Jul 15, 2011 at 8:35 pm #1276773
One of the things that I like about alcohol as a fuel is that it's clean, safe, and inoffensive (and multi-use if you need to remove adhesive or something). But, on long trips that involve a lot of cooking, you need to carry a large volume of it.
I'm not suggesting anything exotic with astronomical chemical energy like boranes. Aliphatic hydrocarbon fuels (kerosene, white gas, etc.) are often foul-smelling and always more toxic than methanol, but they have a much greater energy density than alcohol so you can carry less of it. What about "ultra pure" paraffin lamp oil, or maybe something with a bit more vapor pressure? It would be nice to be able to use high energy density fuels without the weight and complexity of traditional aliphatic hydrocarbon stoves.
I have a chemistry degree and I am fully aware of the hazards inherent to this kind of experimentation, so please try to resist the urge to scold me for being reckless (or for endangering others by encouraging unsafe experiments).
I tried hexane in an MYOG puck-stove (pepsi-can), but it became a fireball (not a hazard, though, since I had taken a ridiculous number of precautions). Nonane or decane might work better (less volatile), with some hole-pattern design changes. Any ideas or experience?Jul 15, 2011 at 9:40 pm #1759873
@climberslackerLocale: Your guess is as good as mine.
You could compile a list of easily available fuels with a higher energy density then the traditionally available alcohol and test them all out in a controlled environment.
Oh yeah, take videos. I like watching flames.Jul 16, 2011 at 5:43 am #1759910
Acetone?Jul 16, 2011 at 6:11 am #1759916
@jdw01776Locale: Southeast Texas
One advantage of alcohol is that it is easy to find. I don't see many convenience stores carrying decane, but many of them carry HEET…Jul 16, 2011 at 6:45 am #1759920
@michaelreaganLocale: Southern California
Although I haven't experimented with this idea, one might be able to use a wick-type stove with kerosene. A possible advantage to this would be that if the stove were placed in a small white paper bag you would have a luminary to provide a small amount of camp light and gain double use for your stove.
MichaelJul 16, 2011 at 7:10 am #1759926
Alcohol (ethyl, methyl, denatured) would be better than any other liquid fuel you could come up with simply because of easy availability while on the trail without a mail drop?Jul 16, 2011 at 7:19 am #1759928
"But, on long trips that involve a lot of cooking, you need to carry a large volume of it."
How long of a trip?
What volume of fuel?
For how many people?
Just curious what the drivers are…Jul 16, 2011 at 10:17 am #1759957
@redmonkLocale: Greater California Ecosystem
I don't think the typical alcohol stove can provide sufficient oxygen to burn larger carbon chains.
I would think that, unless using a candle type design where the flame is limited to an exposed wick, larger fuels are just going to make more soot.Jul 16, 2011 at 11:19 am #1759972
@socal-nomadLocale: North San Diego county
I own a Trangia alcohol stove it the best built welded seams pressurized alcohol stove around has been around for 80 years developed for military and campers. I am sure in those 80 years the Trangia company have done tests under controlled environments to see if different fuels would work in the stove with out it blowing up under pressure.
Our alcohol stoves are pressurized are different than pressurized fueled camp stoves is the fuel storage is part of the burner and depends on the heat of the flame to pressurized the fuel in right next to flame stove.
Instead of a copper tubing heating tube that helps pressurize the separated fuel tank.
Like the old Seva 123 climbers stove that used white gas I used that was real fun to use when it worked right and some times if would catch on fire for no reason and engulf the whole stove in flames. I would have to throw dirt on it before it exploded.
Different fuels have different explosion/flash point properties when under pressure and proximity to a flame and you take the chance of having the stove becoming a bomb and the metal turning in to shrapnel and hurting or even killing you.
I would only feel comfortable using other fuels for non pressurized stoves like Altoids stoves, Zelphs stove ,wick stove. Lots of fuel burns off quicker than Alcohol and can explode in flames when you add fuel to a hot stove like white gas fuel.
I use to know all the explosion/flash points of different fuels because my job in the US Air Force was munition maintenance.
TerryJul 16, 2011 at 12:15 pm #1759979
Here is a short list of approximate heats of combustion in air:
Alcohols (in Kj/g):
Methanol (HEET): 22
"Denatured alcohol": 27 (90/10 ethanol/methanol blend)
Isopropanol: 30 (rubbing alcohol)
The heat of combustion in air increases with the length of the carbon chain. All of these alcohols are readily available from companies that sell solvents, but you wouldn't be able to find the longer chain alcohols (butanol and up) in town on a thru-hike. They are all safe (not ingestable), clean, and none have unpleasant odors. 1-heptanol smells a bit like freshly mown grass and 1-octanol smells like cucumber. Longer chains aren't practical because the melting point gets too high. Octanol solidifies at 3F, but nonanol solidifies at 19F.
Propanone: 28 (Acetone)
Butanone: 31 ("Methylethylketone" or "MEK")
These ketones are also relatively innocuous and clean (much more so than kerosene or white gas). They have odors that most sources describe as "pleasant" and several, including 2-pentanone, are used as flavoring additives in foods. They have higher vapor pressures (they are more volatile) than the alcohols. These are available without any special license from industrial supply companies, but you couldn't find them (except acetone) on a thru-hike.
liquid alkanes (Kj/g):
Alkane-based commercial fuels:
Diesel fuel: 45
Paraffin oil: 46
White gas: 46
The liquid alkanes are noxious irritants, and they leave a pungent, greasy mess if spilled, but they have high heats of combustion. The commercial fuels are readily available and cheap.
Laurel, acetone is a good idea, because it is clean and readily available, but it doesn't have much of a combustion energy advantage over HEET. Given the same stove efficiency, someone carrying 6 ounces of HEET would only reduce their fuel requirement by about 1.3 oz (to 4.7 ounces) using acetone.
The long chain alcohols look interesting to me. They are very chemically similar to the HEET that so many of us already use in our alcohol stoves. Heptanol and octanol are clean, safe, and inoffensive. They are a major component in perfumes. I noticed that octanol is available on ebay right now for $10 for 4 fluid ounces, so it is a bit more expensive than HEET. A person who needs 6 ounces of HEET could use 3.3 ounces of heptanol or 3.2 ounces of octanol.
Cameron raises a good point, though. Isopropanol is more sooty when burned in an alcohol stove than methanol (HEET). The longer-chain alcohols might have this problem as well. This would substantially reduce the heat of combustion (the above numbers are for complete combustion).Jul 16, 2011 at 1:17 pm #1759993
@tallblokeLocale: DON'T LOOK DOWN!!
Olive oil has a heat of combustion of around 40Kj/g and works well with a wick if preheated. I made a simple stove using a beer can bottom can for the alcohol with two tealight holders for the olive oil in the middle with a wick coming out to one side.
The alcohol brought the water to the boil quickly and preheated the oil at the same time. Once the alcohol had gone the oil took over and simmered my pasta for 14 mins until done.
Quite a good weight saving and a nice heat intensity for simmering. Downside is a slightly oily residue on the pan exterior but it burns well with little soot if the oil is hot. The best thing of all is if you have some excess olive oil fuel as you near the end of your trip you simply consume it in your food. I like it on bread in the morning. :-)
A worthwhile improvement might be to use a ring of beer can as a stove stand to keep the oil pot away from cold damp ground so it stays hot once the alcohol has gone. The boiling pan of water in contact with the top stove edge helps of course, as does the flame from the wick conducting heat through the stove body.
.Jul 16, 2011 at 1:36 pm #1759997
Rog, that's a very clever stove. I like the idea of using edible oils for fuel, and the simplicity of wick stoves is appealing. In this thread, though, my interest is alternative fuels for common perforated chamber alcohol stoves (i.e. white box, pepsi can, penny stoves, etc.).Jul 16, 2011 at 1:45 pm #1760001
@tallblokeLocale: DON'T LOOK DOWN!!
Colin, fair enough, sorry to clutter your thread.
In my experience, alcohol is a good compromise because it copes with a variety of climatic conditions and altitudes and is easily miscible with water if you need to adjust heat intensity. I haven't played with the exotic fuels you list, but I'd love to know how to make them so I could have a play.
Now, where's that book on DIY cracking columns gone? :-)
H&S disclaimer. Anyone thinking of brewing fuel should read this first:Jul 18, 2011 at 4:44 pm #1760615
I didn't know the exact numbers, thanks for the info. The weight difference between acetone and HEET might yet get me to use an "alcohol" stove rather than our Snowpeak; since I always cook for two, the fuel adds up.Jul 18, 2011 at 5:10 pm #1760630
This story made me wary of experimentation. Given your background you sound fine, but others might not be wise to experiment.
http://cityroom.blogs.nytimes.com/2011/06/13/after-accidents-firepot-manufacturer-stops-sales/?scp=3&sq=fire%20%20skin%20burns&st=cseJul 18, 2011 at 11:32 pm #1760759
@socal-nomadLocale: North San Diego county
I bought some of this gelled alcohol from a vendor at the Delmar fair a couple years ago. It nasty stuff I experiment with it in altoids tin with a couple blobs in the tin to heat some water in my pot to see if it would be viable fuel as a altoid stove . It burned pretty fast but like the article said it kind like napalm and it would stick to your skin burn you really bad.
TerryJul 19, 2011 at 9:09 am #1760857
Laural, be very careful with the acetone, if you decide to experiment. Do it outside, with a breeze or a strong fan, and wear protective clothes and a face shield. Acetone has a high vapor pressure and, when exposed to the air, it immediately forms an explosive and invisible vapor cloud. It will boil off at a much lower temperature than HEET, so a conventional alcohol stove full of acetone will probably become a fireball. I know of two cases in which a person lost their eyebrows trying to start a barbeque with acetone.
I also completely agree with Terry and John and others who have expressed general concerns about safety. It goes without saying that anyone who decides to do any experimentation with any kind of stove, no matter the fuel, should do it outside (not in the garage), with a fire extinguisher of the appropriate kind, and protective apparel (a coat and full face shield at least).
I also think it is worth noting that the alternative fuels that I suggested(long chain alcohols like octanol) are very safe as far as stove fuels go. Others on these forums report experiments with homemade high-pressure propane and butane stoves, and Terry just described experimenting with gelled alcohol. I'm not advocating any of those. Also, these forums and others are replete with discussions about making stoves out of cat food cans, altoid tins, and beverage containers, using denatured alcohol, automotive fuel additives (HEET), isopropanol, and other flammable liquids. Heptanol and octanol have lower vapor pressures (less explosion risk) and are less toxic than the methanol we all routinely use. They have a potential to be more efficient and safer than conventional alcohol stove fuels.
So, let's be prudent and take precautions when doing our experiments, but also let's refrain from being alarmist.
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