Researchers Have Discovered That Concrete Spheres Are Great for Energy Storage. Testing Is Underway off the Coast of California

The StEnSea project, developed by Germany’s Fraunhofer Institute for Energy Economics and Energy Systems, aims to revolutionize energy supply by providing clean, renewable energy while minimizing environmental impact. The project’s components are large concrete spheres resting on the ocean floor.

After a successful test with a smaller sphere in Lake Constance in the Alps, the German government and the U.S. Department of Energy are preparing for a second test off the coast of California. This upcoming project will begin with a 30-foot sphere, followed by a massive 100-foot sphere.

As research continues, the idea of submerging giant concrete spheres beneath the seabed is starting to make sense.

Spherical Storage on the Seabed

The system is surprisingly simple. Concrete spheres are located at a depth of 1,600 to 2,000 feet, where gently sloping shores allow for easy installation. These hollow spheres have two key features: a power supply system and a valve equipped with a pump turbine.

These giant spheres function as remarkable batteries. When connected to the grid via an underwater cable, they draw water from inside the sphere using electricity generated by renewable energy sources. Despite remaining empty for future use, they withstand the pressure of the surrounding water.

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When additional energy is needed, such as during the night when solar power isn’t enough or on windless days, the underwater battery comes into action. By opening the valve, the natural pressure from being submerged hundreds of feet underwater allows water to flow back into the sphere. This water movement turns the turbine, and the generator converts the mechanical energy into electricity.

With an efficiency ranging from 75% to 80%, the main advantage of this system is its estimated storage cost of only $0.052 per kWh. Additionally, the lifespan of concrete spheres is projected to be around 50 to 60 years. The mechanical components, including the valve and generator, will only need replacement every 20 years to ensure optimal performance.

Using 100-foot concrete spheres increases the capacity by a factor of 27 compared to the 30-foot prototype currently in development. This advancement could pave the way for underwater electric energy parks. These parks would support the expansion of renewable energy and play a crucial role in addressing peak demand during times when other energy sources may not be enough.

Image | Cristian Palmer

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