The Doldrums are caused by solar radiation from the sun, as sunlight beams down directly on area around the equator. This heating causes the air to warm and rise straight up rather than blow horizontally.
Coal is burned: Electrical Centrals burn coal with which they get enough heat. The coal might be pulverized to increase the effective combustion area.
Water boils, creating steam. The heat generated by the burning coal is used to create water vapor that rises and moves turbines. This occurs when water passing through some tubes is heated by the hot gases coming from the burning coal, turning it into high-pressure steam.
Moving steam turns turbines. The high-pressure steam is taken to turbines where it expands and moves the rotor which is the moving part of the turbines.
Turbines generate electrical energy. The turbines are connected to a generator that transforms the energy produced by the rotor into electricity.