The word “cryogenic” may sound like something that belongs only in science fiction, but it is really just a scientific term relating to making things very cold. In the case of energy storage, it refers to energy storage by use of very cold air, so cold it has condensed into a liquid.
When air is chilled to 79°K (-195°C, -318°F) it liquefies. When it is heated up again, it boils, just as water does when it gets hot. And the air it produces can be used to drive an engine, just as steam from boiling water can drive a steam engine.
Cryogenic energy storage is a little different from steam engines, however. It does not need fossil fuels for heat, because just about everything on Earth is hot enough to boil it. And so there are no pollutants or climate emissions from its use. The only real catch is where to get the electricity needed to run the very powerful refrigerators needed to make air condense.
There are interesting advantages to storing energy in liquid air. One of the most obvious is that the storage system requires nothing special in the way of exotic chemicals. Where lithium-ion batteries may require lithium and cobalt, and flow batteries might use large amounts of vanadium, cryogenic energy storage is based on just air.
We live in interesting times. A new energy paradigm based on renewable energy is emerging as a challenge to the old vision of base-load, coal-burning power plants belching soot and augmented by whatever high-cost electricity will cover demands above the base load.
In the new paradigm, we need to deal with the variable nature of energy generated by the sun, wind, and water. The problem is not that the sun is not always shining and the wind is not always blowing. We can overcome those issues by overbuilding renewables. The real problem is what to do when there is too much electricity.
Historically, renewable energy production was curtailed when production was too high. An alternate solution, which is growing rapidly, is to use that excess production for something. And a great way to use it is to use it for energy storage. And that is where we can get the electricity to drive the huge refrigerators to liquefy air.
Right now, a large facility to do just that is being developed in the U.K. Highview Power, a company based in London, has been developing cryogenic systems. After building two pilot plants in the U.K., it has entered into a joint venture to build a facility outside the city of Manchester. It says the CRYOBattery™ will be able to deliver 50 megawatts of electric power and will store 250 megawatt-hours (MWh) of electric energy. This will make it one of Europe’s largest battery storage systems
The project has been well received. The U.K. Department for Business Energy & Industry Strategy has awarded it a grant of £10 million. Also, Sumitomo Heavy Industries has invested £35 million in Highview Power, which it will use for this project.
Construction of the CRYOBattery™ project near Manchester is to begin later this year, and the facility is expected to be in commercial operation in 2022. Highview Power and Carlton Power plan to co-develop as many as four additional systems, with total energy storage coming to over 1,000 MWh.
In a recent press release, Highview Power noted, “At giga-scale, CRYOBatteries paired with renewables are equivalent in performance to – and could replace – thermal and nuclear baseload power in addition to supporting electricity transmission and distribution systems while providing additional security of supply.”
Baseload power, from coal, gas, and nuclear sources, is not needed for this new paradigm. Pollution can be cut to practically nothing. Greenhouse gas emissions are cut to practically nothing. And this is happening at just a time when offshore wind power is competing with natural gas in the U.K. And onshore wind power and solar power are even less expensive.