The growing use of renewable energy sources leads to a growing need for energy storage facilities which store energy for later use. More and more sun and wind are becoming key sources of energy.
In mountainous regions, the most cost effective method is to use water reservoirs as batteries, other regions must find a different way. To find out whether air could be used instead of water as a way of storing energy, a research project (RICAS 2020 of which SINTEF is a member) was created in which scientists from Europe will try to realise this idea.
A few places around the world utilize the idea to use surplus energy generated by wind and sun to compress air, which is then stored in an underground cavern. When power needs to be made available, the air is released through a gas turbine that generates electricity.
Currently, the two largest compressed air stores in Germany and USA, lose a large proportion of the potential energy of the compressed air. In order to reduce these losses, the participants in RICAS 2020 have incorporated an extra station that stores heat in their solution.
According to SINTEF’s project manager Giovanni Perillo, this technology could raise the efficiency of the system to as much as 70-80%, whereas the existing storage sites are about 50% efficient. This solution has longer lifetime and lower capital cost per kWh of stored energy, so has an advantage over batteries. The only requirement with respect to the choice of site is to use existing underground spaces to house the compressed air, as it would be too expensive to excavate new caverns and make them safe.