The worldwide expansion of renewable energy makes new electricity storage techniques paramount as they are capable of offsetting the fluctuations inherent in solar and wind energy. So far, pumped-storage power stations have been the most important energy storage solution by far, accounting for 96 percent of all energy stored the world over. However, they have very limited potential owing to their geographical prerequisites.
Scientists and entrepreneurs around the globe are thus searching for novel storage techniques. The BBC is also addressing this topic, having dedicated a series entitled ‘The Disruptors’ to market-changing innovations. Two of the pilot projects presented on the TV show are being tested in Europe. The episode is compelling, featuring multimedia storytelling and background information on a major topic.
The concept has been debated for quite a while and tested elsewhere: using EVs as electricity storage units. The BBC is showcasing an exemplary project in Denmark in order to illustrate the basic principle and the associated challenges. The Danish power utility Frederiksberg Forsyning can connect the batteries of up to ten EVs to special charging stations to form a ‘virtual power plant’. This allows the vehicles to help out not only when electricity is in high demand, but also when generation exceeds consumption, which is important above all in countries with a high proportion of renewable energy. One challenge consists in ensuring that the electric cars have enough battery capacity when they are needed. Another is that the constant charging and draining can reduce the performance and lifetime of a battery.
Pumped storage power stations can only be built where there is a substantial drop. Another storage method also depends on special geographic conditions: In subterranean caves, air is compressed and used to drive a turbine to generate electricity when needed. Therefore, research is being conducted on storage techniques that can be built near renewable energy plants independent of such factors. One such project is a liquid air storage unit commissioned by the UK company Highview Power in 2018. It cools air to -196 degrees Celsius and stores it in tanks at low pressure. When energy is required, the liquid air can easily be converted back to its gaseous state to drive a turbine. Little research has been conducted on this technology thus far. But experts are convinced that creative minds are needed in order to achieve the Paris climate goals.