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Comment by gpm | Hacker News Reader

Why is there still a gigawatt of natural gas based energy being produced when energy costs are negative? Is pricing regional so some power is still valuable or something?

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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.

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.

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.

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.

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.

Note you can toggle off sources in the chart by tapping on them in the legend.

Gas plants can respond quickly to changes in load, but they need to be up and running to do that. In the future this will be done with batteries but we don’t have enough of those yet. California does have about 20x more batteries than it did a few years ago, check out the Record Tracker link. There was a new record for battery discharging 5 days ago.

It could be inertia, solar doesn't have any spinning mass to maintain the frequency. https://www.nationalgrideso.com/electricity-explained/how-do...

Would the 2.5 GW of nuclear/geothermal/hydro not do that? Maybe not enough (or geographically distributed properly)?

I thought that too on the graph, but I think that's a bug in labeling. When I look at the actual scale, that colour appears to be nuclear (and the other straight line is geothermal). This also makes more sense as they are sources that actually cannot be turned down to respond to electricity demand the way in which natural gas can.

I see 1.14 GW nuclear, and 1.1 GW natural gas at 12:20 PM PST, the nuclear is a flat line at the bottom of the graph (and I agree it makes sense), the natural gas is a dark blue section in the middle-ish, which shrunk from ~3GW overnight and does vary with time.

I don't think that what I'm seeing suggests a bug with labeling.

There's a blog post on net ramps, which covers a lot of it: https://blog.gridstatus.io/net-load-ramps/

At least here in Germany transmission is the bottleneck.

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