The link between waste management, circular economy and solving climate change
Currently more than 50% of all municipal solid wastes on the planet end up in a dump or landfilled1. These waste management practices contribute to the release of methane (CH4) and carbon dioxide (CO2) into the atmosphere as anaerobic bacteria degrade the organic materials buried in the landfill trenches. Although the CO2 is biogenic, the methane, also known as landfill gas (LFG), is considered anthropogenic and contributes to climate change. Methane has a global warming potential (GWP) of 28. This means that one tonne of methane is the equivalent of 28 tonnes of CO2, therefore, even small amounts of methane contribute significantly to global warming and climate change.
In the paper “Completing the picture: How the circular economy tackles Climate Change”, the Ellen MacArthur Foundation2 estimates that 45% of current global emissions come from how we currently make, use and dispose of products and food. Moving away from the typical ‘take-make-waste’ linear model of production and applying strategies of circular economy to the food system as well as to industrial materials such as plastic and aluminium could help to reduce total emissions by 45% by 2050, which is 5.2 bn and 3.7 bn tonnes of CO2 respectively. Waste reduction, use of secondary materials and reuse of durable materials are at the heart of a circular economy.
The GHG emissions from materials production arise as a result of high temperature processes, production emissions and end-of-life emissions. According to the Ellen MacArthur Foundation’s paper findings, a circular economy approach could reduce these emissions by at least 40% (3.7bn tCO2) by applying two core principles: design out waste and keep products and materials in use. Waste could be significantly minimized throughout the entire value change by implementing for example, efficient product design and lightweight material design. These design-driven waste elimination strategies alone could enable 0.9 billion tonnes of CO2 reduction by 2050 for steel, aluminium, plastics and cement.
Another big part of emissions reduction for these materials comes from reuse of products and components and recirculation of materials. Keeping products in use by remanufacturing, refurbishing or sharing them and by increasing their use intensity enables longer energy preservation, avoidance of new product making and end-of-life treatment. As such, these practices help to reduce a further 1.1 billion tonnes of CO2 emissions. Recirculation of materials via collection, sorting and recycling activities could help to achieve the biggest share of emissions reduction by 2050 of 1.7 billion tonnes of CO2. Recycling of materials and their secondary use in goods production significantly reduces energy use and avoids the most energy intensive production processes. As a result, recycling helps to avoid the hardest-to-abate emissions and incineration emissions.
The circular economy initiatives could also contribute to decarbonisation of the food system and reduce its emissions by 49% by 2050, that is 5.6 billion tonnes of CO2 in total. A crucial part of these strategies is composting of food waste which has a potential to reduce 0.3 billion tonnes of CO2 per year in 2050. Not only does composting enable avoidance of methane release but also the use of compost instead of fertilizers reduces emissions from mining minerals, production of fertilizers and energy pumping for irrigation. The rest of the emission reductions come from waste elimination and regenerative agriculture principles.
Landfills and dumps are forms of waste management that are known to contribute to climate change and other environmental impacts:
- The organic waste component releases methane as it decomposes directly contributing to climate change.
- Treatment of the waste (e.g. burying) does not match the waste generation rate. Therefore, the waste can end up in the environment and lead to plastic ocean pollution, soil and ocean acidification and extremely high levels of micro plastics.
- Recyclable wastes are treated in emissions intensive ways and are not recirculated into the production cycle. Therefore, production of virgin material increases and as such generates much more emissions from energy and production processes than using processed recycled materials.
- According to the World Bank, the world generates 2.02 billion tonnes of municipal solid waste per year.
- Based on the current trajectory, global annual waste generation will increase by 70% to 3.40 billion tonnes on current levels by 2050.
- Food waste accounts for the largest share of total waste emissions of around 45%, followed by paper and cardboard (17%), and plastic (12%).
- Most of the waste ends up in open dump (33%) or landfill (25.2%).
- In 2016, solid waste generated 1.6 billion tonnes of CO2e emissions, or 5% of global emissions because of methane release.
- Paper, cardboard, plastic, glass, and metal – all recyclable materials – comprised 38% of the average waste mix in 2018 .
- Recycling can significantly reduce emissions as it allows reuse of secondary materials that cut emissions from energy and production processes.
- For example, 1 tonne of plastic produced from secondary materials could reduce 1.1-3.0 tonnes of CO2e emissions involved in the production of the same tonne of plastic from virgin fossil feedstock2.
Based on the EU Taxonomy3, US EPA WARM model4 and Project Drawdown5, iClima identifies 6 potential waste management practices that enable avoidance of GHG emissions compared to the landfilling and dumping baseline. According to iClima, avoiding emissions from waste can be achieved by either capturing the landfill gas and using it for electricity production or displacement of natural gas; or by processing and diverting the waste towards other uses which includes recycling, recovery, composting, anaerobic digestion and incineration for energy production.
The EU Taxonomy, for example, identifies and defines some of these alternative waste management solutions:
- Separate collection and transport of non-hazardous waste with the aim of preparing for reuse and/or recycling. Recovered and recycled materials in waste can be processed into secondary materials or finished products, replacing the production of virgin materials and thereby avoiding energy use. Materials such as plastic, glass, metal, paper and cardboard can replace production of high/low density polyethylene, polypropylene, virgin glass, virgin pulp and other virgin raw materials.
- Separation of the organic components in waste for composting and use as fertiliser/soil improver.
- Separate collection of organic waste to be treated in an anaerobic digester for biogas production which can be used for electricity generation or as an alternative to natural gas.
- Capture of landfill gas to be used directly for electricity or injected into natural gas grid while methane leakage is controlled.
Another solution identified by iClima that is not considered a green alternative by the EU taxonomy and considered a “regretful solution” by Project Drawdown is waste-to-energy. This entails collecting the waste and destroying it through burning, pyrolysis, or gasification, generating heat that is used for energy generation6. In the short-term, iClima believes that waste based energy production could displace coal and gas energy generation and help to avoid methane release.
iClima’s index contains a number of companies that provide these alternative waste solutions. For example, Republic Services and Waste Connections are companies that collect and transport wastes, and also own and operate recycling, composting and waste-to-energy facilities. Republic Services is one of the largest waste managers is the US and recycles more than 2 million tonnes of material each year, including paper (79%), plastic (7%) and electronics. Waste Connections also operates in the US as well as internationally and recycles more than 1.5 million tons of waste annually. In 2019, Waste Connections recovered 32.5 bn cubic feet of landfill gas, of which 61% was used for energy. Covanta, from the Green Energy sector, also produces steam for electricity generation through the combustion of waste and recycles 550,000 tonnes of metal that could displace virgin material.