Fuel Price Survey Results (as of Dec 2011)

Wow, great list. Please don't take this as a nitpick, but more of a question–wouldn't the better way to calculate it be kCal/$ instead of grams of fuel/$? The Coleman fuel is cheaper in terms of g/$, but propane as I understand it is less calorie dense than butane, so in terms of kCal/$ the price differences between the fuels might be very different. That's of course a pile more work when you're already doing a really amazing public service, but just asking!

Ben,

Interesting idea, but out in the field in real world conditions, you won’t notice a lot of performance differences in terms of the heat output of the various canister gasses unless it’s so cold that one gas or another isn’t vaporizing, but that’s a separate issue.

Burner design, jet aperture size, pot height, type of pot, use of a heat exchanger, etc. are going to impact the perceived heat output far more than the particular gas that you use.

Beyond that, trying to figure out the percentages of the various gasses and then calculate k/cal per gram, and and and… Uh, maybe if I were being paid for this, but I’m not. :)

HJ
Adventures in Stoving

Yeah, that's an awful lot of confounding factors! If I recall correctly the difference in energy density is something like 12% between butane and propane, and that difference could evaporate real quick, especially when you're talking about blends.

Yes, exactly. And almost all canister fuels are blends. Even if you start with, say, an 80/20 butane/propane blend, it will be 100% butane by the end of the life of the canister. Trying to figure out actual heat yield is a fool’s errand just from the perspective of the gas itself. Then throw in all the other factors, and … well, it’s just not relevant.

HJ
Adventures in Stoving

>"Uh, maybe if I were being paid for this, but I'm not. :)"

Jim, Please keep doing what you're doing – it's a great public service! At least it is for me.

I was putting together a spreadsheet with heats of combustions, gas densities, steel/fuel, and fuel/air ratios thinking that people might find it useful. (I'm that sort of engineer while Jim – you're "playing with fire" as a avocation, right? – your vocation is in a different arena of geekdom, I thought.)

Anyway, short answer, since it came up:

Net BTU/lb for the most common BP fuels:

Canister Gas:
Propane 19,944
n-Butane 19,680
Isobutane 19,629
Proxies for Unleaded Gas:
n-Hexane 19,403
Toluene 17,620
White Gas Proxy:
Naphtalene 16,708
Carbide anyone?:
Acetylene 20,776
Alky stove users:
Methyl alcohol 9,078
Ethyl alcohol 11,929

Source: Perry's Chemical Engineer's Handbook, 6th Edition, Table 9-30, Combustion Constants.

I used Net (rather than Gross) values because no one is condensing water vapor into liquid water.

So while I totally agree with Jim that differences in stove design, pot size, wind screens, heat exchangers, etc, trump fuel content BY A LOT (except for hydrocarbons versus alcohols), I'd also point out that ALL canister gases are within about 1% of each other. I suspect a bigger factor is steel per unit of fuel (obviously bigger canisters are better) and how that varies by manufacturer and by fuel mix (more propane seems like it should have more steel for the same storage temperature rating). But, again, steel/fuel isn't as big as stove design and use variables.

"Uh, maybe if I were being paid for this, but I'm not."

HJ, don't think in terms of how much it would cost. Just think what it would be worth!

The next president could appoint you as the new Backpacker Fuel Czar.

–B.G.–

>"something like 12% between butane and propane"

Ben: I show a difference of 1.3% in propane's favor if looking at fuel only.

I get 18% advantage to a butane mix if I compare Coleman 8 oz (227 gram)Butane/Propane Mix to Coleman 16.4 oz (468 gram contents) Propane due to the higher steel weight in the pure propane canister.

A different canister size would have a different steel/fuel ratio.

>"difference could evaporate real quick"

Ah, don't pun-ish me so!

lol. Thanks, Bob, but that’s Mister Czar to you. ;) lol.

HJ
Adventures in Stoving

David, thanks for clearing that up–I clearly misremembered, rendering my point moot! Probably transposed a decimal point or something..

David Thomas wrote: > Jim, Please keep doing what you’re doing – it’s a great public service! At least it is for me.

Thank you, David, and I truly enjoy it.

We are buying a house though, so I’ll probably be raking leaves and watering the lawn instead of blogging as much starting some time (God willing) next month. We’ll see.

My particular area of geekdom is computers. Pyromania, er, I mean stoving, is just a hobby. :)

David Thomas wrote: > So while I totally agree with Jim that differences in stove design, pot size, wind screens, heat exchangers, etc, trump fuel content BY A LOT (except for hydrocarbons versus alcohols), I’d also point out that ALL canister gases are within about 1% of each other.

Thank you. That was my memory too, but I didn’t have the numbers at hand. There are caloric content differences between the various gasses used, but relatively speaking they are insignificant.

David Thomas wrote: > I suspect a bigger factor is steel per unit of fuel (obviously bigger canisters are better) and how that varies by manufacturer and by fuel mix (more propane seems like it should have more steel for the same storage temperature rating). But, again, steel/fuel isn’t as big as stove design and use variables.

Yep. The weight of the empty canister is a big deal.

I never buy the 113g sized MSR canisters even though they’re more stable than, say, a Snow Peak 100g canister. The steel to fuel ratio is quite high. Generally speaking, with backpacking canisters, the bigger the canister, the less steel you’re carrying. You’re way better off carrying one 220g canister than two 110g canisters in terms of the steel to fuel ratio.

100% propane canisters are generally a different story that propane blends. More on that in an upcoming blog post (of course). :)

HJ
Adventures in Stoving

>"100% propane canisters are generally a different story that propane blends. More on that in an upcoming blog post."

Jim, I believe they meet different DOT standards. They certainly could take a bigger hit than a BPing canister.

Do you have any of the old, officially refillable propane canisters? I knew a plumber who jealously guarded his 14 oz refillable WITHOUT the "$25,000 fine for transporting refilled containers across state lines" label.

So if I don't transport them across state lines? . . .

Have you done or seen any burst-strength testing on different canisters? At what temp will things truly get bad with mixes versus pure propane? I could imagine a hole in the ground, with an electric heater aimed at a cansiter, and a thermocouple on a VERY long wire.

But then I live on 13 snowy acres.

David, David, David. You can’t expect me to reveal all my secrets in one day. :) lol.

No, I haven’t got an old style refillable canister, and I haven’t done bursting tests (I live in an apartment; the landlord tends to frown on such testing).

But let’s just say I’ve got a backpacking practical way to use 100% propane. More to follow…

HJ
Adventures in Stoving

A dude with your hobbies lives in an apartment?!?

That's just not right!

13 acres helps on many fronts, but the 10-foot, 2-inch-caliber snowball cannon shot farther than the 600 feet to the property lines. For longer distances, there's 20 miles of salt water off our beach and no one living on the other side. I just try to not bonk any beluga whales swimming by.

A dude with your hobbies lives in an apartment?!?

Well, we’re in escrow on a house right now. The ironic thing is that I’ll probably have to cut back on the blogging since the house will take a lot of time. The house does have a small workshop off the carport though…

HJ
Adventures in Stoving

"13 acres helps on many fronts, but the 10-foot, 2-inch-caliber snowball cannon shot farther than the 600 feet to the property lines."

OK, where are the plans for the snowball cannon?

Snowball cannon. Now that’s cool. :)

HJ
Adventures in Stoving

Jim and Randy:

We are pretty indulgent with birthday parties at our house. The kids get to pick a theme (magic, coin collecting, dogs, priates, Harry Potter, rock climbing, etc) and we take it from there. It's been great in recent years that they've been able to participate in more of the baking, sawing, wiring, soldering, etc.

Anyway, the first snowball cannon was styled after a shipboard cannon for a pirate party:

There's a reservoir in the base and you throw open a 1-inch ball valve to fire it. It would take a 1-inch branch off a spruce tree. But, as these things always go, we needed to push the technology.

it has a longer barrel, a bigger reservoir and a bigger valve – 2-inch. It shoots maybe 1,000 feet. The next step would be to get a pilot-actuated valve to let compressed air open the valve instead of doing it manually. Then there's ignited VO5. And then propane plus pure oxygen. Then gunpowder, then . . . and pretty soon low-earth-orbit satelites are at risk.

"It's only fun until someone gets hurt." and

"You could put someone's eye with that."

A MUCH easier way to have an afternoon of fun: A bucket of soapy water and a garden hose from your natural gas supply. Then, obviously, you light the bouyant methane cloud as it floats away. It's not a birthday party if the mothers aren't a little nervous.

I'm actually prouder of another project you can see in the lower photo: that clothes dryer and the 2×6 with the hole in it.

My son was in a rock collecting phase and wanted to get a rock tumbler and, sure, we can afford it, but I don't like the idea of spending $79 in a catalog if it could be a father-son garage project.

So we snagged a free cast-off gas dryer from the dump, wedged two boards in the drum, drilled a peanut-butter-jar-sized hole in the boards, wise-gripped the timer knob to "on" and left the gas disconnected. Viola' – a rock tumbler. Interest waned in a few months and the dryer went back to the dump.

It’s not a birthday party if the mothers aren’t a little nervous.

lol. I’d better not repeat that around my wife. She will completely fail to see the humor in such a statement.

HJ
Adventures in Stoving

A MUCH easier way to have an afternoon of fun: A bucket of soapy water and a garden hose from your natural gas supply. Then, obviously, you light the bouyant methane cloud as it floats away.

Got video?

HJ
Adventures in Stoving

That is cool. I only have 3 acres but my neighbor won't mind if I shoot into his property. He's got 2 civil war cannons so this would be right up his alley.

Psssttt: You can still blog to your hearts contentment and be an adult. You just have to make time for it is all. That is what I do! I write in the morning for example, before my kids are up. And hey, the leaves will always wait for you. Or at least they will start mulching on their own ;-)

>"Got video?"

No, but here's a still:

Less crosswind and you can develop a taller methane cloud before it breaks free due to its bouyancy.

Hot water and cold air make for more bounancy.

It looks wicked at night. Time to get some snaps of that.

This is 100% natural gas. NOT pre-mixed. Fuel air explosives are a vastly under-utilized technology, but the kids and I would be wearing "eyes and ears" with pre-mixed gases. And standing a lot farther back.

No one has called the Fire Department. Yet. YMMV.

David,

You just got my vote for "world's coolest dad." lol.

HJ