Many countries are replacing heavily carbon-emitting sources of energy, like natural gas, coal and oil, with biomethane and biogas, which are produced from the breakdown of organic matter and release less of both CO2 and methane, making them greener energy alternatives.
However, researchers at Imperial College London have identified potential risks in energy supply chains for these climate-friendlier gases, concluding that more efforts should be made to reduce methane leakage.
The study, published in One Earth journal, found that supply chains for biomethane and biogas release more than twice as much methane as the International Energy Agency (IEA)’s previous estimation. It also reveals that 62% of these leaks were especially concentrated in a small number of facilities and pieces of equipment within the chain, which they call ‘super-emitters’.
The researchers say urgent attention is needed to fix the methane leaks, and knowing precisely where the majority of them are happening will help production plants to do so.
Lead author of the study Dr Semra Bakkaloglu, of Imperial’s Department of Chemical Engineering and Sustainable Gas Institute, said: “For them to really help mitigate the warming effects of energy use, we must act urgently to reduce their emissions. We want to encourage the continued use of biogas and biomethane as a renewable resource by taking the necessary actions to tackle methane emissions.”
The biomethane industry suffers from poorly designed and managed production facilities as well as a lack of investment for modernisation, operation, and monitoring when compared to the oil and gas industry.
According to Science Daily “The researchers analysed 51 previously published studies on mobile methane measurements and site data taken from emission sources along the biomethane and biogas supply chain. They analysed the data and calculated the total methane emissions using a statistical model called Monte Carlo. This allowed them to consider all measurements of total supply chain emissions at each stage of the chain, which they then compared with the off-site emissions reported from whole-site measurements in previously published studies.
“They found that the supply chains release up to 343 g of CO2-equivalent methane per megajoule higher heating value, which may account for 18.5 megatonnes of methane per year. IEA estimates had reported emissions as just 9.1 megatonnes in 2021.
“While overall methane emissions from biogas and biomethane are lower than those from oil and natural gas, the amount of methane released from their supply chains relative to total gas production is much higher than for oil and gas.”
The reasons identified behind the leakiness of supply chains are intermittent emissions patterns; insufficient usage of process equipment; and inadequate operations and maintenance strategies.
Dr Bakkaloglu said: “To prevent biogas methane emissions negating the overall benefits of biogas use, urgent attention is needed including continuous monitoring of biogas supply chains. We believe that with the proper detection, measurement, and repair techniques, all emissions can be avoided. We need better regulations, continuous emission measurements, and close collaboration with biogas plant operators in order to address methane emissions and meet Paris Agreement targets.”