New Energy Storage: Caves Full of Compressed Air An unusual project that would store renewable energy in huge amounts of compressed air in two man-made caverns for use in energy generation has been green-lighted by the European Union.

Energy company Gaeletric project, which will be created under the coastline of Northern Ireland County Antrim, will be funded with the help of a EU grant of 6.5 million Euros ($7.1 million).

The Compressed Air Energy Storage (CAES) facility, which would be one of only a few in the world, would solve one of the major problems with wind and solar power. Both forms of renewable energy generation tend to fluctuate based upon whether the sun is shining or the wind is blowing. But if a producer could store energy from those sources and then transmit it to the grid in a more regular flow, it would be easier to compete with fossil fuels.

In CAES, the surplus energy from solar and wind installations to compress air into the caverns, which would be carved nearly a mile underground inside geological salt layers deep underground. When the energy was needed, it would be used to drive turbines that generate electricity.

While that all sounds sustainable, BBC reports that some environmentalists are worried because the company will take the salt removed to create the caverns and eject it into the ocean waters off Northern Ireland coast. They™re concerned that it will raise the salinity and to a level that marine life won™t be able to tolerate.

According to BBC, Gaelectric says that effect is only temporary, and that marine animals will come back into the area after the salinity subsides a few years later.

The first CAES facility was built in Alabama back in the early 1990s, and used to store unused off-peak electricity from a coal-fired power plant 20 miles away, according to the New York Times. But recently the technology has been repurposed for use with renewables.