Alcohol Stove efficiency
Display Avatars Sort By:
Robert Coleman
(jbo_c) - F
Alcohol Stove efficiency on 12/22/2010 16:06:41 MST Print View

At what point(days) is it more weight efficient for you to carry a cannister stove rather than your alcohol stove? For me, "cooking" two meals a day and one hot beverage, it seems to be about 4 days. More than that, and I approach the weight of a cannister stove in alcohol.

What about you?

Jbo

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Alcohol Stove efficiency on 12/22/2010 16:11:59 MST Print View

The Thru-Hiker website has an article on this topic, comparing the weight of various stoves and fuels over time.

We would expect somebody with the name of Coleman to be interested in stove efficiency.

--B.G.--

John Donewar
(Newton) - MLife

Locale: Southeastern Louisiana
Re: Alcohol Stove efficiency on 12/22/2010 16:32:11 MST Print View

Robert,

>>For me, "cooking" two meals a day and one hot beverage, it seems to be about 4 days. More than that, and I approach the weight of a cannister stove in alcohol.<<

I recently made this same discovery about my whitebox solo stove. The stove is light as a feather but the alcohol that I was carrying actually had me carrying more weight for a lighter stove.

I now carry an Optimus Crux canister stove with an eight ounce canister. I start out initially weighing about the same as a bottle of alcohol and the solo stove together. I cook faster and ultimately end up weighing only a few ounces more at the end of approximately 10 days of hiking than my empty alcohol bottle and solo stove. Canister stoves are effectively twice as efficient as alcohol stoves.

Eight ounces of canister gas can do the work of sixteen ounces of alcohol. I also have the option to simmer that is unavailable with my solo stove.

Party On,

Newton

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
re on 12/22/2010 17:00:18 MST Print View

http://www.backpackinglight.com/cgi-bin/backpackinglight/comparative_fuel_efficiency_and_weight_of_stoves_pt2.html
talks about how much fuel is used for alcohol and canister

James Marco
(jamesdmarco) - MLife

Locale: Finger Lakes
Alcohol Stove efficiency on 12/22/2010 18:37:49 MST Print View

Well yes and no. The article cited is a poor one. He uses, perhaps, the least efficient WG stove that could be found. Mine typically does better by 50%. More if I am tight on fuel and need to conserve. I tend to ignore lab results, anyway. About 1/3 difference is the norm. I therefore don't trust his results because he assumes that stoves are close to the same, yet at twice the fuel usage, I think this is a false assumption.

Anyway, research for a break even on the transiton between the two fuels finds about a 3-5 day run. This varies on a lot of things. Water temp, whether you boil a 10oz cup or 8oz cup, etc. 4-5 days sounds reasonable for solo use. I think you will find they don't differ enough to matter, unless we are counting grams, not ounces. An 8oz canister will usually weigh around 5oz. So, don't forget to add this to the fuel weight while calculating. A PET bottle for WG or Alcohol weighs about 1/3-1/2oz.

My thoughts only. . .
jdm

Franco Darioli
(Franco) - M

Locale: Melbourne
Alcohol Stove efficiency on 12/22/2010 18:46:09 MST Print View

Gas works particularly well when you start with a full canister and your trip ends when the canister is empty.
(That is if your stove works well and don't use it at full throttle)

If your canister runs out the day before, than it isn't so efficient.
Franco

kevperro .
(kevperro) - F

Locale: Washington State
Efficiency on 12/22/2010 19:50:57 MST Print View

For the most part, all my trips at this stage are 3-4 day affairs but I'm not sold on the idea that it is heavier for longer trips than that. As pointed out, the canister alone is 5oz. My entire system, pot, stove, windscreen, cup, cozy, lighter, spoon is <8oz. A five day supply of alcohol (two dehydrated meals, two cups of coffee/day) is about 15oz of fuel estimating high. Density of Ethyl Alcohol is .789g/mL so unless my calculator is off that is 15.5oz. for a full five day supply of cooking at a rate higher than my normal use. Realistically I would never use more than 2-2.5oz/day.

I think alcohol is pretty tough to beat for overall carry weight on solo trips for trips of <1 week duration. If you need to melt snow or cook for groups the equation changes. In the real world of use the ability to carry exactly what you need and meter it has a lot of value too. With canisters I'm always carrying two on trips and at that point you are carrying 20-24oz in just canisters not counting the stove or cookset.

Edited by kevperro on 12/22/2010 19:52:48 MST.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
re on 12/22/2010 19:52:30 MST Print View

An alcohol stove weighs about 0.75 ounce. Fuel bottle 0.75 ounce.

Canister stove weighs 3 ounces. Empty fuel bottle weighs 5 ounces.

Canister weighs 6.5 ounces more.

Canister takes 1.25 ounces of fuel to boil 5 pints for one day (how much I use anyway). Alcohol takes 2.5 ounces. Alcohol takes 1.25 ounces more per day.

At the beginning of a 5 day trip, canister and alcohol weight are the same. By the end of the trip the alcohol will weigh 6.5 ounces less. Of course, at that point your pack will be way lighter so maybe it doesn't make that much difference.

This assumes you take the exact amount of fuel needed, but probably you want to plan on an extra day or two of fuel, so the break even point is 3 or 4 days.

If you boil more or less than 5 pints per day you can calculate that.

Some alcohol and canister stoves weigh more than that so you can figure that in if you have a different number. Those weights are about the minimum available.

Maybe the main conclusion is that there isn't really that much difference between alcohol and canister so take whichever one you prefer.

Mark Verber
(verber) - MLife

Locale: San Francisco Bay Area
Re: alky -vs- canister efficency on 12/22/2010 22:32:16 MST Print View

I found that the more efficient alcohol stoves such as the the old ion design (as well as esbits) ended up having a slightly lower aggregate daily carry weight for any length of trip assuming very basic boiling. Just about the time the canister's higher energy density was to pass the less efficient alcohol stove, the fuel was used up in the canister which meant another canister came into play, and the old canister had to be packed out resulting in dead weight for the rest of the trip.

Of course, stove choice is about more than just lowest carry weight. With a group I would want a more powerful stove that could bring to enough water to a boil reasonably quickly.

--Mark

James Marco
(jamesdmarco) - MLife

Locale: Finger Lakes
"Alcohol Stove efficiency" on 12/23/2010 04:14:48 MST Print View

Pretty much my conclusion, too. It doesn't really matter within any reasonable time frame.

Generally for short trips (2-3 nights) I like alcohol. It IS lighter. For longer trips, >week, I bring WG. I just don't bother switching back to canisters for inbetween. I push the alcohol to 4-5 days at the slight weight penalty. Then go
directly to WG for 5-7 days with the weight weight penalty. I find this much simpler on my gear rather than maintaining a stable full of stoves to meet every possible condition. Indeed, I gave away several stoves and about 20 canisters since I dropped them to simplify.

Alky and canister stoves (unless you have the larger 16oz cans) are very similar in heat content. The raw fuel has roughly 5/8 the heat content of butane (isobutane, propane blends, etc.) The carrying mechanism is often a PET bottle for Alky, about a 1/2oz (worst case,) for up to 16oz. A 4oz gas canister has 4oz of fuel, and ~3.75oz of carry mechanism. (I think Jerry was saying 6oz for an 8oz canister... they are variable amungst the different manufacturors.)Adding the fuel weight and the can weight will quickly give similar results for either fuel. In either case, it is what we strap in our packs that counts, not *just* heat content.

That said, there are differences. High heat output is not really possible using alky. Canisters pump the BTU's out. Simmering and cooking is not really that great with alky. Turning down a canister to the lowest setting helps with fuel efficiency (less heat wasted.) Extra heat screens with alcohol stoves, more fiddle factor. Excelent "green" efficiency with alky. A lot of less tangible things that can still mean you want to use a canister stove or push an alky stove beyond pure weight efficiency. The "packet" nature of canisters can be bad, as Franco said. Or it can be good. How do you handle a partial canister? But, these are all subjective. Really hard to call it based on these items.

My thoughts only . . .
jdm

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
re on 12/23/2010 08:00:15 MST Print View

I agree it's subjective - different opinions for different people and at different times

White Gas - Occasionaly, when I make a user error, when lighting it flares up and singes my eye brows. The soot gets on the bottom of my pan. Occasionally I contact the liquid fuel which has a nasty smell. Occasionally it leaks on my pack. Occasionally the line plugs up and you have to take it apart to clean it - if you're mechanically inclined and it's nice weather no big deal but if it's raining or whatever it's sort of a pain.

Alcohol - I've only used this a very little bit. Lots of fiddling - for each pot of water heated up you have to measure out a Tablespoon. You probably end up getting some on your hand - some formulas aren't too bad but some have some nasty components. Soot on the bottom of your pan.

Canister - Nirvana (I'm biased). Just screw on stove and turn it on. It's the most expensive but less than $1.00 per day so a small amount compared to food. The stove is pretty cheap. No soot on pot bottom. Yeah, you have to manage packetness - I always weigh the canister, subtract 5, divide by 1.25, write the number of days of fuel left on the bottom. If I go for a couple days I usually have a partial canister so I don't have to carry too much extra fuel. It doesn't work below 20 F or so, but that is about my limit anyway - below that your water freezes, my hands get cold, it's just generally a pain.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: white gas on 12/23/2010 10:13:22 MST Print View

"White Gas - Occasionaly, when I make a user error, when lighting it flares up and singes my eye brows."

If it flares up that way, you are doing something wrong. It is supposed to singe the hair on the back of your right hand.

--B.G.--

John Donewar
(Newton) - MLife

Locale: Southeastern Louisiana
Re: "Alcohol Stove efficiency" on 12/23/2010 11:22:56 MST Print View

I did some quick "internet research" and came up with these figures.

Alcohol has roughly 656.25 Btu's per ounce.

A mixture of propane and isobutane has roughly 716.33 Btu's per ounce.

That works out to a ratio of 1.09 : 1 for "canister gas" to alcohol.

But it has been my experience that I can boil 2 cups of water in half the time using a canister stove versus my alcohol stove.

From the above figures and what I have gathered from these forum posts if I adjust my canister stove for "efficiency" everything seems to equal out. If I carry 12 ounces of alcohol in a 1/2 oz container with a 1.5 oz stove my total weight ends up being 14 ounces. If I carry my 2.5 ounce stove with 8 ounces of "canister" gas plus approximately 4.5 to 5 oz of canister my total weight is 15.5 ounces. I don't really notice a 1.5 oz difference in wieght but I do notice the quicker boil times.

My 12 ounces of alcohol gives me approximately 10 "boils". From what I have gathered form these and other forum posts an 8 oz canister of fuel can yield 30 or more boils if used efficiently. What I gather from all of this is that I can boil my water quicker and get more boils out the canister gas than I can out of my alcohol container.

For me the final outcome is that for no real weight penalty I can do more boils quicker.

Curiously 12 ounces of alcohol versus 8 ounces of canister gas works out to a ratio of 1.5 : 1 not the 1.09 : 1 of the Btu values from above.

Subjectively, I believe that I will be happier with my canister stove.

Objectively, I believe that the plus' and minus' of the two systems cancel each other out. That being said I know that there are diehard fans of alcohol stoves and just as many fans of canister stoves.

The single main advantage to me personally is not having to deal with a toxic substance on the trail when Everclear is not readily available and DNA must be used in its place.

Party On,

Newton

Edited by Newton on 12/23/2010 11:25:27 MST.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
re on 12/23/2010 11:54:37 MST Print View

Thruhiker.org doesn't directly give the 2:1 ratio of alcohol to canister, but you can interpret it from their plots.

Will's article gives a 2:1 ratio in the mountains but it's smaller at sea level.

Roger C has done some articles where he measures in controlled manner and came up with a similar value, but I'm too lazy to look it up.

From my own use, I know I get 4 pints per ounce in actual use for canister. I've done a small amount of testing with alcohol - 2 pints per ounce.

Maybe those numbers you got are for fluid ounce, not ounce weight? or doesn't include real world efficiency.

To do accurate comparison, you have to accurately measure the amount of water, accurately measure change in temperature, account for differences in wind which can drastically change the result,...

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
re on 12/23/2010 12:01:59 MST Print View

I have to ackowledge that with alcohol you can save up to 6.5 ounces given those number, or even more if you have to carry a full canister, especially for short trips/if you don't boil a lot of water per day.

John Donewar
(Newton) - MLife

Locale: Southeastern Louisiana
Re: Alcohol Stove efficiency on 12/23/2010 12:24:10 MST Print View

Jerry,

>>but I'm too lazy to look it up<<

>>To do accurate comparison, you have to accurately measure the amount of water, accurately measure change in temperature, account for differences in wind<<

+1 for quote number one.

As for quote number two; that sounds like work to me. Let's just go hiking. ;-)

We could all just carry our titanium wire grills, used over a wood fire, in a ring made of stones, fire lit by a bow drill made on the spot from materials found on site.

Come on, we can do it! Total weight 0.9 oz (25.5 g) not including your choice of cooking pot. Are we true ultralighters or not? ;-) ;-) ;-)

Merry Christmas Jerry to you and yours,

Party On,

Newton

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Re: Alcohol Stove efficiency on 12/23/2010 12:38:35 MST Print View

"We could all just carry our titanium wire grills, used over a wood fire, in a ring made of stones, fire lit by a bow drill made on the spot from materials found on site."

For fire training, I recommend the 1981 movie Quest For Fire.

--B.G.--

John Donewar
(Newton) - MLife

Locale: Southeastern Louisiana
Re: Re: Re: Alcohol Stove efficiency on 12/23/2010 12:57:23 MST Print View

Bob,

>>For fire training, I recommend the 1981 movie Quest For Fire.<<

LOL :-)

How about using two hard contact lenses popped out and positioned back to back so as to form an ultralight miniature magnifying glass. Dual use gear?

Wait, with the lenses out who could see to assemble the magnifying glass? ;-)

And if that task were accomplished would you be able to see to aim and focus the beam of light? ;-)

Merry Christmas Bob to you and yours,

Party On,

Newton

James Marco
(jamesdmarco) - MLife

Locale: Finger Lakes
Re: Re: "Alcohol Stove efficiency" on 12/23/2010 13:13:52 MST Print View

>>Alcohol has roughly 656.25 Btu's per ounce.

>>A mixture of propane and isobutane has roughly 716.33 Btu's per ounce.
I do not believe these are the correct values for the heat content of the fuel.

According to http://en.wikipedia.org/wiki/Heat_of_combustion
The heat ratio is slightly less than 5/8, ethanol/butane. Roughly 2.1:1 ethanol:butane, given the eutectics at 95% or denaturizer (usually methanol in SLX)
and the propane(more) added to the isobutane(less.)
Various mixes can be computed from these tables. But your numbers don't seem to represent anything on these tables. Have you already computed the container weights?

Nope, that doesn't jive, either. I am a bit confuesed I guess. I am really terrible with numbers. Can you straighten me out?
Thanks, Newton!
jdm

Franco Darioli
(Franco) - M

Locale: Melbourne
Alcohol Stove efficiency on 12/23/2010 13:44:23 MST Print View

From Newton
"If I carry 12 ounces of alcohol in a 1/2 oz container with a 1.5 oz stove my total weight ends up being 14 ounces. If I carry my 2.5 ounce stove with 8 ounces of "canister" gas plus approximately 4.5 to 5 oz of canister my total weight is 15.5 ounces. "
Coming back from that trip with an empty cartridge would be a best scenario situation.
Now lets assume the worst scenario.
Lets assume that we can do 6 days with the above.
Now we need to do 7 days.
Add another 7oz for the gas set up(small canister) , add another 3 oz or so (two ounces of fuel plus one for a slightly bigger container..for the alcohol set up.
New total about 17oz for alcohol, about 22oz for gas.

The single main advantage to me personally is not having to deal with a toxic substance
True . In the end it is down to personal preference and not everyone is paranoid.
Franco