Researchers from Rice University have revealed a new, low-emissions method to convert plastic waste into hydrogen that ultimately could pay for itself.
The findings hold new promise for the future of hydrogen, which has been touted as an important alternative to fossil fuels, though its traditional production methods are considered carbon heavy or too expensive. For example, most of the nearly 100 million tons of hydrogen used globally in 2022 was derived from fossil fuels and produced roughly 12 tons of carbon dioxide per ton of hydrogen.
Researchers exposed plastic waste samples to rapid flash Joule heating for about four seconds, bringing their temperature up to 3100 degrees Kelvin, which vaporizes the hydrogen present in plastics and leaves behind graphene, an extremely light, durable material made up of a single layer of carbon atoms. The research team published their findings in Advanced Materials.
“In this work, we converted waste plastics -- including mixed waste plastics that don’t have to be sorted by type or washed -- into high-yield hydrogen gas and high-value graphene,” Kevin Wyss, a Rice doctoral alumnus and lead author on the study, said in a statement. “If the produced graphene is sold at only 5% of current market value -- a 95% off sale! -- clean hydrogen could be produced for free.”
Clean hydrogen, which is produced using renewable energy sources to split water into its two component elements, currently costs roughly $5 for just more than two pounds.
The study was conducted using funding from the United States Army Corps of Engineers, researchers at the Tour lab at the university acquired the necessary equipment to characterize the vaporized contents.
The study also comes as the United States is heavily investing in hydrogen production, pouring $7 billion into hydrogen hubs around the country. The funding from the Department of Energy aims to initiate hydrogen production, storage, and delivery hubs and will specifically support seven Regional Clean Hydrogen Hubs that are expected to collectively meet about a third of U.S. 2030 clean energy production targets.
Other countries are also viewing hydrogen as a big opportunity for energy production. Germany and the U.K. recently penned an agreement to accelerate the hydrogen global market and prioritize production in their own energy policies.
“The main form of hydrogen used today is ‘gray’ hydrogen, which is produced through steam-methane reforming, a method that generates a lot of carbon dioxide,” said James Tour, Rice’s T. T. and W. F. Chao Professor of Chemistry and a professor of materials science and nanoengineering. “Demand for hydrogen will likely skyrocket over the next few decades, so we can’t keep making it the same way we have up until now if we’re serious about reaching net zero emissions by 2050.”
