Instead of becoming a persistent environmental pollutant or requiring complex, energy-intensive processes for recycling, plastic waste can represent a source of hydrogen production. Researchers in the U.S. and South Korea have advanced alkaline thermal treatment (ATT) technology as a means of upcycling such waste to yield clean hydrogen fuel.

The method described in Proceedings of the National Academy of Sciences applies a combination of sodium hydroxide and heat to drive hydrogen production from organic material. The process, previously applied to seaweed, proved effective on a mix of polyethylene terephthalate (PET), polyethylene (PE) and polypropylene (PP) waste in a single reactor, yielding hydrogen gas at purity levels exceeding 90%.

During thermal oxidation pre-treatment, the plastics are briefly exposed to mild heat in the air before the main reaction. That phase introduces oxygen-containing functional groups into the polymer chains, creating reactive sites where the alkaline treatment can occur.

ATT efficiently converted both individual and mixed plastic waste into hydrogen without requiring extensive separation and sorting, demonstrating its commercial potential and scalability with real-world waste compositions. The process also outperformed conventional gasification while minimizing carbon-based byproducts. The carbon released during the reaction was captured by the sodium hydroxide reagent and converted to solid sodium carbonate.

According to the scientists, “By reducing the sorting costs and process complexity that have been major barriers to commercialization, this technology has the potential to become a next-generation core technology that supports both the hydrogen economy and the circular economy."

Researchers from Ewha Womans University, Korea Aerospace University, Kangwon National University, Sogang University and the University of California, Los Angeles contributed to this development.