One for the Road: Turning Whiskey Waste into Renewable Biofuel

by Rasaq Abolore (TU Dublin/RTE) Analysis: leftover grain accounts for 85% of total waste generated by distilleries. What if it could be used to fuel cars and planes? -- ... Irish whiskey is mainly produced from barley and corn while wheat, rye, and oats are utilised in smaller quantities.

The spent distillers' grain is the remainder after filtering-off the liquid (wort). In Ireland, an estimated 350,000 tonnes of grains are used every year by the Irish whiskey distilleries. It is estimated that one tonne of grains could produce between 372 and 378 litres of ethanol, generating between 457kg and 479kg of wet, spent grain. This means almost half of the initial grain ends up as waste, with spent grain accounting for about 85% of the total waste generated from the distilleries. This leftover grain presents a huge environmental burden globally, including in Ireland.

Also, the leftover grain is very wet and spoils very fast due to its high water content and can not be stored, plus it is expensive to transport due to its weight and volume. Drying to less than 10% for easy storage and transportation is also very expensive due to high energy cost, while disposing of these spent grain in landfill is also not an environmentally friendly alternative.

However, recent technological advancements have presented an opportunity to convert food waste into renewable biofuels, such as bioethanol which can be used in automobiles and aircraft engines.

The three major solid components of this food waste are: cellulose, hemicellulose and lignin. Other smaller fractions, such as protein and fibre, are also present. Cellulose and hemicellulose are the only fractions required for bioethanol production.

Finally, the use of these inexpensive materials from Irish distilleries as raw materials for the production of bioethanol will improve the value of these underutilised food wastes, reduce the bioethanol production cost, and reduce dependence on non-renewable fuel sources, as well as reduce the environmental burden of food waste.

It will also draw Ireland closer to the European strategy of providing new technology to upgrade existing bio-based industries into integrated bio-refineries and will play an important role in achieving the Sustainable Development Goals. READ MORE; includes AUDIO