How are river and stream connected?

The flow of energy

In daily life, the ability of energy to do work is used to provide very many services. One example is the transport of people and goods by cars, trains, ships or planes.

Other examples are the heating and lighting of houses, the work of motors, pumps and other systems such as cooling devices or melting furnaces in industrial plants, the use of medical devices in clinics or all modern communication. The growth of plants and the life of all other organisms would not be possible without the constant supply of energy.

How does energy get to where it is needed?

Energy is transported using so-called energy carriers. In the case of plants, it is sunlight, so the energy is supplied to the sun by electromagnetic radiation. Oil, gas, coal, electricity or district heating are used as energy sources for heating. Many devices that we use every day would not work without electricity, just like the Deutsche Bahn transport network. Other transport systems require a constant supply of fuels such as gasoline, diesel or kerosene for air traffic.

Energy flow in Germany in 2015

Energy sources such as heating oil, various fuels and electricity must first be generated through technical processes, because they do not occur in nature - in contrast to sunlight, wind, hydropower, coal, crude oil or natural gas. For this reason, these are also called primary energies. They are the sources that feed our very complex energy system, at the end of which are the diverse services required by the four end energy sectors economy, transport, trade-trade services (GHD) and households.

How much primary energy is required to keep the entire energy system running continuously depends on the wide range of energy services. For this purpose, the primary energies are converted into energy carriers using various technical processes. Energy carriers are therefore also referred to as secondary energies. In some cases, such as coal, gas or sunlight as the light source, the primary energy and energy source can be identical.

Nuclear energy is available as an additional primary energy source. For this purpose, the energy is used that is generated in the nuclear reactions of heavy chemical elements. Above all, this includes uranium, because when the atomic nucleus of uranium-235 is split, energy is released in the form of heat. This is used in nuclear power plants to generate electricity with the help of steam turbines, very similar to a coal or gas power plant.

In all probability, hydrogen could establish itself as a further energy carrier for our energy system. But hydrogen must also be obtained from primary energy using conversion techniques. Hydrogen is therefore not an energy source but a medium that can be converted into heat or electricity in a very environmentally friendly way.