German Institute Aims to Launch Underwater Electricity-Storage Test

The tests will be a continuation of the StEnSea project from 2016, which involves submerged hollow concrete spheres to store electricity. The IEE has tried out a three-meter sphere at depth of 100 meters in Lake Constance. Now, the institute intended to submerge a nine-meter sphere at a depth of 500-600 meters off the coast of Long Beach. 

“By emptying the sphere, the storage is charged,” writes the IEE on its website. “When water flows in, electricity is generated – it is discharged. The power of this prototype is 0.5 megawatts, the capacity 0.4 megawatt-hours.” 

The test will go operational by the end of 2026 at the latest. The German Ministry for Economic Affairs and Climate Action is funding the project with nearly EUR 3.4 million euros while the US Department of Energy is chipping in some USD 4 million. 

The institute added: “The global storage potential of this technology is 817,000 gigawatt-hours in total. At the ten best European locations, it is still 166,000 gigawatt-hours. In comparison, the capacity of existing pumped storage power plants on land in Germany is just under 40 gigawatt-hours… The lifespan of the concrete sphere is 50 to 60 years. Pump turbines and generators would need to be replaced every 20 years.”