[ViewTrick1002]

Keep some of the existing natural gas plants around as an emergency reserve. Run them on hydrogen or hydrogen derivatives for zero carbon fuel, if the emissions are large enough to matter.

[PunchyHamster]

that costs a lot of money

[ViewTrick1002]

Not really. That is how the grid works today. Especially open cycle turbines, which are essentially stationary aircraft engines.

Lowest possible fixed costs, high operating costs.