Energy transformation is the process of changing energy from one form to another. This process is happening all the time, both in the world and within people. When people consume food, the body utilizes the chemical energy in the bonds of the food and transforms it into mechanical energy, a new form of chemical energy, or thermal energy. Energy transformation is an important concept in the application of the physical sciences. The ability for energy to be transformed automates, lights, entertains, and warms the world in an astounding multitude of ways.
The concept of energy transformation can be illustrated in a number of common activities. An engine, such as the engine in a car, converts the chemical energy of gas and oxygen into the mechanical energy of engine movement. A light bulb changes the chemical energy of the bulb into electromagnetic radiation, or light. Windmills harness the energy of the wind and convert it into mechanical energy in the movement of the turbine blades, which is then converted to electrical energy. Solar panels transform light to electricity.
Energy transformation can also be explained in terms of potential energy, the stored energy of a system, which can be converted into kinetic energy, the energy of movement. For example, a roller coaster sitting at the top of a hill is said to have potential energy. This potential energy is gravitational, which is gained when the coaster moves up the hill. Once the coaster begins to move down the hill, the force of gravity is exerted and the potential energy is transformed into the kinetic energy of the car moving. During energy transformations, potential energy is often transformed to kinetic energy and back again to potential energy.
During any kind of energy transformation, some energy is lost to the environment. As a result of this loss, no machine is ever 100% efficient. Commonly, a portion of the energy lost during energy transformation is lost as heat. This can be observed in practice by noting the heat emitted by a computer, a car, or another type of machine that has been in use for a period of time.
The ability of a given machine or system to convert between forms of energy is called the "energy conversion efficiency." All systems have different energy conversion efficiencies. Water turbines, for instance, have an extremely high energy conversion efficiency of nearly 90%, while combustion engines have from 10% to 50% conversion efficiency. Engineering and physics are constantly in pursuit of systems capable of achieving high energy conversion efficiency.