Double methane from biogas/biomethane supply chain

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A new study by researchers at Imperial College in London shows that methane leakage from biogas production and distribution systems are twice as high as previously thought. If biogas plants are to fulfil their potential to reduce greenhouse gas (GHG) emissions, then they must take action to reduce such leaks for both environmental and economic reasons.

The new Imperial study found that supply chains for biomethane and biogas release up to twice as much methane as the International Energy Agency (IEA)’s previous highest estimation.

Lead author of the study Dr Semra Bakkaloglu, of Imperial’s department of chemical engineering and sustainable gas institute, said: “Biomethane and biogas are great candidates for renewable and clean energy sources, but they can also emit methane. 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.”

Tim Elsome, managing director of anaerobic digestion (AD) specialists FM Bioenergy, recently spoke at the World Biogas Expo about the risks of biogas leakage and how they can be monitored, and welcomed the study.

“We know from our own commercial monitoring of AD plants just how much gas can be emitted from even a small leak, so these findings are not as surprising as they may seem,” he said. “However, they also show that the footprint of the global biogas industry could be much better. At a time of very high energy prices, the value of biogas means that it is far too valuable for plant operators to be losing it to the atmosphere, not to mention the environmental consequences of methane leakage.”

The new study reveals that 62 percent of the leaks were concentrated in a small number of facilities and pieces of equipment within the chain, which the researchers dubbed ‘super-emitters’, though methane was found to be released at every stage.

“In our own work we have found that 85 percent of surveyed plants suffer from some gas leakage, and that the UK biogas industry could be losing of 37 GWhe of energy generation potential a year, resulting in 6,000 tonnes of methane escaping into the atmosphere,” added Tim. 

“There are certain hotspots which can be more prone to leakage than other areas, such as cable grommets, valves, covers, compressors, membranes and pipe connections. It is highly likely that many of the ‘super-emitters’ identified by Imperial College are centred around these parts of plants.

“To minimise financial and environmental consequences from gas leaks, plant operators and managers should ensure regular Leak Detection and Repair (LDAR) programmes (including leak detection surveys) are carried out, usually annually unless a risk assessment suggests a different timetable.”


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