nuclear fusion
Heat from a wood fire can boil a pot of water. If you put an egg in the pot, you can eat a hard boiled egg in 15 minutes cool it down first! . The energy to cook the egg was stored in the wood. The wood got that energy from the Sun when it was part of a tree. The Sun generated the energy by nuclear fusion. You started the fire with a match. The head of the match stores energy as chemical energy. That energy lights the wood on fire. The fire burns as long as there is energy in the wood. Once the wood has burned up, there is no energy left in it. The fire goes out.