Trips & expeditions
Which stove and fuel work best at high altitude?
For most climbs, a canister stove running on an isobutane and propane blend works well up to the high camps, as long as the canister is kept warm. For deep cold, long expeditions and melting large amounts of snow, a liquid-fuel stove running on white gas is the most reliable choice, which is why almost every party on Denali uses one. Alcohol and solid-fuel stoves are fine in the valleys and weak in the cold.
Canister stoves: what works and what does not
A gas canister only works while the liquid inside it can boil into vapour. Butane stops at about −0.5°C31°F at sea level, isobutane at about −12°C10°F and propane at about −42°C−44°F, so mountain canisters are isobutane and propane blends. Altitude helps: lower air pressure lets the gas boil more easily, roughly one degree Celsius for every 300 m (about 1,000 ft)about 1,000 ft. Cold hurts, and so does a half-empty canister, because the propane burns off first.
Keep the canister in your jacket or sleeping bag before use, and stand it on foam, not snow.
A stove with a pressure regulator keeps its flame as the canister cools.
A remote-canister stove that runs with the canister upside down draws liquid fuel and copes with far more cold.
Never heat a canister with a flame or surround it with a windscreen.
Liquid-fuel stoves: the cold-weather standard
A white-gas stove such as the MSR XGK EX or WhisperLite runs on fuel you pressurize with a hand pump, so the cold cannot take its pressure away. It has to be primed before lighting and cleaned now and then, so practise at home. Keep gloves on when handling fuel in the cold: white gas at −25°C−13°F can freeze bare skin in seconds. Kerosene works too, but burns dirtier.
How much extra fuel does altitude take?
Mostly the extra fuel goes into melting snow, not into the altitude itself. Turning snow at −15°C5°F into water at 80°C176°F takes about 700 kJ a litre, against about 290 kJ to heat stream water at 10°C50°F. In practice a litre of hot water from snow costs about 30 to 50 g of gas, so a standard 230 g canister gives five to eight litres. On Denali the National Park Service suggests 0.15 to 0.30 litres of white gas per person per day (Denali: practical issues). On Aconcagua our guide allows about 125 ml, doubled if you boil all your water (Aconcagua: practical issues).
Tips for melting snow
Start with a little water in the pot, or the snow scorches and tastes burnt.
Use dense old snow or ice, not powder, and keep a lid on.
Collect it from a clean spot upwind of camp, away from the toilet area.
Add electrolytes or salt: snow water carries almost no minerals.
Is cooking in the tent safe?
Only with the door open. Stoves burn less cleanly in thin air and make more carbon monoxide, and carbon monoxide is more dangerous at altitude. Climbers have died of it in sealed tents on Denali. Cook in the porch with a vent open, or outside, and never fall asleep with a stove burning.
Can I fly with my fuel?
No. Airlines do not carry gas canisters or stove fuel. Buy it where the climb starts: from the air-taxi company for Denali, in Mendoza for Aconcagua, in Azau or Terskol for Elbrus, and in Kathmandu or through your operator for Everest. Clean the stove and empty fuel bottles before you fly.