I'm looking for methodologies to compare the costs a food production requires with the gains it delivers (not in economic terms).
I'm aware of energy returned on investment. Are there other methods used in literature (also including qualitative approaches)?
To be a bit more precise (or rather unprecise?): Costs may include the input of fuel, feed, energy in general or - for me most interesting - the environmental burden to our environment (for example the carbon footprint) while gains should refer to the nutritional output of the product (energy, protein content, other (rare) nutrients).
The purpose is to link (or discuss) the burden of food production chains to their benefits but to find a unit that is quantitative comparable (except the pure energy content) doesn't seem so trivial - so I'm very happy with suggestions how to approach that - in the best case with a link to studies that employed the method.