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The EU awarded 90 million euro for the design and build of a Compressed Air Energy Storage (CAES) plant in Larne, Northern Ireland. The concept behind CAES is to store power for use when it is needed. Air is compressed in a chamber, this stores the energy, when it is needed, the pressure is released and can be used for generation.

It sounds simple, but it is complicated by a number of factors. As a gas is compressed, it heats. CAES systems that fail to capture this thermal energy are not very energy efficient. Theoretically, if the heat energy from compression is captured, CAES could operate at close to 100% energy efficiency, meaning that no energy is lost during the storage process.

Backers of Compressed Air Energy Storage (CAES) systems believe they can achieve very high efficiency, well above 70%

Of course, real world systems never operate perfectly, but backers of CAES systems believe that they can achieve very high efficiency, well above 70%. There are only two CAES power plants in the world at this time, both built in the last century, one in Germany and one in Alabama, U.S. The Alabama CAES operates at only 24% efficiency and is paired with natural gas electricity generation. Due to their low efficiency, CAES projects lost their luster by the 2000s.

However, CAES looks exciting again. The great challenge for many green power sources is energy storage. With fossil fuel power plants the energy is produced on an as needed basis. But with solar and wind the energy requires storage. Battery technology is rapidly advancing, but it is not inexpensive and can be impractical on a large scale. CAES facilities can be built in salt mines and pumped out aquifers, big places, for lots of power storage, enough power for 100,000 or more homes.

This ‘industrial-sized’ energy storage aspect has engineers excited. It has caught the attention of the Europeans who are experimenting with a surprising number of energy systems. The European Union designated the CAES in Larne as a Project of Common Interest, which means that information on the progress of the design, build, and operation will be available to the public and other researchers. It is a demonstration project that will share the knowledge with everyone, in order to build better systems in the future.