Energy is a concept with various definitions and a very wide scope. Energy is a scalar physical quantity that is connected to the condition of one or more objects, technically speaking. The ability to perform tasks or generate heat is the definition of energy.
Friction is the process by which kinetic energy of moving mass, is transformed back into thermal energy when an automobile is stopped by its brakes.
Numerous ways exist for storing energy. It is kept as potential energy inside the battery.
Chemical energy is stored as energy in food.
Energy in the form of air is referred as wind energy. It's stored in the earth in the form of gravitational energy.
Thermal energy is the term used to describe the energy that is stored as heat.