My guess would be the limiting factor is actually the capacity of the turbines, not that of the reservoir, in which case it makes sense to talk about watts. I a

My guess would be the limiting factor is actually the capacity of the turbines, not that of the reservoir, in which case it makes sense to talk about watts. I agree that it is a weird way to talk about it though? edit: quote from http://www.mercurynews.com/business/ci_24331470/california-adopts-first-nation-energy-storage-plan http://www.mercurynews.com/business/ci_24331470/california-a... "The 1.3 gigawatts is a capacity target, because different storage technologies have different rates at which they can accept and discharge energy, and the mandate aims to be technology-neutral."