Compressed solutions

RWE Power has joined forces with GE to develop an Advanced Adiabatic Compressed Air Energy Storage (AA-CAES) system with higher efficiency than current available solutions.

The intermittent nature of wind energy means that there is a need for the energy generated from wind turbines to be stored efficiently so that it can be recovered when needed.

And, according to Chris Bullough from Alstom Power Technology Centre in Leicester, whilst pumped hydro storage, batteries and fuel cells have some advantages, only compressed air energy storage (CAES) has the storage capacity of pumped hydro, but with lower cost and less geographic restrictions.

In a paper he presented at the 2004 European Wind Energy Conference, Bullough said that existing diabatic CAES plants lose heat energy from the cycle during compression, which must be re-generated before the compressed air is expanded in a modified gas turbine. Adiabatic CAES, on the other hand, uses a separate thermal energy store during the compression part of the cycle. During the generation part of the cycle the thermal energy store is used to reheat the air, which is then expanded through a sliding pressure air turbine.