RICAS2020 is a design study for the European Underground Research Infrastructure related to Advanced Adiabatic Compressed Air Energy Storage (AA-CAES) which provides concepts to set-up a research infrastructure dedicated to underground storage of very high amounts of green energy. The big advantage of the new concepts is that the underground energy storage can be performed independently from the encountered geological conditions and also at all places where high energy demand exists. For more information, see www.ricas2020.eu.