Renewable Energy is not only solar and wind energy. There are many types of renewable energy and each has its specific role and position in the energy market. Here, we will briefly introduce five of them: how they work, their advantages and disadvantages, and their power to make a difference.
Renewable energy 1: Electricity from hydropower.
In hydroelectric power, turbines convert the kinetic energy of a water source (i.e. a river) and potential energy into electricity1. There are run-of-river power stations and storage power stations. The former uses the flow of rivers and streams to generate electricity. Storage power stations produce green electricity using the water from a reservoir.
Electricity from hydropower has the same advantage as bioenergy: you can store it. For example, the pumped storage power station.1 There, water flows into a storage reservoir and then can be drained off in seconds if necessary. It then flows through turbines, which generate electricity.
The contribution of hydropower to climate protection.
The share of hydropower in total electricity consumption was less than three per cent in 2018 in Germany. In relation to green electricity consumption, it amounted to 7.3 per cent. Worldwide, 19 per cent of the world’s electricity is powered by hydropower2.
The potential for expansion in Germany is also more or less exhausted. Nevertheless, hydropower makes a major contribution to climate protection. According to the German Federal Environment Agency, it’s contribution is relatively even among renewable energies. In 2017, hydropower avoided 17.2 million tonnes of CO2 equivalents.
Although the potential for expansion may be as good as exhausted3, it is worth modernising the plants and improving the ecological status of watercourses. Nature can easily integrate smaller hydropower plants.
Renewable energies 2: Energy from biomass.
Biomass can also be used to provide sustainable energy. This is plant and animal matter, such as dung, “energy crops” such as rapeseed, maize and sunflowers, or organic waste4. In biogas plants, micro-organisms decompose biomass. This produces syngas, which can be processed into both electricity and biogas for heat supply5.
The performance of biomass for climate protection.
According to the Federal Environment Agency, biogas avoided around 10.5 million tonnes of CO2 equivalents in the electricity market in 2017. The energy required for fuel supply is low, and biogas production only releases as much CO2 as the biomass previously removed from the atmosphere.
However, the environmental friendliness of biogas production depends heavily on the biomass used. For example, the monocultural cultivation of energy crops such as maize, wheat or grasses damages biodiversity.
Furthermore, it is often associated with high use of fertilisers and pesticides.
Finally, monocultures are much more susceptible to pests6.
Renewable energies 3: Sun.
Put simply, a photovoltaic (PV) system converts sunlight directly into electricity7.
The power of solar energy for climate protection.
According to the Federal Environment Agency, solar energy accounted for 6.6 % of gross electricity generation in 2017. This means that it avoids around 27 million tonnes of CO2 equivalents.
The exciting thing about solar power for the energy turnaround is that many households can use it themselves. More and more homeowners are also becoming producers of green electricity, which is used for the house or electric car, or fed into the public grid.
Renewable energies 4: Wind power.
Wind turbines are used to capture kinetic energy from the wind and convert it into electricity8.
The significance of wind power for the energy turnaround.
Among the renewable energies, wind power is the most profitable and the second most important in terms of gross electricity generation. In 2018 wind power accounted for 36 per cent of gross electricity generation9 and 49.5 per cent of green electricity generation. The contribution of wind power to climate protection is correspondingly high. By generating electricity from wind power on land, greenhouse gases amounting to 59.64 million tonnes of CO2 equivalents were avoided in 2017. Wind power at sea has also avoided around 11.9 million tonnes of CO2 equivalents.
Renewable energies 5: Geothermal energy.
Geothermal energy is heat stored in the earth’s crust10. The deeper you dig, the warmer it gets. In our regions, the temperature increases by about 3°C per 100 metres. To generate electricity, you have to use geothermal energy from a depth of 3,000 metres.
The significance of geothermal energy for the energy revolution.
So far, geothermal energy has played a subordinate role in the electricity market. According to the Federal Environment Agency, its share of total gross electricity generation in 2017 was less than 0.1 per cent. Furthermore, it avoided about 92,960 tonnes of CO2 equivalents. This is not much compared to other renewable energies, but the potential underground is there.