Comment by littlestymaar
1 year ago
> In the studies I've seen the time shift required is on the order of seasons and the capacity required is cost prohibitive.
Another option is too build some kind of overcapacity with the renewable so that you can avoid using the battery and recharge it even when the whether is not optimal. It doesn't work if the weather isn't stable enough[1], but for Hawaii I would be too surprised if it was viable.
[1]: that's why solar + wind in northern Europe is a dead end like what we're seeing with Germany: in winter here we have very little sun and weeks long periods with practically no wind, so you'd need to have something like 10x solar if you wanted the overcapacity strategy to work, which also make things prohibitively expensive.
> so you'd need to have something like 10x solar if you wanted the overcapacity strategy to work, which also make things prohibitively expensive.
In the short-term, gas backup for such scenarios (which are relatively rare, and during which renewables will still operate at some non-100% fraction of the required energy) seems like it might be a reasonable option: we could probably get to (pulling numbers out of thin air) 95% renewable generation or something that way.
Longer term, we'll definitely need some kind of long-term storage though. Perhaps synthetic fuel driven by overcapacity renewables during peak generation times might be an option here?
> we could probably get to (pulling numbers out of thin air) 95% renewable generation or something that way.
No, and it's the problem with pulling numbers out of thin air.
I wrote on that topic a few years ago with a simulation being done on real data from RTE (French electricity transport network) if you're interested[1] you can even play with the LibreOffice spreadsheet[2] by yourself if you like. (Caveat: everything is in French).
And keep in mind that France is actually favored compared to many other countries when it comes to wind stability because it has three wind regions with different dynamics (even though they aren't entirely independent either).
[1]: https://bourrasque.info/articles/20180116-moulins-%C3%A0-ven...
[2]: https://bourrasque.info/images/20180116-moulins-%C3%A0-vent/...
> gas backup for such scenarios (which are relatively rare, and during which renewables will still operate at some non-100% fraction of the required energy)
Now you have built two energy systems and one of them has to be on standby and ready to be used only rarely. Cross your fingers and hope everything still works. You also have to maintain long term storage of gas, staff that knows how everything operates, etc.
> Now you have built two energy systems and one of them has to be on standby and ready to be used only rarely. Cross your fingers and hope everything still works. You also have to maintain long term storage of gas, staff that knows how everything operates, etc.
Well yes, except that the backup system happens to be already built. There's definitely a maintenance cost associated with this, and long-term (beyond the lifetime of existing stations) this wouldn't make any sense. But in the short-term the costs associated with this are relatively low.
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Germany can do it with a combination of wind, solar, batteries, and hydrogen.
The green hydrogen is crucial, to deal with Dunkelflauten and to some extent seasonality. Germany has ample salt formations for cheap hydrogen storage. At the site I linked elsewhere in these comments, the solution for 24/7 power from RE is nearly doubled in Germany if green hydrogen is omitted.
Germany is suffering now from the decision to pay for the 2009-2012 solar builds using long term high rates. When that ends (2032?) the costs should come down a lot. Building out solar now should be much less expensive.
We don't know if 10x will be prohibitively expensive going forward. It can also enable new kinds of uses of electricity we don't have today, offsetting the cost of build-out.
I never said it will be 10x more expensive: if the unit cost is twice as low, then having a 10x overcapacity is “only” 5x more expensive, but that's still too expensive.