Jet fuel made from trash could dramatically cut aviation emissions

Aviation accounts for roughly 2.5 percent of global CO₂ emissions today, and demand for flights is on track to double by 2040. Unlike cars, planes can’t simply switch to batteries at scale, which is why sustainable aviation fuel (SAF) has become the industry’s main decarbonization lever.

The hitch is supply. SAF still represents less than one percent of jet fuel use worldwide because it’s expensive to make and limited by feedstocks such as used cooking oil and energy crops. A new study points to an overlooked, highly scalable input: municipal solid waste (MSW).

By converting everyday trash into drop-in jet fuel through industrial gasification and Fischer–Tropsch synthesis, researchers from Tsinghua University and the Harvard-China Project found a powerful emissions lever. Their analysis shows that airlines could slash lifecycle emissions using this pathway.

Limited tools for clean flying

The researchers found that aviation has surprisingly few practical, near-term tools to cut emissions in a meaningful way.

“Unlike road transport, which is shifting toward electrification, there’s no silver-bullet 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. By converting municipal waste into low-carbon jet fuel that already works in today’s engines, we can start cutting emissions immediately, without waiting for future technology.”

Turning trash into jet fuel

The pathway the team evaluated is well-established chemistry at industrial scale. Mixed municipal waste – including organic scraps, paper and cardboard, a portion of plastics, and other combustibles – is sorted and then gasified into a synthesis gas of hydrogen and carbon monoxide.

After cleanup to remove contaminants, that “syngas” is fed into a Fischer–Tropsch reactor to build longer hydrocarbon chains.

The resulting liquids are upgraded into a kerosene-range blend that meets existing jet fuel specifications. Airlines can use it now without modifying engines or fueling infrastructure.

The headline is the life-cycle assessment: depending on configuration, MSW-derived jet fuel could cut greenhouse gas emissions by about 80 to 90 percent compared with conventional fossil jet.

Savings stem from diverting waste, preventing methane, and substituting petroleum with a far lower-carbon fuel. But a real bottleneck is scaling gasification systems that can reliably process mixed waste with consistent quality and uptime.

Boosting efficiency with hydrogen

Trash isn’t a uniform feedstock, and syngas composition doesn’t always perfectly match what Fischer–Tropsch reactors prefer.

In the scenarios the authors analyzed, only about one-third of the input carbon became fuel without additional process adjustments. This is good enough for big emissions gains, but is definitely improvable.

The analysis shows two levers to push efficiency higher: capture and recycle CO₂ within the plant, and blend in green hydrogen produced with renewable electricity.

Both tactics raise carbon utilization and fuel yield. They strengthen climate benefits and economics, especially in regions with supportive power and carbon policies.

Trash problem to jet fuel solution

MSW is a municipal headache nearly everywhere. Landfills consume land, leak methane, and are increasingly constrained. Incineration reduces volume but brings air quality challenges.

Routing appropriate fractions of that waste to fuel production offers cities a credible “zero-waste” pathway that also displaces fossil fuels.

The researchers emphasize that plastics must be handled carefully to meet sustainability criteria. However, with proper sorting and modern gas cleanup, a large fraction of urban trash becomes a reliable SAF feedstock rather than an environmental liability.

Global potential of trash jet fuel

Policy ambition for SAF is rising fast. The United States aims for up to 35 billion gallons per year by 2050, backed by tax credits.

The European Union is mandating rising SAF blends on all departing flights, from two percent in 2025 to 70 percent by mid-century.

Against that backdrop, the MSW potential is striking. In the study’s “practical” case, existing waste could produce about 50 million tons (roughly 62 billion liters) of jet fuel annually. That is enough to cut aviation’s lifecycle CO₂ by about 16 percent.

With green hydrogen integration and optimized plants, output could climb to 80 million tons per year. That would supply up to 28 percent of global jet fuel demand and avoid as much as 270 million tons of CO₂ annually.

Regionally, Europe’s potential from MSW alone would exceed near-term EU blending mandates while staying within sustainability guardrails.

Under carbon pricing and offset programs such as ICAO’s CORSIA, lower-carbon fuel also carries an economic edge: airlines reduce their compliance costs by burning fewer fossil tons, and incentives help close the price gap with conventional jet.

Scaling depends on policy

Despite strong climate performance, MSW-to-jet won’t scale on chemistry alone. Siting and financing large gasification plants, upgrading waste collection and sorting, securing long-term feedstock contracts with cities, and aligning utility-scale green hydrogen supply all require durable policy.

Production-side tax credits, contracts for difference that guarantee a stable SAF premium, and clear sustainability standards can unlock private capital.

On the demand side, blend mandates that ratchet up predictably give airlines and fuel producers the certainty to invest.

Trash and the future of jet fuel

“This study presents a blueprint for converting urban waste into sustainable aviation fuel, offering future environmental benefits,” said lead author Michael McElroy, a professor of environmental studies at Harvard.

“Broad collaboration among governments, fuel producers, airlines, and aircraft manufacturers will be essential to lower costs, and accelerate aviation’s path to net-zero emissions.”

The big picture is pragmatic. There’s no single fix for aviation. But MSW-derived SAF is one of the few options that can scale this decade using existing airplanes and pipelines. It also helps solve a waste problem that cities already pay to manage.

Pair it with efficiency gains, smarter operations, other certified SAF pathways, and hydrogen or electric aircraft where they make sense, and the sector’s path to deep decarbonization looks a lot more achievable.

The study is published in Nature Sustainability.

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