According to Mother Jones, the waste products from whiskey-making are being turned into fuel.
Here’s how it works: To make Scotch whiskey, you take barley, separate out the sugar, add water and yeast, and ferment it. The result is similar to beer. The next step is to distill the alcohol from that beer in pots. Set it to age in wooden casks, and a few months later, you have whiskey.
The problem is that the process creates a lot of byproduct: First there are the remains of the barley, called draff. And when you distill the alcohol, you’re left with a liquid called pot ale, which is hard to dispose of because it contains biological components that can acidify ecosystems, along with traces of copper that are leached from the pots. Celtic Renewables makes a soup out of the pot ale and draff. Then—through a fuel-making fermentation process that was developed during the leadup to World War I but fell out of favor when it couldn’t compete with petroleum—the company converts the stuff into biobutanol fuel, animal feed, and acetone.
The used corn/grain mash in Kentucky is typically also sold or given to farmers as cattle feed. Lightly alcoholic, it is said to result in very happy cows.