you laugh but i've always thought it would be great to carry a kilo of pure hydrogen in my backpack - just burn it to obtain like 5 litres of water ... I mean why are we carrying all that oxygen in our backpacks when he atmosphere has a plentiful supply of it...

Maybe we need mini packblimps that can not only carry fuel, but part of the pack, the dog, the kid, etc. It could have AI assisted propeller machetes to hack away at wayward branches, geofenced to protect endangered flora of course.

Then if you add some condensing coils and a transparent roof, you could also just leave the backpacking food in there and it'll slowly get moist and solar cook. After a twelve hour hike you'd get lukewarm edible mud, mmm.

Explosions are a minor risk, but if you can make water out of the hydrogen anyway, surely you can put out any resultant wildfires.

Cyberpunk Smokey would be proud.

would this not be considered a drone? drones are not legal in national parks. can only imagine each state following suit for state parks.

Guess we have to get rid of the props and just tether it to the pack like a balloon.

Seriously though, I've often wondered if a weather balloon style lifter tethered to a backpack could help it be lighter. Probably with a less flammable gas, and only in sparsely forested areas.

Less flammable would be Helium. It just so happens that the US is looking to sell the strategic helium reserve. So you just need to find a VC and you can get your backpacker's assistant idea off the ground. hehe

as far as helium balloon, it would have to be a balloon of such enormous size to be of any benefit. To launch a couple pounds of payload to 90k feet required a balloon 8' in diameter on the ground.

A kilogram of lift per cubic meter of helium. At sea level; if you let it expand it only goes bigger at altitude, without needing more helium.

Great, so if I have a 25kg sack, a 1 meter sphere being trailed above is only going to make it 24kg. Like I originally stated, a few pounds required an 8' diameter balloon, so 2.5m balloon. That's friggin huge. FYI, at 90k' altitude, the balloon expanded to about 40' before reaching it's burst limit allowing for a return of the payload.

Lots of fun on windy days!

Have you ever actually seen a canister of hydrogen? Specifically, have you ever felt the weight of that canister? I'd rather just carry the 8lbs of a gallon of water. At least it gets lighter as the water is depleted

Well, the same amount of hydrogen (as in 1kg of water) in the form of methane only weighs ~450g though. And methane, conveniently, turns into H2O when burned.

So in principle you could carry a bottle of methane and burn that to get water. ;-)

roughly half the weight, plus the weight of the burner equipment. again, that weight still remains even after the supply of fuel to make water is depleted. a just of water gets lighter. by the end of the hike, this is very much a nice quality

Where do you find 550g lighters? Surely a pocket lighter to save half a kilogram of water is worth it

What do you expect to do, open the valve, flick a Bic, and the water is going to start flowing? Come on. This was a fun nonsensical thread, and you're now trying to turn it into a magic trick rather than goofy science. You have to capture the flame's exhaust, pressurize it, and whatever other sciencey stuff to get the waste into a liquid

> pressurize it

You "just" have to capture and cool it down.

I mean, it's completely outside of viability, but it's not breaking ground science. You could do it perfectly well in a lab (if you had any reason to).

There's a lot of things that can be done in a lab, but bringing it to the real world is totally different. Nevermind fitting this in the original concept of backpacking

Liquid methane can use normal thermos technology, with the venting fed through a burner to create your water.

Ouch. No, go read the thread again.

You can turn methane into water in theory. And you can technically do it in a lab (even though the easiest way by far to do it uses a lot of water). You can't do it on your backpack.

The way I was picturing it, you light the balloon and, besides some burn marks and a boom heard miles away, water appears in its place and falls into a bucket you placed below.

Not like I know how this stuff works. Someone says methane turns into water when burned, I imagine based on farts that it floats like in a nice balloon or Hindenburg, I figure this do be how this was intended ¯\_(:))_/¯

Carbon is lighter than oxygen, so their plan would work if they brought fully saturated hydrocarbons including ones so long-chain that they were solid at room temperature.

You just described coal. So, you're suggesting taking coal on a backpacking trip along with a very heavy canister of hydrogen. To make water? Anything else you want to do to help destroy the environment you're backpacking through?

You realize this whole thread started with the concept of dehydrated water, right?

Saturated hydrocarbons contain hydrogen. That is what the carbon is saturated with. Coal is not saturated.

Just put the hydrogen in a balloon and it will carry itself.

Just remember, the flame from hydrogen is clear and very hard to see until it catches other things on fire. At that point, it's well past too late

Just need a longer string for the balloon and it'll be ok. And hike in places with less trees (although, after a few mishaps, the trails you frequent will have less trees, too).