There's lots of cost effective storage methods (compressed air, compressed CO2, pumped hydro, inertial/iron oxide/lithium ion/sand/hydrogen batteries, and so fo

There's lots of cost effective storage methods (compressed air, compressed CO2, pumped hydro, inertial/iron oxide/lithium ion/sand/hydrogen batteries, and so forth), but the costs are all mostly up front, requiring major investments that aren't happening. Some of them also require non-trivial time to build.