And, of course, you can lable "Farmhouse Cheddar", but not "Fake Cheddar" ;)
And don't forget the energy requirements don't end at slaughter. The assorted body parts are then processed, stored (in cold rooms, if you're lucky - for a long time if you're not) and distributed.
What would be hugely interesting would be the energy requirements needed to get a frozen lasagne onto someone's plate.
Re: biofuel - doesn't it depend on which sort? Ethanol is energy intensive, but I'd guess methane farming, while smelly and unpleasant, would be much less so. How much methane would the sewage from a large city produce, and what would the energy equivalent be?
As for gathering methane from city waste... you must have missed Nomad's smelly diary Nothing is 'mere'. — Richard P. Feynman
As for agriculture, certainly we have to distinguish between biodiesel (rapeseed/sunflower-seed oil to be used in diesel engines) and ethanol (alcohol to be used in petrol/gasoline engines) -- and then again between different crops used to produce ethanol, since there are considerable efficiency differences. (Sugar cane > sugar beet > maize/corn > wheat etc).
Personally, as far as Europe is concerned, i'm afraid of a scramble to obtain subsidies for ethanol operations based on dubious efficiency, on the part of agri-lobbies (sugar-beet and maize in particular). Ethanol is being touted by pundits as a miracle fix for oil worries. Which it ain't gonna be.
