According to the Institute of Mechanical Engineers, an energy storage system that cools air until it becomes liquid could compete with batteries. The liquid is then stored inside a vacuum flask to keep it in a cold, liquid state until it is needed. Air is a mixture of multiple gases, and most of the liquid is nitrogen.
This wasn’t invented by the IMechE, but the institute was pleased with it. It was invented by Peter Dearman, a garage inventor in Hertfordshire, to power vehicles.
The air has to be kept cold using the insulated flask because it will warm and vaporize easily at room temperature, causing the pressure inside its storage container to increase.
When energy is needed to back up a wind farm, for example, the liquid air is warmed and allowed to exit the flask as it vaporizes, and this causes it to vaporize faster than usual. It vaporizes extremely fast and the resulting pressure and flow rate is so high that it can turn an electricity generating turbine.
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Potential Benefits of Liquid Air Energy Storage
- It can be built to last 20 years, which is more than twice as long as average battery technology. The equipment utilized, including the cryogenic refrigerator, storage tank (vacuum flask), turbine, and plumbing are all capable of lasting 20 years (easily) if built well. Manufacturers have far less control of battery lifespan, but a refrigerator can be built to last 5 years, or 30 if they wanted it to.
- It can be very efficient — the liquid air can be warmed using waste heat radiated from electricity generators, or even from the condenser of the same refrigerator that cooled the air (this is a tremendous amount of heat, by the way). Engineers said that it can be up to 70% efficient.
- When provided with enough heat, it can discharge its energy extremely fast, and this can be slowed down easily by reducing the amount of heat supplied to it without expensive power electronics.
“I get half a dozen people a week trying to persuade me they have a brilliant invention,” head of energy Tim Fox told BBC News. It seems this one might actually be such an invention.
Summary: The electricity generated by wind farms at times when it isn’t needed powers the system, which cools and stores air. Then, when electricity demand spikes at a time when wind speeds are too low, the system releases the air from the tank through a turbine that generates electricity and augments overall electricity production so that electricity demand can be met.
Cryogenic refers to a temperature below -150 °C.