EPA Unveils Game-Changing Insights on Food Waste
New reports confirm prevention is the best solution for food waste
For years, work in the U.S. on reducing wasted food has been framed by the EPA’s Food Recovery Hierarchy, a way of ranking the environmental preferability for solutions to reduce food waste. Now, the hierarchy has gotten a welcome makeover, evolving into the Wasted Food Scale, which provides a level of nuance that is reflective of current research and data. The new scale adds some categories (e.g. sending food down the drain to wastewater, which is ranked among the least preferable) and reorganizes others, including elevating the ranking of composting. As with the original hierarchy, the Wasted Food Scale affirms that prevention, or keeping food from going to waste in the first place, is still the best way to reduce the climate and other environmental impacts of wasted food.
Key differences between the Wasted Food Scale and the previous EPA ranking include:
- Incorporates new pathways: The Wasted Food Scale adds four common wasted food pathways—upcycling, unharvested/plowed in, land application, and sewer/wastewater treatment—but removes the broad pathway of “industrial uses” since there are numerous wasted food pathways (with a range of environmental impacts) that could be covered by this broad term. Anaerobic digestion, now the most common industrial use of food scraps, is now considered as two categories in the scale, with anaerobic digestion with beneficial use of digestate (meaning digestate is treated to be suitable as a soil amendment) ranked higher than anaerobic digestion without beneficial use of digestate (in which digestate is disposed in landfills or incinerators).
- Considers value of end products: The Wasted Food Scale moves composting to the same tier as anaerobic digestion (with beneficial use of digestate). Both composting and anaerobic digestion with beneficial digestate use produce soil amendments that significantly improve soil health, including adding nutrient and water-holding capabilities, enhancing soil structure, and sequestering carbon. The scale also distinguishes within pathways based on whether the products created by a particular pathway (e.g., compost or digestate) have a beneficial end use (such as soil amendments) or whether they are disposed (in landfills, incinerators, or down the drain). Those that have a beneficial end use rank higher.
The Wasted Food Scale reflects the conclusions of two new and groundbreaking reports released in October by EPA. The first report, “From Field to Bin: The Environmental Impacts of U.S. Food Waste Management Pathways (Part 2)”, follows up on the 2021 report, “From Farm to Kitchen: The Environmental Impacts of U.S. Food Waste (Part 1)” (see NRDC’s blog about “From Farm to Kitchen” here). Together, Part 1 and Part 2 of the reports bring together new data and analysis to demonstrate the environmental impacts of wasted food throughout the supply chain, from farm to kitchen to management.
Key insights from the “From Field to Bin” report include:
- Source reduction, donation and upcycling are the most environmentally preferable pathways because they can displace additional food production. In particular, the potential GHG benefits of source reduction (prevention) are an order of magnitude greater than all other pathways.
- The benefits of pathways beyond source reduction, donation, and upcycling are small relative to the environmental impacts of food production; thus, they can do little to offset the environmental impacts of food production. As one example, the potential energy benefits of anaerobic digestion only represent about 20 percent of the energy originally required to produce each unit of food; in addition, combusting the biogas created by anaerobic digestion can create criteria air pollutants similar to the combustion of natural gas, which can be harmful to public health.
- Sewer/wastewater treatment and landfill stand out for their sizeable methane emissions. Transporting food scraps to wastewater treatment via sewer, even when that treatment includes anaerobic digestion, is ranked in the bottom tier due to the rapid decomposition rate of food scraps, which creates methane within the pipelines themselves. Anaerobic digestion at wastewater treatment facilities is only ranked higher than “down the drain” as a pathway in the report if vehicles are used to transport the food scraps.
- All wasted food pathways other than landfill and sewer/wastewater treatment demonstrate beneficial or near neutral global warming potential. Even though pathways other than source reduction require the use of energy and simultaneously produce global warming pollutants, in general, the benefits of avoided production of food that ultimately goes to waste (including inputs such as energy and fertilizer) and the creation of products such as animal feed or soil amendments reduce overall global warming potential.
- Recycling wasted food into soil amendments offers opportunities to make long-term improvements in soil structure and health and help regenerate ecosystems by recovering nitrogen and carbon and returning them to the soil. Compost and digestate (suitably treated) can be added to soil to increase nutrient and water retention, soil health and stability, and carbon sequestration. Increased application of compost and treated digestate to soil can also help reduce reliance on synthetic fertilizers derived from fossil fuels.
- As the U.S. becomes less dependent on fossil fuels for energy, the environmental value of producing energy from wasted food will decrease. The rankings of anaerobic digestion and controlled combustion assume the energy created by these pathways displaces fossil energy; if the U.S. energy supply incorporates more renewable sources, such as wind and solar, the relative benefits for energy production from anaerobic digestion and controlled combustion will decrease, meaning that anaerobic digestion will likely be ranked lower than composting.
The “From Field to Bin” report does an outstanding job of illuminating the environmental impacts and benefits of different food waste pathways – but, in practice, it is important to layer social (including labor) and economic impacts of different options into decisionmaking as well. For example, studies from organizations like the Institute for Local Self-Reliance and the Tellus Institute show composting creates more jobs than disposal. Also, leaving crops unharvested may have social and labor impacts (and economic impacts, for farmers) that should be considered along with environmental impacts.
The second report released in October, “Quantifying Methane Emissions from Landfilled Food Waste,” presents EPA’s first published data estimating the contribution of food waste to fugitive landfill methane emissions, concluding that 58 percent of those emissions is attributable to food waste.
EPA’s analysis estimates annual methane emissions from landfilled food waste from 1990 to 2020 and finds that while total emissions from MSW landfills have declined, methane emissions from landfilled food waste are rising, adding to the imperative need to keep food waste out of landfills.
In the U.S., food is the most prevalent material in municipal landfills, comprising 24 percent of landfill content as of 2018. When food and other organic materials (including yard waste and paper) are disposed in landfills, they begin to decompose (in fact, some of the decomposition begins before arriving at the landfill), and food scraps in particular break down rapidly. In fact, as the report highlights, most food scraps have significantly decomposed before being subject to landfill gas capture systems, leading to the disproportionate contribution of food waste to total landfill methane emissions. Landfills are the third largest source of human-generated methane emissions in the U.S., and methane is a powerful climate pollutant which traps 80 times more heat in the atmosphere than carbon dioxide over a 20-year time horizon. Addressing methane emissions is a critical priority in reducing global warming emissions.
Key insights from the “Quantifying Methane” report include:
- In 2020, food waste was responsible for approximately 55 million metric tons of CO2 equivalent (mmt CO2e) emissions from U.S. MSW (municipal solid waste) landfills. For every 1,000 tons (907 metric tons) of food waste landfilled, an estimated 34 metric tons of fugitive methane emissions (838 mmt CO2e) are released. Across the entire supply chain, wasted food in the U.S. creates greenhouse gas emissions equivalent to the emissions from 50 million gas-powered cars (and if those cars were lined up, according to EPA, they would wrap around the earth nearly four times).
- An estimated 58 percent of the fugitive methane emissions (i.e., those released to the atmosphere) from MSW landfills are from landfilled food waste. In 2020, landfills overall emitted methane equivalent to 94 million metric tons of carbon dioxide (CO2). At the state and local level, landfills are often the largest inventory source of methane. For example, in 2021, a municipal solid waste landfill was the top individual industrial methane emitter in 37 states.
- An estimated 61 percent of methane generated by landfilled food waste is not captured by landfill gas collection systems and is released to the atmosphere. Because food waste decays relatively quickly, its emissions often occur before landfill gas collection systems are installed or expanded. Half of the carbon in food waste is degraded to landfill gas within the short period of 3.6 years; but on average it takes four years after waste deposit before landfill gas capture systems are installed. Consequently, improving gas collection system efficiency does not substantially reduce emissions from food waste, even though it reduces landfill gas emissions overall.
- While total methane emissions from MSW landfills are decreasing due to improvements in landfill gas collection systems, methane emissions from landfilled food waste are increasing. More material is being landfilled overall, including organic material, but landfill gas system improvements mean that more gas is collected once those systems are in place (more of which is from materials like wood which break down more slowly than rapidly decomposing food scraps).
- Reducing landfilled food waste by 50 percent in 2015 could have decreased cumulative fugitive landfill methane emissions by approximately 77 million metric tons of CO2 equivalents (mmt CO2e) by 2020, compared to business as usual. If this reduction had been achieved, it would have roughly equated to the amount of energy used by 15 million homes in a year.
Given these new insights about landfill methane, we need governments at all levels to start paying more attention to food waste reduction as a near-term climate solution. One way they might do that is by cities and states including food waste reduction activities in their climate action plans, and the federal government awarding funding to bring those local projects to life.
As we inch closer to 2030, the year we aim to cut food waste by 50 percent per our national goal, we need the most recent and relevant information to guide the decisions that will help us achieve that goal. Both of EPA’s new reports confirm the need for continuing to work across the scale to prevent food from going to waste and to keep any food scraps out of landfills and incinerators. And the new Wasted Food Scale demonstrates some of the nuances in the ways we manage food waste reduction and highlights where we should be investing our efforts both in terms of resources and policy. These reports and the Wasted Food Scale will help properly guide this movement to achieving our national goal, and beyond. For that, we applaud and thank EPA.