US and Germany back plan for 3D printed, subsea pumped hydro storage pilot

The US and German governments have committed $US7.7 million to support the development of technology and a pilot project which would use automated 3D concrete printing to build a subsea pumped storage facility on the ocean floor.

The bizarre proposal would use technology from California based Sperra, working in conjunction with the highly respected Fraunhofer Institute for Energy Economics and Energy System Technology (Fraunhofer IEE), and Pleuger Industries to build a pilot project off the coast of southern California.

Fraunhofer IEE says it has been developing an underwater energy storage system technology since 2012 “that transfers the principle of pumped storage power plants to the seabed.”

The technology, dubbed StEnSea, uses a hollow, 400-tonne concrete sphere made from 3D printed concrete, and anchors it to the seafloor at a depth of between 500 to 600 metres.

Water is pumped out of the sphere using an electrically driven pump turbine designed by Pleuger to charge, then water is allowed to flow back into the empty spherical chamber, turning the pumps into turbines that generate electricity.

“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,” explains Pleuger.

And given its location on the seafloor, this technology could work in tandem with offshore wind farms and floating solar projects.

Having already trialled a smaller model in Lake Constance in Germany, Fraunhofer and its partners are taking the technology to a coastal area off Long Beach near Los Angeles, California, where they will build a 500kW/400kWh prototype.

The concrete sphere will be manufactured by Sperra, a specialist in 3D concrete printing for applications in the field of renewable energies.

“Pumped storage power plants are particularly suitable for storing electricity for several hours to a few days,” said Dr. Bernhard Ernst, Senior Project Manager at Fraunhofer IEE.

“However, their expansion potential is severely limited worldwide. Therefore, we are transferring their functional principle to the seabed – the natural and ecological restrictions are far lower there. In addition, the acceptance of the citizens is likely to be significantly higher.”

“With the global energy transition, the demand for storage will increase enormously in the next few years,” said Bernhard Ernst, senior project manager at Fraunhofer IEE.

“With the StEnSea spherical storage, we have developed a cost-effective technology that is particularly suitable for short to medium-term storage. With the test run off the US coast, we are making a big step towards scaling and commercializing this storage concept.”

The United States department of energy’s Water Power Technologies Office (WPTO) awarded Sperro a $US4 million grant to advance its 3D concrete printing technology in pumped storage hydropower technologies.

This grant helped to unlock a $US3.7 million grant from the German ministry of economic affairs and climate action to support Fraunhofer IEE and Pleuger’s part in the project.

“This project is a major step forward to realizing the full potential of energy storage to decarbonize our electric grid,” said Jason Cotrell, CEO and Founder of Sperra.