SustainX, the world's leading supplier of energy stores, has brought into service a new large-scale project with no equivalent anywhere in the world.
At the end of the 20th century specialised plants for storing energy were being developed in the USA. They consisted of special sealed cavities into which air was pumped; the air heated up as this was done, and the heat spread through what were in effect caves. When the stored energy was needed, the air was released and heated with natural gas, making it turn the rotor of a turbine. That was how electricity was obtained.
Heating the air is a necessity in such a scheme. This is because the fall in the temperature of the plant makes the cooled air expand sharply, and that can damage the blades of the turbine.
Stores of this type have to use expensive hydrocarbon fuel, and on top of that there was a shortage of material for making the caverns themselves. That is exactly why such plants ceased to be of interest once fuel went up in price.
The new type of station proposed by SustainX, with a power of 1.65 MW, rests on a different principle.
Air is compressed by a construction resembling the lower part of a marine diesel engine. It drives the crankshaft of the engine, which compresses a mixture of air and foaming water. The mixtures obtained are fed into special vessels, gas transport pipes for example. When the stored energy is needed, the air makes the pistons of the crankshaft move, and by this means the generator produces electricity.
Water is the key element in such a mechanism. Having a large heat capacity, it absorbs the surplus heat at night, at the time when there is a surplus of electricity, and gives back the portion that has not had time to dissipate.
The merit of such a mechanism is that no fuel of any kind is needed.
So far only a test platform has been brought into service. A full-size station will be able to deliver about 20 MW over the 6 hours of maximum load during the day.
The main advantage of such a technology is the cost of storage. The developers say that over the station's 20 years of service the plant will cost about $500 per kilowatt-hour of capacity.
The place where the first project will be carried out, SustainX states, will be the People's Republic of China.