jhm
Well-Known Member
Yes, I get that. My point is that you need to count all storage and generation capacity. Generation capacity alone needs to be sized big enough to hit the peaks. Batteries are not really generation supply. You seem to be assuming that Powerpacks alone must be capable of supplying peak consumption with no generation. When you have enough wind, solar, bioenergy/hydro to reliably supply your peak days, then you only need enough batteries to smooth things out and optimize your economics. I don't see how you can size battery capacity needs without consideration of how much and what kind of generation mix is available.
Also the capacity of your distribution network matters quite a lot too. There have been studies showing that in the US a 100% renewable grid is possible WITHOUT storage is possible. Not surprisingly such a system requires enormous transmission capabilities to do things like send Midwestern wind power to Florida. So I very much expect that localized storage will be much more economical than massive transmission. But the point here is that there is a tradeoff to be made between transmission and storage. The more capable the grids of the world are, the less storage is needed even if all power generation is renewable.
So in abstraction, we cannot know that 80 hours of storage will be the most economical level of battery capacity. It very much depends on the generation mix and network capabilities. Lets say we postpone this discussion until Powerpacks have supplied 1 hour of storage capacity globally. That will be enough to radically reshape the economics, and we'll be in a much better position to say if 20 hours, 80 hours or even 360 hours of storage will optimize the electricity markets. Just getting to Powerpacks supplying 1 hour is about 5 TWh of storage. That alone would take about ten Gigafactories to maintain.
