How can one farm having a much higher animal population than another end up with fewer emission reductions than the other if both install similar digestion systems?
This question often arises when discussing emission reductions. The discrepancies sometimes seen between methane reduction estimates for various farms are a result of different ‘baseline’ scenarios. The ‘baseline’ is essentially how the operation would be handling the manure if there was no digester. Certain baselines result in more methane emissions; storage lagoons, for instance, will emit far more methane than manure stacks. Therefore, a digester project that produces large amounts of biogas but originally managed manure in stacks may not reduce emissions by as much as a project on a smaller farm that originally used a storage lagoon to handle manure. There can be other factors that influence emission reductions, but different baseline cases account for most of the disparity.
