Methane emissions along biomethane and biogas supply chains are underestimated

Fossil-Fuel and Food Systems Equally Dominate Anthropogenic Methane Emissions in China

“…The CH 4 emissions from septic tanks and biogas digesters are calculated following the calculation method in Huynh et al (2021), Diaz et al (2011), and Bakkaloglu et al (2021) E normals normale normalp normalt normali normalc = ∑ r normalE normalF × N r × 365 E normalb normali normalo normalg normala normals = ∑ i , r normalE normalF × A i , r where EF is the emission factor from septic tanks (EF = 11.46 g/household/day) , and biogas digesters (6.9 kg/t feedstock); N r is the number of households in region r ; A i , r is the amount of feedstock for animal category i in region r , which is collected from the China Statistical Yearbook (2021) …”

“…where EF is the emission factor from septic tanks (EF = 11.46 g/household/day) 39,40 and biogas digesters (6.9 kg/t feedstock); 41 N r is the number of households in region r; A i,r is the amount of feedstock for animal category i in region r, which is collected from the China Statistical Yearbook (2021). 20 The CH 4 emissions from biomass burning are calculated as (28) where P r str refers to the straw production in region r; Pro r field is the proportion of straw field burning; EF field is the emission factor of straw field burning, and we adopt 3.46 g/kg in this study; E field is the burning efficiency of straw field burning, and we adopt 82.3% in this study; 15 C r str and C r fw is the amount of residential straw burning and firewood burning; EF r str and EF r fw are the emission factors of residential straw burning and firewood burning, and we adopt 4.09 and 2.74 g/kg in this study, respectively.…”

The Danish national effort to minimise methane emissions from biogas plants

“…Open digestate storage tanks are a known, significant source of CH 4 emission at biogas plants (Bakkaloglu et al, 2022;Baldé et al, 2016;Daniel-Gromke et al, 2015;Liebetrau et al, 2017Liebetrau et al, , 2013Reinelt et al, 2017). Eliminating this source of emission may be the cause of the relatively low CH 4 loss for the larger facilities shown in Fig.…”

Technological avenues and market mechanisms to accelerate methane and nitrous oxide emissions reductions

“…Approximately 72% of these emissions arise from the unit processes involved in anaerobic sludge digestion, namely the “the gravitational thickener for the primary sludge, the centrifuge, the buffer tank for the effluent of the digester, the storage tank that contains the dewatered sludge, and the methane slip from the gas engines.” 85 In general, anaerobic digesters are often used to generate CH 4 that is subsequently utilized as an energy source at the wastewater treatment plant; however, CH 4 emissions can occur from leaks along the process train, uncovered tanks, and incomplete combustion of the produced biogas. 83 , 86 Leaks from biogas and biomethane supply chains in particular may be responsible for up to 0.0185 Gt CH 4 emissions per year, 87 almost 5% of the 2019 global CH 4 emissions reported in Table 1 . CH 4 can be emitted from centralized aerobic wastewater treatment processes as well.…”