Germany, a pioneer in energy transition, is exploring innovative solutions to meet its growing need for sustainable energy. Among these initiatives, undersea reservoirs stand out for their exceptional potential. These structures, located off the German coast, could well revolutionize the way energy is stored and used.
By harnessing natural resources in an efficient and environmentally-friendly way, these reservoirs offer a promising alternative to traditional methods. Find out how this technology could transform Europe’s energy landscape and contribute to a greener, more sustainable future.
Concept and operation of underwater energy spheres
The StEnSea project, led by the Fraunhofer Institute in Germany, proposes an innovative solution for storing renewable energy by submerging large concrete spheres in the deep sea. These structures exploit underwater pressure to store energy in the short and medium term. When a sphere is empty, it is considered charged. By opening its valve, seawater rushes in, activating a turbine that generates electricity.
To recharge, water is pumped out of the sphere, using energy from the grid. After successful tests in Europe, a full-scale prototype is planned off Long Beach, California, by 2026, with a production capacity of 0.5 megawatts.
Strategic advantages and overall potential of the StEnSea system
The StEnSea system offers significant advantages for power grids, notably by stabilizing grids through frequency regulation and facilitating energy arbitrage. By storing excess energy when demand is low and releasing it during peak consumption, it optimizes the use of renewable resources.
With an estimated global storage capacity of 817,000 gigawatt-hours, StEnSea could power around 75 million homes in Europe for a year. Storage costs are estimated at around 5.1 cents per kilowatt-hour, making it a competitive solution to traditional methods, while preserving precious land.
Comparison with traditional hydroelectric storage and deployment prospects
The StEnSea system differs from traditional hydroelectric storage in its ability to be installed in a variety of marine environments, eliminating the need for precious land. Although hydroelectric storage is generally cheaper and slightly more efficient over a full cycle, StEnSea offers unrivalled flexibility thanks to its global installation potential. Subsea spheres can be deployed where geographical conditions preclude the construction of reservoirs at altitude.
This adaptability, combined with the ability to stabilize power grids and perform energy arbitrage, positions StEnSea as a key player in the future of global energy infrastructure.
