# Liquid Nitrogen Engine Spells the End of Electric Cars?



## EVDL Archive (Jul 26, 2007)

Weight for weight, liquid nitrogen packs much the same energy as the lithium-ion batteries used in laptops.

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## Jason Lattimer (Dec 27, 2008)

Somehow that just doesn't seem like a practical fuel.


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## Mark C (Jun 25, 2010)

They can install the liquid nitrogen pump next to the hydrogen pump next to the plutonium dispenser. {My apologies for the plutonium part to anyone not familiar with the Back To The Future Delorean.}

In any case, the oilies do not want you driving battery electric because that breaks the umbilical cord. You can generate your own electricity at home, don't know how you could be free of the local "service station," er, I mean "convenience store," if you needed any of the other options.


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## dougingraham (Jul 26, 2011)

Jason Lattimer said:


> Somehow that just doesn't seem like a practical fuel.


You are correct. It isn't practical. There may be plenty of liquid nitrogen right now but as soon as you have a few thousand cars using it as fuel there wont be any surplus and the price will go up. It is fairly energy intensive to make. The reason it is cheap is that it is a by product of the manufacture of liquid oxygen and there are few uses for it. But it is a pretty limited supply. It seems green until you realize that someone is burning coal at a power plant to make the electricity to run the pumps to make the liquid nitrogen.


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## Duncan (Dec 8, 2008)

The big problem with liquid nitrogen is that in order for it to expand - and produce power it requires heat
It can take this heat from the environment - BUT that requires heat exchangers - look at the heat exchangers (radiators) on an IC engined car - a liquid nitrogen car would need less heat than an IC engine rejects - but it would have to operate on a lower temperature difference so It would need similar sized heat exchangers

The story talks about a new advance - but if you read it carefully it is not eliminating the heat exchangers - just moving them to a more convenient location

The other issue is that Nitrogen is dangerous! in any enclosed volume a build up of Nitrogen would be a silent killer
It's NOT poisonous - but it displaces the oxygen in a way that the body does not detect
You simply breath normally and go unconscious and die


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## dragonsgate (May 19, 2012)

I have traveled to many states buy automobile over the years and therefore have spent a measurable amount of time at gas stations fueling my car. On several occasions I have witnessed some stupid people doing some stupid and dangerous things with gasoline. I am surprised that there are not more accidents with gasoline than there are. Nitrogen and hydrogen from what I know is even harder to handle. I do not think the average driver will have enough savvy to handle such stringent protocols for handling fuels like hydrogen and nitrogen. Even electric has its draw backs. The positive side of an electrical accident is if someone has an accident with electricity the odds of killing anyone else beside there self is slim.


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## Jamie EV (Oct 3, 2012)

dragonsgate said:


> I have traveled to many states buy automobile over the years and therefore have spent a measurable amount of time at gas stations fueling my car. On several occasions I have witnessed some stupid people doing some stupid and dangerous things with gasoline. I am surprised that there are not more accidents with gasoline than there are. Nitrogen and hydrogen from what I know is even harder to handle. I do not think the average driver will have enough savvy to handle such stringent protocols for handling fuels like hydrogen and nitrogen. Even electric has its draw backs. The positive side of an electrical accident is if someone has an accident with electricity the odds of killing anyone else beside there self is slim.


Sort of like electric Darwinism, lol!


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## tenthousandclowns (Jun 21, 2012)

Has anyone done the efficiency math for nitrogen making from power plant to wheels vs. electric car vs. gasoline? I''d be curious to hear that percent.

Also curiously I found no obvious OEM interest in google-land.

-Luke


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## aeroscott (Jan 5, 2008)

interesting comments , I like the run out of nitrogen one the best! Someone needs a little Google time .


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## rochesterricer (Jan 5, 2011)

Reminds me of all the miraculous claims about the compressed air car.


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## dougingraham (Jul 26, 2011)

tenthousandclowns said:


> Has anyone done the efficiency math for nitrogen making from power plant to wheels vs. electric car vs. gasoline? I''d be curious to hear that percent.
> 
> Also curiously I found no obvious OEM interest in google-land.
> 
> -Luke


I found reference to a guy who makes his own at a cost of $1.10 per liter and it takes a day to make a liter. He says this is substantially cheaper than buying at the local welding shop. Another reference from 2001 indicates 11.3 cents per liter and an industrial cost of electricity at 4 cents per kwh giving 2.8kwh of electricity to make a liter. I found a reference from 2005 indicating cost to make of 6 cents per liter. At 6 cents per liter we are still looking at approximately 1.5kwh of electricity.

I can drive my car 5 to 9 miles on the electricity it takes to make a liter of liquid nitrogen. How far can you move a car with a liter of liquid nitrogen?

One thing is certain, you would not have problems with air conditioning in a liquid nitrogen powered car.


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## Jamie EV (Oct 3, 2012)

i always wanted to become a snowflake in the event of an accident...


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## aeroscott (Jan 5, 2008)

We talked this system over , but having trouble finding the thread . But 50% eff. was what I remember . If you wanted to store a megawatt for home power or commercial . It would cost way less then batteries . It's probably the most cost effective system in the megawatt size , if you can live with 50% eff.


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## Kalle (Oct 4, 2012)

How do you plan to drive a car with nitrogen? Expanding gas at boil off? Is ther a artickke about this that i am missing?


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## McRat (Jul 10, 2012)

Any time there is a difference in heat, you could make HP from it.

I'm just not sure you could store enough energy in a lb of LN to do anything realistic.


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## McRat (Jul 10, 2012)

Ultimate applications:

Ice Cream Truck
Fire truck
Zamboni


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## tenthousandclowns (Jun 21, 2012)

Wouldn't it work best in hot weather? Maybe in the more distant future a nitrogen system could be an auxiliary or hybrid system with EVs in hot weather, taking care of air conditioning and system cooling, and maybe being able to add HP boost for accelerations, so the electric drive system could be smaller. Looks like the nitrogen system would have to be significantly miniaturized first.

Also for any type of refrigerated transport. 50% efficiency isn't so bad if the other issues could be worked out.

Or if there is some battery system that is great but gets really hot.

Living in hot and humid New Orleans, this cold-drive idea is making me think.


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## dougingraham (Jul 26, 2011)

aeroscott said:


> We talked this system over , but having trouble finding the thread . But 50% eff. was what I remember . If you wanted to store a megawatt for home power or commercial . It would cost way less then batteries . It's probably the most cost effective system in the megawatt size , if you can live with 50% eff.


Its quite a bit better to pump water from a lake at the bottom of a hill to a lake at the top of the hill as an energy storage mechanism. You could probably get over 80% maybe approach 90% efficiency with such a system discounting evaporation losses.


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## aeroscott (Jan 5, 2008)

Not to many diyer's have that . But most people could run a 3 or 4 stage compressor, vacuum bottle and air motor. IF ran off a wind generator or solar panels . I think it was 500 gallons of LN would get near 1megawatt . Great fire extinguisher and make ice for everyone . $200,000 for batteries is out of the question for me . 
I don't have the large wind generator built yet, but if I did I would love to be able to store some of it's output.


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## jeremyjs (Sep 22, 2010)

aeroscott said:


> Not to many diyer's have that . But most people could run a 3 or 4 stage compressor, vacuum bottle and air motor. IF ran off a wind generator or solar panels . I think it was 500 gallons of LN would get near 1megawatt . Great fire extinguisher and make ice for everyone . $200,000 for batteries is out of the question for me .
> I don't have the large wind generator built yet, but if I did I would love to be able to store some of it's output.


I don't know about anyone else, but I simply don't want cryogenic liquids in the car with me.


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## aeroscott (Jan 5, 2008)

jeremyjs said:


> I don't know about anyone else, but I simply don't want cryogenic liquids in the car with me.


I would think you have no experience with them ? I watched a welding gas company owner pour a few drops of LN onto his bare hand and he played with it for 5 minutes , rolling it in his pom . no burns . I was shocked , but it makes a gas layer next to the skin . So as long as it is moved a bit not a problem . Much safer then gasoline .


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## kcameron (Oct 16, 2009)

I've been thinking about the potential energy density of LN2 since I first read the article linked in the original post. Since I haven't seen a proper formulation for this anywhere I thought I'd share my findings here.

The heat of vaporization for LN2 is about 199 J/g (or 55.3 Wh/kg). It's tempting to declare this to be the available energy density. Lancaster made this mistake in his oft-referenced paper: www.tinaja.com/glib/energfun.pdf.

A heat engine using ambient air temperature as the heat source (at Th) and boiling LN2 as the heat sink (at Tc) has a Carnot-limited coefficient-of-performance (COP) given by the formula: COP=(Th-Tc)/Tc. In this case, the COP is the maximum ratio of energy output vs energy absorbed by the LN2.

The boiling point of LN2 is about 77K. Assuming 300K ambient air gives COP=(300-77)/77=2.90. So the energy output of a perfect Carnot heat engine would be 199*2.90=577 J/g (or 160 Wh/kg). This number appears to be what's being referred to in the original article: "Weight for weight, liquid nitrogen packs much the same energy as the lithium-ion batteries used in laptops, mobile phones and electric cars."

Note that, beyond just boiling the LN2, there is additional heat sinking potential in raising the N2 gas from 77K to 300K. The heat capacity of N2 gas is about 1.04 J/gK (1.04 Joule per gram per degree Kelvin) so the heat sink capacity is 1.04(300-77)=232 J/g (or 64.4 Wh/kg). Integrating the above COP equation from 77K to 300K gives an average COP of 0.830. So the available Carnot output energy for the gas phase is 232*0.83=192 J/g (or 53.5 Wh/kg).

Summing the available energy of the boiling and gas phases gives 769 J/g (or 214 Wh/kg) for a perfect Carnot engine. I believe that man will someday build thermoelectric heat engines that very nearly approach Carnot efficiency. For now, we have to accept much lower efficiencies; especially in an engine which is cheap, compact, and powerful enough for a car. I won't try to support it here but I believe that assuming 40% of Carnot efficiency is being very generous for today's technology. Therefor, the most one could reasonably hope for is 769*0.4=308 J/g (or 85.4 Wh/kg). This is roughly 1/2 the energy density of lithium batteries (even before factoring in the necessary vacuum insulated storage tank).

For another perspective, imagine that you're building a car and decide that you need 24 kWh (same as the Nissan Leaf) to meet your range goal. That means you'd need 281 kg (or 618 lb) of LN2. At 0.807 g/ml, you'd need to store 348 l (or 91.9 gallons) of LN2. From my web searches, I've found prices ranging from $0.06/l to $6.0/l. There's no telling what prices a hypothetical LN2 refueling network would produce. However, even at $0.06/l it would cost $20.88 to fill a tank that produces enough energy to drive a Nissan Leaf roughly 100 miles. Assuming $5.00/gallon gasoline, that's about 24 MPGe.

In case it's somehow not clear, I don't think LN2 cars will ever be practical beyond certain highly specialized applications.


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## jeremyjs (Sep 22, 2010)

aeroscott said:


> I would think you have no experience with them ? I watched a welding gas company owner pour a few drops of LN onto his bare hand and he played with it for 5 minutes , rolling it in his pom . no burns . I was shocked , but it makes a gas layer next to the skin . So as long as it is moved a bit not a problem . Much safer then gasoline .


yes and you can stick your hand quickly into a vat of it
without injury. i just wouldnt like to be sitting on over 100 gallons of the stuff in the event of an accident.


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## onegreenev (May 18, 2012)

The reality of the issue is that you can drive further on the electricity that it takes to produce the stuff. Then you must run it in an engine nearly like your common crappy ICE and it would be about as good as your compressed air engine. Maybe. Sorry but I will keep my batteries and charge them up and drive happily to work every day on solar power while all the monkeys try to figure it out and spend a fortune on gasoline then a fortune on nitrogen then to find out that they should have been using battery electric all along.


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## Jamie EV (Oct 3, 2012)

jeremyjs said:


> yes and you can stick your hand quickly into a vat of it
> without injury. i just wouldnt like to be sitting on over 100 gallons of the stuff in the event of an accident.



Terminator 2 taught me that...


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## Jamie EV (Oct 3, 2012)

onegreenev said:


> The reality of the issue is that you can drive further on the electricity that it takes to produce the stuff. Then you must run it in an engine nearly like your common crappy ICE and it would be about as good as your compressed air engine. Maybe. Sorry but I will keep my batteries and charge them up and drive happily to work every day on solar power while all the monkeys try to figure it out and spend a fortune on gasoline then a fortune on nitrogen then to find out that they should have been using battery electric all along.


If you can limit the number of changes of state your energy source needs to go through, this is a good thing. Solar to electrical to chemical to electrical to kinetic energy is pretty good.

How many state changes does liquid nitrogen need?


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## aeroscott (Jan 5, 2008)

jeremyjs said:


> yes and you can stick your hand quickly into a vat of it
> without injury. i just wouldnt like to be sitting on over 100 gallons of the stuff in the event of an accident.


 Better to be setting on 750,000 btu of gas that has burned many people .


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## Caps18 (Jun 8, 2008)

How would one build a tank for this? You would be hard pressed to keep it at the frozen temperature. And if you vent it like it is now, you would lose a lot of 'fuel' between trips. 

I also don't see there being that much power there. Would you be able to burn the nitrogen vapor? The expanding gas barely has enough power to explode a 2 liter bottle (you don't want to be close by it when it does go off though)


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## jeremyjs (Sep 22, 2010)

aeroscott said:


> Better to be setting on 750,000 btu of gas that has burned many people .


I'm not saying it's necessarily any better or worse, safety wise, than gasoline. I'm saying I'd rather have and equivalent amount of batteries.


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## aeroscott (Jan 5, 2008)

Jamie EV said:


> Terminator 2 taught me that...


 The movies are a great place to learn , almost every car crash ends in a big explosion . I didn't think you
would use that as fact.
I'm looking for a very large storage system , not to run a car . I will use batteries for that .
Kcameron's numbers indicate this system will not compete with batteries on weight , size or efficiency . But for a large cheep way of storing gross power it would be workable and safe .


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## Ziggythewiz (May 16, 2010)

It would be interesting to see exactly how the cost/efficiency stacks up against hydrogen. I heard about some guys in Boston that made H2 all summer with their excess solar and it kept the house running off grid all winter.


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## aeroscott (Jan 5, 2008)

Caps18 said:


> How would one build a tank for this? You would be hard pressed to keep it at the frozen temperature. And if you vent it like it is now, you would lose a lot of 'fuel' between trips.
> 
> I also don't see there being that much power there. Would you be able to burn the nitrogen vapor? The expanding gas barely has enough power to explode a 2 liter bottle (you don't want to be close by it when it does go off though)


 Start with a stainless tank and a much larger steel tank , put the smaller tank into the bigger one weld up with a wrinkle belly ( expansion ) tube and supports ( low thermal conducting ) and pull a vacuum .


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## onegreenev (May 18, 2012)

Jamie EV said:


> If you can limit the number of changes of state your energy source needs to go through, this is a good thing. Solar to electrical to chemical to electrical to kinetic energy is pretty good.
> 
> Not always. Solar to batteries in the car then directly driving the car. What if it takes 5kWh to produce a liter of nitrogen. You really think a nitrogen car could go further on that liter than my electric can go on 5 kWh of electricity stored in the battery pack? I usually don't like what if's but it was shown the same with just compressing air and it was more efficient to just use the electricity that would have been used to compress the air to begin with. Now if you have soooooo much excesses power available for nearly nothing and you had no good large storage medium then it may be good to use hydrogen, nitrogen, oxygen and other mediums of storage. But if you are limited just use the electricity. Put it into the storage batterie of the car and go.
> 
> ...


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## Jamie EV (Oct 3, 2012)

onegreenev said:


> Jamie EV said:
> 
> 
> > If you can limit the number of changes of state your energy source needs to go through, this is a good thing. Solar to electrical to chemical to electrical to kinetic energy is pretty good.
> ...


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## rochesterricer (Jan 5, 2011)

Ziggythewiz said:


> It would be interesting to see exactly how the cost/efficiency stacks up against hydrogen. I heard about some guys in Boston that made H2 all summer with their excess solar and it kept the house running off grid all winter.


Got a link?


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## Caps18 (Jun 8, 2008)

I'm still a little concerned about the tank issue, but a pressure valve could be put into it.

Now, I think we should look at this as a range extender/generator for electric vehicles. Not as something to compete against EVs. For long distance trips, this would be the way to go. Have filling stations along the highway. But for around town, you would still use batteries and plug in.

And I do work with Liquid Nitrogen a few times a year, and I feel much safer with it than compressed Hydrogen (or any compressed cylinder in a car)


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## aeroscott (Jan 5, 2008)

Ziggythewiz said:


> It would be interesting to see exactly how the cost/efficiency stacks up against hydrogen. I heard about some guys in Boston that made H2 all summer with their excess solar and it kept the house running off grid all winter.


 It could be used with hydrogen , natural gas or nitrogen even oxygen . It's just a way to recover the coast of compression . That is the big deal about hydrogen( storage) . H2 can be split from water with 75-95% eff. The fuel cells run from 60-95% eff. depending on type and how many amps you are trying to get .they run at .5 volts /cell so very sensitive to amps.


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## Ziggythewiz (May 16, 2010)

rochesterricer said:


> Got a link?


http://www.wired.com/wired/archive/15.03/play.html?pg=9


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## njloof (Nov 21, 2011)

What about just using LN as a coolant source in place of traditional A/C? That seems like it could be relatively simple to implement.


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## Genius Pooh (Dec 23, 2011)

this article is just ignorance of battery's future power.

huh... just same as current battery??

now In LAB lithum - air battery is working now It's 50 time more density than current battery... 

Just some idiot


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## Duncan (Dec 8, 2008)

aeroscott said:


> It could be used with hydrogen , natural gas or nitrogen even oxygen . It's just a way to recover the coast of compression . That is the big deal about hydrogen( storage) . H2 can be split from water with 75-95% eff. The fuel cells run from 60-95% eff. depending on type and how many amps you are trying to get .they run at .5 volts /cell so very sensitive to amps.


*H2 can be split from water with 75-95% eff.*

Somebody ought to tell the academics that - last I saw they were struggling to get better than 30%

Besides you are missing the other huge energy hog - unless you want to tow a zeppelin as a fuel tank you will have to compress the hydrogen - that takes nearly as much energy as you get from "burning" the hydrogen

That step alone is only 50% efficient


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## aeroscott (Jan 5, 2008)

Duncan said:


> *H2 can be split from water with 75-95% eff.*
> 
> Somebody ought to tell the academics that - last I saw they were struggling to get better than 30%
> 
> ...


 Are these academics talking only the electrolyzer portion of the operation as I was , I have never heard of less then 50% on the most primitive electrolyzers . The guy with the hydrogen house has a 75% electrolyzer , and says it is simpler and more coast effective then the higher efficiency units . 

A point if true , urea is said to take 10% of the energy to split than water does , that would make a wast product into a fuel source . I looked and have not found anything in detail about it .
Was this thread not about using cryo to store energy and would that not apply to LH2 .


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