Which Is Lighter – Alcohol Or Gas?

The "prevailing wisdom" seems to live that canister gas is lighter than alcohol on longer backpacking trips.  On the surface, this would seem to build sense.  From a chemical scientific discipline standpoint y'all receive got to comport roughly twice every bit much alcohol (assume 50/50 methanol/ethanol) every bit gas to arrive at the same amount of heat.  Even though alcohol containers are lighter than gas canisters, y'all receive got to comport so much to a greater extent than fuel, at some dot the greater amount of fuel y'all comport for an alcohol prepare volition transcend the weight of an equivalent canister gas laid up.  Or so the thinking goes.  But is it true?

Time to caput into the backcountry.  Uh, promise your heavy pack doesn't ruin your trip.  But what's genuinely lighter?

So, which is genuinely lighter – alcohol or canister gas?  Well, let's "do the math" together with encounter what nosotros come upwardly up with. I'll arrive at iii comparisons of gas stoves against alcohol every bit listed below.

1. Conventional canister stove vs. alcohol
2. Jetboil canister stove, typical use, vs. alcohol
3. Jetboil canister stove,  "gram weenie" (minimalist) use, vs. alcohol

I'll embrace conventional canister stoves vs. alcohol inwards this post.  I'll embrace high efficiency stoves (i.e. a Jetboil) inwards time to come posts.

Conventional Canister Stove vs. Alcohol
OK, so what arrive at I hateful past times "conventional" canister stove?  I'm talking well-nigh simply a regular upright canister gas stove together with a evidently pot, the sort that does non receive got a oestrus exchanger.  In other words, simply an ordinary gas stove with a evidently pot.  Examples would include an MSR Pocket Rocket together with a Snow Peak Gigapower.  Let me pose upwardly the numbers first, together with and so I'll walk y'all through them.  For the sake of brevity, I'm going to trammel my projections to fourteen days.  I'm assuming that most people don't arrive at trips longer than 2 weeks without re-supplying.  I receive got numbers if you're interested that leave of absence to iii weeks. I'll hash out how to asking those numbers later on on inwards this post.

An ultralight conventional canister gas stove

Here are the numbers:

ALCOHOL
Number of days on trail	1	2	3	4	5	6	7	8	9	10	11	12	13	14
ml of alcohol per day	50	50	50	50	50	50	50	50	50	50	50	50	50	50
Total ml of alcohol	50	100	150	200	250	300	350	400	450	500	550	600	650	700
Specific gravity	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8
Total grams of alcohol	40	80	120	160	200	240	280	320	360	400	440	480	520	560
Fuel bottle weight (grams)	18	18	32	32	32	45	45	45	45	45	45	63	63	63
Stove organisation weight	60	60	60	60	60	60	60	60	60	60	60	60	60	60
Total grams (bottle + fuel + stove)	118	158	212	252	292	345	385	425	465	505	545	603	643	683
Weight carried halt of trip (grams)	78	78	92	92	92	105	105	105	105	105	105	123	123	123
CANISTER GAS
Number of days on trail	1	2	3	4	5	6	7	8	9	10	11	12	13	14
Grams of gas per day	20	20	20	20	20	20	20	20	20	20	20	20	20	20
Total grams of gas needed	20	40	60	80	100	120	140	160	180	200	220	240	260	280
Actual grams of gas carried	110	110	110	110	110	220	220	220	220	220	220	330	330	330
Canister weight (grams)	100	100	100	100	100	140	140	140	140	140	140	240	240	240
Stove organisation weight	60	60	60	60	60	60	60	60	60	60	60	60	60	60
Total grams (can + fuel + stove)	270	270	270	270	270	420	420	420	420	420	420	630	630	630
Weight carried halt of trip (grams)	250	230	210	190	170	300	280	260	240	220	200	390	370	350
Number of days on trail	1	2	3	4	5	6	7	8	9	10	11	12	13	14
Start of Trip Difference (grams)	152	112	58	18	-22	75	35	-5	-45	-85	-125	27	-13	-53
Start of Trip Difference (ounces)	5.4	4.0	2.0	0.6	-0.8	2.6	1.2	-0.2	-1.6	-3.0	-4.4	1.0	-0.5	-1.9
End of Trip Difference (grams)	172	152	118	98	78	195	175	155	135	115	95	267	247	227
End of Trip Difference (ounces)	6.1	5.4	4.2	3.5	2.8	6.9	6.2	5.5	4.8	4.1	3.4	9.4	8.7	8.0
Average Difference (grams)	162	132	88	58	28	135	105	75	45	15	-15	147	117	87
Average Difference (ounces)	5.7	4.7	3.1	2.0	1.0	4.8	3.7	2.6	1.6	0.5	-0.5	5.2	4.1	3.1

OK, so let's beak well-nigh the numbers.  These numbers are for a solo stove user.  Use of a unmarried stove past times multiple persons would require an adjustment to the higher upwardly numbers.

The outset trouble for each type of stove is the length of the trip.  The trip is assumed to live "unsupported".  In other words, y'all aren't going to alternative upwardly supplies anywhere along the agency during the trip.

"Unsupported" trips occur inwards areas where resupply is infeasible.  All supplies must live packed in.

Now, nosotros postulate to know the total weight for each laid up.  The total weight is the amount of the weight of the fuel + the weight of the stove prepare + the weight of the fuel container.  Assume for these purposes that nosotros utilisation identical pots.

In the Alcohol section, I larn through some gyrations to calculate the weight of how much fuel I mean value I'll need.  We tin terminate debate just what is the right value for the specific gravity of SLX denatured alcohol (which is what I've been using lately), but the of import dot is that the weight of alcohol is double that of canister gas.

Now, await at the 2 stove laid ups.  I'm allotting 60g each for both alcohol together with canister gas.  I include the weight of a total windscreen with the alcohol stove laid up.  I consider a windscreen essential to the efficient burning of alcohol.   Now, tin terminate y'all detect a canister stove that is lighter than 60g?  Certainly.  And y'all tin terminate likewise detect an alcohol prepare that is lighter than 60g.  For these purposes, let's assume that the 2 stove laid ups weigh the same.

The container weight volition vary with the amount of fuel that nosotros use.  More fuel volition require a larger container or multiple smaller containers.  In this comparison, I'm going to assume that people are going to accept total canisters at the start of the trip, a fairly measure practice.  In the "gram weenie" (minimalist) comparison, I'll utilisation partial canisters to encounter what sort of weight savings I tin terminate obtain.  See Appendix I for a listing of the specific sizes together with weights of the containers used.

At this dot we've got the total weight of each prepare for each length of trip, from 1 to fourteen days.  But that weight is the weight y'all present upwardly with at the trailhead at the start of the trip.  Recall that during the trip, you'll live burning the fuel.  The weight y'all present upwardly at the trailhead volition non live carried throughout the trip.  So, below the "total grams" trouble I present the weight at the halt of the trip after you've burned the fuel.

Next, I present the divergence inwards weight betwixt alcohol together with gas at the start of a trip.  Negative numbers dot the weight savings if gas is used.  Positive numbers dot the weight savings if alcohol is used.  Notice that for trips upwardly to iv days inwards duration, alcohol is lighter but that on the fifth day, gas is lighter.  This seems to tally the "prevailing wisdom" that gas is lighter for longer trips.  But immediately notice that on a 6 solar daytime trip, alcohol reverts to beingness lighter.  What happened?  Well, on a vi solar daytime trip, nosotros utilisation 120g of fuel.  A little canister entirely holds 110g of fuel.  We switched to a 220g canister, together with immediately we're carrying to a greater extent than weight inwards both fuel together with container.  As the duration of a trip lengthens, nosotros in 1 lawsuit again encounter weight savings for 8 through 11 solar daytime trips.  A 12 solar daytime trip shows upwardly with alcohol beingness lighter in 1 lawsuit again because nosotros had to switch to a 220g canister and a 110g inwards social club to receive got plenty gas.  And so on.

But these are starting weight differences.  The adjacent laid of rows shows ending weight differences.  Now here's something a chip startling:  alcohol laid ups are ever lighter past times the halt of the trip.  Why?  Well, container weight.  Take a await at Appendix I.  With a 110g size gas canister, for example, the canister weighs almost every bit much every bit the fuel.  That steel canister is even so with y'all at the halt of the trip. With alcohol, the weight is almost all fuel.

Lastly, at that spot is 1 lastly laid of rows inwards my comparing table:  Average difference.  Here, I'm averaging the starting together with ending divergence inwards weight betwixt alcohol together with canister gas.  Notice hither that inwards entirely 1 instance, at 11 days (highlighted inwards green), is canister gas lighter on average than alcohol.

Preparing Ramen with mixed vegetables together with turkey jerky on an alcohol laid up.

Commentary
Now, ending lite may non ever live your primary goal.  When is y'all pack heaviest?  At the start of a trip, when you've got all your food.  So, having a lighter stove prepare at the start of the trip is genuinely a expert thing, together with thence a gas prepare mightiness live inwards order.  However, that said, it's entirely on longer trips, 10 together with 11 days long, where anything fifty-fifty to a greater extent than or less existent weight savings occur, well-nigh 1/4 of a pound.  The start of trip weight savings when using a gas stove on longer trips are fairly modest, at to the lowest degree with conventional stoves.  I'll hash out results with a high efficiency stove (i.e. a Jetboil) inwards 2 time to come posts.

The biggest drawback to gas stoves is those heavy steel canisters.  The best y'all tin terminate arrive at inwards damage of a fuel to container weight ratio is well-nigh 2:1.  With alcohol y'all tin terminate larn a ratio every bit expert every bit 10:1.  An of import destination inwards trip planning when using a gas stove is to minimize canister weight.

Minimizing canister weight
First, never comport 2 smaller canisters when a unmarried larger 1 volition do.  Your fuel to canister weight ratio is always better with a larger canister.  In cases where y'all postulate to a greater extent than than 220g but less than 331g of fuel, you'd genuinely arrive at improve weight wise with a 450g size canister that has had some fuel burned off than y'all would carrying 2 canisters (i.e. a 110g size together with a 220g size).  If you're planning a trip where y'all simply barely receive got to motion upwardly to the adjacent larger sized canister, y'all mightiness desire to innovation a stoveless repast or 2 or convey a to a greater extent than efficient stove simply so y'all don't receive got to bump upwardly to that adjacent larger canister.  In short, ever strive to bring entirely 1 canister, the smallest, lightest 1 that has plenty capacity for your trip.  Try non to receive got to convey 2 canisters or to receive got to motion upwardly to the adjacent larger size.

In the interests of saving weight, ever comport the smallest sized canister y'all reasonably can.

HJ, your numbers stink!
Don't similar my numbers?  No worries.  You tin terminate receive got my spreadsheets together with plug inwards your ain numbers.  Write me at Hikin dot Jim using the domain Gmail dot com together with inquire for a copy.  Note that at that spot is no "g" inwards "Hikin".  Hopefully, I won't larn inundated here.  I receive got this inwards Excel 2010 format.  If y'all postulate an before format, delight allow me know, together with I'll arrive at my best.

Conclusion
So, inwards conclusion, with a conventional upright gas stove, gas tin terminate live lighter at the start of a trip, but alcohol is ever lighter past times the end of a backpacking trip.  In damage of the average divergence inwards weight throughout the trip, alcohol is almost ever lighter.  If you're looking to salve weight, alcohol stoves are a pretty expert bet.

I promise all these calculations are of some aid to those looking to lighten up,

Thank y'all for joining me,

HJ


Appendix I – Weights
Empty canister weights.  I weighed several unlike brands of canisters on my gram scale.  There is some variability alongside brands inwards both content together with canister weight, but I'm going to utilisation the below weights which I mean value are representative.  I utilisation the discussion "ratio" below but entirely listing 1 reveal for brevity's sake.  Mentally, simply include ":1" after each reveal shown below.
1.  A 110g size canister weighs 100g when empty.  Fuel to container weight ratio = 1.1
2.  A 220g size canister weighs 140g when empty.  Fuel to container weight ratio = 1.6
3.  A 450g size canister weighs 210g when empty.  Fuel to container weight ratio = 2.1

Empty alcohol fuel bottle weights.  I weighed some of the alcohol bottles I receive got lying around.  There may live lighter versions available, but let's utilisation the below numbers inwards our calculations.  I utilisation the discussion "ratio" below but entirely listing 1 reveal for brevity's sake.  Mentally, simply include ":1" after each reveal shown below.
1.  A 125ml fuel bottle weighs 18g when empty.  Fuel to container weight ratio = 6.3
2.  A 250ml fuel bottle weighs 32g when empty.  Fuel to container weight ratio = 7.0
3.  A 500ml fuel bottle weighs 45g when empty.  Fuel to container weight ratio = 10.0


Appendix II – Assumptions

• The outset supposition is of course of written report that alcohol stoves volition run for your vogue of stove use.  If you're doing gourmet cooking or cooking for a grouping of iii or more, together with so an alcohol stove may non run for you.
• Gas to alcohol fuel weight ratio is 2:1.  In other words, y'all postulate to burn downwardly twice the alcohol past times weight to larn the same amount of oestrus every bit y'all would from gas.  Yes, I'm assuming 20g/day for gas together with 50ml/day for alcohol, but the amounts are non so much what is important; it is the ratio that is critical.
• 6 cups (approx 1.5L) of H2O boiled per day.
• Water temperature approx. 10C.
• Very niggling simmering.
• Efficient alcohol prepare (I used a Caldera Cone from Trail Designs to educate my numbers).
• Gas stove is used efficiently (turn it down, utilisation a lid, utilisation a broad plenty pot, etc.)
• Stoves are reasonably shielded from wind.
• Regular canister stove (not a Jetboil, a Reactor, or similar).
• Plain pot (no oestrus exchanger).
• Air pressure level approx 900 mBar.
• The same pot is used for both alcohol together with canister gas.
• Gas together with alcohol stove laid ups are of equal weight.
• A windscreen is included inwards the weight of an alcohol stove laid up.
• No resupply (at to the lowest degree of fuel) occurs during the trip.

A windscreen is essentially mandatory on alcohol laid ups similar this Bobcat prepare from Flat Cat Gear.