Pumped storage has a carbon impact because of the massive amounts of concrete involved. The EU is looking at hydrogen storage instead, with the idea being that

Pumped storage has a carbon impact because of the massive amounts of concrete involved. The EU is looking at hydrogen storage instead, with the idea being that the natural gas distribution and storage network will gradually shift over to hydrogen which is produced from surplus solar and wind. Ofcourse, you first need surplus solar and wind, and that's what the real problem is. There is still plenty of headroom to build more solar and wind for immediate use before we reach the point where some of the produced energy needs to be stored.