All energy sources that nature provides us in inexhaustible quantities are renewable. The most important renewables are solar energy, wind energy, hydropower, biomass and geothermal energy.
In contrast to fossil fuels such as coal and oil, renewable sources do not cause any CO₂ emissions during energy production. They are therefore key to securing humanity’s supply of clean and safe energy for the future.
The almost infinite energy of the sun lights up the earth every day – and it can be utilised to produce electricity using photovoltaic modules on the roofs of buildings and open spaces. The solar cells in the modules convert the energy from the sun’s rays into usable electricity.
Solar energy can also be used to generate heat. In this case, thermal solar collectors take in the energy from sunlight and transfer it to a heat storage tank. The stored energy can then be used for heating or hot water via a heat exchanger.
This means that photovoltaics is a technology that converts sunlight directly into electrical energy using solar cells. Solar thermal energy, by contrast, utilises the heat of the sun to warm up water or other heat transfer media. The thermal energy generated in this way can then be used for heating, hot water or even to generate electricity.
The Monte Plata solar power plant in the Dominican Republic demonstrates the contribution that solar energy can make in the fight against climate change. Thanks to the plant, up to 50,000 households on the island receive renewable electricity and don’t have to rely on fossil fuels. This saves around 50,000 tonnes of CO₂ every year.
Wind is a near constant force of nature, and we can harness its power with wind turbines to produce clean and renewable electricity. Here’s how it works: the wind drives the blades of a wind turbine, and a generator then converts the collected kinetic energy into electricity.
Flowing water contains enormous amounts of energy. Hydropower plants take advantage of this for renewable electricity production. The water flows through turbines in the power stations, which in turn generate electricity.
For example, hydropower plants utilise the kinetic energy of the flow of a watercourse or the potential energy that can be developed by quantities of water stored in a reservoir. The difference in elevation between the reservoir and the turbines is decisive for the amount of energy the turbines generate: the more metres in elevation the water travels, the more electricity can be produced.
Small hydropower plants can provide a local population with a stable power grid, as demonstrated by a project in West Sumatra. Following a renovation, the dam in Salido Kecil ensures a reliable supply of renewable energy and savings of up to 4500 tonnes of CO₂ per year.
Biomass is the umbrella term for a large number of plant and animal substances that can be used to generate energy. These include animal manure, organic waste and “energy crops” such as rapeseed, maize and sunflowers.
The biomass is fermented in special biogas digesters. This produces biogas, which can then be burnt to generate heat and electricity. In this way, renewable raw materials and kitchen waste are used to make clean energy.
A paper mill in Brazil illustrates the effect that biomass can have on climate protection. After replacing a gas boiler with a biomass boiler, it saves over 48,000 tonnes of CO₂ every year. Another advantage is that the mill can reuse the paper sludge from its own production in the biomass boiler to generate heat.
Geothermal energy refers to heat stored beneath the earth’s surface. Basically, the deeper underground, the higher the temperatures. This heat can be used to produce electricity. To do so, water is channelled from the surface through pipes into the earth’s interior, where it evaporates. Back on the surface, the water vapour drives turbines and generators that produce usable electricity.
A project by a Swiss vegetable producer shows how geothermal energy can help reduce CO₂ emissions. Boreholes up to 1200 metres deep enable the company to heat its greenhouses with renewable energy in winter. This ensures the perfect climate for the plants at all times, and the company saves around 2000 tonnes of CO₂ every year.
Fossil fuels such as gas, coal and oil are still used to produce heat and electricity in many parts of the world. However, renewable energy sources are increasingly replacing them and reducing the emission of gases that are harmful to the climate. This makes them one of the most important factors in the fight against climate change.
Calculations by the German Environment Agency provide examples of the impact that renewable energy sources have on climate change. In 2022, for example, emissions equivalent to 237 million tonnes of CO₂ could be avoided in Germany thanks to the use of renewable energy.
The importance of renewable energy was emphasised once again in December 2023. The COP28 climate conference in Dubai marked a decisive moment in global climate policy, with a gradual transition away from the use of fossil fuels being agreed for the first time. We have published more information on this in “COP28: Is the turning point finally in sight?”.
Electricity production is the area in which renewable energy can make the most important contribution by far when it comes to avoiding damaging emissions. The amount of greenhouse gases avoided through sustainable electricity generation has continued to increase worldwide in recent decades.
In heat production, the effect of renewable energies is smaller. But even in this area, the use of biomass is the main contributor to a noticeable reduction in greenhouse gases. Biofuels also ensure that emissions in road traffic and the transport sector are avoided on a large scale. Nevertheless, there is still a lot of catching up to do in these two areas.
German Environment Agency
Fraunhofer Institute for Solar Energy Systems ISE
You can find further exciting information on the subject of climate change and climate protection in our climate booklet