How does burning fossil fuels convert chemical energy into heat and electricity?
The ingenuity people used in harnessing waterpower can be seen in this medieval-style mill. The waterwheel is turned by a stream and is connected to a shaft that leads into the building. At the other end of the shaft is a gear. The connection of a series of gears translates the power from the stream to a shaft that drives a millstone, which grinds flour from grain.
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Burning fossil fuels converts chemical potential energy into heat through exothermic combustion reactions, where the chemical bonds of the fuel and oxygen are replaced by more stable bonds in products like carbon dioxide and water. This process releases energy as heat and light.1
In power generation, this heat is typically used to produce steam in a boiler. The high-pressure steam is then directed into a turbine, where its thermal energy is converted into mechanical energy as it rotates the turbine blades. This rotating shaft drives an electric generator, which converts the mechanical energy into electricity for distribution.23
Some advanced technologies improve this energy conversion efficiency. For example, magnetohydrodynamics can convert a portion of the energy from ionized combustion gases directly into electricity using a magnetic field before the remaining heat is used to generate steam. Alternatively, combined-cycle systems use gas turbines to capture energy from combustion products before utilizing the exhaust to drive a conventional steam turbine.4