[Jenab6]

The average person farts, on the average, 14 times per day. The volume of a day's worth of farts for one person is about half a liter. So an average fart has a volume of 35.7 cubic centimeters.

The chemical composition of fart gas varies with person and diet, but the following are typical volume percentages: nitrogen 59%, hydrogen 21%, carbon dioxide 9%, methane 7%, oxygen 3%. The remaining one percent is the stinky stuff, mostly hydrogen sulfide, methyl mercaptan, methyl indol, and skatol.

That means a fart contains 21.0 ml nitrogen, 7.5 ml hydrogen, 3.2 ml carbon dioxide, 2.5 ml methane, 1.1 ml oxygen, and 0.357 ml of the stinky stuff.

A perfect gas at STP has a molar volume of 22.4 liters, and there are 6.0221415E+23 particles in a mole. Nitrogen, hydrogen and oxygen are all diatomic, forming molecules of N2, H2, and O2 at standard temperature and pressure.

So, in a fart, there are...

Nitrogen: 0.000938 moles
Hydrogen: 0.000335 moles
Carbon dioxide: 0.000143 moles
Methane: 0.000112
Oxygen: 0.000049 moles
Stink: 0.000016 moles

The molecular weights are N2 (28 ), H2 (2), CO2 (44), CH4 (16), O2 (32). The molecular weight of methyl mercaptan (CH3SH) is 48.1. The molecular weight of hydrogen sulfide (H2S) is 34.8.

There are several forms of methyl indol, and all of them are large molecules (molecular weight ~600). Skatol is huge (molecular weight ~56000). The main stink comes from methyl mercaptan and hydrogen sulfide though. The more exotic gases only serve to give the vintage fart a distinctive body and character. I'll assume that the mean molecular weight of the stinky stuff is 50 amu.

That means the masses of the gasses in a fart are...

Nitrogen: 0.0263 grams
Hydrogen: 0.0003 grams
Carbon dioxide: 0.0063 grams
Methane: 0.0018 grams
Oxygen: 0.0016 grams
Stink: 0.0008 grams

The total mass of a fart is 0.0371 grams.

Someone else estimated that farts weigh 1.3 grams per liter. Our average fart contained 1/28th of a liter of gas, and that would work out to 0.0464 grams. That's the same ballpark as my estimate just above.

Yet another person (no bibliography will be appended to this paper) estimated that the emission speed of a fart is 3 meters per second. If that is true, then the momentum imparted by a fart is 0.00012 kg m / sec, and the kinetic energy would be 0.00018 Joules.

If an 80-kilogram person, floating around in space bare-assed, emitted a fart, the reaction would propel him in the opposite direction at a speed of 13 centimeters per day. If he kept using his farts as his only means of propulsion, he could accumulate a delta-vee of 27.6 meters per hour in one year from the recoil. (The average acceleration is 2.43E-10 m/s^2.) Of course, a lunch-wagon spaceship would have to keep him supplied with food to produce flatulence with. (And, of course, the gravitational pull of the spaceship would probably accelerate the farting flier about as much as the farts would.)

If the analysis so far has been correct, there are about 9.6E+20 molecules in a fart. At an emission temperature of 310.15 K, the average molecule would have an energy of 6.4E-21 J. The thermal energy of a fart, then, is 6.2 Joules, which is about 34000 times greater than the kinetic energy.

Now, how about the potential for using farts as fuel? You can get 1.420E+5 Joules per mole of H2 burned in O2, so the 0.000335 moles of hydrogen gas in a fart will yield 47.57 J. You can get 8.904E+5 Joules per mole of CH4 burned in O2, so the 0.000112 moles of methane will give us 99.72 J. The combined combustion potential energy of a fart is, therefore, 147.29 Joules. It would keep a 60-watt light bulb lit for two seconds, if the efficiency of conversion of chemical energy to electricity were 81.5%.

With this (probably optimistic) assumed conversion efficiency, it would require the farts of 3100 average people to keep a single 60-watt light bulb lit all the time.

If an astronaut were to channel his farts into a portable rocket engine (along with the necessary amount of additional oxygen), he might be able to squeeze 1.91 m/s of delta-vee from each fart. In a day, he could change his velocity by 26.8 m/s. In a year by nearly 9.8 kilometers per second. This raises an interesting possibility. If transfer orbit maneuvers are necessary near a body of large-asteroid size (e.g., 120 km radius), an astronaut could perhaps meet his delta-vee requirements by using the chemical potential energy of his own farts. Such a maneuver would typically involve a delta-vee of five to ten meters per second. A rectal tap could be made through a special seal in his spacesuit, leading to a backpack or handheld rocket unit. The tapped fart gas could be compressed into cylinders for storage, until needed.

The total energy of a fart, kinetic and thermal and chemical potential, is 153.49 Joules, which is the same as 0.0367 kilocalories. A kilocalorie is what we mean by a "food calorie." The 14 daily farts of the average person costs him about half a food calorie. It is not, therefore, a major source of energy loss: ~ 0.02 percent of a 2500 kcal daily diet.

Jerry Abbott

[blukatzen]

Jerry, you've got a little too much time on your hands. It's xmas, relax a little...(I'm sure it includes farting.)

Sheesh, what this list has degenerated to.
Farting people popping in and out of dumpsters shooting at cats.

Merry Xmas.

Blu

[pedalling_faster]

does this mean if we rig up all the cows in the US
with colostomy bags (to harvest that naturally
occurring methane), that our natural gas heating
problems are solved ?

looks like the calculations are about halfway done.

old MacDonald had a farm
EROEI EROEI oh

[Jenab6]

$this->bbcode_second_pass_quote('blukatzen', 'J')erry, you've got a little too much time on your hands. It's xmas, relax a little...(I'm sure it includes farting.)

Sheesh, what this list has degenerated to.
Farting people popping in and out of dumpsters shooting at cats.

Merry Xmas. Blu

[I_Like_Plants]

It's actually very funny, but most here are seriously humor-impaired.

some extra LOL's from me!

[gg3]

.
It may light a 60-watt bulb for two seconds, but it'll light a 100 milliwatt LED array for 20 minutes. And that, my friends, is what we call a viable product. With 12 - 16 farts per day on average, you can get 4 to 5-1/2 hours of light. Neat, eh?

Too late y'all, patent applied for. Business plan written. And funded as of last week ($1.2 million in startup capital, mostly for advertising & marketing).

"Fart Funnel! Don't just make a stink about the environment, do something!"

It installs under car seats and household or office seats. To compress the gas into the little cylinder, you simply bounce up & down on the seat once or twice. The output of the cylinder goes into a little thing like a fuel cell, and the output of that is available to light the LEDs. Not quite as powerful as one of those hand-cranked LED lanterns, but enough to work at a desk.

To avoid certain regulatory hassles we're selling it as an "educational kit." $49.95. Click the Buy Now button below this posting.
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<Buy now!>
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uh, is it April yet?

[gw]

$this->bbcode_second_pass_quote('gg3', 'T')oo late y'all, patent applied for. Business plan written. And funded as of last week ($1.2 million in startup capital, mostly for advertising & marketing).

It installs under car seats and household or office seats. To compress the gas into the little cylinder, you simply bounce up & down on the seat once or twice.

[blukatzen]

$this->bbcode_second_pass_quote('I_Like_Plants', 'I')t's actually very funny, but most here are seriously humor-impaired.

some extra LOL's from me!

[TheDude]

Laugh if you want (I did! Funny shit - unintended pun there!) but 19% of anthropogenic methane emissions are from ruminants.



"Who run Barter Town?"

(yeah, pigs aren't ruminants...still...)

[gg3]

GW, your rectal canister is going to need FDA approval as a medical device because it goes "inside."

Whereas the Fart Funnel (TM) doesn't, because it, and its little tank, goes "outside."

"Fart Funnel: Fill up a tank of gas today!"

[Jenab6]

I'm thinking that I assumed twice the chemical to electrical efficiency I should have. One fart at 150 Joules would probably work out to not more than 60 Joules in electricity. A hundred million dedicated farters could produce one continuous megawatt altogether.

The LED light idea was pretty good. I have some handcrank LED flashlights that work, well, not too bad. They keep me from tripping on stuff at night when I need to visit the bathroom. If you can get by with 1 LED and eat beans & cabbage with pepper on them, with a side dish of raisins, you could probably keep a light on all night.

Conversion to electricity might be a problem. With so little energy to work with at one time, you might find it all dissipating as heat before you can do anything with it. A piston goes POP once, and you'll have to work out a way to make a generator's turbine twirl a bunch of times from the reaction.

[gw]

Just in case anybody has doubts about the technology or thinks this is all a bunch of "vaporware", here is the actual patent: No. 6,982,161 issued January 3, 2006, titled "Process for the utilization of ruminant animal methane emissions."

$this->bbcode_second_pass_quote('', 'A')ccordingly, the reader will see that the invention, by providing a process for the novel utilization of the methane contained within the exhalation of a ruminant animal, provides a process which converts a previously wasted form of energy into a useful end-product, converts an environmentally-destructive gas into a useful end-product, provides a direct economic incentive for a ruminant animal methane emissions reduction effort, reduces ruminant animal methane emissions without altering the chemical or microbial make-up of the digestive tract of ruminant animals, reduces ruminant animal methane emissions without requiring ruminant animals to alter their normal/natural behavior patterns, including sleeping and nutrient-consumption, reduces ruminant animal methane emissions without requiring feed reformulations, selective breeding activities, or chemical or microbial modifications to the digestive systems of ruminant animals, can be integrated into ruminant animal ownership operations, utilizes as energy a material never previously considered a viable source of energy, and has the potential, if used widely, to significantly reduce ruminant animal methane emissions.

1. A method for producing methane-utilizing microorganisms in a confined apparatus comprising using the methane exhaled through ruminant animal exhalation as a source of carbon and/or energy for the growth of said microorganisms, comprising: a. collecting methane gas that has been exhaled through ruminant animal exhalation, b. providing methane-utilizing microorganisms which can use said methane as a source of carbon and/or energy for growth, c. providing a growth-culture medium which promotes the growth of said microorganisms, including a nutrient substrate and/or a microorganism immobilization means, d. providing a means for the directed mutual-exposure of said methane, said microorganisms, and said growth-culture medium, including a means for the capture and conveyance of said methane and a means for confining said microorganisms, said growth-culture medium, and said methane to a specified apparatus existing outside of the digestive tract of a ruminant animal, e. mutually-exposing said methane, said microorganisms, and said growth-culture medium to cause said microorganisms to grow in said apparatus using said methane and said growth-culture medium, whereby said methane contained within said ruminant animal exhalation is utilized for the sustained growth of said microorganisms in a specified apparatus, whereby said methane, an environmentally-destructive material and previously unusable source of energy, is used to produce a useful end-product, and whereby said microorganisms can be harvested and utilized following growth, adding economic incentive to a ruminant animal methane emissions reduction effort.

[pedalling_faster]

$this->bbcode_second_pass_quote('', '[')img]http://www.chimpeach.info/images/ruminantmethane.jpg[/img]