The idea is a couple of hundred years old, but liquified air technology was just too inefficient to store energy.
Of course, just like batteries of the 1880’s couldn’t hold a candle to today’s batteries, the technology needed to liquify air today is much more efficient. By compressing and cooling a gas, it can be turned into a liquid and stored in an insulated container. We’re already used to seeing this technology at work in liquified petroleum gas [LPG] canisters and R-134a refrigerant in automotive air conditioning systems.
Liquified air can also be used to store energy, such as in a new plant built in Scotland. The Highview Power Storage company’s plant uses grid power to compress and store gaseous air as a liquid. The liquid takes up much less space in storage, but when it is exposed to ambient temperature it expands back into a gas. This expanding gas is then fed into a turbine to turn a generator to produce up to 60% of the electricity that went into liquifying the air in the first place.
Upfront costs are cheaper than battery technology, but because a liquified air storage plant could last for decades, instead of a few years in the case of batteries, lifetime costs could be much less. If used in conjunction with intermittent power sources like solar or wind, liquified air technology could be carbon-free as well. This same technology could even be used to power vehicles with air motors and allow fast refueling like a conventional vehicle.