Liquid Air Energy Storage (LAES) uses cheap or surplus grid electricity to compress and cool ambient air until it liquefies (≈ −196°C), stores the cryogenic liquid in an insulated tank at near-atmospheric pressure, then later pumps it to high pressure, evaporates it against ambient or waste heat, and expands the resulting cold gas through a turbine to regenerate electricity — the same working fluid, air, simply changing phase and pressure between the two half-cycles.
Charge: W_liq = ṁ · e_liq (e_liq ≈ 0.20–0.35 kWh/kg air)
Discharge: P_out = ṁ · e_exp (e_exp ≈ RTE · e_liq)
Round-trip: η = E_out / E_in ≈ 45–75% (higher with recuperation)
- Charge power — electrical power fed to the compressor train; more power liquefies air faster, filling the tank.
- Discharge power — target electrical output during the turbine half-cycle, drawing down the stored liquid air (capped once the tank empties).
- Cold & heat recuperation — real LAES plants store the "cold" released during evaporation (to pre-cool the next charge cycle) and the heat released during compression (to reheat the expanding gas). Recovering more of both directly lowers the specific liquefaction energy e_liq and raises round-trip efficiency — this is the single biggest lever in the technology.
- Ambient temperature — colder intake air is already closer to its liquefaction point, so less compressor work is needed; warmer air costs more energy to liquefy.
- The plant auto-cycles: it charges until the tank is full, then switches to discharge until it is empty, repeating — exactly how a grid-scale LAES plant is dispatched against daily price swings. Force switch flips the half-cycle manually at any fill level.
Real-world relevance: Highview Power's 50 MW CRYOBattery in Manchester, UK stores air at −196°C and targets round-trip efficiencies around 60–70% once waste heat and cold recycling are fully integrated — competitive with pumped hydro but sited anywhere, not just mountainous terrain.