Comment by looping__lui

Yes, they mention hydrogen caverns and thermal storage on pp. 5–6 — but those are more theoretical potentials than real, scalable solutions today. That’s why even in Fraunhofer’s own scenarios we still see 500–750 GW of wind + PV (6–9× average load) and 100–150 GW gas backup on top. In practice, it’s the massive renewable overcapacity that smooths supply, with storage playing only a limited supporting role.