We recently had the question Can you get burned by boiling water on everest? and not to long ago the question Why aren't there any electric stoves that can be used for cooking where you can't build a fire?

The first teaches us, the higher you go the lower the temperature at which water boils. The second teaches us, by weight battery operated stoves are highly inefficient.

Assuming you packed a small gas stove to the top Mount Everest 8,848 m (29,029 ft) would the gas burn? It is cold, the air pressure is low, the oxygen content is low, it is windy, there are several challenges.

Would a propane stove, wood fire, or other fuel source burn at elevations and conditions at the top of Everest? Is it even possible to light a fire to boil the water that won't get hot enough to cook an egg?

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    This would be a great question to pose on what-if.xkcd.com. The site (run by Randall Munroe) provides what I'll call "entertaining" and fact-based answers to scientific questions. In fact, a recent post specifically addresses the benefits of a liquid-fueled cell phone (what-if.xkcd.com/128) and leads to a kickstarter project which is developing a liquid fueled USB charger. – Jeff W Mar 19 '16 at 13:16
  • just as FYI you might like this link mounteverest.net/expguide/campgear.htm – Erik vanDoren Mar 19 '16 at 14:53
up vote 7 down vote accepted

The short answer to your question is yes you can get a stove to light and cook your egg on the top of Everest if you really wanted to do it.


Backpacking stoves are pressurized

All of the backpacking stoves I've used use some sort of pressurized fuel system. This means that the ambient air pressure isn't going to affect the flow of the fuel.

Fuel

Boiling an egg on the top of Everest is a logical endeavor to persue. Carrying enough wood to the top of Everest to light a camp fire so you can make s'mores while the egg is boiling is pushing the bounds of reason. :)

Kerosene is a pretty common heating oil, and it used to be a pretty common cooking fuel so let's use that instead. Keep in mind you probably want to buy your kerosene at home. Kerosene at the best of times is pretty dirty. Since kerosene has a boiling point between 150o and 300o C I'm going to assume it will remain liquid on Everest. Kerosene's pour point is between -40o and -47o C depending on grade so you'll need to make sure the fuel bottle is kept above that temperature which isn't unreasonable.

Propane or natural gas should work as well. It might even be helpful that they are gases.

The wind

This can be blocked/mitigated by huddling around the stove with your fellow climbers, and strategically placing your packs. Alternatively you can bring up a specially fabricated aluminum enclosure for your stove/fuel/pot system. If you're determined enough to boil your egg then the extra weight shouldn't be a problem

The oxygen

I don't have number handy but I'm pretty sure you can get an anemic flame going on the top of Everest. If that isn't enough to boil the water fast enough you can always co-opt your friend's oxygen tank to enrich the oxygen concentration. This will be easy to do if you bring the aluminum enclosure I mentioned above.

The egg

This baby is going to be delicious. As Jules Verne well knew 70o C is plenty to cook an ideal boiled egg.

In his book “Off on a comet”, science fiction author Jules Verne shows that he was actually aware of the possibility of “boiling” eggs at a temperature lower than 100 °C. He has correctly observed that water boils at lower temperature in high altitudes, and that on a fictional comet of appropriate mass, water will boil at 66 °C. The temperature is wisely chosen, because by keeping eggs at 66° C, you really can’t do anything wrong.

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    Have you used canister stoves (butane/isobutane/propane mixes)? Those depend on outside air pressure, but the lower pressure on everest is actually a good thing as it counteracts the lower temperatures that would otherwise keep the fuel liquid. – requiem Mar 19 '16 at 17:29
  • @requiem I've used propane lanterns/barbecues and JetBoil stoves which use some blended canister fuel but I've never used them above 13k ft. Those are pressurized systems though so I don't understand why that would prevent them from working at extreme altitude. The worst that would happen is the regulator wouldn't be able to prevent a big flame I believe. I think keeping the bottle warm is the real worry. That's one reason I mentioned a liquid fuel like kerosene as a primary choice. – Erik Mar 19 '16 at 17:41
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    Well significantly lower pressure also means less oxygen available overall. The lower pressure itself won't help much in getting more gas out. – nsandersen Mar 19 '16 at 20:00
  • Sure, sorry - comment was actually meant for @requiem. – nsandersen Mar 30 '16 at 15:10
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    @nsandersen Had to re-read this a few times. Using isobutane as an example, it stays liquid below -12°C (11°F) at sea level. E.g. you can open the valve when it's -18°C (0°F) outside and nothing will come out because it's below its boiling point. Take it to 29,000' and the boiling point will now be down around -35°. So, it will easily boil during summit season and thus spew sufficient fuel. The limiting factor, as you say, is the amount of oxygen that can be supplied, so that might result in a yellower flame (richer fuel mix). – requiem Mar 30 '16 at 15:49

For butane/isobutane/propane canisters, the stove design, affecting the temperature in the canister or liquid feed pipe, and the boiling point of the gas mixture would matter. At very low temperatures even the O ring rubber type would matter as some types go less rubbery and do not seal properly.

For instance, if the temperature of an upright butane canister drops below -0.5C/43F at sea level and one bar pressure, then the butane no longer boils/evaporates in the canister and the gas flow stops. There needs to be enough heat from a warmer place (air outside, ground or stove flame radiation) to supply energy to drive enough evaporation for cooking.

Isopropane has a lower boiling point and propane a lower one yet; the temperature where a particular canister becomes impractical under normal use depends on the gas mixture.

(Lower outside pressure will help a bit as the boiling point would be lower, but typically at such altitude the temperature is also lower!)

A more robust winter gas canister stove solution would be one where

a) The canister is turned upside down so the existing gas in the canister drives liquid fuel out of it, ie. you need very little heat directed to the canister.

b) There is a heated supply pipe or heat shunt from the flame to where the fuel enters the burner, which ensures enough energy is supplied to evaporate the fuel before it reaches the burner head once the stove is started.

The latter is an important safety consideration as liquid butane etc. reaching the burner would mean a lot of gas suddenly supplied to the burner as the flame evaporates it, ie. a flare-up. So upside down canisters are best used with stoves designed for that!

Those features (which are unusual) should allow you to use a gas canister stove with a good mixture at -25C or a bit lower at sea level according to Backpacking Light (note only first page is subscription free).

So it may be colder on the top of Everest, depending on the time, but would you be there in that case? :)

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    Boiling point of isobutane at 1 atm is almost -12°C; at 0.33 atm (Everest summit) it's almost -37°C. So, a winter canister mix should still work, as the temps in the climbing windows should only be around -25°C (BTW, have a look at the more recent heat exchanger thread on BPL; it's pretty cool!) – requiem Mar 20 '16 at 4:08
  • OK, as long as unbranched butane or n-butane is avoided (looks like the boiling point for n-butane is around -28°C at one third sea level pressure - encyclopedia.airliquide.com/…), so an isobutane or isobutane/propane mix ought to work. Thanks! – nsandersen Apr 1 '16 at 9:13

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