The reports have just come in of five skiers dying in an avalanche in Austria. This is just the latest news on this front from what looks like another bad season. The incident took place in the Wattental valley, Tirol, and reports indicate that those involved had ignored warnings. The Guardian paper reported that: The experienced […]
How efficient is your stove?
Four of the best mountaineering and backpacking stoves are put to the test: MSR DragonFly, MSR XGK, Optimus Nova and Primus Omnifuel
When you are humping your way up a hill, and every ounce in your pack feels like it is trying to hold you back, I often find my mind starts cataloging everything in my pack (almost of its own accord) trying to figure out where to shave a few grams here and there. High on the list is always my stove and cookware. Between my MSR DragonFly and Alpine Cookset I’m already carrying more than a kilogram (2.2 pounds), and that is before I’ve factored in the weight of the fuel to fire it up (and the food to cook on it). If you figure that you need to carry about 600ml (20oz) of white gas for every 2 hours of cooking then the fuel can add up pretty quickly for longer trips and those when you need to melt snow. So the efficiency of my stove is of more than just passing interest to me.
Which was why I was so interested to stumble across a research paper on stove efficiency by the University of Johannesburg in South Africa. The tests looked at a whole range of stoves including those that use wicks and old-fashioned pressure stoves that you aren’t likely to see unless you are in Africa, India or somewhere similarly poor. For comparison it also looked at four of the best mountaineering/backpacking stoves on the market.
The first table shows the results of the efficiency tests using two different types of kerosene (called paraffin in South Africa) over two separate tests. The first striking result is how much less efficient these burners are when they aren’t cranked up to full power (test 1). Their efficiency easily doubles when the tap is opened. The second points to strike me were that my trusty DragonFly is much, much more efficient than the expedition cooker that MSR makes. That is a far bigger difference than I would have expected. The manufacturers specifications, for instance, claim that the DragonFly and the XGK will boil an identical 5.7 liters of water using 100ml of kerosene.
Equally striking is that the two Swedish stoves, the Primus Ominfuel and the Optimus Nova stand head and shoulders above the competition. That doesn’t completely surprise me – both companies have a reputation for and long history of building really quality gear.
A chart showing the power output of the various stoves is also interesting for it shows both a wide range on the DragonFly (its ability to simmer is its strong point) and a greater tolerance for different grades of fuel. The XGK and Optimus both struggled to reach maximum power using synthetic fuel. The Primus, on the other hand, did well in digesting different fuels and also had a great range of power output.
The final issue worth noting in the study is the maximum temperature the stoves reached with all except the XGK reaching a flame temperature of more than 750 degrees C. Since I’m not a materials scientist I’m not entirely sure what that means but would guess (from the little I know about jet engines) is that in general hotter is more efficient, which would probably seem consistent with the efficiency readings in the first chart. (If you can make more sense of these numbers then please do let me know as I’d love to hear some views on this).
Before seeing these data I’d always been of the view that unless you are crossing the Antarctic on foot then the differences in efficiency between one stove and another would be so minor that they are not worth worrying about. Yet this test seems to show a marked difference with some stoves considerably better than others. Once you are burning a liter or more of fuel it seems pretty important whether you are cranking out 90% of the energy from that fuel compared with 40-50% so it is well worth keeping in mind when choosing a mountaineering or backpacking stove.