Earlier quoted context omitted.
Not sure if I missed it but didn’t see anything in your source to back up this 7 years worth of battery production requirement for what the US needs in stationary storage. Without seeing how we got to the number, I’m skeptical. Things worth considering: 1) decommissioned battery packs from electric cars will eventually have 2nd lives on the grid 2) the manufacturing capacity of li-ion globally today is paltry compare…
> Not sure if I missed it but didn’t see anything in your source to back up this 7 years worth of battery production requirement for what the US needs in stationary storage. The source is a curve of projected battery production. You take the integral of the curve. The US consumes 4TWh of electricity per day. 3 days of storage is 12 TWh. The 3 day capacity estimate already includes solar and wind generation complement…
Apologies for not clearly stating that what I wanted to know was not how you did your math, but your source/the modelling behind the '3 days of storage' number which I didn't see in your source.
The points in my previous reply were all in questioning the need for everywhere to have '3 days of energy storage' in order for us to significantly decarbonize. While it might represent a theoretical metric based on the state of the world today, I am doubtful it includes the points I mentioned, particularly demand response and continent wide grids connected with HVDC transmission lines (both of which are under discussions in various parts of the world).
Additionally, the same principle applies with a server/service uptime reaching 100%. Realistically, we talk about 'how many 9s'. 99% uptime is much easier than 99.999%. Pushing the last 10% of fossil fuels off our grid will be hard, and the last 1% even harder, 0.1% etc as you start covering all the edge cases until we get to 100%. Probably will not get to 100% in our lifetimes. But I'd bet that we will get to 80% and maybe even 90% much faster than what status quo projects.
Using Germany and California as an example, where many of my points above do not apply (and they are still able to get to 50% renewable generation) I view as a good sign. Neither grid has a particularly large amount of installed storage, connectedness to other grids or integrated demand response either. Getting the world to even 80% renewables will require no-where near the '3 days of storage', particularly as other tech (like storing energy as heat in blocks when there is excess energy) becomes viable in this decade. Many parts of the world have less than single digit penetration of renewables today - we have lots of room to go.
Additionally, solar's cost is declining quickly (disclaimer & note: I am in the solar industry and see these cost declines continuing apace) and have seen first hand people starting to 'overbuild' their solar sites. Factor overbuilt solar, and that it has a unique property of 'predictability' (you KNOW for sure the sun will rise tomorrow, you don't know if it will be windy at all in the next 2 weeks). Given that even a very cloudy day can still generate a large fraction of the peak energy capacity - any excess can be curtailed until that capacity can find somewhere valuable to go as the grids and other energy storage tech beyond li-ion evolves.