Re: Democrat 2020
Just cutting the quote short to save space. I actually did half a university course on that (quit because I didn't feel like learning all the formulasOriginally Posted by a completely inoffensive name
). I'm pretty sure that renewables make this easier than fossils. Fossils aren't always as quick as you may think. IIRC a nuclear power plant takes 3 to 5 days to power up or down, but for a big lignite plant it's still about a day, so it's relatively hard to make it react to changes that happen during the day. Gas power plants are among the faster ones. Some residual heat in the pipe of a solar plant will probably cool down faster than you can turn most big power plants off, and they have residual heat as well, that's one reason they take so long.
There is more to it though, becaus in every case, the heat is used to turn water into steam and drive a steam turbine to generate energy. In pretty much all of these scenarios it would be possible to simply divert the steam, stop the turbine and just let the steam from residual heat go to waste while energy generation is stopped completely. In a wind turbine, you could decouple the generator and/or install a gearbox in the first place to throttle generation better. One big difference in design there would be though, that you would want to build your solar thermal plant with a heat storage anyway because that's what would allow it to continue operating at night. So unlike the coal plant, you'd not have to turn it off but just divert the heat from the generator to heating up the heat storage (I think the idea was to use huge insulated tanks with some sand or salt fluid inside that can store a lot of heat for a long time).
Energy storage would also be required if the demand can't be met by sun and wind conditions (although at some point one could have enough distributed panels to be able to meet it anyway).
Regarding the frequency of your grid, I remember that there are a couple of measures taken to keep that fluctuation very low. They're about correctly partitioning the grid, demand forecasting and so on. There are also usually decoupler stations in every grid that can help with managaing the supply and demand (I don't know how exactly it works, but they could just not decouple the generator but "short" or ground it instead so it generates energy and it's just dissipated/wasted until it stops). With respect to renewables, decentralized grids need to be smart grids according to many, which means the grid needs to become more computerized and coordinated electronically to keep the frequencies stable.
And if you need really quick reaction devices, there are also battery parks, e.g. made up of old electric car batteries that still work but don't give the cars sufficient milage anymore. Another storage option, although currently with a big inefficiency, is hydrogen. With more engineering research, the inefficiencies can probably be reduced there, making it a good option to fuel cars as well (first cars already exist anyway).
So I'd say reaction time is not the big issue, especially not with a networked smart grid that handles supply automatically dependent on demand. Storage is currently a bigger issue, but not an unsolvable one. If overproduction were such a big issue, I would also wonder what one would do with all the excess energy from a partial dyson sphere.
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