An overview of potential benefits and limitations of Compressed Air Energy Storage in abandoned coal mines

Compressed Air Energy Storage (CAES) is one of the methods that can solve the problems with intermittency and unpredictability of renewable energy sources. The storage is charged by increasing air pressure with the use of electrically driven compressors, which convert the electric energy into potential energy. The pressurized air is stored in compressed air storage volumes (caverns, voids, porous structures etc.) of any kind and can then be released upon demand to generate electricity again by expansion of the air through an air turbine or gas turbine. Limited availability of salt caverns in Europe creates difficulties in the implementation of this concept on larger scale. This paper deals with underground storage part in CAES concept and lists benefits related to the storage of air in abandoned coal mines. Examples of natural gas storage in abandoned coal mines are given and compared with the compressed air storage. The study shows an example of coal mine volume calculation. The non-exhaustive list of problems and solutions associated with this idea is given in order to develop this concept at larger scale. (paper)