A groundbreaking study centered on the conversion of waste plastics into high-value graphene has unveiled a new method for producing hydrogen that could potentially revolutionize the emerging green hydrogen industry. This breakthrough not only offers a sustainable solution for recycling the approximately 6.3 billion tons of plastic waste globally but also yields high-quality hydrogen gas, a clean fuel. Moreover, the process produces graphene as an end product, rendering the entire procedure economically viable. Details of this breakthrough are outlined in a recent paper published in Advanced Materials.

The cost-effective production of green hydrogen has been a significant barrier to scaling up the industry, as it has been more expensive compared to conventional fossil fuels. Although hydrogen is widely used in various industrial applications, the vast majority of it is produced from fossil fuels, categorized as gray hydrogen. Green hydrogen, produced from clean energy sources, constitutes only a small fraction of the current hydrogen market.

However, if the production of green hydrogen is a by-product of graphene manufacturing, the clean fuel essentially pays for itself while generating a substantial profit. Kevin Wyss, who spearheaded the pioneering research at Rice, explained, “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. If the produced graphene is sold at only 5 percent of the current market value—a 95 percent discount—clean hydrogen could be produced for free.” It is essential to note that for the hydrogen to be considered ‘green,’ the process must be powered by renewable energy sources.

The process leverages a technique known as flash joule heating, developed at Rice University. This technique involves grinding plastic into tiny particles, mixing it with a conductive material, placing the mixture in a tube, and subjecting it to very high voltage. The rapid heating, reaching temperatures of approximately 5,000 degrees Fahrenheit in just 4 seconds, causes the carbon atoms in the plastic to fuse into graphene, releasing a mixture of volatile gases in the process. Notably, a significant amount of exceptionally pure hydrogen is among the gases produced. Additionally, since all the carbon in the gases is converted into graphene, the process does not emit any carbon dioxide.

Despite a somewhat slow start, the green hydrogen industry holds tremendous promise for global decarbonization efforts, particularly in hard-to-decarbonize sectors like steelmaking and shipping. Hydrogen can replace fossil fuels in industrial furnaces, leaving only water vapor when burned, thereby significantly reducing carbon dioxide emissions. Replacing fossil fuels in furnaces operating at 1,500 degrees Celsius (2,732 degrees Fahrenheit) with hydrogen could substantially reduce the 20% of global carbon dioxide emissions originating from the industrial sector, as highlighted in a report by Bloomberg Green.

However, while the potential benefits of transitioning these heavy industries to green hydrogen seem evident, the reality is more nuanced. Green hydrogen production demands substantial amounts of clean energy that might be more efficiently used in other applications. A 2022 report by the International Renewable Energy Agency (IRENA) cautions against the “indiscriminate use of hydrogen” and emphasizes the need for a thoughtful evaluation of green hydrogen’s role in a decarbonized world.

Hence, the scaling of green hydrogen must be balanced with a careful cost-benefit analysis in different contexts. Nonetheless, the added benefits of eliminating plastic waste and generating revenue further enhance the appeal of this remarkable innovation.

By Impact Lab