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Natural gas is primarily methane (CH4) with about half the energy coming from burning hydrogen, compared to 100% coming from carbon in the case of coal, so you

Natural gas is primarily methane (CH4) with about half the energy coming from burning hydrogen, compared to 100% coming from carbon in the case of coal, so you get about %50 CO2 for the same amount of energy produced.

labster 10y ago
I hope you mean that the energy from burning methane comes from breaking C—H bonds, not burning hydrogen gas.
- syrrim 10y ago
  Breaking bonds requires input energy, rather than producing energy. Once the bonds are broken, you have free floating hydrogen and carbon. These can then form new bonds with oxygen, releasing energy as they do.
- semi-extrinsic 10y ago
  I'm pretty sure that's what they meant. But actually, converting methane into H2 is a serious proposal for essentially eliminating CO2 emissions from NG usage. The idea is that you do this at centralised facilities, using various iterations on Steam Methane Reforming (SMR); this method takes CH4 and H2O as input and produces separated H2 and CO2 as output. SMR is already being done at large scale for H2 production (IIRC we would only have to scale it up by 100x), but currently the CO2 is mainly released back to the atmosphere. If instead one would store the CO2 permanently underground in old gas reservoirs and saline aquifers, NG would give us a mostly clean energy source. I really hope we will see this happen, but it depends a lot on government action...
  - twic 10y ago
    There's a nifty new method for extracting hydrogen from methane which involves bubbling it through molten tin: http://www.chemicalprocessing.com/articles/2015/researchers-crack-methane-cracking/ http://www.chemicalprocessing.com/articles/2015/researchers-... The carbon comes off as powder, which is easier to sequester than CO2 because you can just throw it in the bin.
    - afarrell 10y ago
      How much energy does it take to mine tin and how available is it? I'd thought it was not all that common, but I might just be thinking of near-surface tin deposits near Mesopotamia.
      - twic 10y ago
        Loads of energy - as much as two Cornish pasties a day! [1] More seriously, i don't actually know. I think of tin as being quite cheap. Note that it's a catalyst in this reaction, so you don't need a giant supply of it. [1] http://www.cornishpastyassociation.co.uk/about-the-pasty/history-draft/ http://www.cornishpastyassociation.co.uk/about-the-pasty/his...
  - alephnil 10y ago
    You can even pyrolyse methane, and the result us pure hydrogen and pure carbon. This is a side reaction to the most commonly process used to produce acetylene from methane, and this can be tuned to produce mostly carbon and hydrogen. The disadvantage of this method is that it is less economical, since only half the hydrogen is produced per unit of methane compared to steam reforming.

labster 10y ago

I hope you mean that the energy from burning methane comes from breaking C—H bonds, not burning hydrogen gas.

syrrim 10y ago
Breaking bonds requires input energy, rather than producing energy. Once the bonds are broken, you have free floating hydrogen and carbon. These can then form new bonds with oxygen, releasing energy as they do.
semi-extrinsic 10y ago
I'm pretty sure that's what they meant. But actually, converting methane into H2 is a serious proposal for essentially eliminating CO2 emissions from NG usage. The idea is that you do this at centralised facilities, using various iterations on Steam Methane Reforming (SMR); this method takes CH4 and H2O as input and produces separated H2 and CO2 as output. SMR is already being done at large scale for H2 production (IIRC we would only have to scale it up by 100x), but currently the CO2 is mainly released back to the atmosphere. If instead one would store the CO2 permanently underground in old gas reservoirs and saline aquifers, NG would give us a mostly clean energy source. I really hope we will see this happen, but it depends a lot on government action...
- twic 10y ago
  There's a nifty new method for extracting hydrogen from methane which involves bubbling it through molten tin: http://www.chemicalprocessing.com/articles/2015/researchers-crack-methane-cracking/ http://www.chemicalprocessing.com/articles/2015/researchers-... The carbon comes off as powder, which is easier to sequester than CO2 because you can just throw it in the bin.
  - afarrell 10y ago
    How much energy does it take to mine tin and how available is it? I'd thought it was not all that common, but I might just be thinking of near-surface tin deposits near Mesopotamia.
    - twic 10y ago
      Loads of energy - as much as two Cornish pasties a day! [1] More seriously, i don't actually know. I think of tin as being quite cheap. Note that it's a catalyst in this reaction, so you don't need a giant supply of it. [1] http://www.cornishpastyassociation.co.uk/about-the-pasty/history-draft/ http://www.cornishpastyassociation.co.uk/about-the-pasty/his...
- alephnil 10y ago
  You can even pyrolyse methane, and the result us pure hydrogen and pure carbon. This is a side reaction to the most commonly process used to produce acetylene from methane, and this can be tuned to produce mostly carbon and hydrogen. The disadvantage of this method is that it is less economical, since only half the hydrogen is produced per unit of methane compared to steam reforming.