The Fraunhofer Institute for Wind Energy and Energy System Technology said it has completed a four-week test of its Stored Energy in the Sea (StEnSEA) concept. Fraunhofer said it recovered its three-meter diameter hollow sphere from the bottom of Lake Constance on the Swiss-German border, where it had been operating at a depth of about 100 meters. The technology uses water pressure to drive electromechanical pump components within a central tube of the storage unit.
The concrete sphere operates much like pumped storage hydropower. According to the institute, the test successfully proved the function of the storage concept, and researchers are evaluating the data to improve on the developed models.
In a follow-up project, Fraunhofer wants to test a larger sphere in the sea and conduct longer-term tests. For this purpose, Fraunhofer said, the results from the Lake Constance trial have to be assessed in more detail, for example in Southern Europe or in Norway. New tests could take three to five years to complete.