Chemical potential energy is the energy stored in the chemical bonds of a substance. The various chemicals that make up gasoline contain a large amount of chemical potential energy that is released when the gasoline is burned in a controlled way in the engine of the car. The release of that energy does two thingsIn thermodynamics, chemical potential of a species is a form of energy that can be absorbed or released during a chemical reaction or phase transition due to a change of the particle number of the given species.

Food Energy

Foods are composed chiefly of carbohydrates, fats, proteins, water, vitamins, and minerals. ... An older metric system unit of energy, still widely used in food-related contexts, is the calorie; more precisely, the "food calorie", "large calorie" or kilocalorie (kcal or Cal), equal to 4184 joules.