A thermochemical cycle is a type of energy system that uses heat and chemical reactions to produce energy. It works like this: first, fuel is burned to create heat. This heat is used to heat a container of water. As the water gets hotter, it changes into steam. The steam is then used to spin a turbine, and the turbine creates electricity. Finally, the heat created during the process is used to turn the chemical reactions back into the original fuel, so the cycle can start all over again.