Comment by bryanlarsen
19 hours ago
> But it's well suited to seasonal storage of solar energy, as that would be extracted over months, more or less continuously.
But what is that useful for? During almost all of those months it would be a lot cheaper to use renewables & short term storage. And it's not fast enough for the few days it's not beaten by something cheaper.
It's useful for storing cheap solar energy for use in winter. Sizing the solar collectors for winter would require them to be much larger. Basically, this lets 2.5 W of solar in summer deliver 1 W of solar in winter. For a high latitude where the change in insolation is higher than that, this is superior. In Hamburg, for example, insolation varies by more than a factor of 10 from July to December.
Put another way: if you oversize the solar to be adequate in winter, you have enormous amounts of surplus solar in summer. So why not store it?
> So why not store it?
Because 0.10 $/kWh(th) / 0.4 kWh(e)/kWh(th) is expensive.
That's the capex for storage capacity. It's amortized over the number of charge/discharge cycles. Divide by 20 or more. It's amazingly cheap, actually.