Chemical and biomolecular engineers from the Melbourne School of Engineering have found a less expensive, more sustainable method for delivering carbon dioxide to microalgae, which in turn can be harvested to make fuels such as biodiesel.

While carbon dioxide is well known to speed up the growth of microalgae, it has to be free of contamination or the algae will die. The new method purifies the carbon dioxide from power station flue gases by absorbing it into a liquid, which is then pumped through hollow fiber membranes. These hollow fibermembranes are like drinking straws, which can be immersed into microalgae beds.

Carbon dioxide speeds microalgae growth, but must be contamination-free or the algae will die. Image credit: Pixabay.Professor Sandra Kentish, head of the university's Chemical Engineering Department and leader of the research team, says that the process may provide a more viable method of supplying purified carbon dioxide than by extracting it from flue gases, which uses significant amounts of energy and can be expensive.

“The CO2 moves directly from the liquid into the microalgae culture by permeating through the fiber walls," Kentish says of the process.

The researchers say that other products, such as chemicals, proteins and nutraceuticals, can also be produced using this approach.