The sun supplies the Earth with about ten thousand times more energy (in the form of solar radiation) than we humans actually need – and it is set to keep doing so for the next four billion years. Solar cells help us to convert some of that sunlight into the electricity that keeps industrial societies moving. Researchers have brought about rapid progress in photovoltaic technology. Their work has helped develop new materials systems, increase efficiencies, and lower production costs. Concentrated solar power is another way of generating electricity, and is ideal for regions that get a lot of sun. The systems use reflectors to concentrate the sunlight and then use it to produce steam that drives turbines. We can also harness the sun’s energy by installing rooftop solar collectors that provide us with hot water. What’s more, the sun play a big part in helping the wind to blow (driving wind turbines) and plants to grow (giving us biomass and fossil fuels).
Nuclear power plants are fuelled by uranium, a radioactive element whose mining causes serious environmental damage. Inside a nuclear reactor, uranium splits up and forms decay products. Because their radioactivity makes them dangerous to humans and animals, these products have to be kept in isolated storage for many thousands of years. Alongside the risk of a nuclear accident at a plant (caused either by human error or a natural disaster), nuclear waste is also a major problem with this type of power. Repository costs are difficult to estimate, and it is highly unlikely that electricity costs fully factor them in.
In itself, however, the term “nuclear energy” is entirely neutral. It merely refers to the energy that is released when heavy atoms are split (fission) or when very light atoms are fused (fusion). The sun gets its neverending supply of energy from a nuclear fusion reaction in which hydrogen atoms in the core of the sun collide to produce helium. In theory, a power plant down here on Earth could also use hydrogen fusion to produce energy in a controlled way that does not entail the same high levels of risk that are present with nuclear reactors. The technical challenges for this are so huge, however, that researchers say it will be several decades before this kind of power plant could begin operating. An international consortium is currently setting up an experimental reactor in Cadarache in France, which has been designed to clear up some of the obstacles on the road to achieving this goal.
This question was answered by Dr Antonia Rötger, science writer in the communication department of the Helmholtz-Zentrum Berlin für Materialien und Energie.