Turning Trash into Clean Fuel: The Future of Waste-to-Energy

Scientists and energy companies are exploring waste-to-energy technologies to tackle two urgent challenges: reducing pollution and diversifying energy sources. From plastics to organic waste, new innovations are turning trash into clean fuels, offering a promising route to support the global energy transition and circular economies.

Hydrogen is becoming an increasingly important source of clean and efficient energy. One of the main methods for producing hydrogen fuel is steam methane reforming, a process that releases harmful carbon monoxide emissions. To be considered green, hydrogen must be produced through electrolysis powered by renewable sources, ensuring the process is truly clean.

A South Korean research team from the Institute for Basic Science (IBS) Center for Nanoparticle Research has developed a breakthrough that could offer a greener path. In a study published in Nature Nanotechnology, the team detailed a new method that transforms plastic waste into clean hydrogen using only sunlight.

Photocatalytic hydrogen production, where materials speed up chemical reactions to break down plastic and release hydrogen, has long been seen as a cleaner alternative. However, its stability under strong light and chemical stress has been a major challenge. To overcome this, the researchers wrapped the photocatalyst in a hydrogel polymer, allowing it to float on water and remain active even under harsh environmental conditions.

“The key was engineering a structure that works not only in theory but also under practical outdoor conditions,” says Lee Wanghee, Postdoctoral Researcher, MIT, and co-first author of the study. “Every detail, from material design to the water-air interface, had to be optimized for real-life usability.”

The system remained stable for more than two months, even in highly alkaline water, and worked in a range of real-world environments, including seawater and tap water. In outdoor tests, a one-square-meter device successfully produced hydrogen directly from dissolved PET bottle waste using natural sunlight.

Economic models and scale-up simulations suggest the technology could be expanded to cover areas of 10m2 or even 100m2, opening a pathway to cost-effective, carbon-free hydrogen production.

“This research opens a new path where plastic waste becomes a valuable energy source,” says Kim Dae-Hyeong, lead researcher on the study. “It is a meaningful step that tackles both environmental pollution and clean energy demand.”

But turning waste into energy is not limited to plastic. A team of researchers at the Vienna University of Technology, in a study published in Nature Communications, showcased a novel way to convert organic waste into energy. By genetically modifying the bacterium Thermoanaerobacter kivui (T. kivui), the scientists enabled it to metabolize carbon monoxide, a gas that is typically toxic to most organisms, into useful biofuels like ethanol and isopropanol.

Carbon monoxide was initially toxic and inhibited the growth of T. kivui, but through a gradual adaptation process, the researchers trained the bacterium not only to tolerate the gas but to thrive on it, using it as its sole source of carbon and energy. The bacterium developed this ability naturally within just a few generations. The team later identified a specific mobile DNA segment, known as a transposon, that was responsible for this evolutionary leap. Using genetic engineering, they were able to replicate and enhance this capability in laboratory-created strains.

The scientists propose that this carbon monoxide-consuming bacterium could be integrated into biomass gasification plants. There, it could use syngas, a mixture of carbon monoxide, carbon dioxide, and hydrogen produced from waste biomass, as feedstock for gas fermentation, turning it into valuable biofuels. This process could help establish a circular carbon economy based on renewable resources.

Both biomass and trash are increasingly important parts of Mexico’s power landscape. However, despite available technologies such as gasification, waste-to-energy combustion, and biogas plants, bioenergy accounts for just 0.5% of Mexico’s total energy capacity, with 408MW installed as of 2022, according to CONAHCYT data. This energy source generated 2,141GWh in that year, but much of Mexico’s waste remains untapped. Of the 2,250 waste disposal sites in the country, only 61 manage biogas, and just seven of those use it to produce electricity, according to the Mexican Observatory for Methane Emissions.

Guillermo Chaim, Director General, Brimex Energy, one of Mexico’s main biogas companies, says that the country must push for greater energy diversification to strengthen its energy independence.

“It is crucial for Mexico to prioritize the diversification of its energy sources and foster energy independence,” says Chaim. “An additional advantage of biogas production is its non-intermittent nature, as well as its ability to operate without causing disruptions to the grid.”

Research beyond biogas and waste to energy continues in Mexico, with studies also being done in turning other types of waste, such as the sargassum that plagues the country’s Caribbean beaches, into a viable source of hydrogen fuel.