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Comment by calgarymicro | Hacker News Reader

I'd guess it maybe takes time and money to ramp up/down natural gas capacity, so it makes financial sense to maintain capacity at a loss for now to better/more rapidly profit when solar capacity drops and prices go positive again? If I'm reading the day ahead chart on that page correctly, prices should go positive again around 5PM.

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I'm definitely under the impression that that's the case for nuclear (which is famously bad at reacting to changing demand), but I would have thought that even slow gas plants could turn off for hours profitably. Could be wrong.

Plants will typically have a normal operating range (where the minimum is >0). A gas plant can respond fairly quickly within that range, but a cold start requires more time.

So they're paying money (or at least, producing little income) to keep the plants working when it is not needed, so that things are ready to go when it inevitably becomes possible for the plants to spool up and make money when their need increases.

Makes sense.

Exactly. They can do this (i.e. keep producing power when the spot price is negative) because a plant that can respond rapidly to increased demand can charge a large premium in times of need.

It could be that solar or wind can “shut down” much faster than offline natural gas can be brought online, so it’s better to run them at some sort of “idling” power than to turn them off entirely.

Keep in mind it's not just generation that needs to shut down but also re-routing that power. Transmission lines and substations have certain capacities. Shutting down a gas plant for a few hours can mean transferring power from elsewhere in the grid over lines not really designed for that load. It could be easier/cheaper to keep the plant running than to build out higher capacity transmission to power that part of the grid.

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