The governments of the United States and Germany have committed $7.7 million to fund a pioneering pilot project that uses 3D concrete printing to construct a subsea pumped hydro storage facility on the ocean floor. This unique project combines cutting-edge technology from California-based Sperra with the expertise of the Fraunhofer Institute for Energy Economics and Energy System Technology (Fraunhofer IEE) and Pleuger Industries. The pilot project is planned for deployment off the coast of southern California, aiming to bring a new approach to energy storage that leverages the ocean’s depths.
Underwater Energy Storage Concept
Fraunhofer IEE has been developing its subsea energy storage system, named StEnSea (Stored Energy in the Sea), since 2012. The concept adapts the principles of traditional pumped storage power plants to the seafloor, utilizing the immense pressure of deep water for efficient energy storage. At the heart of the StEnSea system is a massive 400-tonne hollow concrete sphere manufactured with advanced 3D printed concrete. Anchored between 500 and 600 meters below the surface, the sphere can store and release energy by pumping water in and out.
To store energy, an electrically driven pump turbine, designed by Pleuger, expels water from the sphere, effectively charging it. When energy is needed, water flows back into the sphere, turning the pumps into turbines that generate electricity. According to Pleuger, “this innovative method mirrors the functionality of traditional pumped storage hydropower but adapts it for the subsea environment, leveraging ocean pressure to store and release energy efficiently.” This subsea setup also presents opportunities for integration with offshore renewable energy sources, such as wind and floating solar installations.
Pilot Project and Future Plans
After successful testing of a smaller model in Lake Constance, Germany, Fraunhofer and its partners will construct a larger 500kW/400kWh prototype off the coast of Long Beach, near Los Angeles, California. The 3D printed concrete sphere for this pilot will be produced by Sperra, a specialist in 3D concrete printing for renewable energy applications.
“Pumped storage power plants are particularly suitable for storing electricity for several hours to a few days,” explains Dr. Bernhard Ernst, Senior Project Manager at Fraunhofer IEE. “However, their expansion potential is severely limited worldwide. By transferring their functional principle to the seabed, we face fewer natural and ecological restrictions, and public acceptance is likely to be significantly higher.”
The anticipated rise in energy storage needs due to the global energy transition makes projects like StEnSea critical. “With the StEnSea spherical storage, we have developed a cost-effective technology that is particularly suitable for short to medium-term storage,” added Ernst. “With the test run off the US coast, we are making a big step towards scaling and commercializing this storage concept.”
International Funding Support
The project received substantial backing from both the U.S. and German governments. The U.S. Department of Energy’s Water Power Technologies Office (WPTO) awarded Sperra a $4 million grant to advance its 3D concrete printing technology for use in subsea pumped storage applications. This funding, in turn, helped secure an additional $3.7 million grant from Germany’s Ministry of Economic Affairs and Climate Action to support Fraunhofer IEE and Pleuger Industries’ roles in the project.
“This project is a major step forward in realizing the full potential of energy storage to decarbonize our electric grid,” said Jason Cotrell, CEO and Founder of Sperra.
Source: reneweconomy.com.au
