Renewable energies have a major drawback: the intermittency of their production. Thus, being able to store production is a challenge, which seems to be taken up by a German research institute which is testing a storage system via submerged spheres.
The success of the energy transition towards green energies also depends on our ability to store this energy, its production having the disadvantage of intermittency. Being able to store overproduction in order to be able to reinject it into the network outside production periods would make it possible to take this transition to a new level and the solution could come from Germany.
It is the German Fraunhofer Institute IWES (Institut für Windenergie und Energiesystemtechnik) which is currently testing a system for storing green electricity from giant spheres immersed in the sea depths. Each sphere with a diameter of 30 meters is connected to a green electricity production system (whether it is a wind farm, photovoltaic or other) and is responsible for storing the electricity produced by the system on which it depends.
An ingenious system
It’s a subtle balancing act that has been designed for the proper functioning of this system called StEnSEA (for « Stored Energy in the Sea »). Thus, during periods of high electricity production, the surplus that cannot be injected into the network is used to operate the pumps located inside the spheres. These pumps can then reject the water they contain, thus creating a pressure differential between the inside and the outside of the sphere. Conversely, when there is no electricity, this time the water is allowed to rush into the spheres via a set of turbines which then produce electricity.
Last September, a prototype sphere three meters in diameter was immersed at a depth of 100 meters in Lake Constance on the border between Switzerland and Germany to undergo numerous tests. If these prove conclusive, it will then be a question of defining a maritime zone in Europe capable of being the scene of tests with life-size spheres.