In 2017, the amount of electricity generated in Europe from wind, solar energy, and biomass was larger than that from coal. The future of energy generation from renewable resources is looking more promising, but we are still some way from being completely sustainable.

In his Editorial in Angewandte Chemie, Philipp Adelhelm, University of Jena, Germany, points out that when discussing energy and the Energiewende (energy revolution), the relevant numbers are so large that they are hard to realize: The yearly energy requirement for Germany, e.g., is 13,500 · 10¹⁵ J. How can we describe such dimensions in a more concrete way to convince the public and politicians that an independent and sustainable energy supply requires significantly more investments? This number above is much better expressed by saying how many kWh a person in Germany needs per day on average.

When solar cell outputs are considered in W/m², we can work out the area required to meet our electricity demands. Simple calculations can also be used to work out how the transportation sector can be made more sustainable by switching to electric vehicles. An example: A battery‐powered electrical vehicle requires about 20 kWh per 100 km driving range. Driving 100 km with a conventional car based on a combustion engine requires 73 kWh.

However, electric vehicles would need several million tons of battery materials per year. Chemists are intensively working on improving lithium‐ion batteries and are seeking for possible alternatives. However, when publishing battery research, overselling the properties of batteries should be avoided, and the costs of materials should be considered. Science should be the frist priority here and not claims about world-record numbers.

• The Energy Challenge, Batteries, and Why Simple Math Matters,
  Philipp Adelhelm,
  Angew. Chem. Int. Ed. 2018.
  https://doi.org/10.1002/anie.201803221