Australian researchers want to turn wine waste into biofuel

ADELAIDE, Australia, Aug. 20 (UPI) -- Researchers in Australia, home of Shiraz, say grape waste could be turned into a competitive biofuel.

Australia is the fourth biggest exporter of wine in the world. Scientists at the University of Adelaide suggest some of the byproducts of the winemaking process, including spent grape skins, stalks and seeds, could be used to make a profitable biofuel.

Post-processing grape waste is often called grape marc. Worldwide, winemakers produce more than 14 million tons of grape marc. In Australia, the number is a few hundred thousand tons. Some of it is used as fertilizer, but most is thrown out at a cost to the winemaker or processor.

But as detailed in a new study, published in the journal Bioresource Technology, a single ton of grape waste can produce 400 liters of bioethanol.

"This is a potentially economic use for what is largely a waste product," Rachel Burton, a researcher and program leader at the Australian Research Council, said in a press release.

After being treated with acid and enzymes, the majority of the carbohydrates in the grape marc can be converted directly to ethanol. And the leftover material can still be used as fertilizer.

Breaking down and processing plants that are grown solely for the purpose of producing biofuels is expensive and involves a variety of complex steps. That's why sourcing already processed biomass is immensely valuable.

"Grape marc is readily available, can be sourced cheaply and is rich in the type of carbohydrates that are easily fermented," said researcher Kendall Corbin.

"We've shown that there is a potential new industry with the evolution of local biofuel processing plants to add value to the grape for an environmentally friendly biofuel," added Burton.