New research published in Nature Food has revealed that recycling food waste through composting, anaerobic digestion, or converting it to animal feed could lead to dramatic reductions in greenhouse gas emissions—particularly methane—and help alleviate pressure on land, water, and energy systems globally. The findings come amid growing concerns about the environmental impact of the agrifood system, which is under increasing stress from population growth, urbanization, and land degradation.
Led by Zhengxia Dou, a professor of agricultural systems at the University of Pennsylvania’s School of Veterinary Medicine, the study analyzed data from 91 field studies conducted in 29 countries. The goal was to provide “a benchmark for countries developing food waste management strategies for a circular agrifood system,” the study’s authors wrote.
“Everyone is involved in the global agrifood system, since everyone eats food,” Dou said in a press release from the university. “Everyone is a stakeholder.”
The scope of the problem is enormous. Nearly one-third of all food produced for human consumption is lost or wasted, Dou explained. That waste not only undermines food security but also results in the misuse of land, water, energy, and other vital resources.
“When finished eating, people tend to just toss what’s left: out of sight, out of mind,” Dou said. “But from the resource and environmental perspective, what happens after actually matters a lot.”
The study focused on the lifecycle greenhouse gas impacts of three specific food waste recycling methods: composting, anaerobic digestion, and re-feed—where suitable food waste is converted into animal feed. The results showed that diverting food waste from landfills to these recycling methods can drastically cut methane emissions, a potent greenhouse gas.
“You can think of a landfill as a ‘biological amplifier,’” Dou explained. Food waste, rich in carbohydrates and other organic compounds, decomposes anaerobically in landfills, producing methane. “Anything you can do with food waste recycling is better than sending it to a landfill,” she added.
The study identified three regions with particularly large agrifood systems and high levels of food waste—China, the European Union, and the United States. All three are significant contributors to global greenhouse gas emissions and consume vast amounts of natural resources. According to Dou, “They are what I would call methane ‘super emitters’ from food waste disposal.”
In their analysis, researchers modeled a scenario in which all food waste currently sent to landfills in these three regions was instead recycled equally through composting, anaerobic digestion, and re-feed. The results suggested substantial reductions in emissions. In the U.S. alone, the emissions savings would be equivalent to offsetting methane emissions from nearly nine million dairy cows—more than 90 percent of the country’s total dairy cow population.
Of the three recycling methods examined, Dou emphasized the significance of re-feed. “I am a big advocate for converting suitable food waste streams to animal feed because it has the additional benefit of reducing conventional feed usage, therefore sparing the use of natural resources and fertilizer,” she said.
In China, for example, the study found that more than five percent of cropland currently used for soybean and maize production could be spared if food waste were recycled into feed. “This spared land could be used for producing human food to enhance food security or for taking land out of production for conservation purposes,” the study noted.
Re-feeding food waste not only alleviates pressure on cropland but also reduces dependency on imported feed—a significant issue for China and several EU nations. The dual benefits of reducing emissions and boosting resource efficiency make re-feed a particularly attractive option for policymakers.
The authors concluded that “food waste composting, anaerobic digestion, and repurposing to animal feed are all practical and viable options that are field-proven, low cost, and highly effective in mitigating emissions with multiple resource conservation benefits.”
In addition to national-level strategies, institutions are already implementing food waste recycling practices. At the University of Pennsylvania, Penn Dining has been integrating sustainable food sourcing and waste reduction practices into its operations. According to Steven Green, Penn Dining’s director of operations, “We focus on repurposing food through donations, using surplus food for animal feed, creating biofuel, or composting, always aiming to keep waste out of landfills. We collaborate closely with partners like Bennet Compost to manage our waste responsibly.”
Chef Shazad Khan added that surplus food from events or closures is donated when in good condition. “Planning menus carefully, training chefs, and continuously reviewing waste data help us cut down unnecessary waste,” Khan said. Tools like the Waste Not program and the Reuzzi app also assist in tracking and reducing food waste on campus.
Ultimately, Dou emphasized that food waste reduction begins with individuals. “We are part of the equation. So, to solve the problem, we need to be aware of the food loss and waste issue and try to cut down our own footprint by reducing our own food loss and waste,” she said.
The study’s findings offer a compelling case for rethinking how food waste is handled globally. As governments seek climate solutions and resilience within food systems, redirecting waste away from landfills and into recycling pathways could become a key strategy for cutting emissions, conserving resources, and improving food security.
COMMENTS