QuietStove.com

Tuesday, August 16, 2011

What's the Best Alcohol for Stove Fuel?

A lot of people interested in going light are trying alcohol as a fuel.  But if you head down to the store, you'll see all kinds of alcohol.  Which alcohols are good choices for stove fuel?  Which ones are poor choices?

Alcohol as a Stove Fuel (in order of best fuel to worst fuel)  The best alcohol fuel is ethanol (ethyl alcohol).  It has the highest number of calories per gram* of any stove fuel suitable alcohol (I really don't consider dirty-burning isopropanol to be suitable as a stove fuel) and burns reasonably cleanly.  If you can get lab grade "absolute" (200 proof) ethanol or 190 proof liquor, that's going to work really well, but both of those (lab grade absolute ethanol or 190 proof "drinking" alcohol) are pretty expensive -- if you can even get them.  Lab grade absolute ethanol is often restricted as to whom can purchase it (i.e. not the general public), and many locations prohibit the sale of high proof drinking alcohol.  Check the Materials Safety Data Sheet (MSDS) on lab grade absolute ethanol which may contain benzene which is toxic.

Another option is "denatured" alcohol which should consist primarily of ethanol.  The problem in the US is that there are no standards for what constitutes denatured alcohol.  In fact, some denatured alcohols in the US are less than 50% ethanol.  In addition sometimes nasty stuff is used to denature the alcohol (render it undrinkable), stuff like methyl ethyl ketone, whose fumes you don't really want to breathe.  "Green" denatured alcohol generally has a much higher ethanol content and a lower "nasty stuff" content.  Check the MSDS.  The higher the ethanol content, the better it is for use as a fuel.  Because higher ethanol content alcohol burns hotter, sometimes the burning will "get ahead of itself," and you'll get some soot.  If the stove is overheating and producing soot, try adding water to the fuel (after you get into your camp site; don't carry it!). Adding water will calm down the burning, allowing the alcohol to mix properly with air and burn cleanly.  Try adding a little water at first, and then add more water as needed to eliminate any soot (up to 25% of the total volume).
"Green" denatured alcohol generally has the highest ethanol content.

Outside the US, there is a particular variety of denatured alcohol sometimes available, methylated spirits.  Methylated spirits is ethanol with methanol used as a denaturing agent.  Methylated spirits is often called "meths" or "metho".   Methylated spirits makes an excellent stove fuel.  Would that it were available in the US.

Methanol (methyl alcohol) is another popular fuel alcohol, frequently bought in the yellow HEET bottle because HEET is so widely available (at least in the US).  You do have to carry a bit more methanol to do the same amount of cooking since methanol contains fewer calories per gram* than ethanol.  Methanol fumes are toxic, and methanol absorbed through the skin is toxic.  How toxic?  If you're cooking out doors, I don't think fumes will be too bad if you're observant of wind direction and position yourself accordingly.   I don't have a way to state a safe limit for skin absorption, but handling with care should be enough.  It's not like you hear about a lot of through hikers on the Appalachian Trail (AT), where yellow HEET is easy to get and very popular, getting stricken with methanol poisoning.   Methanol has a higher vapor pressure than ethanol and works better than ethanol in cold weather.  I can't comment a lot on methanol performance in cold weather because I typically bring a gas or liquid petroleum fueled stove for cold weather.  Conversely, methanol can have "runaway thermal feedback" in hotter weather.  "Runaway thermal feedback" basically occurs when the alcohol gets so hot that it boils really violently and doesn't burn efficiently.  Adding water (see remarks above) can help calm down a burn so that the alcohol can burn more cleanly.

Yellow HEET is methanol.
Red HEET (Iso-HEET) is Isopropanol

LAST choice is isopropanol (isopropyl alcohol).  Isopropanol is easy to find at most any drug store (typically called rubbing alcohol), but it's usually a sooty mess to burn.  Even though Isopropanol has the highest heat content per gram*, it is really not suitable as a stove fuel because it's such a mess to burn.  Isopropanol is toxic in terms of both fumes and in skin absorption.   Red HEET (i.e. Iso-HEET) is isopropanol. Not recommended.

With any alcohol fuel, your flame velocity is going to be fairly low (think candle as opposed to blow torch).  Therefore, an effective wind screen is really essential for an alcohol stove.

SUMMARY
The best choices for fuel for an alcohol stove are:
1.  Lab grade absolute ethanol (200 proof) or high proof liquor (190 proof).  High heat content per gram (relative to methanol), relatively clean burning, and generally non toxic, but check the MSDS on lab grade absolute ethanol which may contain benzene which is toxic.  A good choice for warmer weather.
2.  "Green" denatured alcohol in the US or methylated spirits (ethanol with methanol used as a denaturing agent) outside the US.  Methylated spirits is often called "meths" or "metho".  Good heat content, relatively clean burning, fairly non-toxic depending on the amount and type of the denaturing agent.  In the US, always check the MSDS.  A good choice for warmer weather.
3.  Methanol, for example yellow HEET.  Decent heat content, very clean burning, but definitely toxic in terms of fumes and skin absorption.  Reasonably safe if used with care.  A good choice for colder weather.
4.  You can use Isopropanol, for example red HEET (Iso-HEET), but it is not really suitable as a stove fuel because it's generally a sooty mess when it burns.  Highest heat content, but dirty burning, and definitely toxic.  Not recommended.

Finally:   Drinking anything not intended for human is pretty much a bad idea, but if you're going to do such a thing, always check the MSDS before you drink anything not intended for human consumption.

HJ

*Heat Content of Alcohols
Fuel          MJ/kg     MJ/l 
Methanol      19.930    15.78
Ethanol       28.865    22.77
Isopropanol   30.447    23.93


Related posts and articles:

19 comments:

  1. Thanks for the excellent coverage of a very "mysterious" subject! I'm a bit of a camp stove addict myself, and a vintage boat owner as well......... I have a couple of alcohol stoves I'd like to use in the boat, but fuel has been the sticking point. I think I'll try the high proof vodka. I use the stuff to fill my old wet compasses and it works great for that, so I might as well try it in the stove! If you get the chance, check out my blog: http://sharky-fourbees.blogspot.com/
    I've got quite a number of stove posts mixed in with all the rest of my pages.....
    Thanks!

    ReplyDelete
  2. Hi, Sharky,

    Thanks for your comments. High proof vodka should work well as long as it's around 150 proof or so. Less than 150 proof might not have a lot of heating power.

    I'll have to check out your blog when I get a chance.

    HJ

    ReplyDelete
  3. There are very few locations that sell denatured alcohol with a significant ethanol content. The stuff you have pictured, the Kleen Strip Green denatured alcohol reports that it is >95% ethanol and the balance methanol. It is the only widely available stuff I am aware of. Lowes and Home Depot sell it.

    For priming stoves, I have found the 91% isopropyl alcohol is a clean and cost-effective alternative to methanol. I don't see much soot, though there is some.

    Some stores also sell a gelled ethanol stuff made for some sort of fire place. It comes in a liter bottle that looks like a big pop bottle. I once saw a WalMart store that sold a alcohol gel for starting a grill. It was primarily ethanol. I don't know if these leave any residue.

    One a cost basis, the high proof alchol sold in liquor stores will kill the wallet.

    I once found quart bottles of concentrated windshield washer cleaner. It was pure methanol with blue dye added. Nothing more. Burned great and I thought I was getting a bargain until I noticed the blue dye accumnulating.

    ReplyDelete
  4. The other denatured alcohol that has good ethanol content is Sunnyside brand.

    That's interesting what you say about isopropanol being good for priming. I know it's not much good as an alcohol stove fuel, but for priming, maybe it'll work well. It certainly has plenty of heat content. I'll have to try it.

    You're right about high proof liquor. It makes a good stove fuel, but it is indeed expensive.

    HJ

    ReplyDelete
  5. can isopropanol not be "tempered" with water as well?

    If not, can you help me understand why?

    If so, it would seem to be the BEST approach, both from a cost (more "calories"/cheaper) and weight (add water at campsite) perspective...

    Thoughts?

    ReplyDelete
  6. To be honest, I haven't done a lot of investigating with isopropanol. What little I have done made me lose interest in isopropanol as a fuel. Being around it when it's burning leaves me feeling bad. I may try it some time, but there's more to it than just soot. Isopropanol is quite toxic.

    HJ

    ReplyDelete
  7. Golden Grain. A neutral grain alcohol. THE BEST. Although it is sold as a beverage...dont drink it!!!
    It is 95% pure alcohol which means only 5% is water. In other fuels water is in greater quantity (water does not burn and makes the flame colder duh)as well as some 'additives' which will kill you as in HEET.
    It costs .61 per oz. But on the trail, what difference does a few cents make when you get more heat, use less fuel, and you will be a much happier camper.

    ReplyDelete
    Replies
    1. Well, I'd encourage you to experiment with it. I've found that more pure forms of alcohol burn hotter and can actually be less efficient -- if your stove doesn't handle them well. Like I say, experiment with it.

      HEET is pretty safe for normal use. It's just methanol. But DO NOT drink it.

      HJ

      Delete
  8. One downside of all denatured alcohol brands here in Germany is that they have a very strong bitter taste. Even one drop on my fingers can taste very bitter if I eat something an hour later.

    ReplyDelete
    Replies
    1. Wow! That is bitter. Different countries use different agents to render fuel alcohol unfit for drinking. It sounds like Germany uses a bittering agent -- which is actually probably a good thing. The agent frequently used elsewhere, methanol can cause permanent blindness and even death. Germany's method is better in my opinion.

      HJ

      Delete
    2. The bittering agent seems to not evaporate. It stays behind on my fingers if I spill a drop and also on the inside walls of my Trangia burner. And it is very diffucult to wash it off my fingers. One treat with a hand brush soap and water is not enough. But I think the bittering agent is not harmful. And I take care not to consume a lot of it. I think in Europe we need bittering agents because in some countries, like Sweden, it is very difficult and expensive to get drinks with alcohol and people people tend to try everything possible ;-)

      Delete
    3. I agree that the bittering agent is probably not harmful. It is used to strongly discourage drinking, but is not intended to make a person sick.

      HJ

      Delete
  9. Here is a alcohol stove fuel comparison video where six different fuels are directly compared.
    http://youtu.be/Mt69fbNhCgs

    ReplyDelete
    Replies
    1. I just watched the first half. Interesting, but not conclusive -- the results are just for a Trangia. There are stoves, not many but some that will burn isopropyl alcohols efficiently. The results would be very different for those stoves. That said, most alcohol stoves, indeed the great majority, will burn HEET or denatured alcohol well and will not burn isopropyl well.

      HJ

      Delete
  10. 17 minutes! Yipes. Long video. :) I'll check it when I get a chance.

    HJ

    ReplyDelete
  11. Methanol racing fuel is the best fuel for stoves just because its so darn cheap. $4 a gallon. Its a lot cheaper than the other fuels mentioned. You can get it at shops that sell high performance racing parts.

    ReplyDelete
    Replies
    1. I am going to have to look into that. Thanks for the tip!

      HJ

      Delete
  12. If this double posts, sorry... login issues..

    I don't really understand why Iso is considered so "dirty". But then, I use 99% pure bought by the Gallon from Farm CoOps (Brand: Agrilab) for $12 wholesale or $16-$20 Retail...

    ReplyDelete
    Replies
    1. Have you tried burning it in a stove? It does work, but it leaves a hard to clean black soot on everything unless you have a specialized stove specifically designed for it.

      If you do use it and it's burning cleanly, what stove are you using?

      HJ

      Delete