2011-06-20

Ultralight stove systems: What's the lightest?

It's three-thirty in the morning and in another three hours, I have to leave to go to the first day back at work in over five weeks.
What am I doing up so late??? Making a Microsoft Excel table that determines the efficiency of ultralight backpacking stove systems using various forms of fuel, in terms of total weight and fuel consumption per liters of water boiled.
What else is there to do?!?! (I had to get this off my mind, as I've been pondering it for over a year.)

You would not be the first person to make fun of me for things like this, involving ultralight backpacking gear, but please read on.















Let me set a couple things straight right off the bat...
1. Isobutane stoves need fuel canisters, which add an extra 3 oz of metal for the canister (excluding fuel) to the weight of the stove system.
2. I used a 1 oz (weight) plastic bottle to contain denatured alcohol. That weight was added, like the canister weight.
3. The weight of a Ziploc bag to contain Esbit fuel tabs is negligible, I think. Although, a ultralight extremist once told me that everything weighs something. 'If you hold it out, let go, and it hits the ground... it weighs something.'
4. For the stoves that do not come with their own pot (Soto, cat food can, & Vargo), I used the 5 oz weight of my Evernew 0.9L titanium pot (same pot Andrew Skurka uses).

The overall weight and efficiency of ultralight stove systems: (click on table to view larger image)


















Results: (if I did the calculations correctly)
What does this chart tell us? The number of liters of water boiled per the weight of the stove, pot, and fuel container, i.e., each stove system's efficiency.
Almost always, only the final weight of the stove, pot, and fuel are addressed. But isn't overall efficiency important, too?
Other gear is chosen not only for weight, but also what is the intelligent decision or the lightest, most sensible option.

In this test, neither one Esbit tab nor two Coghlan's fuel tabs were able to bring 1L of water to a rolling boil before extinguishing. The water had bubbles and was close to boiling, but not rolling.

The Vargo Triad XE & Esbit fuel tab system and cat food can system with denatured alcohol are essentially the same weight for any duration.
At about two weeks, the Jetboil Sol titanium stove system becomes lighter than the Vargo Triad XE & Esbit tab system and cat can system with alcohol.    
The cat food can with denatured alcohol boiled 1L of water in 12 minutes at 65° F ambient temperature, whereas the fuel tab system was never able to bring 1L of water to a rolling boil.

Most efficient stove system:
The JetBoil Sol Ti is the most efficient stove system (in this test), not only in liters of water boiled per 100g of fuel, but also in relation to the entire weight of the stove system, as well, although the Soto micro-regulator, cat can/alcohol, & Vargo/Esbit fuel tab combo were not far behind. The Sol Ti boils almost double the amount of water per 100g of fuel compared to the Soto, but only weighs 29% more. Even though the alcohol & Esbit tabs boil less water per weight of fuel compared to isobutane, the low weight of the 'stove' for both makes up much of the difference. The isobutane scores are brought down by the 3 oz weight of the canister needed to contain the pressurized fuel.

Lightest Stove System:
The cat food can with denatured alcohol system is the lightest, most capable stove system in the test, staying very light in all durations and boiled water better than the fuel tab system. Definitely the ultralight choice in all but extreme weather conditions (maybe).

Disclaimers:
1. I tried to select some of the newest, lightest, and best designed stove systems available, as well as the most popular or best-tested. I feel this line-up is a good representation.
2. The JetBoil Sol Ti uses a 0.8L pot, while the MSR Reactor uses a 1.7L pot. This means the Jetboil should weigh slightly more (low pot volume = lower weight) and have a lower final ratio, while the MSR should weigh slightly less for this comparison (high pot volume = higher weight) and score higher in the final ratio. What effect does this have? It would probably bring the score of the JetBoil closer to the Soto, while the MSR would be potentially slightly better than the cat food can/denatured alcohol combo.
3. There is a large difference between the performance of the stoves used in this comparison, although I do not feel that it throws off the results, but, most importantly, changes the selection of the most applicable stove for each planned trip. For example, the cat food can stove is the lightest option, but the MSR Reactor's performance is the same in 40 mph winds as it is in an enclosed room, because it uses enclosed radiant heat instead of an open flame, which can be extinguished by wind or suffer from convective heat loss. This makes the Reactor perfect for exposed alpine bivies or river campsites, but far too heavy for protected forest campsites, where a lighter stove would perform just fine. What about ambient temperature? Isobutane sputters below freezing (below 20F for stoves with micro-regulators like the Soto, JetBoil, & MSR) and denatured alcohol and Esbit tabs throw off such low heat, they struggle to boil water in cold temperatures, although they can be more successful than isobutane, especially at elevation. And then consider the usage of your stove. Are you just boiling to rehydrate meals or will you be cooking?
Not to say that efficiency is the most important factor, but sometimes simplicity is a stronger element of function than design, kind of like a single-speed bike.
There have been many times I've found myself very happy that I carried the extra couple ounces of an isobutane stove, as I did not have to mess with a denatured alcohol set-up.

I did not set out to determine which stove was best in every situation, but like my archaic Sleeping Pad Selection Guide, I wanted to determine the most appropriate stove system for different conditions and user preferences.

One other thing I figured out in this process, although not nearly as cool or in-depth...
In Alaska, you almost have to use white gas stoves in the winter, when temps plummet to 50 below. Anyone who says they've used isobutane in 'winter' in Alaska definitely hit a nice weather window in March, or they were playing just outside of Alaska, in the hills around Anchorage.
So, I decided to tackle the question of what size MSR fuel bottle should I bring on my winter trip?
The 30 oz is 'so heavy' at 7.3 oz, but the 20 oz only weighs 5.25. But I'm only going out for a couple nights... I could get away with the 11 oz bottle, at 2.8 oz in weight. Do the math.
Fuel per weight ratios favor the 30 & 11 oz sizes over the 20, with the 30 being most efficient. Bring the big daddy for a full weekend trip or a few of them for a week, but take the small guy for overnighters. At 40 below zero, you definitely want to err in favor of extra fuel!
Anyone want to buy two 20 oz MSR fuel bottles???

Oh yeah, if any of this doesn't make sense... I'm sorry, but it's 3:30 am and I have to work in a few hours :)

8 comments:

  1. Great review and loads to think about. Thanks for taking so much time to put it all together.

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  2. Regarding white gas stoves (for the other 3 seasons, that is), Ranger Beau Bracken & I figured out in the Fall of 2010 up in the Brooks that, when used 2x per day to boil 1 - 1.5 liters of water in a short/wide pot, the MSR Whisperlite with an 11 oz. fuel bottle would last approximately 4.5 days for two people. Cut that down to a solo trip, and you can probably get away with one 11 oz. bottle for about a week. We also theorized that the stove burns fuel more efficiently when using the 11 oz. bottle, but this was never tested.

    One factor you left out of your analysis of these stoves is their probability of failure in the field. That's another factor where the cat food can (and essentially all alcohol stoves) reigns supreme. I can't remember if the quote was from Skurka or not, but apparently a survey one year on the AT of alcohol stove users reported 0% failure.

    It would be a bit costly to test these other stoves systems out to the point of failure by abusing them, but an interesting endeavor nonetheless. After all, if they do fail in the field, and you can't fix them, no matter how lightweight they are, any value that weight had is now gone.

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  3. Cool, Steve. Good documentation. So, the two of you boiled a total of 2.5L per day, on average, for approximately 4.5 days? That's just over 1L of water boiled per ounce of fuel, which is about right when applied to field conditions and inherent outdoor inefficiency (wind, pot transfer, etc) compared to the 1.5L specs on the website.
    That's pretty dang efficient, but the weight of the stove, pump, and bottle is far more than the others. Plus, I'm sure efficiency would change with a different pot... probably for the worse if you were using a short, wide one.
    Interesting note about failure. Good call. Even within the meths stoves there are different 'failure' potentials... cat food can vs Pepsi can... one can be constructed at a general store, while the other requires extremely intricate cutting & work, not to mention the time to let the glue dry.
    Great thoughts. Thanks for sharing.

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  4. I should've crafted my numbers better. We boiled an average of 1 to 1.5 liters per day TOTAL. Also, we never used up the fuel bottle to the point of exhaustion, so I couldn't tell you exactly how long it would last, but we fired it up 8 times over the span of 4 days, and still had some fuel left when we added more to the bottle.

    Beau seemed to think the short/wide pot helped with efficiency, because of increased surface area. I agree, because when accounting for the wind screen and modified heat reflector use, this pot boiled water faster than mine, which is taller & narrower.

    I would definitely go with one of the canister or alcohol models for 3-season use unless I was mountaineering, and in that situation I might opt for the XGK over the Whisperlite. I forget the blog I read the review/test on, but the XGK is a snow-melting fiend. Unfortunately they're so loud you can't even carry on a conversation around one.

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  5. Ah, ok, that would mean way different numbers.
    Short, wide pots are definitely more efficient! I think the only time a tall pot is better is when using it in a fire, because then you have more side surface area exposed to the flame, instead of underneath. Just get as much area where the flame is, whether it be under or to the side.
    I think alcohol, hexamine, or, even better, wood is the way to go in summer. IMHO, the Whisperlite is the only piece of garbage MSR has ever made. All of the other stoves are better or fit a niche more correctly. The only reason the Whisperlite has been so successful is because of pricepoint... and there is the problem, it's cheap, i.e., poorly designed and falls apart or fails.
    Both my old school XGK and new model Dragonfly absolutely rip. Either is essential for -10F & colder, in my book. Between the two, I think the Dragonfly is a better stove. It seems to burn just as efficient, fast, and hot, but it also offers dual fuel control. However, it packs up a little bigger than the flexible line model XGK.
    I like their loudness, which I don't feel is conversation limiting. It always makes me think, 'Yeah... my stove is kickin' ass!'

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  6. I should also add how awesome the news Whisperlite Universal looks. Very appealing if you only want one stove. I'd still rather have the 2012 WindPro because I could probably get it to work reasonably well at -20F... on canister fuel :)

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  7. Hadn't heard about the Universal. Looks like MSR finally got around to making a stove that's better than the Coleman Fyrestorm Ti.

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  8. Also, the Whisperlite is definitely the one stove I have used more than any other, and speaking from MY experience, I have only had issue with old ones that have been neglected and/or abused (I rebuilt several of the ones in the backcountry cache in Bettles). As long as they're maintained, they won't fail....but therein lies the design flaw.

    Your canister stoves these days require little or no maintenance due to the fact that they have a clean burning fuel, which obviously reduces the collective weight of the stove system, because you need to carry that little red box in case your Whisperlite does go kaput.

    Personally, I like using the Whisperlite, or more accurately, I like watching OTHER PEOPLE use the Whisperlite. It's definitely not the most intuitive user-friendly stove out there...and witnessing a newbie trying to fire it up is highly amusing...until they turn it into a bomb. Then you have to step in and rectify the situation.

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