Regenerative or renewable energy refers to the provision of energy from sustainable sources such as sun, wind, water, geothermal energy or biomass. They are available in almost inexhaustible quantities. The sun still has a lifespan of around 5 billion years. Solar radiation can be converted into electricity or heat. Wind energy, hydropower and biomass are also solar energy in converted form.
In contrast, the reserves of fossil fuels such as coal, oil, natural gas and conventional nuclear fuels are continuously decreasing as consumption continues. These fossil fuels are non-renewable energies. Once they have been burnt in a power or heating plant, they are no longer available. They do not regenerate, they are devalued.
However, the growing world population and the advancing technological development of mankind are leading to an enormous demand for energy, which is constantly increasing. It is also known that emissions of the greenhouse gas carbon dioxide (CO2) from the combustion of oil, natural gas and coal are very high and, according to current knowledge, are the cause of global warming. However, the greenhouse gas emissions from renewable energies are only 1/10 to 1/100 per unit of energy generated compared to fossil energy sources.
The transition of the energy supply from fossil and nuclear fuels to renewable energies is already in full swing and is known in Germany as the energy transition. In addition to the increased expansion of renewable energies, reducing our energy consumption and increasing energy efficiency through technological progress are both key issues and current challenges. In everyday life, we encounter the energy transition in electromobility in transport, in the purchase of energy-efficient household appliances or in the energy-efficient refurbishment of buildings.
Current and quality-assured data on the development of renewable energies in Germany is regularly provided by the Federal Environment Agency.
But what is energy?
We experience the manifestations of energy through the warmth of fire or the power of the wind. We cannot see, hear, taste or smell it and yet we utilise it in many different ways. We know this from physics: Energy is the ability to do work. When a lamp is switched on or a car is moved with petrol, we experience the conversion of one form of energy into another form of energy with the help of energy converters. Energy is therefore not a substance, but a property of bodies. Electric current is not energy either. It carries the energy with it and only releases it in the electrical appliances. Electric current transports energy.
From a strictly scientific point of view, the general use of the terms renewable or regenerative energy is therefore incorrect. Energy can neither be generated nor consumed, i.e. it cannot be renewed. Energy can only be converted from one form to another. Although the amount of energy in a closed system remains constant, the usable proportion of energy varies depending on the conversion. In total, the amount of energy remains the same. More precisely, what we call energy consumption is the devaluation of energy. The use value of energy decreases through conversion and transport. For example, when burning wood, the chemical energy stored in the wood is converted into thermal energy and light energy. When heat is released into the environment, it is no longer useful, it is devalued - we say "used up".
Because our energy consumption is constantly increasing while fossil fuels are shrinking, it is all the more exciting to experiment with renewable energies and to understand how solar energy, wind energy and hydropower can be used to convert and store energy and improve the efficiency of energy transmission.
