How can fission and fusion be used?
Nuclear fusion and fission can both be used to unleash huge amounts of thermal energy. In other words, these reactions produce a LOT of heat energy.
In power plants, the fission of uranium is to heat water to produce steam which turns turbines, which generate electricity.
Nuclear fission is harder to control on earth. The sun uses nuclear fusion when it fuses hydrogen atoms into helium atoms. When a small amount of mass is converted to energy, that energy is released as heat energy. A lot of heat energy!! We feel the sun's heat 93 million miles away, so this is a very effective way to produce thermal energy.
Hope this helps and thanks for the great questions.