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Charging doesn't show up as curtailment, that is mostly due to grid congestion, as transmission lines reach their maximum capacity and physically can't get all

Charging doesn't show up as curtailment, that is mostly due to grid congestion, as transmission lines reach their maximum capacity and physically can't get all the solar power to loads that need it. Also, nuclear plants can't be turned on and off very quickly so they stay on all the time, and some number of natural gas plants must stay running during the day so they are able to quickly ramp up when the sun goes down. So on a nice sunny day that isn't too hot there is a lot of solar power that physically cannot be used and so has to be curtailed. In peak summer when ACs are blasting you'll see less curtailment, and in the future as they keep building out battery storage you'll probably see less curtailment in general.

AnthonyMouse 1y ago
> some number of natural gas plants must stay running during the day so they are able to quickly ramp up when the sun goes down. Doesn't this only take a few minutes for a natural gas plant?
- toomuchtodo 1y ago
  Combined cycle fossil gas units can take up to 12 hours from cold start to full output, roughly 25% can be up to speed within an hour (EIA). ~7-30MW/minute. Once through peakers can ramp faster, but are less efficient (they’re essentially jet engines bolted to the ground), and more expensive than battery storage. https://www.eia.gov/todayinenergy/detail.php?id=45956 https://www.eia.gov/todayinenergy/detail.php?id=45956 https://www.lazard.com/media/xemfey0k/lazards-lcoeplus-june-2024-_vf.pdf https://www.lazard.com/media/xemfey0k/lazards-lcoeplus-june-...
- burkaman 1y ago
  In addition to what the sibling comment says, a few minutes is fine for predictable changes like sunset, but you also need enough dispatchable power online to deal with unexpected changes. What if a transmission line goes down and cuts off a big solar farm? Other plants must respond within a literal second to fill the gap and prevent a cascading failure of the whole grid like what happened in Spain recently. That doesn't have to be natural gas, batteries and hydro and even other curtailed solar plants can fill this role if there are enough of them, but we're not there yet.
- whatevaa 1y ago
  Turbines need be kept hot. Especially for steam, but probably for gas too. Don't want thermal stresses in 1000 ton fast spining objects.

AnthonyMouse 1y ago

> some number of natural gas plants must stay running during the day so they are able to quickly ramp up when the sun goes down. Doesn't this only take a few minutes for a natural gas plant?

toomuchtodo 1y ago
Combined cycle fossil gas units can take up to 12 hours from cold start to full output, roughly 25% can be up to speed within an hour (EIA). ~7-30MW/minute. Once through peakers can ramp faster, but are less efficient (they’re essentially jet engines bolted to the ground), and more expensive than battery storage. https://www.eia.gov/todayinenergy/detail.php?id=45956 https://www.eia.gov/todayinenergy/detail.php?id=45956 https://www.lazard.com/media/xemfey0k/lazards-lcoeplus-june-2024-_vf.pdf https://www.lazard.com/media/xemfey0k/lazards-lcoeplus-june-...
burkaman 1y ago
In addition to what the sibling comment says, a few minutes is fine for predictable changes like sunset, but you also need enough dispatchable power online to deal with unexpected changes. What if a transmission line goes down and cuts off a big solar farm? Other plants must respond within a literal second to fill the gap and prevent a cascading failure of the whole grid like what happened in Spain recently. That doesn't have to be natural gas, batteries and hydro and even other curtailed solar plants can fill this role if there are enough of them, but we're not there yet.
whatevaa 1y ago
Turbines need be kept hot. Especially for steam, but probably for gas too. Don't want thermal stresses in 1000 ton fast spining objects.