Cooking with a Pepsi Can Stove
May 20 '04
The Bottom Line Not for the winter, not for groups, but a boon for lightweight 3 season backpackers.
Take a hike on one of the longer trails in the US this summer, a trail that draws long distance backpackers, and you might be surprised to see a new trend in backcountry cooking. Rather than watching a hungry hiker cook his/her dinner over a traditional high tech backpacking stove (no, “high tech” and “traditional” are not necessarily contradictory here) you may instead watch said hiker sit down and fire up . . . a soda can. No, the hiker is not some hobo making do with what he/she can scavenge from the town dump, the hiker is an adherent of a relatively new trend in backcountry cooking: the alcohol fueled pepsi can stove.
For decades, pressurized alcohol stoves were the default cooking choice on houseboats and larger cruising sailboats. Alcohol (specifically ethanol or an ethyl/methyl alcohol mix such as denatured alcohol) is widely available and easily stored and transported, but its main advantage in marine applications has always been its low volatility and the ease with which its fumes disperse (alcohol fumes are lighter than air and will not concentrate in the bilges.) A leak in a stove fuel line aboard a boat with an alcohol stove will not necessarily result in a catastrophic fiery explosion. Propane, a heavier than air gas with explosive characteristics, has only relatively recently begun receiving acceptance as a fuel for marine uses because of significant improvements in fitting and gas line reliability, more widespread use of gas detectors and bilge blowers, and dedicated and properly vented propane tank storage outside the cabin.
But just as alcohol as a fuel choice is losing popularity with sailors it is quietly and steadily gaining adherents among backpackers. Simple and lightweight alcohol stoves built by hobbyists and a small cottage industry are fast becoming an acceptable alternative to the tried and true white gas and canister stoves that had long been carried. Such stoves are not for every camper or for every situation, but knowing a bit about how they work will help a backpacker make a better stove choice.
Weight
A common misconception among the ultralight crowd is that alcohol is by nature a lighter and more efficient fuel than white gas or the isobutane/propane (isopro) mixes used in canister stoves. Not true. Pound for pound (or gram for gram) of fuel, alcohol is only a little more than half as efficient as the traditional fuels. This is borne out by a look at the fuels’ relative heat content. Denatured alcohol contains ~ 11,500 BTUs/lb (~48 Kcal/gm.) Compare this to the more than 20,000 BTUs/lb (~84 Kcal/gm) contained by both white gas and isopro. In more practical terms, an efficient canister stove such as the MSR Superfly will consume approximately .25 oz (7.1g) of fuel for each pint of water brought to a boil, a comparable white gas stove (the MSR Whisperlite) approximately .23 oz, while the most efficient alcohol stoves consume in the neighborhood of .5 oz (14.2g) per pint boiled under similar conditions. Alcohol stoves are a lightweight alternative not because of the light weight of the fuel, but because of the light weight of their infrastructure.
A Superfly (MSR variety, not Jimmy Snooka) weighs in at approx. 3.0 oz. (85g) – light, to be sure. But the canisters holding the fuel are less forgiving. A canister holding 8 oz. of Isopro fuel will still weigh 4.5 – 5 oz. (depending on brand) when fully empty. Likewise, a Whisperlite weighs in at 12.4 oz. but a 22 fl. oz. fuel bottle will still weigh 4.5 oz. empty, not including the weight of the necessary hose and pump. By comparison, most current alcohol stove designs weigh 2 oz. or less and alcohol can be safely carried in lightweight soda bottles weighing less than an ounce or, for shorter trips, in smaller squeeze bottles weighing enough less than an ounce that the scale at my post office wont register them. In terms of weight carried per day, Alcohol stoves and fuel can be significantly lighter than canister stoves for trips up to 6-8 days. The longer the trip (or longer time between resupply points) the more important fuel weight becomes relative to stove weight and after a week or so (less if you cook a lot, more if you cook very little) canister stoves are to be once again considered a lighter option.
Note: Very little of this applies to any of the alcohol stoves currently in the epinions database. The various optimus stoves listed are pressurized multi-fuel models more like the older marine stoves mentioned earlier. The Trangia is a Swedish military design essentially unchanged since its introduction in 1951. It’s a great stove but at 7 ½ oz. it’s no lightweight.
Stoves
Modern backpacking alcohol stoves fall into three broad design categories. The simplest is the Open Flame type stove. These stoves are simply lightweight metal containers with some kind of wicking agent (such as perlite or tufts of fiberglass insulation) to control fuel delivery in cold weather. Popular and efficient open flame stoves have been made from cat food cans and Altoids tins. Cans of Sterno are, at heart, simply heavy and inefficient open flame alcohol stoves.
Open Vent stoves are often referred to as double wall stoves. With this type of stove fuel is poured into a central reservoir and lit like a wickless open flame stove. As the alcohol heats and vaporizes it will rise between walls of the stove and emerge through small jets like the burner on a gas stove. The Trangia is an open jet type stove as is Scott Henderson’s “Pepsi Can Stove” and its various derivatives. Some recent Brasslite models are also open jet in design.
Pressurized Jet stoves hold fuel in a sealed reservoir. The reservoir requires preheating by a few drops of alcohol in a priming dish beneath the stove or in a depression on top of the stove and fuel vapor is then forced out jets at the top. Most of Aaron Rosenbloom’s beautiful Brasslite stoves are pressurized jet in design as are Don Johnston’s Photon Stove and the derivative Cobra Stove design.
A good repository of alcohol stove designs can be found at http://wings.interfree.it, the Wings Stove Archives.
Fuels
Do not put white gas/coleman fuel or other high enthalpy petroleum distillates in your alcohol stove. What doesn’t explode will likely melt and at the least you will make your local fire department very, very angry. Skin grafts are painful and expensive and while you may deserve the pain, the high expense just raises insurance premiums for the rest of us and that’s not right.
The most common fuel for alcohol stoves is denatured alcohol. Denatured alcohol consists primarily of ethyl alcohol (ethanol), the stuff that you find at frat parties. “Pure” ethanol (grain alcohol) is sold in liquor stores as “Everclear” and will burn satisfactorily in an alcohol stove but is an expensive option. Technically, Everclear is not poisonous. Removing the final portion of water (“denaturing” the alcohol) requires the addition of methyl alcohol and benzene – both of which are seriously toxic. Do not drink denatured alcohol. Denatured alcohol can be found in most hardware/paint stores and also in many Marine Centers where it is sold (at significantly higher prices) as “marine stove fuel.” Outside the US look for “Methylated Alcohol”, “Methylated Spirits”, or, colloquially, just “Methys” or “Meths.”
Pure methanol will also work satisfactorily in an alcohol stove. Methyl alcohol is also sold in hardware/paint stores as “wood alcohol” and is the primary (or sole) ingredient in some automotive gas line de-icers. HEET brand gas deicers come in two versions: yellow and red. Red (ISO-HEET) is made with isopropanol, yellow with methanol. Make sure to get the yellow HEET. Methyl alcohol can do some really nasty stuff to your body (being converted by the liver to formaldehyde is the nice part) and can be absorbed through the skin. A few drops on your finger tips on the weekend while filling your stove probably won’t do great damage but if you use methanol for fuel take precautions to avoid prolonged exposure and for goodness sake don’t drink any of it. Methanol has a slightly lower heat content than ethanol. I find that I need an additional 2-3ml and another 30 seconds or so to bring a pint of water to boil with yellow heet than with denatured. On the other hand, methanol has a higher vapor pressure than ethanol. In practice, this means that your stove will be quicker to start burning through the jets than with ethanol, but will burn at a slightly lower temperature. When using methanol in a pressurized jet stove you should put less fuel in the priming dish and more in the main reservoir.
Methanol is lately coming under more scrutiny as it is an important component in the manufacture of “crank” – crystalline methamphetamine. Don’t be surprised if you get a few weird looks when you buy your “stove fuel” in the summer. I recently picked up a 4 pack of yellow heet at my local auto supply store for some stove experiments and got the knowing wink, wink from the swamp rat behind the counter. Why else would I be buying gas line deicer when it’s 85 degrees under a Carolina Blue sky? I’m not sure if I would prefer that he noted down my license plate to pass on to the sheriff instead.
Try to avoid using Isopropanol. This is the main ingredient in Red Heet and in rubbing alcohol. Most rubbing alcohol comes in at only 70% Isopropyl alcohol (30% water) and will not burn in a stove. You will need at least 91% pure rubbing alcohol to burn at all in your stove. Isopropanol actually has a higher heat content than either methanol or ethanol (approx 14,000 BTUs/lb) but does not burn efficiently in alcohol stoves. If you do use it be prepared for a flickering yellow flame (an indicator of incomplete combustion) and serious amounts of soot on and sometimes in your pot. Yech.
Tips to make cooking easier
Use a thin walled, broad based cooking pot about one inch above the stove burners. The alcohol flames will spread out over the pot bottom. Heavy bottomed pots and pans are handy at home because the act as heat sinks, evening out the heat from the stove. You don’t need this in the woods. Use your fuel to heat up your water, not your pot. Choose a pot with at least a 4 inch base diameter. Less than this and alcohol flames will creep up the sides of the pot, wasting heat. Solo hikers who eschew pots and cook directly in a Sierra cup or the popular Snow Peak 600ml titanium cup may be disappointed with performance. I’ve seen success with MSR’s 0.9L titanium pots as well as with the aluminum Wal-Mart Grease Pot – a favorite among hiker trash.
Use a cover on your pot and a windscreen for your stove. Efficiency is much more important when using small stoves. Once an alcohol stove gets burning properly it’s difficult for a wind to blow it out, but it’s easy to blow the flame away from the pot. Using a windscreen keeps more hot gases in contact with the pot for a longer time. Most windscreens used with white gas stoves can be used with no modifications with an alcohol stove. I use a windscreen fashioned from a length of aluminum roof flashing that also serves as part of my pot stand.
One of the great advantages of using alcohol as a fuel is the ability to recycle lightweight plastic drink bottles or such as fuel containers. This can also be a danger. LABEL YOUR fuel bottles. Label them prominently and permanently. If you pour ½ ounce of your drinking water into stove you have a wet stove. If you pour denatured alcohol into your water bottle you have a permanently contaminated water bottle. If you pour some of these fuels into yourself . . . well, don’t.
Spend some time at home experimenting with how much fuel your stove needs to boil how much water. Alcohol stoves are batch loaded – you put in as much fuel as you think you’ll need and let it burn until it’s all gone. It’s difficult, bordering on impossible, to get unused fuel out of some stoves and back into the fuel bottle. When using soda bottles it’s helpful to remember that one capful equals about 6 ml. 5 capfuls is about an ounce. I like to use a small 4 ounce dispensing bottle with a dropper tip of the type familiar to contact lens users. Mine are marked in half ounce increments on the side of the bottle and cost less than a $1. They are, of course, prominently and permanently labeled. When I’m trying to be extra precise and keep all toxic substances off my hands, such as when I’m testing a new stove or six, I use a blunt needled plastic syringe to measure and add fuel. I use either a 10 ml size syringe of the type included in ink jet cartridge refill kits or a 30 ml syringe of the type sold in supermarkets as “marinade injectors” around Thanksgiving. With these I can precisely fill my #3 Photon stove with 16.5 ml of denatured alcohol and .5 ml in the priming dish (which I know from experience will boil 1 pint of water in weather between 50 and 60 degrees.) Yeah, it’s excessive. No, I don’t take it on the trail with me.
The first few times you use an alcohol stove try to do it around dusk. Alcohol flames are invisible in the daylight and extremely quiet compared to the blow-torch stoves traditionally used by backpackers. Just because you can’t see the flame doesn’t mean it won’t burn you. Learn to listen for the little “whump” when the fuel first catches. Listen for the bigger “whomp” when the open jets of a pepsi can stove start burning alcohol vapor. Listen for the rocket sounds when a pressurized jet stove starts burning while there’s still fuel in the priming dish. Listen for the subtle groaning an aluminum pot makes as water comes to a near boil (about 180 degrees). Listen for the “Look at that honey, that poorly dressed man’s trying to burn a beer can” as the impeccably outfitted by EMS hikers coming up the trail behind you try to process the image of scruffy hiker enjoying a hot meal with nary a brand name in sight.
Even more important than not burning yourself is not burning down the surrounding forest. Open flame and open vent stoves can spill flaming alcohol if tipped over when in use and the priming dish of many pressure jet stoves is right down on the ground where the flammable stuff is. Take extra special care where you set up your stove. Big, flat rocks are best. At the least clear an area around your stove of flammable material and be aware that some forest “dirt” is so high in undecomposed organic matter as to be itself flammable. Alcohol fueled stoves are less likely than others to erupt in a ball of uncontrolled flame but that is no reason to treat them cavalierly.
Many alcohol stove designs, and a few of the commercially available models such as Brasslite or Antigravity Gear, incorporate an integrated pot stand. These make me nervous. Many of these stoves are only ~2 inch diameter at the base. Visualize a full pot of spaghetti resting atop an empty soda can. Now visualize this pot of spaghetti atop the soda can resting on uneven ground. Now visualize yourself stirring this pot of spaghetti. This is a LOT like cooking on a stove with an integrated pot stand. Such stoves have the stability profile of an SUV being driven by a teenager with a cell phone. 99 times out of 100 it’s not a problem, but when it becomes a problem it’s messy. Seriously consider using a separate, broader based pot stand. I use three Ti tent stakes pokes poked through my windscreen. Other options are available.
“Cooking” is perhaps the wrong term to use. Much backpacking “cooking” usually consists of adding the boiling water to the noodles and sauce and simmering for 10 minutes. If you’re looking for sizzling steaks for dinner and fresh omelets for breakfast, you’re looking for a different stove. You’re probably also looking for a reliable pack animal or cheap sherpa. Backpacking alcohol stoves boil water, they don’t bake cakes (although the “bake packer” brasslite sells is certainly intriguing). I would further suggest that you not put too much effort in trying to simmer with an alcohol stove. There have been many suggestions and innovations for adjustable, simmering alcohol stoves. I’ve yet to see a reliable and fuel-efficient solution. Backpackers experienced with the Whisperlite will empathize. Learn to use a pot cozy. When I cook a meal calling for me to, for example, bring to a boil, stir in sauce and simmer for 10 minutes, I’ll instead take the pot off the stove and put it directly in my pot cozy for ~12 minutes. Works fine and saves a lot of fuel.
Recognize, also, the further limitations of an alcohol stove. My pepsi can stove, reliable and efficient as it may be, is absolutely unsuitable for cooking for more than 2 people. Alcohol stoves, like canister stoves, can be balky in cold weather. If I’m relying on my stove to melt snow for drinking and cooking water, the weight of fuel used will quickly eat up any weight gains made by using a lighter stove. Pepsi can type stoves are 3 season alternatives. If you’re out in the mountains in February, carry a white gas stove. I haven’t thrown away my Whisperlite, I just give it long rest every year.
If you haven’t tried hiking with an alcohol fuel stove yet, I certainly recommend it. When I took the my first home made stove into the woods I was amazed by how easy it was to use and light to carry. By the third day out I was skipping along the trail singing “I Got a Pepsi Can Stove” (to the tune of “Basketball Jones”) without feeling the least bit self-conscious – well, maybe just a little bit self-conscious, but then I rationalized that singing the song wasn’t totally narcissistic, I had discovered a new use for the stove: I was scaring away bears.
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Member: Alan Smithee
Location: Wilmington, NC
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