Backcountry Science Fair: White Gas vs Isobutane

I recently read someone’s “Best of 2016” list of backpacking stoves. In the comments on the Facebook page, some people were asking about canister vs liquid fuel (white gas) stoves. Since the site that came up with the list is mostly tilted toward ultralight backpacking, most of this discussion centered around weight. The conventional wisdom is that canister stoves are better suited for shorter trips, but liquid fuel is better for longer trips because the weight of multiple canisters adds up to become heavier than using fuel bottles which can carry more fuel per ounce of container. MSR, the most common backcountry stoves in America, says as much in a 2013 Summit Register blog post. Specifically they claim, “The weight you save [using liquid fuel] versus canister fuel will offset the lighter weight of the canister stove as well.” I began to wonder: When does that crossover happen? How long a trip? After how much burn time? I had never seen any actual data on this.

One of the most hated aspects of parenting has got to be the science fair project. It can be the source of high levels of conflict, frustration, and resentment. One day in March, I received the dreaded notice: “The science fair is coming up. You should be talking to your child about his/her project and submitting a proposal to his/her science teacher.”

You can probably see where I am going with this. I own 2 backpacking stoves: an MSR Pocket Rocket canister stove and a venerable MSR Whisperlite International. I worked with my son to collect some data on the 2 stoves. The following is what we found, which was not necessarily what I expected. If you want to skip to the conclusions scroll down to the Data and Conclusions sections.

Caveats

  • I geared this test, including cooking times, more to the “average” backpacker as opposed to dedicated ultralight or minimalist style. Your mileage may vary significantly based on your cooking habits.
  • This test was limited strictly to weight. Other factors will be discussed in the “Additional Considerations” section.
  • This was not a laboratory precision test, it was more like a side-by-side real world test.
  • This test is specific to these stoves. There are many other models, some with supposedly greater efficiency. My Whisperlite is definitely not the newest model. New ones may be more efficient. I also did some basic maintenance on it, but it was not in pristine condition.
  • I used a digital shipping scale with a stated accuracy of +/- .1 oz
  • I used standard Crown white gas, for the liquid, and MSR brand isobutane for the canister.
  • Air temperature was about 60 degrees with a light breeze.
  • The test was based on a solo backpacker scenario: one person has to carry the stove and fuel (the weight can’t be divided between party members), and the amount of water required for a meal is smaller.
  • After the first burn we discovered that the standard spring kitchen scale (pictured below) was not accurate enough, so we re-did the test using a digital scale

2016-04-12 10.49.54

Method

I wasn’t sure at the start exactly what data would best represent the findings, so I decided we would collect a lot. To make it more like the real world we decided to do the test outdoors in our back yard. I did provide a wind break around the stoves since that is common backpacking practice. I also decided to use very cold water to emulate a snowmelt stream, so I iced water to a temp of 36 degrees F (2.2C). We performed the following test twice to make sure our data was consistent.

  1. Filled and weighed the liquid fuel bottle, stove, and pump for the Whisperlite, and the stove, a full and an empty MSR Isobutane canister for the Pocket Rocket.
  2. We burned each stove for 15 minutes at full power. We burned the stoves simultaneously so conditions were identical.
  3. We measured 2 cups of water, placed in an aluminum backpacking pot (MSR) and timed how long it took to bring to a rolling boil.
  4. We reweighed the fuel bottle and canister to determine fuel usage. The second time we used a canister that was approximately 1/3 full to account for some loss of pressure.
  5. We calculated fuel usage for ounces/per minute, minutes/ounce, and ounces per meal (definitions below).

Definitions

We came up with some terminology to make the data easier to present.

  • Carry Weight – The weight of everything required to use the stove, including stove, bottle, pump, canister, and fuel. In the case of the canister stove the weight increases in larger steps since you can’t fill the bottles with the amount of fuel you need for a specific amount of time. I did not use the wind screen on the Whisperlite as this test was based on minimum weight.
  • Meal – My son likes Top Ramen, so we decided to use that as a standard meal. We decided a reasonable meal would include bringing to a boil 2 C water, keeping it boiling for 3 minutes, then boiling another 2C for drinks, cleanup, etc. Obviously this will vary depending on what you cook and your camping habits, but it seemed like a reasonable baseline for comparison for average backpackers cooking their own food as opposed to ultralighters who rely more on rehydrating.

Data

In the “Fuel Only” table below, I compare the weight of only the fuel and container (bottle vs canister). You can also view it in a spreadsheet by clicking the image

Fuel Only

Some particular items pop out in the burn time (table on the left):

  • Isobutane is much more efficient, requiring only .85 ounces per meal, while the white gas required 1.1 ounces. That is an efficiency gain of about 23%.
  • White gas is faster boiling, but as noted above, requires more fuel to do so.
  • Initially, white gas has a clear advantage. For 40 minutes of burn time the white gas and bottle weigh 8.4 oz while the canister weighs 13.2. However, due to the increased efficiency, the longer you burn, the more weight efficient the isobutane becomes. At times it is actually more weight efficient than the white gas.

Overall, however, looking at the table on the right which compares fuel weight per meal, white gas stays consistently ahead, though never by more than just under 6 ounces.

Which brings me to the “Carry Weight” table.

Fuel Carry Weight

Once you add in the weight of the stove, the whole table flips. Some items of note:

  • The Pocket Rocket has an 8.5 ounce advantage over the Whisperlite
  • In “Carry Weight”, the Pocket Rocket starts out with a 3.6 ounce advantage over the Whisperlite.
  • The weight advantage per meal (table on right) for the Pocket Rocket mostly hovers around the 5 ounce mark. That is a difference the white gas is never able to make up, directly contradicting the claim made by MSR.
  • UPDATE: Based on some feedback I added a table based on fuel use per day assuming that breakfast would be more likely a rehydration meal (e.g., instant oatmeal) that does not require cooking. There are 2 places that the liquid fuel wins when you have to add a canister at the same time you are maximizing the fuel storage in the bottles (maximum weight efficiency).

Conclusion

In my test, with weight as the sole consideration, there is no scenario in moderate conditions under which the Whisperlite makes sense. (See below for comment on cold conditions). That was frankly astounding as it contradicts everything I have read and assumed. The fact that you could carry 2 Pocket Rockets and still not be any worse off is even more amazing.

However, the difference is never more than a little under half a pound, and mostly around 1/3 of a pound, so if you aren’t counting every ounce, it may not matter to you. Which brings me to…

Other Considerations

While weight is certainly a prime factor in choosing a stove you will be carrying on your back, there are many other factors to consider. MSR discusses them in their blog, but I will cover them with my own spin here.

Speed and convenience

How long do you want to wait for dinner? Winner: canister stove, hands down!

  • The Whisperlite needs to be assembled by screwing in the pump, connecting the feeder hose, and pumping it up. Then it needs to be primed by burning liquid fuel to heat the gas generator. This requires a liquid fuel flame which takes practice to do safely, additional time to perform, and should NEVER be done inside a tent. Disassembly has to be done carefully to avoid getting fuel on everything else. There is also the risk of a leak or spill in your pack.
  • Canister stoves are as easy as it gets. A canister stove just screws on and is ready to light. You can be heating up your water in less than a minute after unpacking it.
  • You cannot ship or fly with pressurized fuel canisters. In theory you can’t fly with fuel bottles either, but there is anecdotal evidence you can get away with it as long as they are clean.
  • Maintenance – there is not much to maintain on the Pocket Rocket. The Whisperlite requires maintenance. However, it is largely field repairable, while the Pocket Rocket is not.

Volume

How big a pack do you want to carry? Winner: mixed.

For the fuel, white gas wins, unless you are on a very short trip (2 days). But the Pocket Rocket stove is tiny compared to the Whisperlite.

  • An 11 oz fuel bottle can hold fuel for about 9 meals in about 30 cubic inches (2.5in x 6in). An 8 oz isobutane canister with fuel for about 8 meals takes up 46 cubic inches, or about 50% more space in your pack. A 22 oz fuel bottle carries fuel for about 19 meals in 56 cubic inches. 19 meals would require two 8 oz and one 4 oz canister, which would take up 125 cubic inches. That is almost 2.5 times more space than the liquid fuel!
  • The Pocket Rocket can offset some of the fuel volume because it is small enough to store in the pot with enough room to pack some food in with it.

Cost

How much would you pay? Winner: it depends, but I say the canister.

  • At the time of this writing, the cost of a Whisperlite International and 11 oz fuel bottle on a major outdoor retailer’s website is about $118. A Pocket Rocket is $40.
  • A quart (32 oz) of Crown white gas is $7. That translates to .$21/ounce. An 8 oz MSR Isobutane canister is $6, or $.75/ounce, more than 3 times the price per ounce.
  • You can buy 13 canisters, or 100 meals, with the price difference.
  • It would take something like 150 canisters for the $82 lower price of the stove to be offset by the higher price of the fuel.

Environmental

Worried about your carbon footprint? Winner: white gas

  • Liquid fuel bottles are reusable. Fuel canisters are only sometimes recycleable
  • Manufacturing liquid fuel is a lower footprint process

Other variables

  • Conditions – Results would likely be very different in cold conditions (below freezing) when you have to melt snow for water. Canisters do not perform well in cold conditions. Systems that can run an inverted canister perform well, but the stoves are more similar in weight and volume to a liquid fuel stove. Winner: white gas
  • Fuel availability – Canisters are not available everywhere. Winner: white gas/multi-fuel
  • Party size – Splitting the weight between partners can render the weight differences negligible.
  • Leftovers – When you have a partial canister left, if you don’t have enough fuel for your next trip you bring a new canister (which may also end up partly full) or you end up carrying the weight and bulk of an additional canister.

Further Investigation

I would like to do some additional testing with newer stoves. Some of the system stoves are supposed to be very fuel efficient. Other factors like water temperature, air temperature, wind exposure, etc. could strongly influence the data.

My Preferences

  • I think for solo trips in moderate conditions requiring only 12 ounces of IB fuel or less (one 8 oz +1 4 oz canister) I will stick with the Pocket Rocket.
  • For the same duration with 2 or 3 people I would consider 2 Pocket Rockets, with the additional convenience of having a second stove either for backup or for 2-pot meals or simultaneous cooking.
  • For longer trips I would probably still opt for liquid fuel unless I thought I would need to cook in the tent or vestibule.

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About langleybackcountry

I am a member of Cascade Backcountry Ski Patrol (CBSP), a volunteer National Ski Patrol organization loosely based in Seattle. Our group operates as volunteers with USFS Ranger Districts outside of developed ski areas in the Cascade Mountains near Snoqualmie, Blewett, Stevens, and Washington passes.
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4 Responses to Backcountry Science Fair: White Gas vs Isobutane

  1. Chris says:

    He Mark,
    you should try this in below freezing weather, I think you will see a marked difference in your results. With that said, I rarley use my WG stoves anymore.

    • Thanks Chris. I updated some of the text to clarify that I was considering moderate conditions.
      I think my next test should actually be comparing system stoves (Jet Boil, Reactor, WindBurner) with an open burner like the Pocket Rocket. A Pocket Rocket with a titanium pot is still lighter – sometimes by a few ounces – than a system. That is where the difference in efficiency might add up so the heavier system becomes more weight efficient at some point.

  2. Daniel barwick says:

    What a great article! Thanks.
    The only thing missing is the grade. 🙂

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