28 Mar 2009
On the subject of methane from cattle surely the arguement is the same as using biomass for energy the carbon is not coming from fossil fuel but grass which has only recently grown and so is a closed loop. The amount of carbon coming out of the cow is the same as that they have eaten whether is is co2 or ch4 or am I missing something
30 Mar 2009
I understand what you're saying, but there is actually a significant difference.
With biomass, most of the carbon released is in the form of CO2 - and the carbon that plants absorb when growing is also CO2 - therefore the two balance out (more or less, depending on what aspects of the total biomass energy lifecycle you include).
However, with livestock 'emissions', the carbon is released as methane. Methane has a higher value (equivalent carbon dioxide value) in terms of climate change and global warming. I.e. molecule for molecule, methane is more damaging than CO2 ( more damaging in fact), despite the fact both molecules contain one carbon atom (O2 and H4).
So, although the net carbon input and output from cows is more or less equal, the form that carbon takes is very important when assessing the climate impact, thus reducing methane emissions would definitely be beneficial.
I hope that's useful.