Energy is the capacity of a physical system to perform work.
Energy can be defined as the capacity to do work. It is governed by the law of conservation of energy from the first law of thermodynamics which states that energy can be neither created nor destroyed. However, energy can change forms and can flow from one place to another.
Energy is found in nature in many forms, including:
- Kinetic Energy which is energy associated with mass in motion
- Potential Energy which is energy associated with position in a force field such as a gravitational, electric, or magnetic field
- Chemical Energy which is energy stored in certain materials that can be released by chemical reactions
- Thermal/Heat Energy which is energy associated with random molecular motions within a medium; often associated with temperature
- Radiant Energy which is energy carried by light and other electromagnetic radiation
Another way to look at energy is as a system. How do we get from the base resources used to produce energy, and turn that into the energy services we use on a daily basis?
This energy system can be explained as a chain, starting with Primary Energy and ending with Useful Energy. Resources are extracted and processed to give us Primary Energy. This is a raw form of energy, an example being natural gas. Primary energy then undergoes conversion and distribution to become final energy. Final Energy is a usable form of energy such as electricity or transportation fuel. End-use technologies take final energy and convert it to the last form of energy – Useful Energy. Useful energy refers to the energy associated with the energy services that consumers receive.
The understanding and development of energy is critical for societal advancement. There is a direct correlation between the socio-economic development of a region and its consumption of energy. Our ability to utilize energy enables a society to use technology to substitute human labor. Energy also helps to improve quality of life, such as its integral role in the entertainment and leisure industries. For those who have access to energy, it is hard to imagine a life without it.
While energy is pervasive in all aspects of modern society, there are numerous negative impacts on human health and the environment associated with its production and use.