Companion forum thread to:

The Performance of Alcohol Fuels for Backpacking Stoves
Part Two: Water/Alcohol Blends

So I was wondering, what about using hydrogen peroxide instead of water? Either the common 3 percent stuff from the supermarket or "food grade" 35 percent from your local health food store? I suppose cost would be a major negative factor.

Great article, thanks for doing the work.

Rather than a heavy syringe, one could simply carry a tiny 30cc (1 oz.)measuring cup, like the kind that comes with several cold medicines. The graduated lines could allow one to add small quantities of water. I usually carried my alcohol in a talking rain bottle, and used the cap for measuring fuel. I started carrying the 30cc measuring cup bec. I always seemed to spill a bit each time.

Lately, I decided to switch to Everclear to minimize toxin exposure, and to have something to use in a pinch as an antiseptic, etc. In the US, you can't buy 95% EtOH in many states. In WA, one needs a permit. I had a friend bring me a jug from Oregon. Unfortunately, I can't fly on a plane with it and most stores near trailheads don't have it. I can't seem to find a source that lists which states allow one to purchase Everclear. Maxine

"I can't seem to find a source that lists which states allow one to purchase Everclear. Maxine"

Hi Maxine,
Search Wikipedia for Everclear. They have the info you are looking for. I purchased it in Arizona at a Liquor Barn.

Thanks Tom, I must admit I felt a little weird asking shop owners if they sold Everclear in little towns near Yosemite last year. Maxine

http://www.absoluteastronomy.com/topics/Everclear_(alcohol)

Hi Maxine,
I forgot to add that I was in AZ when I purchased it. I took it over to FedEx and theywrapped and shipped it to WA for me. I don't know if Liquor Barn will ship. Just don't want to confuse. :)

edited by ouzel 5/15

Everclear cost me $18 for a fifth, an acceptable price for the peace of mind that comes with knowing that no nasty VOC's are wafting up into my nostrils and on into my lungs and bloodstream.

Edited by ouzel on 05/15/2009 17:05:01 MDT.

Hi Maxine,

No Everclear in California, regrettably. IIRC there's also a big bump in the tax on liquor at and above 100 proof (50%), which would paobably make it too expensive to burn.

Now for folks in San Diego county, a run across the border opens a whole new world of fuel options (PCT thruhikers take note).

So I am an esbit or canister stove guy, but the article is interesting none the less. My conclusions and questions are as follows:

If I were to decide to use alcohol, 95% Everclear ethanol (locally available in Idaho) would be my choice. I am convinced that adding a moderate amount of water to reduce sooting might be worthwhile. The known tradeoff would be increasing the boiling time by half or more.

But what about CO emissions? Does CO concentration go up with increased water, or down? I would have thought it would go up, but seeing less orange flame makes me think the opposite. Care to speculate Roger?

Hi Jason

> But what about CO emissions? Does CO concentration go up with increased water, or down?
> I would have thought it would go up, but seeing less orange flame makes me think the
> opposite. Care to speculate Roger?

Um .... well, the flames from most alcohol stoves are oxygen-poor - see http://www.backpackinglight.com/cgi-bin/backpackinglight/stoves_tents_carbon_monoxide_pt_4.html for numerical data.

Adding water does slow the burn down a bit, which MAY result in slightly less CO emission. But truth to tell, I have not measured this yet. 'Speculate' is right.

Cheers

Thanks for a great pair of articles. I'll need to investigate the make-up of my "denatured" alcohol. Based on my past experiences, it may be lighter to use my Jet Boil with propane than the Trangia w/denatured alcohol. I'll have to see if the weight penalty is due to the unlisted contents of the alchohol.

"It is therefore quite reasonable to expect that when some alcohol stoves are coupled with narrow pots, the efficiency of the whole system may rise slightly when a small amount of water (up to 20% even) is added to straight alcohol, due to the reduced flame size."

The above quotation captures the essence of my concern. You use the word "may" in describing the benefits of adding water to pure alcohol. It seems to me that your whole article is aimed at dealing with this issue of flame energy wasted up the side of the pot with larger burners when combined with smaller diameter pots such as beer cans.

Why then did you not answer that question?

Forgive me if I seem dense but this whole scientific experiment seems to have been an obvious issue. Water dilutes and therefore one gets less energy from the fuel. DUH! If there were some suspected tradeoff benefit, then your experiments should have focused on that. Spending so much energy and print space to come to the conclusion that alcohol's energy is diluted by adding water seems so obvious as to beg the further question: why waste your time and effort? Unless there is some benefit you can test. That one would have to carry more (hence heavier)fuel mix to achieve the same energy value is a corralary DUH as well.

What am I missing here? I don't usually find fault with your experiments, Roger, et al. But this one just plain mystifies me.

Part 1 was very useful and I have switched from Yellow HEET to Ethanol because of it.

Edited by mitchellkeil on 06/05/2009 12:14:18 MDT.

Hi Mitchell

Maybe Tony will want to answer you as well. But for me, yes it is NOW fairly obvious what is going on. But before doing the research it was not obvious to me at least just what would happen.

Sure, one could hypothesise that the water would just dilute the energy, but the world is full of assumptions that turn out to be not true. The only real way of KNOWING is to do the experiments and make the measurements.

The other way of looking at this is to ask whether there is anything which I have overlooked beforehand? Sure, a simplistic analysis would say that the water would just dilute the energy, but what if I have been a bit too simple and neglected something? How will I ever KNOW that my assumptions are right, unless I do the experiment and make the measurements?

So yes, it is all very obvious in hindsight. Good: that means we have some understanding of what is going on.

Cheers

I think Roger has answered your questions very well.

Before I started to tests alcohol water mixes I thought that the obvious was that adding water to alcohol would dilute the energy but after analyzing some early results it became obvious that this was not true that is why I spent the time to do the tests.

And yes adding water to alcohol before journeys start is not weight efficient but adding as you go might have a very small advantage but my personal conclusion is that adding water to alcohol is just not worth the effort.

The issue of stove efficiency vs pot diameter was addressed in a forum thread of mine some time ago http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=11467&disable_pagination=1
but it seems to me one possible advantage of adding water to alcohol as a stove fuel is on small diameter pots as most stoves are to big for small pots slowing down the flame some gains might be made.

Tony

Edited by tbeasley on 06/05/2009 18:43:58 MDT.

This is what I ended up with early last year experimenting with adding water to my 95% Ethanol. A 15-85% mix worked best. It increased the time from start to boil but also gave me a longer burn time, possibly useful for re-hydrating when simmering is not much of an option, as with the White Box stoves I was using. The main advantage was a narrower flame, so that it would not shoot up the sides as it does with my pots otherwise.
Obviously you would add the water on the spot, not that 1/5th or less of an ounce would make much difference to me...
Franco