Methane (CH4) is a potent greenhouse gas pollutant. It has a significantly shorter lifetime than carbon dioxide (CO2). Methane has a Global Warming Potential of over 80 times the carbon dioxide’s one over the first 20 years after it reaches the atmosphere. It is responsible for half the 1°C heat gain since the pre-industrial era. Methane is the main component of natural gas, which is a relatively clean fossil fuel. It is also the second gas contributing to the greenhouse effect after carbon dioxide. But what is the Global Methane Pledge?

It is therefore key to quickly reduce methane emissions if we want to keep global warming to 1.5C within reach. US President Biden and EU President Von der Leyen announced during COP26 that they will commit to reducing methane emission through the Global Methane Pledge. A total of 109 countries have joined, including United Kingdom, and Canada.

The Global Methane Pledge requires taking action to reduce global methane emissions by more than 30% by 2030 from 2020 levels. This would avoid 0.2C warming by 2050.

But where does Methane come from?

The main contributors of methane are:

• Agriculture; rice cultivation produces methane as microbes produce methane in a process called ‘methanogenesis’ in the water filled rice fields.
• Fugitive emissions mainly from fossil fuel production, from extraction to transport of oil and gas.
• Waste: not only from landfills but also from poor management of Anaerobic Digestion and Composting facilities with significant methane leakage.
• Livestock (cattle, sheep, and goats) produce methane.
• Land use change and forestry from the incomplete combustion of burning of agricultural waste, and forests.

But, how to effectively reduce methane emissions? First, it is key to map the sources of methane.

Methane sources

The main issue with methane is that it is sometimes difficult to locate the source. But we are getting better at it. From using limiting ground sensors in oil industry and landfills. Today we are using aircraft and satellites to detect methane emissions from space.

Recent research shows that a few ‘super emitters are responsible for a significant share of methane emissions, particularly in the fossil fuel industry. Carbon Mapper is a US non-profit that is tracking and mapping methane and carbon dioxide from air and space (planes and satellites). They have pinpointed almost 6,000 point sources in the US alone.

There are two basic categories of methane emitters. First, point sources are plumes of highly concentrated methane. Typically created from the oil and gas infrastructure, landfills, wastewater treatment plants, manure, anaerobic digestion, composting facilities, and wildfires. Second, area sources are typically distributed over large areas from 1-100 km. An example can be the methane from agricultural sources or livestock. These are harder to monitor as the concentration of methane is low and over a large surface.

The NASA Methane Source Finder has identified over 4,000 plumes. They have cross-referenced them with existing infrastructure for California: Agriculture, Energy, and Waste. This exercise provided great results. The good news is that it is possible to fix most local sources.

For example, by fixing leaks in the pipes of oil and gas infrastructure, avoid landfilling and better managing livestock. The site distribution follows the Pareto principle: by fixing 20% of the leakages, almost 80% of emissions (kg/hr) are avoided. Focusing on key identified sources, it is possible to effective abate methane emissions.

Although this study focuses on specific areas of the United States, the results are global. They can be applied to other areas.

How to reduce methane emissions

Oil and gas industry

The oil and gas industry needs better practices. The right framework needs to be in place enforcing that owners and operators of the infrastructure fix the leaks. Several programs with satellite imagery are targeting the gas infrastructure to identify leakages and fix them. Fixing the leaks will not solve the CO2 problem. In addition, clean fuels like hydrogen need to be used.

The International Energy Agency (IEA) states in a report from January 2021 that “Reducing methane emissions from oil and gas operations is among the most cost-effective and impactful actions that governments can take to achieve global climate goals.” IEA developed a regulatory roadmap and toolkit to define the framework to reduce methane emissions by 70%.

Waste

Methane is generated by the decomposition of organic materials without air. This happens mostly in Landfills. Alternatives such as designed compostin and AD facilities limit methane emissions although not totally. Waste to Energy is yet another alternative to generate electricity and heat from waste that cannot be recycled. In Denmark the technology together with Carbon Capture will allow Copenhagen to become Carbon Neutral by 2025 (Copenhill).

In 2001, there were over 1,000 landfills collecting landfill biogas worldwide. The landfills that capture biogas in the US collect about 2.6 million tonnes of methane annually. 70% of biogas generates heat and/or electricity, the rest is flared. However, not all generated gas is collected, efficiency ranges from 27%-80%.

Although other treatment alternatives for waste generate less methane. Landfill is the cheapest for developing countries. Globally, landfills produce 75 billion cubic meters of methane per year. Less than 10% of this potential is captured and utilized. Banning landfill is important, but there is a long way to go. According to US EPA, in 2018, over 146 million tons of MSW were landfilled of a total generation of 292 million tons in the US. Only 69 million tons were recycled. Even if landfill biogas is collected, too much is leaked.

Is the Global Methane Pledge feasible?

Existing technologies can cut global methane emissions by 57% by 2030. In addition, 40-50% of the methane emissions in oil and gas operations provide savings higher than the investment costs. The value of the captured methane is higher than the abatement measures. In waste management, it will require baning landfills, and installing landfill gas capture systems in existing ones (if possible). In agriculture, livestock, and forest use sectors there are other opportunities to abate methane emissions.

Methane mitigation is needed to keep warming to 1.5C to support broader decarbonization strategies. The abatement can come at no costs in some sectors, and with low costs in others, below $600 per tonne of methane. It would correspond to 21 $/tCO2e (considering IPCC Fifth Assessment Report’s GWP100 value of 28) or even 7 $/tCO2e, considering a shorter time frame of 20 years, which might be more important for the climate emergency.

We need firm commitments, the right framework, and the right financing to make it happen. Which is much more than the Global Methane Pledge announcement at the COP26.

Duren, R. M., Thorpe, A. K., Foster, K. T., Rafiq, T., Hopkins, F. M., Yadav, V., … Miller, C. E. (2019). California’s methane super-emitters. Nature, 575(7781), 180–184. https://doi.org/10.1038/s41586-019-1720-3

A Third of California Methane Traced to a Few Super-Emitters, JPL, NASA

IEA (2021), Driving Down Methane Leaks from the Oil and Gas Industry, IEA, Paris https://www.iea.org/reports/driving-down-methane-leaks-from-the-oil-and-gas-industry

United Nations Environment Programme and Climate and Clean Air Coalition (2021). Global Methane Assessment: Benefits and Costs of Mitigating Methane Emissions, Nairobi.

The Global Methane Pledge site.