My understanding from them is that while Li-ion batteries cannot create weeks long capacity, rust batteries may be able to in the future.
Check out Form Energy[0] for an early version of this, they're claiming ~100 hours of storage right now and if they're right about the science and can manage the engineering it could grow past a month. These batteries are challenging to run, a bit like a mini-chemical plant, but they do actually seem plausible.
(No personal association with the company, some of my coworkers know the founders though)
With those number we can then look at rust batteries. If we take a country like Germany we can estimate the longest period of low wind conditions in order to estimate how long capacity is required to have the country exclusively run on wind+batteries, and how often such periods occur to calculate the charge cycle. Can rust batteries create an return of investment within a reasonable time frame (with nuclear energy prices as the economical limit for what the market will bear).
It would be very interesting to read a reply.
1. The cost of these iron flow batteries is almost entirely in operations, the cost of battery material is negligible. It's early days so it's really hard to say how low ongoing costs for things like valves, pumps, control systems, etc. are going to be.
2. In principle, flow batteries shouldn't need to discharge at all. This is why researchers are confident they can create batteries with multi-month capacity.
If the cost can be reduced so much that a single discharge is all that is required to both repay the production cost and charge costs (assuming reasonable sell price for the energy) then it would be like a fuel and could be stockpiled as much as could be expected to be used.
If the technology is so much in early development that there aren't much concrete numbers, could you at least give a suggestion about where the costs are right now? How far the economics of nuclear is the technology?
For context of why I am asking this, my country has set the date 2030 as the year when no more IC cars might be sold. We do not have a date for IC power plants and we really should have. It is wrong to continue to burn fossil fuels just because the alternatives are more expensive.
Previous attempts at these batteries have run into a lot of operational problems and have had trouble keeping the batteries up and running long enough for them to be useful. There's a lot of novel engineering and chemistry that's gone into operationalizing the system.
Essentially, in order to produce it in any reasonable quantity, assuming highest available efficiencies, required such massive overbuilding of renewables that economics started to take second position to just plain "zomg" effect.
It got better if you combined it with nuclear, but there the free market that EU insists on in energy actually made it harder to achieve anything useful, so you end up with massive overbuilding still. It had a little chance if you overbuild wind & solar while also making it so you had nuclear providing close to 100% of the "base load" (defined as "floor in daily electricity consumption") while possibly providing green hydrogen as extra sink for renewables to recoup costs... but it still was problematic economically :(
What green hydrogen need to do is become economical, and to my knowledge it is even more expensive per w/h then nuclear is.