Comment by pfdietz
3 days ago
We don't need another few-hours storage technology. Batteries are going to clobber that. What we need is a storage technology with a duration of months. That would be truly complementary to these short term storage technologies.
We need anything that scales quickly, safely, and cheap. Just getting us through the duck curve would be a tremendous win for energy. https://en.wikipedia.org/wiki/Duck_curve
Batteries already solve that.
https://blog.gridstatus.io/caiso-solar-storage-spring-2025/
We need every approach that's viable. Batteries are part of the solution, and will be in future. But I don't see why we we should assume they're better in every way than this approach
A principle in engineering is that for any market niche, only a few, or even one, technology persists. The others are driven to extinction as they can't compete. It's the equivalent of ecology's "one niche, one species" principle.
There are far more technologies going for the hours scale storage market than will survive. Sure, explore them. But expect most to fail to compete.
This is not true for batteries at all. Just take a look at [1]. Many of these battery chemistries are in wide use. Batteries have several performance metrics: total storage, peak/avg power, round-trip efficiency, lifetime, capex, opex,etc. The relative value of these metrics is different for different applications, so we end up with many different types of batteries being used.
Grid level batteries have another very important metric. The actual possibility of buying a particular types of batteries from friendly nations. Simpler technologies like this CO2 battery have a huge advantage here.
[1] https://en.wikipedia.org/wiki/List_of_battery_types
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The definition of "market niche" must do too much work for my liking to make this true.
For example, for the market niche "getting people from one location to another" there are quite many technologies, like walking, bicycles, scooters, cars, trains, ships, airplanes, helicopters etc., none of them evolved as a clear winner that displaced the others.
You might say, that's a whole market, not just a market niche, but it's also a niche of the larger transportation market.
When we look at something like grid-scale energy storage, how do we know if it's a winner-takes-all niche? Maybe constraints such as availability of space, availability of funding, weather, climate, grid demands etc. create sub-niches with their own winners. Or maybe not, but how can we known?
A few hours are sometimes enough to start generators when renewable energy supply decreases. Obviously, the more capacity the better, but costs will increase linearly with capacity in most cases.
Pumped-storage hydroelectricity - where it is feasible - is the only kind of energy storage close to "months".
You can store energy for months pretty easily as chemical energy. Just get some hydrogen, then join it to something else, maybe carbon, in the right proportion so it's a liquid at room temperature making it nice and easy to both store and transport.
Wait a minute...
The point is that's already a well-served market. These competitors are like alternative semiconductors going up against silicon.
Oh: pumped hydro is not a "months" storage technology. The capex per unit of storage capacity is far too high.
Had heard a lot about flow batteries few years back. I am guessing they are slowly taking off as well, the trial and error that explains their feasibility , need and ability to pay for themselves in a market like ERCOT is the key.
This is one place where I think by 2030 a clear no of options will be established.
> What we need is a storage technology with a duration of months
Actually, having expandable, highly re-usable tech like this is much better when the capacities are in terms of hours.
This storage, combined with say 2.5x solar panel installation, could essentially provide power at 1x day and night.
Yes, and we have that. It's called Li-ion batteries.
They are good for about 1000 cycles.
This system can run for decades.
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Hell, even week will do a lot, you can start importing energy from areas that have currently better renewables conditions over night, even preemptively for a period of bad weather
I don't understand. Why is a duration of months preferable? What is the benefit above storing energy beyond say peak-to-peak? I suppose you can flatten out seasonal variation, but that's not nearly as big of a problem.
To see the importance, go to https://model.energy/
This site finds optimal combinations of solar, wind, batteries, and a long term storage (in this case, hydrogen), using historical weather data, to provide "synthetic baseload". It's a simplified model, but it provides important insights.
Go there, and (for various locations) try it with and without the hydrogen. You'll find that in a place at highish lattitude, like (say) Germany, omitting hydrogen doubles the cost. That's because to either smooth over seasonal variation in solar, or over long period drop out of wind, you need to either greatly overprovision those, or greatly overprovision batteries. Just a little hydrogen reduces the needed overprovisioning of those other things, even with hydrogen's lousy round trip efficiency.
Batteries are still extremely important here, for short duration smoothing. Most stored energy is still going through batteries, so their capex and efficiency is important.
You can also tweak the model to allow a little natural gas, limiting it to some fixed percentage (say, 5%) of total electrical output. This also gets around the problem. But we utimately want to totally get off of natural gas.
I suspect thermal storage will beat out hydrogen, if Standard Thermal's "hot dirt" approach pans out.