Electricity for transport
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 The unloading pier at Deptford power station. © NMM | As well as gas, London required an electricity supply for its underground and tramway system. Later, it also needed an electricity supply for homes.
Power stations were therefore built alongside the river where coal could easily be unloaded from barges. This 1921 photograph shows the crane and unloading pier at Deptford power station.
Inside the power station
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| No. 15 Parsons turbine at Deptford power station. © NMM | After being unloaded at the power station the coal was crushed to a fine powder. Then the powder was put into furnaces built into a big steam boiler.
Tubing inside the boiler circulated water, which turned to steam because of the powerful flow of heat from the burning coal.
In a two-stage system, the steam first transferred its energy to one turbine before returning to the boiler to obtain more heat and entering the second turbine. Both turbines were usually mounted on a shaft, which drove an electricity generator.
Completing the cycle
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| Cooling ponds at Canning Town power station, c. 1904. © NMM | After leaving the second turbine, the steam was condensed back to water in a condenser and recirculated. The condenser released the heat either through direct cooling - in ponds - or by evaporating water into the atmosphere through a tall chimney or cooling tower.
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| Cooling towers at Canning Town generating station, c. 1984. © NMM | Canning Town station (built in 1903) originally used cooling ponds, but these were later replaced by two natural draught towers. Each tower was 85 m (280 feet) tall. These were eventually demolished in 1984.
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