Source?
> if grid scale storage were prohibitively expensive or impossible.
It's currently both [1].
BTW. Case in point: https://twitter.com/energybants/status/1647799729734971396
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[1] Edit: This is a nice quick overview from a year ago https://www.nsenergybusiness.com/features/energy-storage-ana...
"Cheapest" option is pumped hydro storage. To cover Europe's need you only need to build 70 1.5 GW hydroelectric stations at a cost of $92 billion (in reality much higher) while greatly damaging ecology in large areas.
The most expensive option is Li-ion batteries, clocking in at a measely 1.1 trillion dollars.
Cheap and feasible.