Compressed air energy storage (CAES), according to researchers is the latest technology in conserving intermittent energy. Intermittent energy is any energy source (e.g. the wind or a tidal wave) that though predictable is beyond human control and cannot be harnessed at will. Researchers are increasingly talking about using compressed air energy storage systems. This technology envisages a situation where intermittent energy can be stored on a very large scale and released as and when required. The greatest glitch in storing this kind of energy is that unless electrical energy is converted into another form it cannot be stored. This causes tremendous efficiency losses and is not an economically viable solution.
The basic premise on which the CAES works is that excess power on the grid powers an electric motor to drive a compressor. The product is compressed air. The temperature of this compressed air is brought down and then is stored at pressures of 60 to 70 bar. Researchers admit that the concept is not new and that CAES plants have been functioning in Germany and Alabama since 1978 and 1991 respectively. But these plants use a large amount of carbon-based fuels to restore the high temperatures so that the stored compressed air can be expanded in a gas turbine. As a result both these plants record high levels of efficiency losses in the form of heat.
Researchers worldwide are exploring the possibility of storing the heat generated when the compressors are working. The objective is to use this to rewarm the air when required. This is known as Advanced Adiabatic CAES or AA-CAES. A major problem faced by technologists is that when the air is compressed to 60 – 70 times atmospheric pressure, the heat energy generated can go up to 650 degrees and becomes difficult to manage.
Prof of Dynamics, Seamus Garvey at the Nottingham University has proposed a cost effective CAES system. According to him, Energy Bags with butyl rubber bladders and outer surfaces made of polyester-reinforced fabric coated with steel straps are the perfect solution to the problem. These bags can be stored underwater as the sea acts as the pressure machine.
As technologists worldwide are gearing up to work on AA-CAES, it remains to be seen whether this innovative solution will finally be able to resolve the problems of intermittent energy conservation in the long run.
