The possibility of using whisky by-products as a next generation biofuel is being explored by a Scottish start-up.
The company is working to capitalise on the tonnes of waste produced by one of Scotland's most valued industries and turn the dregs of whisky-making into fuel.
Celtic Renewables has refined its process based on a century-old fermentation technique and is now taking the step towards a commercial plant, according to an article in Chemical and Engineering News, the weekly newsmagazine of the American Chemical Society.
Draff and pot ale "have no commercial value, and in the modern context they represent a disposal issue," said Martin Tangney, founder, president, and chief scientific officer of the Edinburgh-based firm.
The process of making whisky requires three ingredients: water, yeast and a grain, primarily barley.
But only 10 per cent of the output is whisky, and the rest is waste.
Each year, the industry produces 500,000 metric tonnes of residual solids called draff and 1.6 billion litres of a yeasty liquid known as pot ale, according to the article.
These by-products are usually spread on agricultural lands, turned into low-grade animal feed or discharged into the sea.
Rather than inefficiently re-using these materials or letting them go to waste, Celtic Renewables has taken an old industrial process developed to turn molasses and other sugars into chemicals and fine-tuned it to convert draff and pot ale into acetone, 1-butanol and ethanol.
The latter two can be used as fuel. The company is scaling up its process with the help of the UK Department of Energy and Climate Change, private funds and Bio Base Europe.