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Waste Methane

The waste sector is one of the world’s largest methane emitters

Waste is the world’s third-largest source of anthropogenic methane emissions, accounting for 20% of the global total with the majority stemming from solid waste decaying in dumpsites and landfills. Waste methane emissions are tightly tied to growth and development in much of the world and are projected to increase significantly without fast action.

Landfill waste

A large and growing challenge…

Humans generated 2.24 billion metric tons of solid waste in 2020.

The World Bank estimates human generated solid waste will increase 73% by 2050.

Methane emissions from waste (solid waste and wastewater) are expected to increase by 13 megatons per year over the next decade alone.

What is waste methane?

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We can take action now

Cost-effective, readily available solutions exist to reduce emissions from the waste sector today, with up to 60% of mitigation measures having low or negative costs, including:

  • Food Waste Prevention
  • Organic Waste Diversion
  • Dump Site Rehabilitation and Landfill Design & Operation

Many national and subnational governments have already committed to reducing their methane emissions, with some setting specific goals and targets to reduce waste methane. Some countries have enacted policies to improve waste management and reduce waste methane emissions – tapping into co-benefits that include:

  • Reduced air pollution and improved environmental and public health
  • Cost savings and improved cost recovery
  • Improved land values
  • Job creation and improved working conditions

…but challenges persist

Current barriers to methane mitigation in the waste sector include, but are not limited to:

  • Lack of understanding of the importance of reducing waste methane emissions
  • Lack of information and data identifying sources of methane from landfills and dumpsites
  • Lack of access to best practices and evidence-based methane mitigation measures
  • Lack of funding and capacity within national and subnational governments

Our work in waste methane

CATF is working to help governments around the world understand and prioritize the waste sector in methane mitigation plans and goals. We build local capacity and advise on policies that tighten controls on landfill methane emissions and improve organic waste management. We also support financial instruments and other solutions that can be used to scale up mitigation and dramatically reduce methane from solid waste on a global scale. We focus on:

  • Raising awareness around the importance of reducing methane emissions from the waste sector
  • Developing new and innovative tools to increase understanding of waste methane emissions, share data, best practices, and solutions to spur action
  • Engaging with governments around the world to conduct detailed assessments of methane emissions, building capacity through education, training, technical assistance, policy design, and peer-to-peer knowledge sharing
  • Utilizing state-of-the-art measurement technologies from ground, air, and space to highlight the methane pollution problem and catalyze effective, data-driven decision-making

Waste methane FAQs

How does waste contribute to climate change?

Waste sector methane emissions stem from the breakdown of organic waste — food and yard waste, as well as paper, cardboard, and wood — in anaerobic (i.e., oxygen free) environments. At a high-level, waste sector emissions can be split into emissions from solid waste and wastewater. Solid waste emissions from landfills and dumps represent the majority of methane emissions from the sector. Here, organics decay slowly over decades, releasing what is commonly known as landfill gas (LFG), a combination of methane and carbon dioxide.

How can we reduce emissions from solid waste?

Proven, cost-effective solutions to reducing methane emissions from solid waste include:

  • Food Waste Prevention involves reducing the amount of food that we consider to be “waste,” and diverting it for use. In practice this can mean promoting “ugly” produce programs, revising food best-by and use-by dates so good food is not thrown away, linking large producers of food waste to food banks, and raising awareness of the importance of waste prevention, among a variety of other solutions.
  • Organic Waste Diversion is the next step in keeping this waste out of landfills. Organic waste can be separated at the source by waste generators (i.e., keeping a separate bin for food waste in your kitchen) or at a facility designed for separating mixed municipal waste. The two most common organic waste treatment options are composting and anaerobic digestion.
  • Dump Site Rehabilitation and Landfill Design & Operation is critical to capturing methane generated from organics that are not diverted, as well as waste already in landfills and dumps. Open dumps, present in much of the developing world, pose human and environmental health and safety risks. Though up-front costs are high, dumps can be redesigned to include environmental control systems, including technologies to mitigate emissions. Existing sanitary landfills with LFG capture systems can focus on maximizing collection and use of the generated gas.

How much do solutions to waste methane cost?

Cost-effective solutions to reduce emissions from the waste sector are available, with up to 60% of mitigation measures having low or negative costs. The average cost of methane mitigation in the waste sector* is $2 per ton CO₂e but can range from -$74 to $50 per ton CO₂e. These values include solid waste and wastewater mitigation measures. Costs were calculated based on measures identified in the Global Methane Assessment6 and converted from a CH₄ basis to CO₂e using the AR6 20-year global warming potential.

Does solid waste produce other climate pollutants?

Yes, in places where waste collection and management services are lacking or non-existent, open burning of solid waste is common. Incomplete combustion of this waste results in emissions of black carbon and other air pollutants. Black carbon is a short-lived climate pollutant and component of fine particulate matter – which causes a number of human health (e.g., premature death, heart attacks, asthma and respiratory problems, etc.) and environmental concerns.

How do we currently estimate emissions from solid waste?

Most national greenhouse gas inventories use something called a First Order Decay (FOD) model to estimate emissions from landfills. FOD models assume that organic waste decays slowly over time at the landfill site. The main pieces of information that these models use to estimate GHG emissions include the mass of solid waste in a landfill or dump, the waste decay or methane generation rate, and the methane generation potential – the latter two values vary based on type of organic waste (i.e., food, garden, wood, paper, etc.). These models also consider methane captured through landfill gas capture systems, if present, and methane oxidized by soil covers. However, these models are increasingly criticized for being based on old field studies and faulty assumptions. Studies show that the accuracy of the models increase as more site-specific data is used, but this data is often not collected, and default values are utilized.

How can satellites and remote sensing help us to better understand waste methane emissions?

Advanced cameras installed on aircraft and satellites promise to give us a bird-eyes view of landfill emissions. These remote sensing instruments observe the landfill’s sunlit surface and look for minute changes in radiation intensity that could bare the signature of large methane concentrations above the landfill. These techniques were well known to scientists for a long time but have recently made great strides in terms of practical applications due to improved technology, low-cost access to space, and global interest in methane monitoring, especially in the Oil & Gas industry. Such remote sensing instruments are already providing new insights for landfill emissions around the world. For example, in a recent study, scientists used a combination of satellite instruments to monitor emissions from landfills in Buenos Aires, Delhi, Lahore, and Mumbai; they detected emissions reached a staggering 29 tonnes of CH₄ per hour and up to 2.6 times the officially reported values. Moreover, they found that landfill emissions can reach up to 50% of the emissions of the city.

What are the benefits of improving solid waste management practices?

Improving solid waste management to mitigate the climate impacts of the sector has a number of co-benefits:

  • Public and human health impacts from reduced transportation and open burning of waste; reduced odors and pests from organic waste decomposition.
  • Contribution to renewable energy goals and energy security if landfill gas or biogas from anaerobic digestion is used to generate electricity or upgraded to biomethane.
  • Reduced waste management costs for cities from diversion of waste from landfills, extended landfill lifetimes, and reduced transportation costs for waste.
  • Connections to the United Nations Sustainable Develop Goals
  • Connections with marine plastics initiatives through increased emphasis on waste collection and segregation.
  • Job creation
  • Improved land values and tourism revenues from having cleaner streets and beaches