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A Liquid Air Economy

Founder Lightsphere

I know very little about the very little and even less about the very large. A lifetime of study and experience has yielded a pretty good feel for transport phenomena, thermodynamics, scaling...

  • Member since 2017
  • 7 items added with 4,404 views
  • May 11, 2022

                                                                                                         A Liquid Air Economy

                                                                                                               Why Liquid Air?

A liquid air economy has many benefits. Liquid air can be made anywhere, no need to mine it, no need to refine it, it is non-polluting, relatively safe, and it can be made at low cost with SuperHero Claude cycle liquefiers.


Fig. 1 SuperHero Claude Cycle Compressor and Liquefier Schematic

The motor driven SuperHero turbomachine in the upper spherical container in Fig.1 uses recirculating water as a periodic liquid piston to provide near isothermal air compression.

The compressed air from the upper spherical container can be expanded in the lower spherical container by a SuperHero expander turbine to liquify the air in a Claude cycle.

Liquid air can provide short-term and long-term storage for intermittent sources including photovoltaics and wind.

Liquid air is attractive as a “utility”. It is cheaper to distribute liquid air in a district or a building for air-conditioning, air make up, compressed air, refrigeration, electricity production, fan operation, electronics cooling, and electronics powering, than to provide these services individually. Liquid air can be supplied via a recirculating loop manifold. Personalized cool, clean fresh air can be provided at low cost and with low noise and heat can be added via electricity from SuperHero liquid air turbogenerators.  

Compressed air is also an attractive utility and would be used much more with greater access. Superhero turbomachines can provide quiet compressed air at low cost. Compressed air can be provided from liquid air by “U” tube type SuperHero turbomachines. Compressed air can be provided by SuperHero liquid piston recirculating water air compressors. Compressed air can be provided by liquid air ported to a storage vessel and then closed off from the supply vessel and using atmospheric heat to evaporate  and thereby pressurize the air in the compressed air storage vessel. Compressed air can be provided by a pump made from a pair of check balls with a heat exchanger between. Compressed air can be provided by liquid air pumps and heat exchangers for continuous supply.  

Liquid air can be transported by pipelines, trucks, trains, planes, and ships. Storage can be refilled as needed.

Liquid air allows existing fuel stations to become liquid air stations.

Liquid air offers fast fill vs. the long waits associated with battery systems.

Liquid air is storable without pressurization. Oil and gasoline storage tanks can be converted to liquid air storage tanks.

Liquid air controls require less cost, mass, and volume than electrical controls, including those required for automotive battery systems.

Liquid air storage vessels can be used as structural elements for mobile and stationary systems. Car, truck, train, plane, and ship structures can be made of tubes used for liquid air storage. Building structures can be formed from tubes used for cryogenic liquid storage. 

Energy density. Liquid air at high pressure can have energy densities ~200Whr/kg, less than Li-Ion, but greater than Lithium Iron Phosphate, which Tesla and other EV mfrs. are transitioning due to the reduced cost and increased safety. Electric vehicle batteries require costly heating, cooling, and control systems that further reduce their useful energy density. Liquid air vehicles have reduced mass with travel, especially important with aircraft.

Power density. Liquid air SuperHero atmospheric source heat engines can provide power densities 10-100 times as great as battery systems and without the concern of overheating.

In server farms Superhero liquid air turbogenerators can both power and cool the electronics. Electronics can operate at much higher power densities and with better efficiency, reliability, and durability via lower operating temperatures and modularity and cryogenic cooling allows the use of lower bandgap semiconductors such as Germanium.

A liquid air economy will use liquid nitrogen and liquid oxygen. Liquid oxygens reactive potential makes it much more valuable than liquid nitrogen. Liquid oxygen can be used for combustion to greatly improve power density and to prevent oxides of nitrogen, it can be used for breathing, it can be used for high altitude operation, including rockets for point to point and space travel, and it is useful in many chemical processes. Liquid oxygen can be used for a  SuperHero combustion engine topping cycle and liquid nitrogen can be used for a SuperHero cryogenic engine bottoming cycle.

                                                                            SuperHero Atmospheric Source Heat Engines

SuperHero Atmospheric Source Heat Engines can have high thermodynamic efficiency with cryogenic fluids.  Additional benefits include safety, no need for ignition, no reaction time limits, no combustion space needed, drag heating utility, and boundary layer viscosity reduction via reduced temperature. See

 Atmospheric source heat engines are limited by atmospheric air mass flow rate and this can be increased by increasing travel speed, a positive feedback loop.                                             

                                                                                                 Bottom up Thermodynamics

Thermodynamic efficiency is limited by the absolute temperature ratio. Sadi Carnot gives us the thermal equivalent of height. If the temperature ratio is half, half is available as work as this means the temperature has fallen half way. 

Maximum thermodynamic efficiency=1-Tlow/Thigh.  For liquid air Tlow @780K and ambient temperature Thigh @2730K (1-78/273=0.71), or 71% maximum thermodynamic efficiency.

To achieve a similar thermodynamic efficiency with ambient temperature being Tlow, Thigh must be ~9000K (1-273/900=0.7). The higher operating temperature requires costlier materials and implies heat loss to the environment rather than heat gain from the environment as is the case with liquid air.

SuperHero turbomachines with cryogenic propellants can convert sensible heat from atmospheric air and latent heat from atmospheric water vapor to rotational motion which can be used for electricity generation, shaft work, or thrust.

Atmospheric energy conversion. Sensible heat. A vehicle travelling at 120k/h (33m/s) provides ~42kg/s of air to a 1m2 aperture. 42kg/s X 1000K ∆T X 1kJ/kg/0K=4.2Mwt. A portion of the thermal energy can be converted to rotational energy and used to generate electricity, mechanical drive, or thrust. 

Atmospheric energy conversion. Latent heat. Water liquid/gas latent heat of phase change energy =2.3kJ/gm. A vehicle travelling at 120k/h (33m/s) provides 33m3/s of air to a 1m2 aperture. Air at STP and 50% humidity contains 33m3/s X 11.5 gms H2O/m3 X 2.3kJ/gm=873kJ/sec or 0.87Mwt. 100% humidity doubles this figure. Hydrocarbon and hydrogen fuels cause net water production and the water can be used for purposes including air compression and evaporative cooling. Cryogenic SuperHero turbo machines can provide freshwater from the atmosphere via condensation.

SuperHero cryogenic turbomachines are attractive for working in hot areas, foundries, metalworking, ceramics, and glass industries. SuperHero cryogenic liquid nitrogen turbomachines are attractive for working in flammable and explosive environments.          

                                                                                                          Cryogenic CO2 Capture

SuperHero cryogenic turbomachines can reduce the exhaust temperature from carbon containing fuel combustion sufficient to change the phase of CO2 from a gas to a solid while delivering useful power. The CO2 can be inertially separated at the source vs. trying to separate CO2 from the atmosphere @400 parts per million.

LNG regasification facilities can be used to produce liquid air.

A thermos of liquid air and a small cryoturbine fan can provide a portable air conditioner without electricity.

Liquid air SuperHero turbomachines can power refrigerated delivery vans. Large numbers of refrigerated trucks spend their day in traffic with engine idling and with the refrigeration system operating to keep the food cold and with an air conditioner operating to cool the operator.

Liquid air can be used for projectile propulsion.

SuperHero cryogenic turbomachines can use heat from solar radiation, engine exhaust, industrial processes, and other sources to increase efficiency and power density.                                                                                                          


Liquid Air Vehicles (LAVs) will displace EVs due to lower overall cost, including lower overall environmental cost. We will look back and say you know there were people who thought that batteries would be cheaper than air.         

Visit: for more information. The technologies outlined in this document are the exclusive property of John Popovich at New Economy Technology and are subject to patent pending. Contact: John Popovich at for consulting and licensing.
















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