Dearman Liquid Air Engine

Dearman liquid air engine

Dearman liquid air engine

In this age of cutting edge, high tech everything, you have to love the fellow working in his shed and coming up with a more efficient way of running an engine on liquid nitrogen, or in this application, liquid air. Peter Dearman has patented his process and it's called the Dearman engine.

The basic operation is pretty straightforward. When a gas is chilled to a very low temperature, it becomes a liquid. Air itself, once turned into a liquid can be stored in an insulated container, not a high pressure cylinder, so storage is actually quite easy and fillups are relatively quick. If you introduce the liquid air into a confined space while exposing it to ambient temperature, the gas expands rapidly, creating high pressure as it returns to its gaseous state. You can use this high pressure to drive a piston or spin a turbine and the gas itself is the exhaust. There's no burning to create any other chemical compounds, you've simply chilled a gas that naturally occurs, then warmed it again to return it to the atmosphere as a completely non polluting exhaust, cold air.

The problem is coming up with a way to heat the super cooled liquid efficiently, and Dearman uses a recirculating fluid that runs through a heat exchanger, though the engine can also be used in conjunction with a regular internal combustion engine, using the waste heat from the ICE to warm the liquid.

There are several examples given on the company website of this engine being used in vehicles, but the real future for this engine may be in stationary applications where it can make use of the waste heat generated by other processes.

Dearman uses liquid nitrogen in his demonstrations, but says liquid air is what the engine is actually designed for. Maybe it's just me, but I've never heard much about liquid air, oxygen and nitrogen of course, but air? Perhaps because there's not much use for it that we don't see it produced, but with the Dearman engine, we'll have a reason to chill the very air we breathe and change it into a fuel for our cars, or as a way to store energy produced by those intermittent sources from the sun or wind.

The company is currently working with Ricardo Engineering to turn it into a commercially viable engine. Pretty cool, ...or should I say, very cold?

Link: Dearman Engine

Video below:


  1. Mike says

    ” There’s no burning to create any other chemical compounds, you’ve simply chilled a gas that naturally occurs”

    That’s not really true. You actually use a compressor, heat exchanger, and a column separator to produce liquid air. Which use electricity to run typically, and more than half that electricity is produce in a coal fired plant in the US. Since compressors and heat exchangers aren’t particularly efficient, you’re still producing a lot of carbon to make the fuel for a liquid air engine.

    • mark says

      Hi mike,
      I agree with your sentiments that the energy input of liquefaction of air seems to be over looked but in saying this if the energy was sourced from renewables then the carbon side is reduced. On a grid systems people don’t choose where your electrons come from but you do choose what you assist in financing by choosing green energy options on your bills and this has significant impacts on investment into renewables.
      Air has some great potential and a motorbike was developed last year utilizing a air engine developed in Australia. I believe that manufacturer is talking quite seriously to the motor industry.
      The engines are there (in some ways this is the easy part – the weak point has been the storage of the compressed air – carbon fiber tanks stepped up the stake quite significantly. If liquid air can up the anti again then i think air will be a great option for urban areas and from my opinion better than electrification on a number of levels – i have been following this for a while – go pressurized air!

      As for the set up of a bike – the frame holds the tank and the engine is integrated into the rear hub. Actually it would be very easy to do a all wheel drive using this configuration too – like ohlins did with the Yam tt ( I think) but they used a fluid to a hub mounted engine – It might actually suit dirt bike very well.
      These thing would be light as F*&k too : )

    • says

      It is true, there’s still a source of pollution. It’s a bit of a misrepresentation to call any energy or transportation technology “clean.”

      Having said that:

      The idea is to reduce our pollution to as few point sources as possible. Right now in the US we have millions of cars and thousands of power plants. For the sake of argument, let’s assume they put out roughly the same amount of pollutants. What if we could eliminate one of those sources of pollution? After eliminating one of those sources, which would be easier to minimize the pollution further?

      In my opinion, I would push to eliminate the pollution from automobiles. The reasoning behind that is that the current and nascent technologies (scrubbers, algae farms, etc etc tec) to minimize pollution, are much more effective on larger scales. It’s easier to negate the pollution from a few thousand, non-moving powerplants, than it is to do the same for millions of cars.

    • Clawbrant says

      It should be noted that, despite the negative connotations that coal holds with most of the population, a steam turbine power plant is much more efficient than any gasoline auto engine. A power plant does not have the same size, weight and economic restrictions that a motor vehicle has and can operate constantly at its peak efficiency. Other technologies, such as electric motors, can be scaled down much more effectively for personal use. By using a nonemitting drivetrain in vehicles in conjuction with a larger, more efficient external power plant you reduce overall emissions and establish an infrastructure to support zero-emission travel in the future.

    • RobC says

      Agreed Mike.
      This is a very inefficient way to power anything.
      There are so many processes involved in creating the liquid air that use energy wastefully. The IC engine is still one of the most efficient converters of fuel to energy there is on the planet.

  2. Renegade_Azzy says

    Or you could use nuclear to get that electricity, which makes power whether the lights are on or not.

  3. Kyle T says

    Liquid air is a really bad energy storage device (compared to liquid chemical fuel like gasoline or diesel).

    The enthalpy of liquid air at 1 bar and 75 K is about -132 J/g. At ambient temp and pressure, it’s about 300 J/g. This is a net change of ~432 J/g, which is the most energy you’ll get out of the system in my memory serves me right (it’s been a while).

    Gasoline, on the other hand, has an energy density of 46 MJ/kg. That’s 46,000 J/g, or about 100 times that of the liquid air. In other words, you’ll need to carry 100 gallons of liquid air to get as far as you can get on 1 gallon of gasoline.

    (Note of interest: these numbers put liquid air in the ballpark of batteries as an energy storage device. Why not just use batteries, then?)

    Sources: CRC Handbook, wikipedia (

    • Paul Crowe says

      Gasoline is by far, the energy density champion, we’ve said that all along, but when you have all of these alternative ideas out there, they’re interesting to look at.

      You ask, why this instead of batteries? Quick refills, to begin, you just transfer more liquid air and you’re off, no time consuming recharge. Easy to add capacity, too, just put in a larger tank instead of figuring out how to install and connect a lot more heavy batteries. No recycling and disposal issues as with batteries or high cost replacements when the batteries age. Those are just off the top of my head.

    • mark says

      thats why the economy is biased – it does have a lot of energy stored
      Remember fossil fuel use is why we have climate change.
      And believing in human induced climate change or not – who cares what the average joe thinks – the science proves it – the end

      • mark says

        “And believing in human induced climate change or not – who cares what the average joe thinks – the science proves it – the end”

        PS that was’nt directed to you Kyle – just the mountain of morons that mix their opinion with observed facts from science on this subject – and yes the full picture is still being worked out on anthropogenic climate change.

  4. Tanshanomi says

    Very cool idea (no pun intended), even though it is purely academic. As other commenters have already pointed out, compressing and storing the liquid air takes gobs of energy, which makes the whole thing rather inefficient.

    But just because it’s currently of no practical use doesn’t mean it’s pointless. Perhaps something that will be a springboard to something more useful someday, but even without that, it’s a pretty neat toy.

  5. B50 Jim says

    Another good idea that needs work, but who knows? With the folks at Ricardo on it, a commercial machine is not far off. Why not use a bank of solar cells to power the compressors and other equipment to make the liquid air? It would need rather a lot of solar cells, but it’s not prohibitive. Worth a look, and it would have a near-zero carbon footprint.

    Liquid air is mostly liquid nitrogen (about 80%) with the rest oxygen, CO2 and a few other gases. It’s everywhere (cleaner in some places than others), so there’s no need to source pure nitrogen.

    I love the Popular-Science vibe of these projects. Usually that’s the kiss of death, but some might make it.

    The only problem is handling liquid air — it’s mighty cold stuff and will cause instant frostbite when it touches skin. But we’re accustomed to handling a dangerously flammable liquid to run our vehicles, so some liquid gases shouldn’t be too much of a drawback.

    • BigHank53 says

      Actually, liquified air will be entirely nitrogen and oxygen, with perhaps a teensy bit of argon. The carbon dioxide and methane will be frozen solid, and you’d want to filter them out to make sure they didn’t jam up your valves.

      • B50 Jim says

        I based my post on what I remember from grade-school science classes. Maybe this is why he runs it on pure LN. A slug of dry ice would bollox up the works pronto. It gets complicated, doesn’t it? No wonder gasoline still is the main choice — but we’ve had 120 years’ experience using the stuff. There were some spectacular “incidents” in those early days.

    • Paulinator says

      I had to run some extreme cold weather operational tests on a machine once. My quick source Arctic climate in July was a huge bottle of liquid nitrogen. The flex-hose was about 18 inches long and about face height. Crack the ball valve and you could freeze hell over in about 45 seconds. It always puzzled me why you don’t need a license to have kids or to rent huge bottles of liquid nitrogen.

    • says

      Liquid nitrogen isn’t instant frost bite. In many situations it simply boils so fast that an insulating blanket of gas forms and the liquid rolls off. I’ve actually had some poured over my hand, just felt a bit cold. It’s most dangerous if the liquid nitrogen is held against the skin. So splashes are harmless, but soaked cloths or tools are trouble.

      Another fun fact about liquid air, Oxygen liquifies 5-10 degrees warmer than nitrogen. It’s a BAD thing when a liquid nitrogen supply line starts dripping “condensation”

    • matrickz says


      If we use solar cells to run the compressors and coolers to make the air then yeah it would be clean but inefficient. You could better use that solar power to boil water and turn a turbine.

  6. Paulinator says

    This is just an an expansion on the compressed air engine (ok I slid that pun in there). The overall efficiency looks much better if one can utilize the “waste heat” generated during the liquefying process. Domestic hot water come to mind.

    • mark says

      you dont – just insulate the hell out of the tank and use the energy as you need – probably lots of toping up – how would it be on a hot day – don’t know?

  7. GenWaylaid says

    You really, really don’t want to introduce the safety and handling issues of cryogenics into everyday transportation. If Dearman has developed a more efficient cryogen engine, that’s still a good thing.

    There are existing applications that already involve cryogenic liquids which could benefit. There might be some application to liquid-fueled rocket engines. Perhaps the Dearman engine could be used in reverse to create liquid air more efficiently. There’s no need to make claims about vehicle applications which would require all sorts of additional safety precautions to be practical.

  8. travis says

    you could use this for a super high compression ratio engine, make it a two stroke and spray gas in one side and super compressed air in the other, you could have 1,000 to 1 compression, on pump gas.

    • Kyle T says

      How would this let you run 1000:1 compression?

      How are you going to build an engine that has 100 times the stroke of common engines? That implies strokes on the order of 4 meters. A 16-foot diameter crankshaft seems like a really, really bad idea (for a motorcycle or a car).

      • todd says

        Kyle, instead of making the capacity of the cylinder larger with a longer stroke, you would just raise the compression ratio by decreasing the size of the combustion chamber. Simple. Now I can only guess the tiny clearances involved in a 100cc cylinder with a 0.1cc combustion chamber.


  9. Kenny says

    I think Paul is right about this concept being used in stationary applications.
    Could make for a whole new generation of energy efficient power stations.
    Storing excess generated power as compressed liquid air, possibly combined with the underground compressed air storage concept.
    Add some next gen. heat exchangers to the mix,
    If any of it would be practical would require a bit more research but it can’t hurt to dream.

    • Jiro says

      I am wondering about vehicles that need air conditioning. The heat in the vehicle could be absorbed by the liquid air, causing it to boil. The heated air would run thru the air motor and the left over air could be used to in the engine. This would be especially useful in local bus service. Resupplying with liquid air could be irritating if storage volumes are limited. How much heat does liquid air absorb? Could this replace an a.c. unit?

  10. says

    So your 2nd car sits in the driveway for 3-4 days and all the liquid air boils away, “super insulation” or not. Now it’s out of “gas” and you have to somehow acquire, carry, and refill liquid air in the context of a home setting. Not so attractive now, eh?

    • mark says

      “So your 2nd car sits in the driveway for 3-4 days and all the liquid air boils away”

      Only put in your tank what you need. Maybe what happens in this scenario is that the spare fuel gets decanted and stored properly – this would take energy which a person would have to pay – more leverage for a behavior change.

      Petrol is so good it has made us lazy and wasteful of energy. When it gets too expensive see how people will change.