Pee Engine

[Souper]

Human urine is comprised of 90+% water.

Water is H20.

H20 can by electrolized into hydrogen (fuel) and oxygen (oxidizer)

Fuel + Oxidizer = Delta-V.

Therefore, 3 humans + machine that feeds urine to a reverse fuel cell = large drinking water supply = NOT REALLY STRANDED!

[EdFred]

Human urine is comprised of 90+% water.

Water is H20.

H20 can by electrolized into hydrogen (fuel) and oxygen (oxidizer)

Fuel + Oxidizer = Delta-V.

Therefore, 3 humans + machine that feeds urine to a reverse fuel cell = large drinking water supply = NOT REALLY STRANDED!

There's the issue.

[Camacha]

Therefore, 3 humans + machine that feeds urine to a reverse fuel cell = large drinking water supply = NOT REALLY STRANDED!

So, how much dV can three humans provide, according to your calculations and assuming an optimal scenario?

[Souper]

Hmmm.....you know what? Let's instead say we install a system that converts the urine of NASA employees into hydrogen and oxidizer. NASA wouldn't need to pay as much for fuel!

[Kryten]

Gaseous hydrogen is a pretty poor fuel, and the equipment to liquify it isn't exactly light. The ISS already uses electrolysis for oxygen, and they just dump the hydrogen overboard.

[Tech Support]

what about the remaining 10% ?? won't the chemicals and acids damage the converter ?? points for originality though

[Souper]

Well...this had a lot of ambition at first, but looks like i've wasted my time.

[EdFred]

Also, don't they recycle/purify the urine to be used as drinking water again so they don't have to take as much water on missions?

[LordFerret]

You forgot to mention that urea, a chemical found in urine, is used in making explosives. So not only can pee be used for rocket fuel and drinking water, it helps with some nifty explosions as well.

[RainDreamer]

Well now...how about making a mass driver and launch solid waste through it as reaction mass?

[Cirocco]

It's all a cost vs. benefits discussion. NASA and other space agencies have already thought about electrolysis of urine for different purposes. As mentioned before, the ISS already uses electrolysis of waste water for oxygen generation.

The best way to go about using waste products is to convert them back into usable materials rather than expelling them. That requires energy, but the advantage of just requiring energy is that energy-producing equipment can provide energy for years and years for comparably low weight. What changes is that the rate at which energy is generated goes up if you use better (heavier) equipment. If you recycle almost all your matter, you'll need a lot of energy, but low starting supply weight. If you expel waste matter as a propellant, either through mass driver or converting it into rocket fuel, then that part of your supplies is gone forever, so you need a lot bigger initial supply. This would be the problem with a mass driver expelling solids. (also, amon other problems, accelerating non-ferrous solids without a propellant would be difficult)

Of course, if you have sufficient resources on-site, then ideas such as converting water into rocket fuel suddenly do become a lot more appealing. Current plans for Mars return missions are looking at rocket fuel procuction on site on Mars in order to save weight on launch.

In essence: on missions where raw materials are extremely limited in supply (such as deep space), you want to expel of as little matter as possible because every atom you expel is one you're never using again. On missions where you have access to a large supply of raw materials, on-site production of goods is very attractive because it saves on launch weight.

[Accelerando]

Well now...how about making a mass driver and launch solid waste through it as reaction mass?

Hell, just cut to the chase and turn it into a railgun. Your enemies may be able to clean the mess out of their decks, but they'll never be able to wash away the shame.

[Kryten]

Hell, just cut to the chase and turn it into a railgun. Your enemies may be able to clean the mess out of their decks, but they'll never be able to wash away the shame.

Last time I checked human waste generally wasn't conductive.

[sal_vager]

You need to eat more cereal Kryten

[Jovus]

I'm confused. If you already have a large supply of drinking water, why not just electrolyze it before ingestion?

[Accelerando]

Last time I checked human waste generally wasn't conductive.

Last I checked, nobody said you can't encase it in a metal shell. Or do what Sal suggested.

[Scotius]

Heads up, guys! Yes, right now ISS dumps excessive hydrogen to space. But soon, when nifty new module of experimental VASIMR engine will be attached to the station, this excessive hydrogen will become locally created fuel for the plasma engine You can call it a first practical implementation of ISRU in LKO I can't wait for Ad Astra to finally send their engine up - it will be so awesome.

[Souper]

Or just jury-rig a fuel cell's intake to take in purified urine as rocket fuel. Your crew would be thirsty, yes, but at least all that converting adds up to a noticeable increase in DeltaV.

[Moesly_Armlis]

We need further analysis on this, up for discusion the

. Can audio cymatics be somehow be at play here?

Edited January 23, 2015 by MoeslyArmlis

[Goddess Bhavani]

Well...this had a lot of ambition at first, but looks like i've wasted my time.

Don't worry, maybe Top Gear can pick up the research where you left off.

Their engineering motto after all, is Ambitious But Rubbish

[kerbiloid]

Real pee engine is even more simple. No hydrogen tanks, no electricity.

The pee stream itself creates reactive force itself. Just put your pee nozzle out of the viewport and aim in correct direction.

Of course, need to be carefull and not keep the window opened too long.

[Goddess Bhavani]

Wow, that's going to tick off the people at Health & Safety.

I have a suggestion to avoid endangering our dear Kerbonauts to exposure.

Cows. Connect the back end of a cow to some sort of methane tank and feed the cow. Cow produces methane, methane is pumped into some sort of system to compress and refine it and you'd have a biological propellant facility in space.

I suspect we could also connect the septic plumbing of the spacecraft to the biomethane factory for an added boost to flatuency. In such a case, we just hook Jeb up to the space toilet funnel attachment, turn the vacuum on and feed him endless supplies of beans, chili and onion.

There we go, no more "returning from Jool is impossible" complaints.

[Cirocco]

Heads up, guys! Yes, right now ISS dumps excessive hydrogen to space. But soon, when nifty new module of experimental VASIMR engine will be attached to the station, this excessive hydrogen will become locally created fuel for the plasma engine You can call it a first practical implementation of ISRU in LKO I can't wait for Ad Astra to finally send their engine up - it will be so awesome.

Wow, seriously? I did not know this! awesome! Is it just for testing or are they planning to actually use it to help counteract orbit degradation?

[Dispatcher]

Now its up to Squad to release an update with the Wizz Engine! Perhaps this will be an incentive to send crewed missions to space (for the fuel, etc.)!

[softweir]

Connect the back end of a cow ...

Front end of a cow. Cows ferment their food in their stomachs, not their guts, and that's where the methane is produced - and it gets belched out. (If, for some reason, they can't belsh then they are in very serious difficulty and a veterinarian needs to puncture the affected stomach-lobe. They have a 4-part stomach.) The bacteria in their guts don't have a lot to work on, so a lot less fermenting goes on. Instead, that's the point where the animal absorbs the nutrients released by fermentation in their stomachs. As a result, they fart a lot less than they belch.