Blog: The role of biomethane in decarbonising the gas grid

Biogas is produced as a result of anaerobic digestion, a process where bacteria decompose organic waste in the absence of oxygen. “Until 2014, biogas has been burned to make electricity,” explains John Baldwin, CEO of biomethane producer CNG Services. “But nowadays the high availability of electricity from offshore wind has made this unnecessary. A better alternative for unlocking the potential of biogas is that of upgrading it to biomethane that can be injected in the gas grid.”

Biogas consists of about 45% methane, 43% CO2, and small percentages of other gases. By removing the CO2, it’s possible to obtain about 98% biomethane. This is pure enough to be injected into the gas grid, helping decarbonise our entire gas infrastructure.

But this is not the only benefit of biomethane. In the past, the CO2 removed during the production process used to be simply vented, but now it is possible to capture it, either to be repurposed for industrial applications – for example in breweries – or to be safely sequestered. This turns biomethane projects from carbon neutral to carbon negative, contributing to removing harmful CO2 from the atmosphere and thus helping in the fight against climate change.

Lastly, another benefit of biogas is that digestate – the material remaining at the end of anaerobic digestion –can be used as a good-quality fertiliser.

“Biomethane, CO2 and digestate are fairly attractive products for their respective markets,” comments Baldwin. “So there is growing interest in further developing the biomethane industry. There are several ways to increase the amount of biomethane we can currently have access to, and all could drastically improve our chances to decarbonise the gas grid.”

Boosting biomethane production  

Today, there are about 7 TWh/year of biomethane injected into the British gas grid. This figure is expected to gradually increase, reaching 20 TWh by 2030 – the equivalent of 20 70,000 tonnes liquefied natural gas (LNG) ships.

To reach – and ideally surpass – this target as fast and efficiently as possible, there is growing interest in producing biomethane in countries with a large availability of organic feedstock, such as Ukraine, and shipping it to the UK. Ukraine is renowned for its quality soil and favourable climate, which represent great resources for agriculture.

The presence of empty pipelines, which used to transport fossil gas to Germany, means that there is the infrastructure in place to extract biomethane from agricultural waste and ship it abroad. An agreement with Ukraine would allow the UK to source up to 10 TWh of biomethane a year.

Another interesting source of biomethane is through the upgrade of synthetic natural gas (SNG), which is produced through the gasification of woody biomass. ABSL is developing its first large-scale industrial bio-SNG plant at the Protos Energy Park in Ellesmere Port, Cheshire. The facility will be able to produce biohydrogen and biomethane, while capturing CO2 to prevent harmful emissions. Each ABSL plant can produce one TWh/year, and it’s reasonable to expect that about ten of them will be operational by 2030, for a total of 10 TWh/year.

Lastly, biomethane can be produced through the reaction of bio-CO2 and hydrogen. By capturing all available bio-Co2, we could reach 2.5 tonnes by 2030, which could react with hydrogen to produce up to 10 TWh/year of biomethane.

“A wide variety of sources can provide our country with up to 90 TWh/year of biomethane by 2030, covering 20% of the predicted demand,” adds Baldwin. “By 2050, this figure could be doubled, and biomethane production could be coupled with Direct Air Capture and Carbon Capture and Storage to reach 100% green gas.”

Many applications

What are the best applications for the high amount of biomethane we’ll be able to produce? With most of our electricity demand covered by offshore wind, it seems that the best applications are those where electrification isn’t an option.

“Right now, biomethane can be combined with natural gas for residential heating,” explains Baldwin. “But by 2030, we expect that to be replaced by high-temperature heat pumps and e-boilers. However, another promising application is in the decarbonisation of logistics, in particular for long-haul, heavy good vehicles.”

Electric and hydrogen trucks might be developed in the future, but biomethane trucks are already commercially available from brands such as Scania, Iveco and Volvo. Biomethane also represents a great opportunity for agricultural vehicles, with New Holland already commercialising biofuel tractors to replace their diesel equivalents.

There are also specialist applications, now at the R&D stage, that by 2040 could become standard, such as applications in the plastics or chemical industries.

Finally, biomethane could be stored to cope with periods of Dunkelflaute, which tend to happen every year. The German term Dunkelflaute refers to high-pressure spells characterised by low wind and cold weather. During these periods, wind energy supply can drop to as low as 1-2% of the usual output, and this can last for up to two weeks. In this case, biomethane can provide a valuable fuel alternative.

What support is needed?

Given the many applications of biomethane and its key role in accelerating the net zero transition, the UK Government is already taking action to support the biomethane market.

For example, the Renewable Transport Fuel Obligation (RTFO) mandates that suppliers of relevant transport fuel in the UK must be able to prove that a percentage of the fuel they supply comes from renewable and sustainable sources. Another important incentive is the Green Gas Support Scheme (GGSS), which provides tariff support for biomethane produced via anaerobic digestion that can be injected into the gas grid. 

The gas industry is also taking action to increase the amount of biomethane that reaches our pipelines. For example, stakeholders in the gas and biomethane industry are collaborating to accelerate the adoption of reverse compression systems. Reverse compression is a mechanism that allows biomethane to enter the grid in periods of low demand, when pipes would be normally full with natural gas and unable to receive new gases.

“Government initiatives and the collaboration of the overall gas industry are really helping in decarbonising the grid,” comments Baldwin. “The next step will be working to improve the planning process, which at the moment is a real barrier to further accelerate decarbonisation. There is no good reason why this shouldn’t be fixed, and I sincerely hope that excessive red tape for biomethane projects will become a thing of the past.”

“The UK is already using a wide variety of fuels to decarbonise its power system,” concludes Victoria Mustard, Decarbonisation Strategy Lead at Xoserve. “Electrification will certainly play a crucial role in reaching net zero, but it is not the only solution. By diversifying our approach to replacing fossil fuels, we can accelerate the net zero transition and achieve a more resilient and sustainable power system.”

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To learn more about how Xoserve supports the decarbonisation of gas, view our decarbonisation knowledge centre. 

If you have any questions, feedback or suggestions for our Decarbonisation Team, please email us. 

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