We are not conserving energy,we are conserving resources which produce energy
Energy can neither be created nor destroyed but only transformed from one form to another"
Mechanical energy, such as the kinetic energy of motion, can be converted to heat energy, for example in the heating of a car’s brakes when it slows down. Chemical energy in the gasoline of the car can be converted into both heat energy in the exhaust and heating the engine, and into mechanical energy to move the car. Potential energy, such as the gravitational potential energy stored in an object which is on a high shelf, can be converted into kinetic energy as the object falls down. Electrical energy can be converted to heat or mechanical energy or sound energy in a variety of useful ways around the house using common appliances.