Satisfying the COP26 Methane Pledge

Methane emissions were the focus of much scrutiny at COP26, and not without good reason: the Intergovernmental Panel on Climate Change’s latest report¹ estimates that a 0.3 per cent reduction per year in methane is equivalent to net-zero for carbon dioxide — there would be no additional warming if this level of reduction is achieved.

The significance of methane emission on global warming was matched only by the strength of language of the delegates at COP26: Ursula von der Leyen was one such delegate, pronouncing, “Cutting back on methane emissions is one of the most effective things we can do to reduce near-term global warming and keep to 1.5°C”. With methane being responsible for about 30 per cent of global warming to date, perhaps the European Commission president’s comments should not be taken as hyperbole.

Scope of UK Methane Emissions

Turning to the UK, in 2019 Department for Business, Energy & Industrial Strategy (BEIS) estimated that methane accounted for about 12% of UK emissions when weighted by global warming potential.² Therefore, satisfying the methane pledge should have a marked impact on the UK’s warming effect of the UK’s GHG emissions.

With the UK being a signatory to the methane pledge, we should expect eyes to now turn to identifying the main sources of the UK’s methane emissions and identifying the cost-effective solutions to minimising if not eradicating those emissions.

The most recent BEIS report on GHG emissions² doesn’t provide a sector-by-sector comparison of the UK’s methane arisings (instead presenting a comparison of each sector’s contribution to collective GHG emissions), but BEIS’s predecessor, Department for Energy & Climate Change did publish a report  in 2010³ that estimated the following split of the UK’s methane on a sector-by-sector basis:

Clearly tackling methane emissions in the agriculture and waste management sector should be a priority for the UK.

Methane sources in these sectors arise in part due to the anaerobic fermentation of organics arising from:

• the storage of slurry and manures in uncovered or permeable-covered slurry stores; and
• the rotting and fermentation of crops left in the field (which can often occur where the farmer cannot find a market for the produce, or it is rejected by the purchaser);
• the rotting and fermentation of crops that are harvested but rejected (perhaps because they are deemed unworthy for sale to customers);
• anaerobic fermentation of foodwaste in landfill when mixed waste is send to landfill without pre-treatment; and
• the storage of by-products from meat and dairy processing facilities.

Steps have already been implemented to work towards avoiding the methane emissions identified above:

• pig and poultry farmers are already required to cover lagoons (subject to exceptions), and
• local authorities will be required to provide foodwaste collections for residential properties from 2023),

The steps mentioned above provide only part of the solution: those materials also need to be treated in a manner that achieves the maximum environmental benefit.

The UK is fortunate that it has a well-established anaerobic digestion sector that can make use of these organic “waste” streams. As well as avoiding the release of methane gas into the atmosphere, AD can green biogas (a valuable fuel), capture carbon (as part of the biomethane upgrading process) and create fossil-fuel-free fertiliser and soil conditioner (avoiding further GHG emissions in the Agriculture sector).

The question is what steps can be taken to (a) maximise the collection of the organic material; and (b) ensure that the material is directed towards solutions such as AD that have the potential to add value to the various “waste” streams and turn a burden of waste into a market for a resource. One would now expect the UK Government, as signatory to the methane pledge, to identify the means through which this might be achieved.

Sources/Footnotes:

¹ https://www.ipcc.ch/assessment-report/ar6/

²https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/957887/2019_Final_greenhouse_gas_emissions_statistical_release.pdf

³ https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/48424/5556-methane-factsheet.pdf