Page 60 - Plastics News December 2017

TECHNOLOGY

Artificial photosynthesis system may lead to greener plastics

cientists have developed a device that mimics This copper catalyst was subsequently introduced into
Sphotosynthesis and uses sunlight, water and carbon an artificial photosynthesis system to convert carbon
dioxide to produce ethylene gas - a key chemical used in dioxide and water into ethylene using only solar energy.
large quantities for manufacturing plastics, rubber and "Carbon capture is a key step in fighting human-driven
fibres. The method, developed by researchers National climate change. There has been a steady increase in the
University of Singapore (NUS), could be scaled up to atmospheric concentration of carbon dioxide, because the
provide a more eco- friendly and sustainable alternative rate of carbon dioxide emissions exceeds that of carbon
to the current method of ethylene production.
capture," said Jason Yeo Boon Siang from NUS. "This has
Ethylene, which is the building block of polyethylene, is an been attributed as a major cause of global warming which
important chemical feedstock produced in large quantities leads to undesirable environmental changes," Siang said.
for manufacturing plastics, rubber and fibres. More than "Our device not only employs a completely renewable
170 million tonnes of ethylene was produced worldwide in energy source, but also converts carbon dioxide, a
2015 alone, and the global demand is expected to exceed greenhouse gas into something useful. This could
220 million tonnes by 2020. Current industrial production potentially close the carbon cycle," he said. The team
of ethylene employs steam cracking of fossil fuels at also incorporated a battery in the prototype device to
between 750 to 950 degrees Celsius, which consumes a attain stable and continuous production of ethylene, a
large amount of energy and poses a strain on natural fuel key challenge in artificial photosynthesis systems. The
resources. The current method also leaves a significant battery stores excess solar energy collected in the day
carbon footprint, emitting about two tonnes of carbon to power the device at night or under low light, ensuring
dioxide for every tonne of ethylene produced.
that operations are not interrupted by varying amount
Recognising the need for a more eco-friendly method, of sunlight throughout the day. The invention marks
researchers tapped into renewable energy to produce a significant milestone in the realisation of a scalable
ethylene. The team first designed a copper catalyst artificial photosynthesis system for clean and sustainable
that could generate ethylene from readily available production of important organic molecules like ethylene,
water and carbon dioxide when powered by electricity. researchers said.

Plastics News December 2017 60