If developed
further, liquid air energy storage (LAES), also known as cryogenic energy
storage (CES), could become the lowest-cost way to store excess renewables
generation on power grids. Like many other clean energy technologies, upfront
cost is a big hurdle. However, new analysis suggests it could be the
lowest-cost option for the long-duration grid storage needed for renewable
energy integration.
According to Wikipedia:
“Cryogenic energy storage (CES) is the use of
low-temperature (cryogenic) liquids such as liquid air or liquid nitrogen to
store energy. The technology is primarily used for the large-scale storage of
electricity.”
The process utilizes the
Claude Cycle, which is only 25% efficient, but efficiency is increased to 50%
by adding cold storage and reusing the cold for the next refrigeration cycle.
When the heat is acquired through process heat recovery, efficiency as high as
70% has been claimed. Air is cooled to -196 degrees Celsius, the point at which
it becomes liquified. When it is re-gasified, the pressure increases so that it
can be used to spin turbines. At gasification, the air rapidly expands to about
700 times its liquid volume, and the pressure drives power turbines.
Cryogenic energy storage can
be constructed just about anywhere, in contrast to pumped hydro energy storage
and compressed air energy storage, which require specific geography for pumped
hydro and existing mines, wells, or caverns for compressed air. CES/LAES also
uses off-the-shelf components, such as air-condensing technologies that have
long been part of the chemicals industry.
CES/LAES involves cooling air until it liquifies, then
storing it in insulated and pressurized tanks. The air is re-gasified when
needed to run turbines for power.
An article in Linquip Tech
News explains the processes in an LAES system:
“A typical LAES system follows a three-step process. The charging process is the first step, in which excess (cheap) electrical energy is used to clean, compress, and liquefy air. Step 2 is the storing procedure, which involves storing the liquefied air from Step 1 in an insulated tank at 196 °C and at about ambient pressure. Step 3 is the discharge process, which recovers energy by pumping, warming, and expanding it in order to regenerate power during peak hours when electricity is in high demand and expensive. Step 2 also comprises the storage of heat from Step 1’s air compression process and high-grade cold energy from Step 3’s warming process. The stored heat and cold energy can be employed in Steps 3 and 1 to improve the power output and minimize the liquefaction process’s energy consumption, respectively.”
The article also acknowledges
the challenges of LAES and the opportunities to hybridize it with things like
process heat recovery from power plants and industry. It can be integrated with
natural gas peaking plants. It can be integrated with concentrated solar power
plants. It can also be integrated with the LNG re-gasification process, which
can also be integrated with carbon capture, as I noted in a recent post
about LNG-Coupled Near-Cryogenic Direct Air Carbon Capture Via LNG
Regasification and Physisorbents. The cold energy could be used for
local cooling, and it could receive local waste heat.
Below are basic layouts and schematics for different LAES configurations, integrating with a gas plant, a solar thermal plant, and a nuclear plant.
Consumer Energy Center
describes the steps of LAES, basically charging, storage, and discharging, as
follows:
Consumer Energy Center touts
LAES as a good method of grid storage, noting below its advantages and
disadvantages.
The Linquip Tech News article
goes on to make technical and economic comparisons of LAES with compressed air
storage, pumped hydro storage, and other potential grid storage methods such as
flow batteries and hydrogen, which are given in the sections below.
Technical Comparisons
“When compared to connected energy storage systems,
LAES, like pumped hydro and compressed air energy storage technologies, has a
long discharge time (hours). The power discharge rate, on the other hand, is
determined by the scalability of the energy storage technologies’
power-regenerating unit. Pumped hydro storage makes use of hydraulic turbines
to regenerate electricity and so has the highest power discharge rate (up to
several gigawatts). The power rate of compressed air energy storage is in the
hundreds of megawatts range due to the utilization of typical gas turbines or
steam turbines for power regeneration.”
“The power rate of a LAES turbine is expected to be
slightly lower than compressed air energy storage, but it can still reach
hundreds of megawatts. An LAES turbine is similar to a gas turbine but has a
lower expansion temperature, so the power rate is expected to be slightly lower
than compressed air energy storage. However, because flow batteries and
hydrogen storage are difficult to scale, their power output is estimated to be
less than a megawatt.”
Pumped hydro has a round-trip
efficiency between 65% and 85%. Compressed air is at 40% and LAES averages
50-60% with up to 70% possible utilizing waste heat recovery. Thus, pumped
hydro is a little more efficient but much more restricted on where it can be
built.
Environmental Comparisons
LAES/CES is difficult to beat
in environmental comparisons if powered with renewables, as is surmised. Pumped
hydro destroys habitats and generates methane. Lithium and other battery
chemistries are heavily reliant on mining. LAES uses air as the medium, which
is readily available and environmentally benign.
Economic Comparisons (and Viability)
As detailed below, the
capital costs of LAES, pumped hydro, compressed air, and flow batteries are
similar, but flow batteries have much shorter life spans than the other three.
“The cost of charging and discharging devices is closely
related to the capital costs per unit of power. High power capital costs
(>$10,000 kW–1) characterize hydrogen storage. Pumped hydro storage, flow
batteries, and compressed air energy storage, and LAES all have around the same
power capital costs (between $400 and 2000 kW-1). Because of the effect of
discharge durations, capital costs per unit of energy cannot be utilized to
accurately measure the economic performance of energy storage devices.”
“The capital cost of storage systems like a dam for
pumped hydro storage and a storage tank for LAES is an alternate measure.
Because the energy carriers are either flammable or at high pressure, hydrogen
storage and compressed air energy storage are projected to have the greatest
storage costs. Due to its low energy density, pumped hydro storage has a cheap
cost. Despite the fact that insulation is required, LAES and flow batteries
offer the lowest cost.”
“Mechanical-based systems such as pumped hydro storage,
compressed air energy storage, and LAES should have a lifecycle of 20–60 years
because they are based on traditional mechanical engineering, and the lifecycle
is mostly governed by the lifetime of mechanical components. The lifespan of
hydrogen storage and flow batteries, on the other hand, are predicted to be
around 5–15 years.”
With all economic factors
combined, LAES may be the cheapest long-duration energy storage option for
power grid storage operations.
According to Consumer Energy
Center, LAES continues to see incremental improvements:
“Innovations such as enhanced insulation techniques and
more efficient liquefaction processes are improving overall performance while
reducing costs. This evolution creates a pathway for a more resilient
infrastructure capable of responding effectively to fluctuations in energy
supply and demand.”
Researchers at MIT did an
economic feasibility analysis for LAES. Their findings were published in the
journal Energy. They modeled net present value (NPV) at a discount rate of 7%.
“They found that under some of the scenarios they
modeled, LAES could be economically viable in certain locations. Sensitivity
analyses showed that policies providing a subsidy on capital expenses could
make LAES systems economically viable in many locations. Further calculations
showed that the cost of storing a given amount of electricity with LAES would
be lower than with more familiar systems such as pumped hydro and lithium-ion
batteries. They conclude that LAES holds promise as a means of providing critically
needed long-duration storage when future power grids are decarbonized and
dominated by intermittent renewable sources of electricity.”
The modeling requires
predicting how LAES will compete in future markets when power demand exceeds
supply and predicting prices when supply exceeds demand. They modeled 18 U.S.
regions and eight decarbonization scenarios. Unfortunately, economic viability
only occurred in the most aggressive decarbonization scenarios, which are also
considered to be the least likely, and only for two states, Florida and Texas.
They analyzed time periods of one day, one week, and one month, noting that
weekly storage is more economically viable than monthly storage. They also
noted that economic incentives could push projects into economic viability.
They calculated a levelized cost of storage (LCOS) of $60 per MWh, about one
third that of lithium-ion storage, and half that of pumped hydro. According to
one of the paper’s authors, Shaylin A. Cetegen, a PhD candidate in the MIT
Department of Chemical Engineering:
“While LAES systems may not be economically viable from
an investment perspective today, that doesn’t mean they won’t be implemented in
the future. With limited options for grid-scale storage expansion and the
growing need for storage technologies to ensure energy security, if we can't
find economically viable alternatives, we’ll likely have to turn to least-cost
solutions to meet storage needs. This is why the story of liquid air storage is
far from over. We believe our findings justify the continued exploration of
LAES as a key energy storage solution for the future.”
An article in Power
Technology notes that LAES projects are represented in far less than 1% of
upcoming thermal energy storage projects.
“We [LAES] also pull very mature components from the
existing oil and gas supply chain; all we’re doing is configuring them in a
different way,” LAES developer Highview Power’s business development director
Mark Vyvyan-Robinson tells Power Technology.
A 2025 paper in the Journal
of Energy Storage found that hybridizing LAES with natural gas in a
configuration they call LAES with added gas firing, or LAES-AF, could be
economically viable, but only under high natural gas price scenarios that are
not reasonable for places like the U.S. Even at maximum theoretical efficiency,
it is hard to find economic viability. Thus, as one researcher put it: “Constructability
cost can be a more important metric than efficiency.” The bottom line is
that LAES will likely remain expensive and a niche technology for the
foreseeable future, unless more cost improvements are found.
Even with waste heat
utilization, cooling recycling and efficiency gains, and hybridization with
natural gas or solar thermal, and some subsidization, the economics are
challenging. Without them, however, they are more challenging.
Korean Researchers Develop LAES Innovations
Despite the challenges just
mentioned, researchers at the Korea Institute of Machinery and Materials
(KIMM), under the National Research Council of Science and Technology (NST),
have developed some key LAES technologies and innovations. The project is known
as "Development of Core Machinery Technologies for Large-Scale Liquid Air
Energy Storage."
An article in TechXplore
explains the innovations, which include a newly designed turbo expander and a
cold box with improved heat loss resistance:
“The KIMM research team, led by Principal Researcher Dr.
Jun Young Park at the Department of Energy Storage Systems, independently
designed and manufactured a turbo expander and cold box, achieving Korea's
first successful air liquefaction test for energy storage. The system can
produce up to 10 tons of liquid air per day, providing a foundation for future
commercialization.”
“KIMM's innovations include a high-speed turbo expander
with static gas bearings for stable rotation exceeding 100,000 RPM and a hollow
shaft with thermal insulation that prevents heat ingress at ambient
temperature. The cold box, employing multi-layer insulation and an ultra-high
vacuum to reduce heat ingress, also recycles cold energy from power generation
for more efficient liquefaction.”
"Large-scale energy storage is essential for Korea's renewable energy future," said Principal Researcher Jun Young Park. "Our achievement positions LAES as a viable, eco-friendly solution, free from geographical limitations, and accelerates the pathway to commercialization."
Neetika Walter at Interesting
Engineering calls the Korean innovations bottling air, or rather, bottling electricity.
The UK has the world's largest LAES project deployment, According to the article in Power Technology:
"In Manchester, UK, Highview operates the world’s
first commercial-scale industrial LAES plant. The operational plant has a 50MW
charge/discharge rate and 300MWh capacity, but Highview’s four planned
facilities would each have a much larger storage capacity of 2.5GWh. These
would represent more than 10% of the country’s non-battery storage, and a much
larger move toward LAES than seen anywhere else in the world."
"The UK developments are enabled by the
country’s “cap and floor” pricing scheme, which eliminates the cost effects of
extreme prices for operators. Vyvyan-Robinson says this elimination of risk is
essential to obtaining finance for any country eyeing LAES: “It’s difficult for
a bank to take a view on future revenues, and therefore to make projects
‘bankable’. You need some support around the revenues, and ‘cap and floor’
allows you to raise finance.”
References:
Cryogenic
energy storage. Wikipedia. Cryogenic energy
storage - Wikipedia
What
is Liquid Air Energy Storage? By Linquip Team. Last Updated: March 29, 2023.
Linquip Tech News. Liquid Air
Energy Storage: Efficiency & Costs | Linquip
Liquid
Air Energy Storage Overview. Greg M. Consumer Energy Center. March 28, 2025. Liquid
Air Energy Storage: Unlocking the Power of the Atmosphere
Researchers
develop core technologies for liquid air energy storage to support Korea's
energy superhighway. Science X staff. Tech Xplore. September 11, 2025. Researchers
develop core technologies for liquid air energy storage to support Korea's
energy superhighway
Using
liquid air for grid-scale energy storage: New research finds liquid air energy
storage could be the lowest-cost option for ensuring a continuous power supply
on a future grid dominated by carbon-free but intermittent sources of
electricity. Nancy W. Stauffer. MIT Energy Initiative. April 10, 2025. Using
liquid air for grid-scale energy storage | MIT News | Massachusetts Institute
of Technology
Explainer:
does liquid air energy storage hold promise? The world’s most available
substance could unlock a new opportunity for long-duration energy storage. Jackie
Park and Matt Farmer. Power Technology. July 18, 2025. Explainer:
does liquid air energy storage hold promise?
New
liquid air storage system bottles electricity on demand, producing 10 tons
daily. Neetika Walter. Interesting Engineering. September 12, 2025. New
liquid air storage system bottles electricity on demand, producing 10 tons
daily
Evaluating
economic feasibility of liquid air energy storage systems in future US
electricity markets. Shaylin A. Cetegen, Truls Gundersen, and Paul I. Barton. Energy.
Volume 321, 15 April 2025, 135447. Evaluating
economic feasibility of liquid air energy storage systems in future US
electricity markets - ScienceDirect
Benchmarking
of liquid air energy storage with and without added firing against batteries
and gas-fired power plants.Carlos Arnaiz del Pozo, Ángel Jiménez Álvaro, and Schalk
Cloete. Journal of Energy Storage. Volume 106, 15 January 2025, 114800. Benchmarking
of liquid air energy storage with and without added firing against batteries
and gas-fired power plants - ScienceDirect
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