After my second series physics course I have begin to wonder how power plants control energy production to match the usage of a city.
There are several possible answers in my mind listed below:
Does it always over-produce the amount of energy that a city needs so that a certain amount of electricity is wasted?
Does it over-produce the amount of energy but stores the excess energy in molten salt, or pumping water?
Does it match exactly the current energy need?
The reason that this question has come to my mind is that if option 1 or 3 is true, then solar power and wind power is completely useless, as the generated energy must be used immediately, but I have to list as an option as I often don't see dams or molten salt reservoir around solar and wind power generators.