In a distillery, only 10 percent of what flows out of a still is future whisky. (National Geographic uses the spelling "whiskey" to refer to the spirit in general but "whisky" when referring specifically to Scotch or Canadian whisky.) Most of what remains is draff, the residue of the grains of barley; and pot ale, a copper-laden liquid. Scotland's distillers churn out 1.6 billion liters (422.7 million gallons) of pot ale and 500,000 metric tons of draff annually. Getting rid of all that leftover muck hits manufacturers' bottom lines. "They have a major disposal problem," said Martin Tangney, Celtic Renewables founder and president.

If Celtic Renewables meets its goal of turning a "high percentage" of all that waste into biobutanol, Tangney