[dragontamer]

You can dispatch nuclear power plants.

Its just that their high costs make that an uneconomical decision. Nuclear fuel is damn near free, so why would you ever want to turn it off unnecessarily? Only if the price of electricity reaches into negative-territory is it economically viable to turn off a nuclear power plant.

Same thing with wind / solar. As long as the price of electricity is positive, there's no point in turning them off.

--------

Now think about coal / natural gas. The price of fuel in these cases dominate. Which means its economically viable to turn off when the price of electricity drops (even if its still above $0).

[pydry]

Nuclear fuel is not free but it is cheap, especially compared to the eye watering capital costs of nuclear power.

It is helpful to turn off power production to stabilize the grid. It's not always about production costs. This is why nuclear plants and wind turbines sometimes just "waste" excess energy.