The turbines engines used for natural gas based electrical power production can be throttled up and down over a wide range. IIRC from maximum power down to abou

The turbines engines used for natural gas based electrical power production can be throttled up and down over a wide range. IIRC from maximum power down to about 15%. But, no you do not want to just shut them off. There are natural gas based diesel generators that can be turned on and off, but being Diesel engines they really only run efficiently over a small power output range and you control how much power is generated by how many you turn on. You need rows and rows of the Diesels to match the power from a gas turbine and each diesel needs to be individually matched into the power grid. So, there are reasons to go with gas turbine electrical power generation to meet peak power demands. OTOH, CA is tearing down recently built plants because of over capacity which is just crazy and obviously a boondoggle for the electric companies. But, building the plants was driven by the craziness that immediately preceded it; CA's NIMBY driven under capacity and being forced to meet peak power demands by buying outrageously priced power from out of state. Just bad planning, more bad planning, and certainly more bad planning to come.