems will be capable of flexible power generation and storage, with grid connectivity. The systems and technologies developed can be used for flexible power generation, with thermal/electrical energy storage, in geothermal applications, as well as lowtemperature waste heat and solarthermal applications, to be commercialized in Phase III with industrial partners. Additional benefits will be decarbonization of waste effluents and production of “green H2” at lower costs than current “green H2” technologies.