An innovative liquid air energy storage technology is being trialed at a cement works in the U.K. as an energy-saving alternative to traditional compressed air technologies.

The Peak Reduction by Integrated Storage and Management of Air (PRISMA) system developed by Innovatium and Birmingham University stores energy in liquid air form to provide compressed air, allowing inefficient partially loaded, variable-demand compressors to be turned off, which improves the total system efficiency by up to 25%. PRISMA charges up using cheaper off-peak electricity to create a store of coldCheaper off-peak electricity is used to create a store of cold liquid air that can then be discharged to provide compressed air. Source: InnovatiumCheaper off-peak electricity is used to create a store of cold liquid air that can then be discharged to provide compressed air. Source: Innovatium liquid air that can then be discharged to provide compressed air

The system deployed at the cement works uses a latent energy cold storage tank filled with a phase-change material to store thermal energy. Functioning as an air battery, this thermal storage vessel harnesses a huge amount of liquefied cold air at -150° C.

During charging, the liquid air store is supplied with ambient temperature compressed air, which is chilled through a sensible cool store to the condensation point where liquefaction begins. In the same vessel, this saturated air passes to a second latent cool storage system that contains the phase-change material and is fully liquefied for storage in an integrated vacuum insulated tank.

When required, the cycle is reversed, passing liquid air back through the latent cool store where it picks up the stored heat removed from the charging process and becomes gas. It then passes back through the sensible cool where it again picks up stored heat to then discharge as usable ambient temperature compressed air. ​

The demonstrator stores 200 kg of liquid air, charges from empty to full in 100 minutes and discharges in 40 minutes.

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