3 ms·
Coal plants also can’t produce on demand because of inertia and long start times (though they can balance a bit). The only thing that can ‘produce’ on demand is
by dpierce9 6y ago
Coal plants also can’t produce on demand because of inertia and long start times (though they can balance a bit). The only thing that can ‘produce’ on demand is battery. Combustion Turbines come in a close second.
The peaks in the grid utilization curve actually tends to match the solar production curve pretty well (there are local deviations, running an aluminum smelter at night). Look at the demand curve in CA, you will see that it is flat midday. Before solar there was a peak midday. This creates issues on the ends (duck curve) of course but the key point is that solar production very closely matches peak electricity use.
- hinkley 6y agoHow long does it take for a coal plant to ramp up or down? I wonder how much battery buffer you'd need to have the plant work on a pure control theory basis instead of long term forecasting?
- dpierce9 6y agoDifferent plants have different ramps depending on where they are in their output curve, how hot they (or various parts) are, and how their operators want to run them (max ramp is generally higher than economic ramp) but, while it isn’t my business to know this stuff anymore, IIRC it is 2-5 MW/min for coal. This is ignoring the control loop.
- etimberg 6y agoSome answers to that here: https://www.quora.com/Whats-the-typical-ramp-rate-i-e-MW-s-for-hydro-and-thermal-power-stations?share=1 https://www.quora.com/Whats-the-typical-ramp-rate-i-e-MW-s-f...
- twic 6y agoGas turbines are on-demand enough. There's a bunch of stuff grids can do at shorter timescales to deal with variations in demand that don't involve actual batteries. There used to be a great article on Wikipedia how about this is done in the UK, but it was deleted. Notionally, it was merged into the main article about the National Grid, but all the interesting content was discarded when that happened. I think the worry was that the article was unsourced - it was pretty clearly just a Grid engineer who sit down and bashed it out one day. Anyway, here it is: https://en.wikipedia.org/w/index.php?title=Control_of_the_National_Grid_(Great_Britain)&oldid=680713385 https://en.wikipedia.org/w/index.php?title=Control_of_the_Na...
- dpierce9 6y agoNeat reference. I agree with you on CTs. The original poster suggested two things: solar is not responsive to demand and that coal plants are responsive. My response is intended to be narrow to those points: coal plants don’t really produce on an instantaneous demand signal any more than solar or wind. Coal produces at some amount and then ramp up or down based on a longer-horizon demand signal (e.g., a 5-min Grid solution). Wind and solar can’t ramp up but they can dispatch down on the same signals. My other point is that solar generally matches peak demand pretty well so you don’t need a ton of demand responsiveness (given that electricity demand is already inelastic).
- novok 6y agoWikipedia needs a section of their website where people like grid engineers can bash out original sources like that that dont want to maintain their own personal page. Call it wikisource and instead of deleting just move it to there.
- dane-pgp 6y agoThe other half of that problem is finding a way for a grid engineer writing such a page to prove that they really are a grid engineer. Perhaps a tweet from their employer linking to and endorsing the wikisource page would suffice.