RE: Future predictions on Renewable energy sources!24 Mar 2021 21:08
Kalasin - it is interesting but it is an extreme case - he is trying to get 100% electricity supply from Solar, wind and Batteries and not considering longer term seasonal storage options such as hydrogen or biofuels. This is why he comes up with an optimum battery storage duration of 35-90 hours. This is fine if you don't want to consider those other seasonal options and are trying to push people into assuming they need batteries that are only competitive at 35 hours plus.
As https://www.nrel.gov/docs/fy19osti/74184.pdf shows the trouble is that A) the first 8 hours of storage can be used on an almost daily basis, but then the next 8-16 hours (B) may only be used 50 times a year and then hours 16-24 (C) maybe only a dozen or so times a year, and then the final 24-32 (D) hours maybe only a couple of times a year when you know the wind is going to be low in the winter.
Thus you can consider a 32 hours battery as 4x 8 hour batteries - A which is cycled daily and used very effectively, B which is only used a quarter as much, C a twentieth of the time and D one percent of the time.
If the technology were Lithium ion then A,B,C and D would all cost the same amount and you can see it is definitely not a wise use of capex.
If the technology is flow battery life is better as B, C and D can be obtained simply by adding in extra electrolyte (so the cost is less than A), but although C and D cost just as much as B they only get used a fraction of the time of B.
The lowest cost solution is to use a flow battery for 8 hours as the LCOS for an 8 hour VRFB is as good as that for Lithium and it provides additional flexibility and lack of degradation, combined with a seasonally optimised energy storage technology.