Plastic waste and greenhouse gases are two scourges on our planet, but what if we could repurpose them into something green with the help of the sun?
If that sounds like wishful thinking, think again.
Scientists at the University of Cambridge have devised a system whereby these two harmful wastes can be turned into useful products simultaneously with the help of a solar-powered reactor.
The reactor can convert plastics and CO2 into different products for use in various industries. In one test, for example, greenhouse gas was transformed into synthesis gas, a building block for sustainable liquid fuels, while plastic bottles were transformed into glycolic acid, a common ingredient in cosmetics.
“Plastic pollution is a huge problem across the world, and too often, a lot of the plastic we throw in bins is incinerated or ends up in landfills.says Erwin Reisner, a chemistry professor who directs the Cambridge Circular Plastics Center and was lead author of a paper, “Turning garbage into something useful using solar energy is one of the main objectives of our research.”.
Solar energy to process plastic waste and CO2
To facilitate the joint conversion of the two wastes, the researchers developed an integrated reactor with separate compartments: one for plastic and the other for greenhouse gases. The reactor uses a perovskite-based light absorber, an alternative to silicon in state-of-the-art solar cells.
“A solar-powered technology that can help tackle plastic pollution and greenhouse gases at the same time could be a game-changer in developing a circular economy.”, underlines Subhajit Bhattacharjee, co-author of the article.
“We also need something that can be tweaked so you can easily make changes based on the final product you want.”, adds Motiar Rahaman, another scientist involved in the project.
Different catalysts designed by the scientists were integrated into the light absorber so that each catalyst produced a different end product under normal temperature and pressure conditions. Tests have shown that the reactor can efficiently convert PET plastic bottles and CO2 into different carbon-based fuels such as CO, synthesis gas and glycolic acid.
Even better, the specially designed reactor produced these products at a much higher rate than conventional photocatalytic CO2 reduction processes, say its inventors.
Co2 and energy conversion
“In general, converting CO2 requires a lot of energy, but with our system, basically, you just turn on a light and it starts turning harmful products into something useful and sustainable. Prior to this system, we had nothing that could selectively and efficiently manufacture high-value products.Rahman explains.
“What’s so special about this system is its versatility and adjustability. At the moment, we are producing fairly simple carbon-based molecules, but in the future we could fine-tune the system to produce much more complex products simply by changing the catalyst.says Bhattacharjee.
Over the next few years, scientists will work on developing their reactor so that it can produce more complex molecules from plastic waste. One day, techniques like this could power a fully solar-powered recycling plant, experts say.
“Developing a circular economy, where we make useful things out of waste rather than dumping it in landfills, is vital if we are to meaningfully address the climate crisis and protect the natural world.says Reisner. “And powering these solutions with the sun means we’re doing it cleanly and sustainably.”.