This meta-analysis quantifies the changes in greenhouse gas (GHG) emissions from dairy farms, caused by anaerobically digesting (AD) cattle manure. As this is a novel quantifiable synthesis of the literature, a database of GHG emissions from dairy farms is created. Each case in the database consists of a baseline (reference with no AD system) and an AD scenario. To enable inter-study comparison, emissions are normalised by calculating relative changes (RCs). The distributions of RCs are reported by specific GHGs, and operation units. Non-parametric statistical tests are applied to the RCs in order to identify statistical di↵erence of AD with respect to baseline scenarios (Wilcoxon rank test), correlations (Spearman test) and best estimation for changes in emissions (Kernel density distribution estimator). From 749 studies identified, 30 papers yield 89 independent cases. The median reductions in emissions from the baseline scenarios, according to operation units are: -71.2% (n.s.) for storage, -76.7% for field application of slurries, -100.7% for o↵set of energy from fossil fuel and -91.6% (n.s.) for o↵set of inorganic fertilisers. The leaks from digester are found to significantly increase the emissions from baseline scenarios (median=+1.50%).

MIRANDA Nicole D.;  TUOMISTO Hanna Leena;  MCCULLOCH Malcolm D.; 

2015-12-09

AMER CHEMICAL SOC

JRC95108

0013-936X,   

http://pubs.acs.org/doi/abs/10.1021/acs.est.5b00018,    https://publications.jrc.ec.europa.eu/repository/handle/JRC95108,   

10.1021/acs.est.5b00018,