Field measurements of fugitive methane emissions from three Australian waste management and biogas facilities

Methane emissions along biomethane and biogas supply chains are underestimated

“…The residual gas potential, digestate temperature, substrate amount, level of filling, and meteorological conditions all have a significant influence on the emission rate from open digestate storage tanks ll and lagoons. 15,19,43,44 Figure 3 clearly demonstrates that the closed tanks can still emit CH 4 , although emissions from closed tanks can be avoided with improved covering materials, effective design, and regular maintenance. The facilities should consider becoming accredited under the Publicly Available Specification (PAS) 110 standards, 45 which recommend coverage of digestate to diminish emissions.…”

“…Substrate storage tanks and biomass-receiving units, such as feedstock piles, runoff ponds, screw conveyors, and mixing (homogenization) tanks, are the main sources of emissions, although few studies have investigated emissions from this stage. 15,17,19,22,46,49,[59][60][61] Feeding system emissions are included in substrate storage emissions (see Table S1). These emissions are mainly fugitives, predominantly from open storage tanks and feeding units.…”

“…Previously reported CH 4 emissions from hygienization tanks, anaerobic digesters, and post-digesters are included in this stage (see Table S1). [15][16][17]19,41,49,50,59,[62][63][64][65][66][67][68][69][70][71][72][73][74][75][76] These emissions are fugitives and venting. Biomethane production: Biogas upgrading process The biogas can be upgraded into biomethane by removing impurities.…”

“…19 Emissions data by digestate types (e.g., solid or liquid) and storage properties (closed or open tanks) were collected from previous studies (see Table S1). [15][16][17]19,23,24,43,44,49,50,59,62,67,[71][72][73]85,[87][88][89][90][91][92] The emissions are mostly fugitives and venting from open PRVs. The emissions associated with digestate use, such as fertilizer application and post-composting, were excluded from the supply chain because digestate is not always used in the operation area and their emissions are only reported in a few studies.…”

A comparative study of biogas and biomethane with natural gas and hydrogen alternatives

“…Although recent studies demonstrate that AD emits considerable amounts of CH 4 , 8,14 there is a paucity of information on what would happen to biowaste material if not utilised for biogas generation and if gas were obtained from other sources, such as natural gas or hydrogen. Without this comprehensive counterfactual, it is difficult to fully assess the merits of biomethane production in the context of climate change mitigation.…”