Copyright Interesting Engineering
A new way to fly cleaner may be hiding in your garbage bin. Scientists have found that municipal solid waste, including food scraps and discarded packaging, could become a major feedstock for sustainable aviation fuel (SAF), drastically cutting carbon emissions from air travel. Aviation accounts for around 2.5 percent of global carbon emissions, and demand for air travel is set to double by 2040. While electric cars are taking off, planes have no easy path to decarbonization. That’s where SAF steps in, the fuels made from renewable or waste-based materials that can replace conventional jet fuel without engine modifications. But so far, SAF contributes less than 1 percent of global jet fuel use, hampered by high costs and scarce supply. The new study, led by researchers from Tsinghua University and the Harvard-China Project on Energy, Economy, and Environment, offers a way forward by transforming municipal solid waste into low-emission, cost-effective jet fuel. The research found that such waste-derived fuel could cut lifecycle greenhouse gas emissions by 80–90 percent compared with fossil jet fuel. “Unlike road transport, which is quickly shifting toward electrification, there’s no silver-bullet solution for achieving carbon-neutral aviation,” said Jingran Zhang, the study’s first author and a postdoctoral fellow at the Harvard-China Project. “Turning everyday trash into jet fuel could be an innovative but major near-term step toward cleaner aviation.” Turning waste into wings Municipal solid waste includes organic matter, plastics, paper, and metals, which are typically landfilled or incinerated. Converting that waste into jet fuel through gasification and Fischer-Tropsch synthesis offers dual benefits: reducing emissions and shrinking landfill dependence. The researchers found that using real-world industrial-scale data, waste-to-fuel systems could transform up to 33 percent of carbon inputs into liquid fuel. Efficiency could improve further by capturing carbon dioxide or adding green hydrogen during production. Beyond cutting emissions, this approach could help cities manage rising waste volumes while supporting their zero-waste goals. “By converting municipal waste into low-carbon jet fuel that already works in today’s engines, we can start cutting emissions immediately,” Zhang said. Global flight path forward The potential scale is enormous. Globally, municipal solid waste could yield about 50 million tons (62 billion liters) of jet fuel, roughly 16 percent of the sector’s greenhouse gas emissions. If green hydrogen is added, output could jump to 80 million tons, enough to meet 28 percent of global jet fuel demand and cut 270 million tons of carbon dioxide each year. Such output would exceed Europe’s upcoming SAF mandates, which require 2% blending by 2025 and 70% by 2050. In the U.S., the government aims to produce 35 billion gallons of SAF annually by mid-century. “This study presents a blueprint for converting urban waste into sustainable aviation fuel, offering future environmental and economic benefits,” said Michael B. McElroy, lead author and chair of the Harvard-China Project. “Moving forward, broad collaboration among governments, fuel producers, airlines, and aircraft manufacturers will be essential to increase production, lower costs, and accelerate aviation’s path to net-zero emissions.” The study was published in Nature Sustainability.
