When people talk about grid-scale energy storage, the conversation almost always goes straight to batteries — lithium-ion at various scales, maybe vanadium flow batteries for longer duration. But there’s a different approach that’s been quietly advancing in the UK, and it doesn’t use any exotic chemistry at all. It uses air.

Liquid Air Energy Storage, or LAES, works by cooling atmospheric air down to about -196°C until it turns into a liquid. That liquid is stored in insulated tanks — similar to the cryogenic vessels used to store liquid nitrogen. When energy is needed, the liquid air is allowed to warm up, expanding dramatically as it returns to gas, and that expansion drives a turbine to generate electricity. Store cold, release heat, make power.

It sounds almost too simple, but the thermodynamics check out, and Highview Power, a company founded in the UK, has been developing commercial-scale LAES systems for over a decade.

Why It’s Interesting for Grid Storage

The core problem with variable renewable energy is that it generates when the wind blows and the sun shines, not necessarily when demand peaks. Solving that requires storage, and the economics of storage depend critically on duration — how long you can hold the energy before releasing it.

Lithium-ion batteries are excellent for short-duration storage: a few hours of capacity is their sweet spot. But they don’t scale well to the long-duration storage that a high-renewable grid really needs — the 8, 12, or 24 hours of capacity that lets you bridge a cloudy, low-wind day.

This is where LAES has an inherent advantage. The liquid air is stored in tanks, and tanks are cheap. Adding more storage capacity means adding more tanks, not more expensive electrochemical cells. The energy density is lower than lithium-ion, but the scaling cost is much more favourable for long-duration applications.

Highview quotes a round-trip efficiency of around 60-70% for their CRYOBattery systems — somewhat lower than lithium-ion at 85-90%, but comparable to pumped hydro, which is currently the dominant form of long-duration grid storage globally. The efficiency gap is partly offset by waste heat recovery: if the LAES system is co-located with an industrial facility that produces waste heat (a data centre, a power station, an industrial process), that heat can be used to warm the liquid air on release, improving the round-trip efficiency significantly.

The UK’s First Grid-Scale Plant

Highview Power has been working with partners to develop the first large commercial LAES plant in the UK. The planned facility in the North of England — the exact location has shifted during planning — is targeting 50 MW of output with 250 MWh of storage capacity. That’s five hours of full-output delivery, placing it firmly in the medium-to-long-duration category.

The plant would connect to the national grid and participate in the Capacity Market and balancing mechanism, the same commercial routes used by gas peakers and large battery storage facilities. The business case is increasingly solid as the grid’s need for flexible capacity grows with renewable penetration.

LAES also has a particular advantage in siting: it doesn’t require specific geology (like pumped hydro’s need for suitable terrain) or access to particular minerals. It can be built on brownfield industrial land, of which the UK has a considerable supply. Former power station sites, in particular, are well-suited — they have grid connections, planning history as industrial sites, and often access to waste heat sources.

Competing Technologies

LAES sits in the emerging long-duration energy storage (LDES) space alongside several other technologies, each with different tradeoffs.

Pumped hydro is the incumbent — it’s proven, efficient, and scalable, but requires suitable geography and faces years-long planning and construction timelines. The UK has limited new pumped hydro potential beyond a few sites in Scotland and Wales.

Iron-air batteries (Form Energy’s technology) offer very long duration (100+ hours) at potentially low cost, but are still in early commercial deployment.

Compressed air energy storage (CAES) uses similar principles to LAES but stores energy as pressurised air in geological formations (salt caverns, depleted gas fields). Siting is constrained by geology in a way that LAES isn’t.

Thermal storage — heating or cooling a medium (molten salt, water, sand) — is cost-effective for heat applications but less efficient for electricity reconversion.

LAES’s niche is grid-scale electricity storage at 4-24 hour duration, on sites where geology and geography aren’t constraining factors.

Where Does This Leave Home Storage?

LAES isn’t for homes. The technology makes sense at megawatt scale and above, not for domestic installations. If you’re thinking about home energy storage, lithium-ion home batteries (Powerwall, Enphase, Growatt, and others) remain the right answer, particularly when paired with solar PV and smart export tariffs like Octopus SEG.

The relevance of LAES to households is indirect: a grid with more long-duration storage is a more stable grid, which makes flexible tariffs like Octopus Agile more valuable (lower overnight prices when renewable surplus is stored rather than curtailed) and makes the economics of time-of-use EV charging more predictable.

Policy Context

The UK government’s Electricity Storage Network and the Long Duration Energy Storage Council have been advocating for specific support mechanisms for LDES technologies, on the grounds that LDES is necessary for a fully decarbonised grid but doesn’t yet compete directly with short-duration technologies under current market rules.

There’s been progress on this front: the contracts-for-difference mechanism has been extended in discussions to potentially cover LDES, and Great British Energy’s mandate includes storage infrastructure as a priority. The practical outcome for LAES developers like Highview is better visibility of the revenue stream they need to make the capital investment viable.

Long-duration storage is one of those pieces of the clean energy puzzle that doesn’t get the consumer-facing attention of solar panels or heat pumps, but matters enormously for whether the grid can actually accommodate the level of renewable generation the UK needs to hit its targets.