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What I posted was just two paragraphs from this article:

You might like to read this one also.

Here is just a sample from it

Thermal power stations

Conventional power stations fission a material or burn a fuel to obtain heat that is used to boil water and superheat the resulting steam which is fed to the steam turbines (some power stations also use gas turbines in combination with steam turbines). The turbines drive turbogenerators that make electricity.

A power station takes days to start producing electricity from a cold start. Time is needed to boil the water, to superheat the steam, to warm all the components of the power station, and to spin the turbogenerators up to operating speed.

Each power station is designed to provide an output of electricity. It can only provide very little more or very little less than this output (i.e., a power station has a "low turndown ratio").

Electricity demand matching

Electricity is wanted all the time but the demand for electricity varies from hour to hour, day to day, and month to month. The electricity grid has to match the supply of electricity to the demand for it at all times. This is difficult because power stations cannot be switched on and off as demand varies.

The problem of matching electricity supply to varying demand is overcome by operating power stations in three modes called "base load," "generation," and "spinning standby."

Some power stations operate all the time providing electricity to the grid, and they are said to provide "base load."

Other power stations also operate all the time but do not provide electricity all the time. They burn (or fission) their fuel to boil water and superheat the resulting steam which is fed to the steam turbines that are thus kept hot and spinning all the time. Of course, they emit all the emissions from use of their fuel all the time. But some of this time they dump heat from their cooling towers instead of generating electricity, and they are then said to be operating "spinning standby."

One or more power stations can be instantly switched from spinning standby to provide electricity to match an increase to demand for electricity. It is said to be operating "generation" when it is providing electricity. Power stations are switched between spinning standby and generation as demand for electricity changes.

Thus the grid operator manages the system to match supply with demand for electricity by switching power stations between "generation" and "spinning standby."

Windfarm input to electricity

Windfarms only provide electricity when the wind is strong enough and not too strong. So, they suddenly provide electricity when the wind changes. The grid operator must match this changed supply of electricity to the existing demand for electricity. Of course, the grid operator achieves the match by switching a power station to spinning standby mode. That power station continues to operate in this mode so it can provide electricity when the windfarm stops supplying electricity because the wind has changed again.

Windfarms only force power stations to operate more spinning standby. They provide no useful electricity and make no reduction to emissions from power generation. Indeed, the windfarm is the true source of emissions from a power station operating spinning standby in support of the windfarm.

Windfarms have capital, maintenance and operating costs that add to the cost of electricity. These costs are their only contribution to electricity supply.