Waste from winemaking could make cheap biofuel

Leftover solid grape waste from winemaking could be used to produce competitive alternative fuel.

Researchers from the University of Adelaide, Australia, are investigating the potential of transforming waste that is left over from the winemaking industry into biofuel. The researchers showed that as much as 400 liters of bioethanol could be generated by fermentation of a ton of the solid grape waste annually, which would be beneficial on many levels, including to wineries in Australia, which currently must pay for the disposal of an estimated several hundred thousand tons of this waste, which is produced every year.

An estimated 13 million tons of grape marc waste is produced globally every year.

Grape marc is the term used to describe the solid leftovers of grapes used in winemaking, including skins, stalks, and seeds. PhD student Kendall Corbin at the School of Agriculture, Food and Wine at the University of Adelaide, Australia, analyzed the composition of grape marc and discovered that in dry weight, approximately 31 to 54% of grape marc was made up of carbohydrates. Of this full amount, approximately 47 and 80% was soluble in water.

Corbin studied both cabernet sauvignon and sauvignon blanc grapes, and also studied how to pre-treat grape marc with enzymes and acids to be able to amplify efficiency. Using the enzymes and acids, a tone of the solid grape waste could be transformed into as much as 400 liters of bioethanol. The remainder of the grape marc could be used as animal feed or fertilizer.

Grape marc has the potential to produce cheap and environmentally friendly biofuel.

Corbin explained that utilizing plant biomass to produce liquid biofules can be a challenge due to the complex nature of its structure that cannot always be broken down with ease. She added that “Grape marc is readily available, can be sourced cheaply, and is rich in the type of carbohydrates that are easily fermented.”

Associate professor Rachel Burton, Programme Leader with the Australian Research Council Centre of Excellence in Plant Cell Walls in the School of Agriculture, Food and Wine, University of Adelaide, said that making biofuel from grape marc is a “potentially economic use” for what is currently mostly a waste product.

Burton said that “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.”