This technology provides a more eco-friendly solution to convert non-biodegradable plastics into fuels and chemical feedstocks. In Singapore, about 96% of the plastics waste is incinerated, which contributes to Singapore’s CO2 emissions and aggravates global climate change. The remaining 4% is recycled only after the plastics have been cleaned and pre-treated by energy-intensive processes. Furthermore, many of these plastics are indiscriminately discarded worldwide, resulting in the widespread pollution of the marine ecosystems.
The technology, when fully developed, offers a potentially greener solution to turn non-biodegradable plastics, such as polyethylene, polypropylene, polystyrene, and other such derivatives into chemical feedstocks, some of which can be directly used in fuel cells. The technology uses light to trigger the chemical degradation, but could eventually involve a combination of light and electricity instead of heat, which will be more easily deployed worldwide. This technology should be of interest to companies manufacturing plastics that need end-of-life solutions to their products, and also companies and government agencies that are working to recycle plastics.
The technology owner has developed chemical (non-biological) photocatalysts that can use visible light to break down plastics with the polyethylene backbone (e.g. polyethylene, polypropylene, polystyrene, polymethyl methacrylate, but not polyesters and polyamides) into simpler chemical products such as formic acid. Currently, it was shown that the process is complete after 6 days using small, milligram quantities of commercially sourced polyethylene only. Based on other experiments, the reaction can tolerate some contaminants, meaning that extensive cleaning or pre-treatment may not be necessary.
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This technology can be used by the plastics recycling industry to turn the plastics into more valuable chemical feedstocks and fuels. Currently, plastics are typically recycled for the same applications, which limits their versatility since the recycled plastics will have to be of similar or better quality than newly produced plastics. The technology changes this market model by converting the plastics into simpler chemicals that are feedstocks for other processes, which can be more widely used.
The global market for formic acid is currently almost 1 megaton per year as a feedstock to other chemicals, preservative, cleaning agent, and tanning agent. However, with increasing interest in renewable energy, formic acid can be directly used in fuel cells or as a liquid organic hydrogen carrier that can release hydrogen gas for fuel cells. The market for formic acid can grow dramatically if a cost-effective process to produce it is available.
Currently, plastics are mostly incinerated (which contributes to global warming), discarded in landfills (which will remain indefinitely), or disposed in the oceans. Plastics recycling usually requires a single stream of feedstocks that have to be sorted and cleaned beforehand. During the recycling process, virgin plastics are usually mixed in to ensure that the materials property remains the same, and all the reactions are driven by heat.
This technology can potentially use unsorted and untreated plastics. In addition, the energy source is currently light, but we plan to develop it into a system that uses light and electricity. This gives the versatility to employ renewable energy like sunlight or wind-powered electricity to drive these reactions. Moreover, the technology can also be exported to other countries where renewable electricity is available from geothermal (e.g. Indonesia), hydroelectric (e.g. Vietnam, Laos, and Cambodia), or solar (e.g. Australia) energy.