Researchers of Karlsruhe Institute of Technology (KIT) and their European partners plan to develop an innovative sulfur-based storage system for solar power. Large-scale chemical storage of solar power and its overnight use as a fuel are to be achieved by means of a closed sulfur-sulfuric acid cycle. In the long term, this might be the basis of an economically efficient renewable energy source capable of providing base-load power. The pre-development work under the PEGASUS project will be funded by the EU with about EUR 4.7 million.