This makes a few of the classic mistakes that makes it, at best an extreme upper limit on the storage required. They admit that they know that in the conclusio

This makes a few of the classic mistakes that makes it, at best an extreme upper limit on the storage required. They admit that they know that in the conclusion, but not in the title. Specifically: No curtailment, on the specific day they know the delta between production and demand will be greatest, and then assuming an inflexible lower bound for non-renewable generation that must run.