It is now possible to turn the dregs of whisky-making into fuel.
Scotland’s Celtic Renewables, formed in 2011, refined its process based on a century-old fermentation technique and is now taking the next step toward a commercial plant.
Making whisky requires three ingredients: water, yeast and a grain, primarily barley. But only 10 percent of the output is whisky, and the rest is waste. Each year, the industry produces 500,000 metric tons of residual solids called draff and 1.6 billion liters of a yeasty liquid known as pot ale. These by-products usually end up spread on agricultural lands, or 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 fuel.
The company is scaling up its process with the help of the U.K. Department of Energy & Climate Change, private funds and Bio Base Europe. If all goes well, a commercial facility could be next.