Basically, that's the gist of Liquid Air Energy Storage.
Some general LAES facts
- Liquid air history: air liquefaction processes date back to late 1800's and since then they became a standard and widely adopted industrial process through which atmospheric gasses like Oxigen, Nitrogen and Argon can be distilled and separated.
- How to turn air into liquid: dry air contains 78.08% Nitrogen(N), 20.95% Oxygen (O), 0.93% Argon (Ar), 0.04% Carbon Dioxide, and small amounts of other trace gases. N,O and AR have similar phase change curves and below 196° C they change phase from gasseous to liquid
- If you found the previous point confusing: this will trigger Thermodynamics Police, but for the sake of clarification - think of water. Heat it to 100° C and it will start turning into steam, or if you will, phase change from liquid to gas. However if you lived on a planet where it's always 200° C, you would experience gaseous water most of the time, but if you cooled it down to 99° C it would turn into a liquid.
- Air in liquid form is reduced in volume by a factor of roughly 700 and can be stored in non pressurized vessels, as long as it is kept at temperatures below the boiling point of Nitrogen
- When heat is added air reverts back to gas phase and consequently expands by a factor of 700, which can be exploited to exert mechanical force on some form of machinery such as a turbine.
- History of LAES: the idea of using the air liquefaction and re-gassification cycle as a mean to store energy was first investigated in 1970's by the University of Newcastle, but only several years later in 1998 field tests were run by Mitsubishi Heavy Industries and Hitachi
- 2010's to present day: thanks to the work of the University of Leeds and Highview Power Storage Company the first fully integrated Liquid Air Energy Storage plant was developed, paving the way for more to be built around the world.
What got our attention
- Air liquefaction is a proven tech = an industrial ecosystem already exists
- The process requires removal of moisture, CO2 and pollutants from the gas mix
- From a thermodynamic point of view , air liquefaction is a relativley simple process, and a reversible one at that
- Non pressurized vessels means cost reduction
- Regassification can exploit of any heat source available to improve RTE
- Studies on LAES start during the energy crisis of 1970's. Probably not a coincidence
- As demand for energy storage soars, further research into LAES prove it is a viable storage solution
A couple additional perks of LAES
CO2 capture
While not a Carbon Capture and Storage system per se, over the course of its operational life a LAES removes CO2 from the atmosphere due to the nature of liquefaction process, which requires the gas mix that is liquified to be purified from CO2 (more on that HERE ) .
If the CO2 removed is then stored (or reused for other industrial processes) the LAES becomes effectively carbon negative, a quality that no other energy storage technology can boast.
Scalability
The total storage capacity of a LAES can be increased by simply increasing the size of the liquid air storage tank.
Portability of the energy storage medium
While given the current state of the art this should be considered a fringe and future benefit, liquid air as an energy storage medium could be transported from a production site to a separate regassification plant that could use it for energy generation. As said above, as of present day it would be an extremely inefficient if not quasi illogical thing to do, but who knows what tomorrow holds...
RTE boost
Once air is in liquid phase and in storage, the heat needed for regasification can potentially come from just about any source. Given that the most common occurence of energy loss comes in the form of heat, it becomes self evident that a LAES can benefit from pairing with a number of industrial activities which have considerable outputs of waste heat.
Versatility ( 1 )
A Liquid Air Energy Storage system has a number of collateral applications which, if properly exploited, might be of interest to some stakeholders. A LAES generates heat (during its charging / air liquefaction phase) and cold (during its discharge/ air regassification phase) streams. Once it is taken into account that a massive amount of energy worldwide is used either for heating or cooling it becomes evident how such features could be extremely relevant under certain conditions, e.g. the coupling of a LAES with data centers, constantly hungry for cooling as they are, would result in a benefit for both ends of the equation.
Versatility ( 2 )
A unique feature of a LAES among energy storage systems is that the charge phase of the reversible process through which energy is stored results in the production of a medium that has other industrial applications i.e. liquid air, from which it becomes easier to extract the individual elements as N, O and Ar. A production facility that relied on any such element could potentially exploit a LAES beyond its nominal energy storage limits, turning the surplus of liquefied air into an additional source of the needed gas.