[HN Gopher] Burning Buried Sunshine (2003)
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       Burning Buried Sunshine (2003)
        
       Author : dredmorbius
       Score  : 25 points
       Date   : 2021-08-17 20:05 UTC (2 hours ago)
        
 (HTM) web link (plus.maths.org)
 (TXT) w3m dump (plus.maths.org)
        
       | criticaltinker wrote:
       | _> to produce one litre of petrol it takes 1.29 kg of oil, of
       | which 85% (1.1 kg) is carbon. And as only 1 /10,750 of the carbon
       | remains from the plants that were buried millions of years ago,
       | our one litre of petrol is the result of 1.1 x 10,750 = 11,825 kg
       | of carbon from ancient plants. Finally, as plants are
       | approximately half carbon, that means that 23.65 tonnes of plants
       | were required to make just one litre of the petrol available at
       | your local station _
       | 
       | Wow, and this is a lower bound because it doesn't even consider
       | manufacturing and distribution.
       | 
       | My cognitive dissonance at the gas station is approaching an all-
       | time high.
        
         | version_five wrote:
         | Maybe a pedantic point: I think there is a difference between
         | saying 24 tonnes of plants were "required" and saying 1 L
         | represents 24 tonnes of plants. The same way 1 kg of iron
         | represents some, I imagine incomprehensible amount of fusion.
         | But if you want 1 kg of iron, you don't need to go out and
         | expend that energy, any more than you need to go out and expend
         | 24 tonnes if plants. Both are basically finite, with geological
         | or astrophysical origins, rather than something we can make
         | again on human timescales
        
           | Robotbeat wrote:
           | The difference being that iron is recyclable and can be re-
           | smelted (if oxidized) without needing to be fused in stars
           | whereas with fossil fuels we aren't so lucky. (However,
           | synthesizing hydrocarbons IS feasible.)
        
           | _3u10 wrote:
           | Yeah, its almost as annoying as when people talk about
           | "using" water. The cycle time is 9 days, in 9 days it comes
           | back down as rain, very little water ever gets "used".
        
       | lovecg wrote:
       | A pedantic point, but hydrocarbons don't actually "store energy".
       | The energy from the combustion actually comes from the oxygen! We
       | just don't think of it as the "fuel" since it's so abundant.
       | 
       | A better intuition is this: plants, etc. used energy to create
       | two products, oxygen (which went into the atmosphere) and
       | hydrocarbons (buried in the ground). When we recombine them and
       | add heat, we reconfigure some bonds and release energy in the
       | oxygen bond. The hydrocarbons act as a "sponge" for the oxygen
       | atoms, and the denser the sponge the more energy we can release.
       | 
       | If it was the oxygen buried underground we would probably call it
       | "fuel"!
        
         | Robotbeat wrote:
         | Whether you consider the energy stored in the oxygen or the
         | hydrocarbon doesn't particularly matter. The energy is in them
         | being split apart.
         | 
         | I read a proposal to send an aircraft to Titan and bring along
         | oxygen as the energy source to burn with the methane in the
         | atmosphere. (It works... sort of. In a methane and oxygen
         | stoichiometric reaction, the oxygen is 4/5ths the mass so it's
         | not nearly as good of a deal as it is on Earth.)
        
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       (page generated 2021-08-17 23:00 UTC)