Sydney — Next-generation bioplastics could be produced from algae.
Shawn Price, a doctoral student at University of Technology Sydney (UTS), is five months into a three-year research project to extract biomass from primitive algae, known as cyanobacteria, which photosynthesize.
He told Plastics News algae can produce biomass which can be harvested and used to create petrochemical-equivalent bioplastics.
A major bonus of using algae is reduced greenhouse gas emissions. Algae's photosynthesis takes carbon dioxide out of the atmosphere and turns the carbon molecules into starch, releasing oxygen as a byproduct.
He is working with polyhydroxybutyrate (PHB), the energy storage molecule micro-organisms use to store excess carbon.
"It's like polypropylene, with almost identical chemical properties, except it's biodegradable," Price said. "But the cost of PP is cheaper than the algae alternative and that's the bottleneck."
Price said there is a high cost in cultivating and harvesting algae in large volumes of water, but his research project includes an economic analysis to identify and potentially overcome cost barriers.
He is also examining ways to boost algae yield to reduce costs. Algae can be grown in open ponds, which is cheaper, or closed bioreactors, where carbon dioxide inflow can be controlled to boost the growth rate.
UTS has installed two ponds and a bioreactor on the roof of its science building.
Price said it's possible to use the same equipment as traditional petrochemical plastics processing, although there are some downsides, like a narrower melt range. "Some process optimization is needed, for example, temperature changes," he said.
"Technically, it's 100 percent viable, but the problem is getting the cost down." Price said plastics made from PHB polymers from plants currently cost three times as much as equivalent petrochemical resins.
Price's supervisor, Professor Peter Ralph, already has contacted industry representatives to gauge interest in Price's research.