Jan. 22 (UPI) -- To store energy generated by renewable sources in Europe, scientists want to fill giant rocks beneath the North Sea with compressed air.
The North Sea is home to large porous rock formations. According to a new study published in the journal Nature Energy, underwater sandstone could store enough energy to meet Europe's electricity needs in the winter, when demand is highest.
One of the problems with renewable energy sources is their variability. Solar and wind power are weather dependent. Efficient energy storage can solve the problem of variability, but current technologies for the large-scale storage of renewable energy suffer from a variety of deficiencies.
"Meeting inter-seasonal fluctuations in electricity production or demand in a system dominated by renewable energy requires the cheap, reliable and accessible storage of energy on a scale that is currently challenging to achieve," the study authors write.
In the newly published paper, researchers at the universities of Edinburgh and Strathclyde detailed a novel approach to energy storage -- the use of large underwater rocks.
The concept works as follows: energy produced by renewable sources is used to power an engine that pumps compressed air into a well drilled into sandstone deposits. To use the stored energy, the compressed air is released, powering an electricity-producing turbine. The electricity can be fed into the mainland power grid.
Similar energy storage systems are currently used in Germany. Compressed air is stored in deep caves instead of underwater sandstone.
Researchers used mathematical models and surveys of North Sea geologic formations to estimate the region's energy storage potential. The analysis suggests the region's sandstones could store one-and-a-half times the United Kingdom's average electricity demand for January and February.
"This method could make it possible to store renewable energy produced in the summer for those chilly winter nights," Edinburgh geoscientist Julien Mouli-Castillo said in a news release. "It can provide a viable, though expensive, option to ensure the U.K.'s renewable electricity supply is resilient between seasons. More research could help to refine the process and bring costs down."