Comment by rgmerk
1 day ago
We can and do, and there are detailed plans based on those weather scenarios (eg for the Australian east coast grid; there is AEMO’s Integrated System Plan).
Things in the US are a bit more of a mixed bag, for better or worse, but there have been studies done that suggest that you can get very high renewables levels cost effectively, but not to 100% without new technology (eg “clean firm” power like geothermal, new nuclear being something other than a clusterfumble, long-term storage like iron-air batteries, etc etc etc).
The best technologies there are (IMO) e-fuels and extremely low capex thermal.
There are interesting engineering problems for sources that are intended to operate very infrequently and at very low capacity factor, as might be needed for covering Dunkleflauten. E-fuels burned with liquid oxygen (and water to reduce temperature) in rocket-like combustors might be better than conventional gas turbines for that.
Curious - any references for those “rocket turbine” motors, particularly for this application? I’ve not seen that idea before.
It's mostly something I thought about myself. The prompting idea was how to massively reduce the capex of a turbine system, even if that increases the marginal cost per kWh when the system is in use, and also the observation of th incredibly high power density of rockets (they're the highest power density heat engines humanity makes). So, get rid of the compressor stage of the turbine, be open cycle so there's no need to condense steam back to water, and operate at higher pressure (at least an order of magnitude higher than combustion turbines) so the entire thing can be smaller.
You'd have to pay for storage of water and LOX (and making the LOX) so this wouldn't make sense to prolonged usage. On the plus side, using pure LOX means no NOx formation, so you also lose the catalytic NOx destruction system a stationary gas turbine would need to treat its exhaust.
I vaguely recall some people in Germany were looking at something like this but I don't remember any details.