Talk:Liquid nitrogen economy

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This article was the subject of a previous vote for deletion. An archived record of the discussion can be found here.

Redwolf24 02:08, 22 August 2005 (UTC)

Contents 1 References 2 Validation needed 3 Some figures 3.1 Research 4 Avoiding an edit war 5 One meter cube of liquid N2 = 320 miles ? 6 Efficiency questions 7 Liquid Nitrogen Economy: throwing in another factor. 8 Sorry!

[edit] References

Does anyone have a real-world reference for this concept that so far can only be found on the Wikipedia? No original research, eh? Anyone who'd seen how liquid nitrogen was made would not seriously suggest it as an energy currency - it makes the hydrogen economy boys look like Shell Oil in comparision. --Wtshymanski 13:33, 13 July 2005 (UTC)

---

Take a look at

1. http://www.aa.washington.edu/aerp/CRYOCAR/CryoCar.htm
2. http://www.mtsc.unt.edu/CooLN2Car.html
3. http://www.howstuffworks.com/question133.htm

Lumos3 15:03, 13 July 2005 (UTC)

Original reference dates back to 1974! There are plenty of current papers with a modern bent on the topic.--Pete 19:11, 8 August 2005 (UTC)

Thanks for that...still looks pretty far-out to me, and the fact that not much seems to have happened since 1997 reinforces the idea that a "liquid nitrogen economy" is not really a viable answer to energy distribution problems. The heartbreaking point is that a cryogenic plant needs .45 kwh to make a kilogram of LN2 that at best yields 0.055 kwh - this 8:1 input:output ratio really undermines the case for LN2. None of the sites talked about the energy required to liquify nitrogen. I stand by my edits. --Wtshymanski 15:58, 13 July 2005 (UTC)

Wikipedia does not just report the viable, but all areas of human endeavour. It is possibly too early to judge whether there is a workable technology here but it is an area worthy of note and does not deserve the label crackpot. I believe it should be referenced in articles where it is a possible future avenue of development (with caveats) like solar power and energy storage. Lumos3 08:38, 14 July 2005 (UTC)

That is the crux of the problem. I think the credibility of serious articles in Wikipedia is undermined if we don't at least flag some of the more...oh well, I'm going to say it...crackpot notions as such. I also think this article has NO quantitative assessment of what a "liquid nitrogen economy" means - there are NO factual numbers in the article, and no response to my objection above that any currency that pays out 12 cents on the dollar is not going to be a popular medium of exchange. The original author doesn't show any signs of having done any arithmetic. Extraordinary claims require extraordinary proof, and an article that posulates such a radical change in the way things are done should have some back-up if it wants to be taken seriously. Even the articles on the LN2 cars are very very shy on performance statistics and don't talk about the manufacture of LN2 at all. I don't think this is a fruitful area for future energy development either. At one time hanks of hair were part of weapons of mass destruction, but no-one today is advocating hair-powered transportation as the solution to the oil price crisis. The author might be well advised to consider why this is so and how this is analogous to the many problems with his unique idea of a liquid nitrogen "economy".--Wtshymanski 17:36, 14 July 2005 (UTC)

Can you please explain where you got your numbers that you used to calculate the 8:1 input:output ratio? My quick calculations indicate that the efficiency of a heat engine using a standard temp (zero celcius) heat source and a LN heat sink would be about 70% efficient (1-77/273 = 0.718). What am I missing? --Flatline 20:47, July 14, 2005 (UTC)

Nothing is missing. The Carnot cycle is a starting point to discus efficiency, an upper bound. It takes a lot of losses to drop to the level of a car. Efficiency does take second place to convenience and energy density. A liquid is convenient and the Hydrogen economy struggles with way to compensate. A big plus for the Methanol economy and bio-fuels economy. Efficiency relevant but not principle to success, consider the long running use of petrol despite the losses associated to the cracking process. SUV’s make an interesting statement about the importance of efficiency.

With petroleum convent to distribute, cheaper than milk and great energy density its demise is a concern to us all.

L2N does take a considerable effort to make per kg. This is good, as it relates to the energy density. The process is reversible and a reasonable proportion of the effort can be recovered. Some prototype L2N vehicles use L2N like water in a Steam Engine. Efficiency is at a level it’s wasteful. Stirling engines are less wasteful (more efficient than diesel engines). I could lead on with altenative heat engines but time is limited…

Thanks for your comments. Pete

Yes, the Carnot cycle efficiency is OK as you've calculated it. But practical refrigeration plants aren't anywhere near the Carnot limit. I did a quick Google on "liquid nitrogen kwh kg" and soon found this www.sciteclibrary.ru/eng/catalog/pages/2909.html manufacturer of liquification plants. This is somewhat consistent with my steel industry experience, where I knew that the Air Liquide plant next door used a few megawatts to make a few tons/day of liquid O2 and N2. The LN2 car is like the concrete toboggan - though engineering students can make them work, so far these have had little impact on the transportation industry. There's more analysis on this talk page than on the Web site linked in the article. --Wtshymanski 13:49, 15 July 2005 (UTC)

Regarding cost, liquid Nitrogen is remarkably cheap right now, something like $.50 per gallon delivered. But that, I understand, is because it is essentially a byproduct of the creation of more valuable liquid gases, like Oxygen, etc. If it were to become a chief product the economics would change. I'd also read (but don't see mentioned here) that it could be practical to create liquid Nitrogen "onsite" at refueling centers, thus saving transportation costs (both monetary and energy). Lastly, regarding original research, this is a well-discussed topic in the real world. Cheers, -Willmcw 19:20, July 18, 2005 (UTC)

[edit] Validation needed

It's not good Wikipedia form to cite your own website as an external link. There's no analysis of the practicalities of the proposed system. What is "L2N" supposed to mean, anyway? This article is seriously flawed until it gets some facts, not just hypothesizing. --Wtshymanski 04:32, 18 July 2005 (UTC)

[edit] Some figures

According to this paper http://www.phys.unt.edu/~cordonez/IMECE01.pdf

The ideal (Carnot) specific work available by using the heat of vaporisation of liquid nitrogen is given by w =L[(Th/Tc )-1]

• For liquid nitrogen L, the heat of vaporisation is 200kJ/Kg
• The boiling point of liquid nitrogen is 77Kelvin
• The temperature of atmospheric air is ~ 300Kelvin

And this gives 570 kilojoules of energy per kg of Liquid nitrogen Lumos3 15:47, 18 July 2005 (UTC)

Yep, and the energy density of gasoline is 45,000 kJ/kg. Do you see the crack-pottery aspect? Plus you've come up with a higher number than I've seen elsewhere which I suspect is faulty; how can you *more* than the heat of vaporization out of each kg ( you seem to have Th and Tc interchanged)? ...though it doesn't seriously affect the plausibility. And why hasn't the proponenent done even high-school-level maths calculations in his web site? --Wtshymanski 17:02, 18 July 2005 (UTC)

Your approach is analytical. However you do seem to grapple disparate approaches, valid enough, you are among good company. Drop the emotive comments.

Like any engineer I need time! A solution needs to be complete and compatible, as does your critique. The Carnot engine is a steady state, reversible engine. Why have you just proved the Carnot engine does not achieve the temperature dependant efficiency required of a reversible Carnot engine? Pete

The article you have just quoted is supportive of the exploration liquid nitrogen and heat sink for a Stirling engine or Carnot equivalent. My initial thought, is that you have proved the steam engine is not about to return in force. I view that I share! Pete

See Wikipedia:No original research. I am unable to find even on the Web any other public discussion of a "liquid nitrogen economy", aside from what appears to be your very own web site. Please cite some other publication that discusses the ramifications of a "liquid nitrogen economy". Your writing style is more than a little opaque and perhaps I'm having trouble understanding you. Please explain to me how making liquid nitrogen at 0.45 kwh/kg and then using in propulsion at a yield never better than 0.055 kwh/kg makes any economic sense or reduces CO2 emissions. An engineering proposal generally is worked out in some numerical detail before it hits public view. Please sign your comments with date and time, using either four tildes in a row (--~~~~) or else the button at the top of the editing window (if you're using Wikipedia's own editor). --Wtshymanski 20:31, 18 July 2005 (UTC)

Regarding Lumos3's energy calculations, are you simply measuring the thermal difference? I'd heard about some engines that used the expansion of compressed (or liquified) gases, essentially updated steam engines. [1][2][3] Pneumatic engines have a long history of use. I'm not an engineer so I don't know how the force generated by expansion can be calculated. Cheers, -Willmcw 21:59, July 18, 2005 (UTC)

The two university research projects listed , though they do not use the exact phrase Liquid Nitrogen economy, show that the idea of using LN as a means of storing energy has been and is on the energy agenda and it deserves a mention on Wikipedia. The phrase itself is not out of place amongst the alternative approaches like Hydrogen economy and ethanol economy. Lumos3 09:39, 19 July 2005 (UTC)

I must disagree. No-one else in the world is seriously considering liquid nitrogen as a substitute for petroleum. Yes, you can propel a golf cart across the campus boiling off liquid nitrogen, just as you can get down a hill on a concrete toboggan; but it's not relevant in the slightest to the general problems of energy and environmental issues. The very problems with hydrogen and ethanol are the low density of energy storage, cryogenic liquid handling (for H2, anyway, in some cases) and the poor level of energy returned at use to energy input in manufacture. You could probably run a car on enough D size flashlight batteries, but no-on is proposing *that* as a solution either. I plan to nominate this article for VfD. --Wtshymanski 14:34, 19 July 2005 (UTC)

I'm not sure what VfD is but it sounds fatal. Would you find the page less offensive with a different name? Pulling together a sound article that fits well with other well crafted pages takes time. How about a move to entertaining cryogenic energy usage, Another concrete sledge or Cryogenic energy storage.

Take a look at the limitations section and let me know what you think? Add to it as you see fit. --Pete 20:06, 19 July 2005 (UTC)

Impracticality is not a criteria for deletion. As long as we use verifiable sources and treat the issue in an NPOIV manner, there is no reason to delete the article. -Willmcw 20:40, July 19, 2005 (UTC)

True, there's a lot of impractical things on Wikipedia but they are *identified* as such. The article, as such, discusses something that coesn't exist and so is not a fit subject for an encyclopeida article; this article is in serious danger of *becoming" the only public discussion of its nominal subject. "Cryogenic vehicle propulsion" would be a better place to put the contents, less grandiose than "Liquid Nitrogen Economy". --Wtshymanski 21:25, 19 July 2005 (UTC)

The hydrogen economy does not exist either, nor does the Freedom Tower, yet we have NPOV, sourced articles that properly describe the plans, designs, and problems for those things which may become reality. I think the propulsion suggestion may be too limited, as liquid Nitrogen can also be used for cooling, etc. -Willmcw 22:09, July 19, 2005 (UTC)

Wtshymanski Nice edits. Well reasoned. --Pete 18:16, 21 July 2005 (UTC)

[edit] Research

This article is intended to be a summary of research, of which there is plenty. Please refrain from expressing your empire building plans.--Pete 19:03, 15 August 2005 (UTC)

(Pete deleted the whole discussion and replaced it with the above statement. Please dont delete a discussion page its seen as very bad behavior in WikiP Lumos3)

[edit] Avoiding an edit war

I can see this article getting into a close edit war with every statement in favour being balanced by a qualifying one against. This benefits nobody as the article becomes unreadable. The way out of this is to have the argument for clearly set out and then section(s) arguing against. Please keep for and against arguments within the two areas and refrain from mixing them point by point. Lumos3 21:18, 15 August 2005 (UTC)

The article suffers from the deficiency of not addressing the energy cost of manufacture of liquid nitrogen in the first place. There was text in an earlier revision which I see has been removed that spoke of this problem. The achievable (not Carnot) efficiencies of practical crygen engines have not been tabulated. The SAE paper by Knowlen et al, cited as Reference 1, does not address these points. The article talks about Stirling engines but Reference 1 does not, and seems to be using the nitrogen gas as a working fluid in an expander - this is not a Stirling cycle. The paper does not give a value for "comparable" range - using the figures in the article and 15 kW as typical road power consumption on flat ground at steady 80 km/h, I get a range of about 130 km for the 350 l tank, (20 HP for a light SUV at 50 MPH = 14.9 kW at steady 80 km/h, 70 WH/l *350 L = 24.5 kWH, 24.6/14.9=1.6hrs * 80 = 132 km) which would be about 1/4 the range one would expect of a gasoline powerered car (and of course much less due to start/stop traffic and the less than Carnot efficiency any practical engine would have). The paper should perhaps have said "range comparable to a primitive electric car". The 350 litre capacity cited does not yield near as much energy as a 50 litre tank of gasoline, and 3600 litres would be more accurate. --Wtshymanski 21:51, 15 August 2005 (UTC)

While performing our own calculations may be interesting, and serve as a check on references, please remember that actually adding any editor-dereived figures to the article would be original research. Thkans, -Willmcw 22:00, August 15, 2005 (UTC)

Well, yes - but multiplying a few numbers is hardly original. In any case that's why the ciphering is here...the referenced paper seems to have a degree of bogosity about it. Time to nomitate for VfD, I think. --Wtshymanski 00:03, 16 August 2005 (UTC)

Any original research, which includes deciding which numbers to plug into an equation, is not worth including. Which paper has bogosity and on what basis do you make that assertion? Thanks, -Willmcw 00:15, August 16, 2005 (UTC)

The paper cited in today's version of the article as "Ref. 1" , the SAE paper by Knowlen, et. al. - as I referred to at the start of my earlier response today. --Wtshymanski 00:24, 16 August 2005 (UTC)

That paper mentions some interesting conclusions. Comparing the use of liquid Nitrogen as a storage medium to lead-acid batteries they find it has a significantly higher specific energy content. They give an estimate of the energy cost, one of your issues, (~0.5 kW-hr/kg-LN2). They discuss the use of a Rankine engine rather than a Stirling engine. 132 km is not far from the range of most electric cars, IIFC. Again, the valid comparison is to batteries, Hydrogen, or other storage medium, not gasoline. If we had gasoline at $.50 a gallon forever then no one would care about these exotic technologies. Finally, this paper seems to have been paid for by the DOE so it has some respectability. It's not just some inventor looking for investors. If you want to apply some hard-nosed editing to an engineering article then I wish you'd take a look at quasiturbine. Bogosity? -Willmcw 06:16, August 16, 2005 (UTC)

[edit] One meter cube of liquid N2 = 320 miles ?

The research vehicle used a preheater.

For the Stirling use a precooler.

(Stirling H2 is cooled by N2 exhaust gas before it reaches the N2 liquid

Summary of Nitrogen properties:

http://www.uigi.com/nitrogen.html

.808(199.1+195.8x1.04) = 325.4 Kj per liter

divide by 3600 = .09 KWH/liter or 90 KWH per cubic meter

Total cost per liter to liquefy is $0.22 = $220 per m^3

http://www.rigakumsc.com/cryo/nitrogen.html

Say 80% efficiency and 4 miles per KWH = 320 miles

Incorrect since heat capacity is proportional to °K Need to integrate from boiling to ambient.

[edit] Efficiency questions

What is the efficiency of creating a kilowatt of LN₂, storing it safely for an hour, and then converting it back to energy at STP? What is the volume of 1 kw of LN₂

What is the loss per mile of pipeline?

[edit] Liquid Nitrogen Economy: throwing in another factor.

Thanks to all for the interesting discussion on Liquid Nitrogen, it seems it has some efficiency or power density issues. But I'm not solving vehicle power here. Let me introduce a problem from another field: How to store energy generated by wind turbines.

I'm just thinking about base load for the electricity grid. When the wind blows, create lot of LN (or even liquid air) as efficently as you reasonably can, and store it in large insulated tanks. When the wind stops, use the LN to run stirling engines to geneate power.

The size of the tanks is big enough that NH losses due to warming up are small over say a 3 week period while the wind doen't blow (Such a long period is very rare.)

[edit] Sorry!

I was trying to split this off as another discussion. Ooops.