The fast-flowing narrows between the isles of Islay and Jura, off the Scottish mainland, are home, according to local lore, to very big prawns. Their growth is helped by millions of gallons of pot-ale from Islay’s eight world-class whisky distilleries, which is poured under licence into the waters each year.
Pot ale, which is 96% water, is but one of two forms of waste left behind by Scotch whisky distillers. The other, partly germinated raw barley “draff”, weighs in at 750,000 tonnes each year.
Today, the Scotch whisky industry is thriving, selling nearly £5 billion a year of the product globally. The ambition is to double in size over the next decade.
“If so, something has to be done with the waste,” says Macroom, Co Cork, microbiologist, Martin Tangney of Edinburgh’s Napier University and founder of Celtic Renewables. Today, most of the world’s biofuel is ethanol, where yeast and water is added to organic matter, with “the yeast taking the glucose and converting it to ethanol”.
Tangney’s focus, however, is not on ethanol, but on butanol, first produced 100 years ago as a by-product from the manufacture of acetone needed for explosives before the first World War.
By the 1960s, the butanol/ acetone industry was the second-biggest in the world before it was priced out of the market by the then rapidly-growing petro-chemical industry.
“The chemicals were easier to make from cracking oil, an incredibly complex substance – though it survived profitably in closed markets such as apartheid-era South Africa,” he says.
In the United States in 2005, butanol’s comeback began when David Ramey “drove a 1992 Ford Buick 10,000 miles fuelled entirely by butanol”. Ramey showed that butanol worked, that it was 30% more efficient than ethanol and that, unlike the latter, “it ran in a totally unmodified engine”. And it can be added to petrol without complications.
For Tangney, the key was finding a consistent supply of ingredients that were cheap, consistent and readily available: “I’d like to say that there was a Eureka moment, but there wasn’t. “It was in front of me,” he says, pointing to the pot-ale which is mostly poured away and the draff which is used by Scottish farmers as a poor-quality animal feed, or else put into landfill. “We learned how to combine the two of them, to make a ‘soup’, as it were, so there was no extra no water needed, which is, of course, an advantage.
“The glucose has been taken out so you couldn’t make more ethanol, but there are plenty of other sugars, such as zylose. Our bugs will happily take the remaining carbon and convert it into acetone.”
Unlike most in his field, Tangney had no interest in publishing research to international academic acclaim: “My objective was to make this an industry. We wanted to protect the idea.”
Ties were developed with the Scottish government,including first minister Alex Salmond, who is already heavily behind wind and tidal energy. Scottish Enterprise gave a “proof of concept” grant, helping Tangney to get the idea to a point where other investors came forward, though it held the right “to claw back the money”.