Hi all! We are a group of four seniors in high school working on creating a better method as to melting snow to be used for drinking water. We got this idea while one member of our group was climbing Mt. Rainer and utilized a gas stove to melt snow. Our team feels that we can create a more efficient and lightweight method for melting snow for drinkable water. It would be a big help to us if you could take the time to fill out a brief survey we created in order to better help define this problem. The survey can be located at https://goo.gl/forms/VoRFNC9fMOHsqRK62 and should take no longer than 3 minutes to complete! Thank you for your time and feedback it is much appreciated!

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The results of your survey are biased, because only those that have a Google account and are willing to log in may participate. I did not.

Sorry but this survey doesn't make much sense to me. Questions like how do you get water, do you like to carry it, what do you put it in...

These have obvious answers and if you can't determine those answers already how would you be able to develop a new way to get water that no one else has ever thought of?

Obviously most people put their water in either a cardboard box or an old grocery bag right?

mrchad9 wrote:Obviously most people put their water in either a cardboard box or an old grocery bag right?

Hey, I never thought of that one! Sounds like a great idea to save some weight; up until now I've used bottles, but a grocery bag surely must be much lighter, and when I don't need it anymore I can start a camp fire with it!

So, this kid climbs Mt Rainier with a 60 pound pack (!?!?) , which is par for the course when you first climb Rainier I guess, then comes to the conclusion that melting snow for water takes a lot of time and fuel, which is also par for the course for mountaineering/alpine climbing in general.

If this kid is some kind of genius and finds a way to turn frozen water into un-frozen water without using a heat source, well he kind of deserves a Nobel Prize. What would be the opposite of Ice 9? That might work.

More efficient? Sure. Stoves are not really optimized for melting snow - they burn much hotter than needed for that so a lot of heat is lost to convection and radiation. If you designed a snow-melter from the ground up, you'd use a slower burn (maybe a fuel cell instead of a flame?), much more insulation (and less ventilation), a better heat exchanger, etc etc. You'd pay a price in weight and bulk (and time to melt), all to save a few tablespoons of fuel, weighing practically nothing. Propane, kerosene, or gasoline are all around 46MJ/kg - that's kind of hard to beat.

Supposing you did build such a thing, it would have limited usefulness unless it also functioned as a normal stove. Most climbers carry a stove because not only do they sometimes need to melt snow, they *often* like to have hot coffee, noodles, etc.

You could use a crotch pot. It would be slower and perhaps a tad uncomfortable, but it's a method that has been used before. At least in dire bivouacs.

In a more serious vein, I've wondered if something akin to a bomb calorimeter would work for melting snow or cooking food.

Radiothermal generators are the only way to go.

A mylar space blanket will melt snow in the sun and has little weight along with multiple uses.

I like black lawn/leaf bags. Melt/consolidate snow with help from the sun, and makes a nice impromptu pack cover if needed. Though you really need a basecamp situation where the bag filled with snow can melt/consolidate sitting in the sun while you're off climbing during the day.

A leaf bag isn't going to work in the cold. And I'm not certain but I suspect plutonium has some disadvantages.

Probably the best bet is to try and improve stove efficiency.

Which stove is the current fuel efficiency champ in cold conditions? Is it the Reactor?

JD wrote:A leaf bag isn't going to work in the cold.

Define cold, cause it definitely worked and saved fuel in AK. Might not make completely the melt to liquid water, but definitely will consolidate material prior to finishing the process with a stove.

96avs01 wrote:Define cold...

That's a good question.

Obviously *it depends*. If you assume the sun is directly overhead, zero atmospheric loss, 100% conversion of radiation to heat and zero conduction/convection losses then you only have to worry about radiative losses. In that scenario the ideal garbage bag will boil water at sea level.

But in the real world the sun isn't directly overhead, sometimes clouds block the sun and you lose heat to the surrounding environment. So how much snow is melted or just warmed/seasoned for later melting in a stove will vary.

I've done it on spring ski trips a few times. But in the winter I've never bothered. There is just too much melting that has to happen in too short a time, and it's usually in the morning or evening when the already low-on-the-horizon sun is even lower.

It's interesting to hear that you found it useful in Alaska, presumably in the height of summer when the sun is higher in the sky than in the Sierra winter. I wonder though, how much did it really save you in fuel or time?

JD wrote:It's interesting to hear that you found it useful in Alaska, presumably in the height of summer when the sun is higher in the sky than in the Sierra winter. I wonder though, how much did it really save you in fuel or time?

The summer sun in AK is probably not much higher (possibly lower) than the Sierra winter sun, but it has a far better advantage - it stays out almost all the time. Get up at 6am and the sun's been up for two hours already. Go to bed at 11pm and it's still out. You never see the moon and stars unless you happen to be up at 3am, and even then it's only twilight.

Bob Burd wrote:The summer sun in AK is probably not much higher (possibly lower) than the Sierra winter sun, but it has a far better advantage - it stays out almost all the time.

The sun is always significantly higher in AK in the summer than in the Sierra in the winter. For example, at noon on Feb 1 the sun was at 36° in Fresno and at 2pm on July 1 it was at 52° in Anchorage. Those were the peaks for those days. When you take into account both the angle (assuming the garbage bag is flat on the ground) and the additional atmosphere that the light passes through at lower angles the peak irradiance in AK was very roughly 75% greater (ignoring clouds). And the difference increases earlier/later in the day.