Fugitive methane emissions from an agricultural biodigester

The use of agricultural biodigesters provides a strategy for reducing greenhouse gas (GHG) emissions while generating energy. The GHG reduction associated with a biodigester will be affected by fugitive emissions from the facility. The objective of this study was to measure fugitive methane (CH4) emissions from a Canadian biodigester. The facility uses anaerobic digestion to produce biogas from cattle manure and other organic feedstock, which is burnt to generate electricity (1 MW capacity) and heat. An inverse dispersion technique was used to calculate emissions. Fugitive emissions were related to the operating state of the biodigester, and over four seasonal campaigns the emission rate averaged 3.2, 0.8, and 26.6 kg CH4 hr−1 for normal operations, maintenance, and flaring periods, respectively. During normal operations the average fugitive emission rate corresponded to 3.1% of the CH4 gas production rate.

► Biodigesters reduce greenhouse gas emissions.
► Net emission reduction affected by fugitive emissions.
► Fugitive CH4 measured at agricultural biodigester (1 MW generating capacity).
► Emissions were 3.1% of gas production.
► Emissions lower than assumed in carbon credit protocols.