How can photosynthesis provide renewable energy sources

Renewable energy

Energy transition decisive for climate goals

Germany must significantly reduce greenhouse gas emissions by 2050 - this is what the federal government's climate protection plan prescribes. Because Germany has set itself the goal of becoming greenhouse gas neutral by 2050 - i.e. only emitting as many greenhouse gases as can be bound again.

In order to achieve this goal, we need the so-called energy transition, i.e. the conversion of the energy supply. That means moving away from coal, gas, oil and nuclear power and towards energy from renewable sources.

The aim is to implement the Paris Climate Agreement. The agreement provides for global warming to be kept well below two degrees Celsius - compared to the average temperatures from the time before the industrial revolution, i.e. up to the first half of the 18th century.

The advantage of renewable energies: They do not dry up, they are not finite like coal, oil and gas. And their use is sustainable - so it ensures significantly lower greenhouse gas emissions.

According to the Federal Environment Agency, the basic principle of renewable energies is "that on the one hand processes that take place in nature are used. On the other hand, electricity, heat and fuels are generated from renewable raw materials".

Solar energy

Solar energy can be used in different ways. With PhotovoltaicSystems that are installed on the roof of buildings, for example, generate electrical energy.

Solar collectors convert sun rays into thermal energy. A liquid circulates in the collectors of the system, which transfers heat from the so-called collector to a water storage tank via a heat exchanger. In Germany, such solar thermal systems are mainly used in households to prepare hot water.

Especially in countries where the sun shines a lot, are also suitable solar thermal power plants.

Wind energy

The use of wind energy has a long tradition. The windmills of yore, with which the grain was ground, are now more of a rarity. Modern wind turbines have huge rotors, and several systems are often arranged in wind farms.

In wind turbines, the wind turbine absorbs the kinetic energy of the wind via the rotor and converts it into a rotary motion. Electricity is then generated from this energy in a generator. A wind turbine works in a very similar way to a bicycle dynamo.

Energy from wind plays an important role in Germany when it comes to electricity from renewable energies. It is mostly obtained on land, but also at sea in so-called offshore wind farms.

Biomass

The term "biomass" encompasses various raw materials that grow back again and again. Behind all these substances is the sun: It is its energy through photosynthesis and thus the growth of plants.

Biomass can be used in liquid, solid and gaseous form: Plants - such as maize, rapeseed, grain, wood - can be burned for energetic use of biomass. Liquid fuels, so-called biofuels, can be obtained from the plants. However, biomass can also be converted into energy-rich gas when microbes ferment organic substances.

"The charm of biomass is that it can be used in all sectors - heat, electricity, transport," explains Volker Quaschning, Professor of Renewable Energy Systems at the Berlin University of Technology and Economics.

Solid plant components such as wood, like coal, can be used directly for heating. The oil from energy crops such as rapeseed can replace liquid fuels such as gasoline and diesel. Corn and other plants and plant residues can also be used for energy when they are converted into gas.

Hydropower

People have been using hydropower for a long time. Water wheels were driven on streams and rivers, the energy of which was used to grind the grain. Sawmills were also often operated with water power. Until 2004, hydropower was the most important source of renewable energies.

It came mainly from storage and run-of-river power plants. There the flowing water of a dammed river is directed over a gradient onto turbines. The turbines drive a generator that converts the energy into electricity.

In Germany, hydropower plays a minor role in direct power generation. As a storage medium in pumped storage power plants, it is nevertheless important and the most common form of energy storage in Germany.

In pumped storage, if there is too much electricity, water is pumped from a river or lake into a higher pond. When the demand for electricity increases, the water is drained off and electricity generators are used to generate electricity.