Researchers at the Korea Institute of Science and Technology (KIST) have developed a method to convert plastic waste into hydrogen, which can be used for clean energy. They published their findings in Engineering.
(a) Detailed schematic representation of the PEC degradation mechanism employed for PS waste using a WO3 photoanode. (b) Quantified hydrogen and carbon dioxide production from the PS-coated WO3 system, as related to the experimental conditions described in Fig. 2(a), over a duration of 4 h. ppm: parts per million. Credit: Love Kumar Dhandole et al.
Using a photocatalyst to oxidize plastic
The researchers engineered a porous tungsten oxide (WO3) photoanode that interacts with polystyrene (PS) plastic. PS is widely employed in the food-service industry as rigid trays and containers, disposable eating utensils, and foamed cups, plates and bowls. According to Statista, more than 26 million US tons of polystyrene are produced globally each year.
The research team dissolved PS in chloroform, and a dip-coating technique was used to deposit the dissolved PS onto the WO3 photoanode. The WO3 then absorbs light and uses the energy to oxidize the PS into CO2 at the anode while hydrogen gas is produced at the cathode.
Hydrogen for clean energy
The hydrogen gas that is produced through this process can be used to create clean energy through fuel cells. Hydrogen can also store excess energy from solar or wind power and act as a battery.
Carbon dioxide, although typically a waste product, can also be used to generate clean energy. Carbon recycling methods can capture CO2 and use it to grow algae for biofuels or produce chemicals like methanol. Researchers at the University of Michigan developed a method to capture CO2 and turn it into metal oxalates to be used in cement production.
A cleaner alternative to incineration
The value of this new process lies in avoiding the incineration of plastic, which releases much more CO2 and other toxic chemicals. According to the Center for International Environmental Law (CIEL), the production and incineration of plastic in 2019 alone emitted more than 850 million metric tons of greenhouse gases. From production to incineration, one kilogram of plastic releases about six kilograms of CO2 into the atmosphere.
The method also has the potential to become carbon-neutral if the hydrogen produced is used for clean energy production, offsetting fossil fuel use and neutralizing the CO2 emitted by the reaction.
Another way plastic can make a usable product
Scientists at the University of Edinburgh have genetically reprogrammed E. coli bacteria to convert plastic into paracetamol, the active ingredient in Tylenol. Like plastic production, the production of paracetamol uses fossil fuels and has a large carbon footprint. This new method turns plastic into a usable material and has little to no carbon emissions.
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