Glossary
The English version of our glossary is currently under construction and will be regularly updated.
Energy
Energy is the ability to do work, produce heat or emit light. It describes the status of a body and is a conserved quantity. In a closed system, the total energy remains unchanged.
Energy can be subdivided into a variety of types and can be used by human beings when it flows from one place to another or is converted from one form into another. Primary energy (also referred to as energy sources) is the energy contained in natural resources (e.g. coal, crude oil, natural gas, uranium) and which has not been converted by human beings. By means of purification (natural gas), refining (oil in oil products) or conversion into electricity or heat, it becomes secondary energy. When secondary energy is supplied to consumers, it is referred to as end energy (e.g. electricity from a power socket), where it becomes usable energy (e.g. light). Every day, the sun provides tremendous amounts of energy in the form of rain, wind, radiation, etc. Part is stored in biomass or rivers and can be utilised by human beings; other parts can be directly utilised, e.g. sunlight, fresh air, and ambient heat.