# How many farts will it take to fuel the shuttle?

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Typical gas volume percentages in a fart:
Nitrogen: 59%
Hydrogen: 21%
Carbon dioxide: 9%
Methane: 7%
Oxygen: 3%
Stinky stuff (hydrogen sulfide & methyl mercaptan): 1%

An average fart has a volume of 35.7 cubic centimeters.

Nitrogen: 21.0 milliliters
Hydrogen: 7.5 milliliters
Carbon dioxide: 3.2 milliliters
Methane: 2.5 milliliters
Oxygen: 1.1 milliliters
Stinky stuff: 0.357 milliliters

A perfect gas at STP has a molar volume of 22.4 liters. That means a fart contains:

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

Nitrogen, hydrogen and oxygen are all diatomic, forming molecules of N2, H2, and O2 at standard temperature and pressure. 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. That means the masses of the gases 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
Stinky stuff: 0.0008 grams

The total mass of a fart is 0.0371 grams.

The "fuel" value of a fart is in the hydrogen and methane. You can get 142000 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 890400 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 one second, if the efficiency of conversion of chemical energy to electricity were 40.7%.

The rest is up to you. Find out how many Joules of chemical potential energy is contained in the usual load of fuel for the spacescuttle, then divide that by 147.29 Joules. The ratio will be your answer. However, I read somewhere that it takes about 1E13 Joules to put the spacescuttle into orbit, so the approximate answer is: 68 billion farts. Everyone on Earth would have to contribute ten farts.

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New challenge: find a way of fueling the shuttle that is more expensive than this.

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3 minutes ago, cubinator said:

New challenge: find a way of fueling the shuttle that is more expensive than this.

Done.

Saffron has an energy content of 1,298 kJ/100 grams, or 12,980 kJ/g.

Based on 1E10^13 J to orbit, it will take 770,416.025 kg of saffron to put the Space Shuttle in orbit.

Saffron currently goes for \$13,980 USD/kg.

The total price to put the Shuttle in orbit using saffron as fuel:

10,770,416,029.50 USD, or 58.5% of NASA's budget.

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@Dman979 But is that more expensive than collecting ten farts from every human?

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Just now, cubinator said:

@Dman979 But is that more expensive than collecting ten farts from every human?

Do the math and get back to me. Buying .77 million kg of saffron is sure to drive up the cost significantly, and without a price to go against, saffron is the reigning king.

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You guys and gals are really bored to come up with this, and answer it.

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Punted to Science subforum.

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2 hours ago, cubinator said:

New challenge: find a way of fueling the shuttle that is more expensive than this.

graphite epoxy motor with diamonds instead?

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1 hour ago, Dman979 said:

The total price to put the Shuttle in orbit using saffron as fuel:

10,770,416,029.50 USD, or 58.5% of NASA's budget.

That's absolutely ridiculous!  Your estimate is way too low.

You've forgotten to figure in the cost of engineering a way to fuel the SSMEs with saffron, as well as actually converting the engines and fuel system.  There's also going to be the procurement process to acquire the saffron, plus how many lawyers and other suits to write up the contracts?  And testing.  How well do NASA's current engine test stands handle saffron-fueled engines?  That's going to take a team to figure out how to reconfigure the testing procedures.  Not to mention the enormous quantities of saffron that will be used for the testing period.

Now, we're going to need storage facilities for all the saffron.  Do you think NASA just keeps saffron-storage sites available?  Of course not!  We're going to need contractors to build these things.  But wait!  How much saffron can be stored in a single location?  Have we done studies on bulk storage of this much saffron?  Do bulk quantities need special handling?  How much saffron can we fit into a silo before it reaches critical mass?  Does anyone have an MSDS sheet for saffron?  What Personal Protective Equipment do we need to provide for working with saffron?

We're going to need to science and engineer the hell out of saffron before we're going to be able to provide a full total cost of fueling even a single shuttle launch with it, much less committing to an entire flower-stamen based space launch economy.

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1 minute ago, razark said:

That's absolutely ridiculous!  Your estimate is way too low.

You've forgotten to figure in the cost of engineering a way to fuel the SSMEs with saffron....

Homework.

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Quote

How many farts will it take to fuel the shuttle?

2 hours ago, DuoDex said:

Punted to Science subforum.

So-o Kerbal...

7 hours ago, SkyKaptn said:

so the 0.000335 moles of hydrogen gas in a fart will yield 47.57 J. You can get 890400 Joules per mole of CH4 burned in O2

Shuttle can't use methane. Also the gas consists mostly of nitrogen, oxygen and contains great amount of sulfur compounds.
That doesn't work so.

Step 1. First they need a lighted candle.
They should heat F-gas in a tube reactor with low amount of additional air. CH4 gets partially oxidised with native O2 and O2 of air and gets converted into H2, CO and CO2. As well as all containing water.
So, no more methane. N2 + CO + CO2 + H2 + SOx.

Step 2. They must remove sulfur compounds and carbon oxides in the absorbing facility. Diethanolamine  in its absorber column absorbs all this stuff and then regenerates in the regeneration column.
So they can get N2 + H2 mixture.

Step 3. They must purify and separate this mixture running it through a cooler and separating gaseous and liquid phases.
They get H2.

As some steps require additional energy, while others produce waste heat, they must put heat exchangers between reactors and add a gas furnace combusting additional amounts of F-gas.

By-products of this process are sulfic acid and carbon oxides.

Edited by kerbiloid
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The most expensive fuel ? A crowd funding to make either saffron / fart fuel working, complete with shuttle relaunch. Either very expensive or very profitable, not sure.

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My 8 year old daughter could definitely help.

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A more expensive way?

A gram of antimatter reacting with a gram of normal matter would produce 1.8×1014 joules of energy. The shuttle, as the OP mentioned, is about 1E13 joules.

Simple division gives us 0.0555 grams of antimatter. According to one website, a gram of antimatter (and we have never made an entire gram of antimatter before) would take 62.5 trillion dollars to make. This is more than three times the USA's national debt. So, more division gives us:

About 3.5 trillion dollars. Not to mention the development cost of an antimatter engine, making 800 more LHC's, and, of course, the gram of normal matter as the other source of fuel. And, why not make it moon rock, a 50k per gram?

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On 3/29/2017 at 9:53 PM, cubinator said:

New challenge: find a way of fueling the shuttle that is more expensive than this.

I dunno bout that.   I'd think this could be a very cost effective method of fueling spacecraft, albeit slow.    Cow Farts probably have more volatiles in them than Human farts [citation needed], and Cows are currently a profitable product to raise.  The Farts from Cows can easily be harvested (some already are and using it as an alternative source of power).  So given the resource is already "free" (or at least not a loss), Cow fart collection systems in most major dairy farms would be easy to setup and run, and it would save space agencies a butt load (pun intended) of money.    Not mention the reduction in green house gas emissions.

@Dman979 Nice sig.  7-14s (1994) here.

Edited by gargamel
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On 3/29/2017 at 10:20 PM, Dman979 said:

Done.

Saffron has an energy content of 1,298 kJ/100 grams, or 12,980 kJ/g.

Based on 1E10^13 J to orbit, it will take 770,416.025 kg of saffron to put the Space Shuttle in orbit.

Saffron currently goes for \$13,980 USD/kg.

The total price to put the Shuttle in orbit using saffron as fuel:

10,770,416,029.50 USD, or 58.5% of NASA's budget.

Bull Semen costs (by some estimates) around \$200,000 per liter.   That cost can only go up for mass production, as if anything ever falls under the category of diminishing returns, this is it.    I don't know the energy content of this material, and data is hard to find, But I'm guessing this method would be far more expensive than saffron.

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Who needs that bulls?.. This is expensive.

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