Researchers from the University of Cambridge and the University of Adelaide have built systems that turn plastic waste into hydrogen fuel with the help of sunlight. The method, called photoreforming, is a photocatalytic process in which solar energy and safe catalysts break plastics down into hydrogen and useful industrial chemicals. Plastics such as polyethylene and polypropylene can be converted into hydrogen, syngas, acetic acid and liquid fuels. Hydrogen is a clean fuel used in refining and in ammonia production. The world produces more than 400 million tonnes of plastic every year, yet only about 10% to 18% of plastic waste is recycled.