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What are the carbon footprints of various rocket fuels?

Discussion in 'SpaceX' started by AudubonB, Jan 3, 2016.

  1. AudubonB

    AudubonB Mild-mannered Moderator Lord Vetinari*

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    A reference to Merlin's CH4-LOX mixture made me contemplate the atmospheric effects of the various by-products of different rocket fuels. As usual, I'll bow out and offer others to perform the calculations (so gracious of me, I know. I cannot help myself from being so charitable).

    I think the relevant question should be couched along the lines of "For a given amount of thrust, how many moles of { CO2; uncombusted CH4; ____?____ } are produced? Another way to present the data would be "In order to bring { X tons of cargo } to { LEO / Lunar Mission / etc. }, how many moles of...?"

    Any such byproducts should be compared against the combustion products of alternative fuels such as

    Kerosene-LOX
    N2O4 - MMH or UDMH

    and so on. I think we can neglect the currently rejected fuels, such as the wonderful bromine pentafluoride (BrF5) we used in grad school. My suspicion is that what outgassed from our laboratory probably damaged the earth's ozone layer more than all the propellants and refrigerants from the rest of North America's bathrooms, kitchens and automobiles combined, and maybe the entire planet's. Not sure about their GHG effects.

    A rigorous analysis of the combustion products need account for the location of all such combustion, as near-surface effects of any GHG are different to when the gases emanate in the upper atmosphere, troposphere, "outer" space, and so on.

    Then, as a follow-on, a full cost analysis should include the dollar-cost including negative externalities of a given fuel OR a given launch, etc. This of course brings us immediately to having to broach the topic of what a carbon tax should be. $50 per ton-equivalent of CO2? $100?

    This is in NO WAY casting aspersion on rocketry. Mr Musk himself has famously said that...well, read my sig-line. It does, however, represent a fuller comparison of various fuels AND it offers a way for the space industry to compare its work against other human activities. It also allows hard number to be offered against those who will - if not now, later - challenge space exploration to defend themselves.

    Is anyone up to performing these calculations?
     
  2. Electric700

    Electric700 Member

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    #2 Electric700, Jan 3, 2016
    Last edited: Jan 3, 2016
    One source says 28 tons of CO2 were emitted per launch + 672 tons of CO2 were also generated per launch in the production of the fuels for the retired space shuttles. Considering that the SpaceX rockets are smaller, perhaps this translates to a lesser value. 230 tons of CO2 overall may be emitted per launch, including the CO2 emitted during fuel production and transportation.

    More here: What Is The Carbon Footprint of The Space Program? : TreeHugger

    There's also electric thrust research:
    RF resonant cavity thruster - Wikipedia, the free encyclopedia

    Electrically powered spacecraft propulsion - Wikipedia, the free encyclopedia


    May be we will one day see things like 100% electric planes carrying space vessels to the upper levels of the atmosphere, where they can be launched using advanced zero-emission electric thrust technology. Beyond that, perhaps we will be able to have zero emission launches from the ground using a highly advanced version of EmDrive technology.
     
  3. Johan

    Johan Took a TSLA bear test. Came back negative.

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    ... Which is really not a whole lot, about what a 747 emits flying one way transatlantic (7 hours, say from London to Boston).
     
  4. James Anders

    James Anders Member

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    Interesting how CO2 is now viewed as the only noteworthy pollutant.
     
  5. AudubonB

    AudubonB Mild-mannered Moderator Lord Vetinari*

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    It's not.
    The most egregious portion of the recent VW scandal was, for example, a function of their hiding NOX emissions data. NOX is primarily a human-health agent rather than a biosphere one.

    There is an understandable current, however, to base all GHGs on a CO2-equivalent, which is understandable and rational.
     

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