This month, Ian Buxton looks at attempts to increase environmental sustainability by Scotland's distillers, through the waste that they generate.

In the headlong expansion of Scotch whisky distilling, it’s the topic that we hear very little about: When the industry was just a farmhouse concern, draff (the used barley grains) would be used as cattle feed and the pot ale (the liquid left in the still after the spirit has been drawn off) could be spread on the fields as a fertiliser.

For hundreds of years, that has more or less been the situation. However, today the operation is a little more sophisticated, is rather more strictly monitored and acknowledges environmental concerns. Much of what goes on in and around the distillery would be unrecognisable to a distiller from the 19th Century.

The scale is breath-taking. According to one estimate, the whisky industry produces 1.60bn litres of pot ale and 500,000 tonnes of draff annually – figures that are set to grow even more as new capacity comes on-stream. Can Scotland’s farmers really handle all that fertiliser and feed? If not, where is it going to go?

A solution must be found if the industry is not to choke on its own waste products.

Hence, we have recently seen the development of innovative projects to use this waste rather more creatively. As befits the largest distiller in Scotland, Diageo has been taking a lead at its Roseisle Distillery and at its new GBP6m bioenergy plant at the Glenlossie distillery complex.

The new plant will produce energy by burning draff at the Glenlossie site near Elgin - which uses around 30,000 tonnes of draff per year. With 17 malt whisky distilleries on Speyside alone, producing over 50m litres of spirit per year, Diageo has a plentiful supply of raw material.

The 'draff fire' will produce steam that will be used in the operations on site, including Glenlossie and Mannochmore distilleries and the onsite dark grains plant, which makes animal feed. Here's the pay-off: By reducing annual CO2 emissions by approximately 6,000 tonnes, Diageo claims this is the equivalent of taking around 1,600 family cars off the road.

The showpiece Roseisle site is capable of producing 10m litres of spirit annually. The majority of the by-products will be recycled on site in a bioenergy facility, helping the distillery to generate most of its own energy and reduce potential CO2 emissions by around 13,000 tonnes (yet more virtual cars left in the garage).

But, Diageo is in the fortunate position of being able to commit investments in the tens of millions of pounds. What about smaller distillers? How can they ensure a green future? And, is burning the draff the only answer?

Scottish startup business Celtic Renewables, a high tech spin-off business based at the Biofuel Research Centre at Edinburgh Napier University, thinks not, and is working with Tullibardine Distillery in Perthshire to offer alternative solutions. The company's research shows that whisky’s byproducts can be converted to biobutanol, a next-generation biofuel. Biobutanol has 25% more energy per unit volume than bioethanol; it has a lower vapour pressure and higher flashpoint (making it easier to store and safer to handle); it can be blended without requiring modifications in blending facilities, storage tanks or retail station pumps; in sharp contrast to ethanol, it can run in unmodified engines at any blend with petrol and could also be blended with diesel and biodiesel; it is less corrosive than bioethanol and can be transported using existing infrastructures.

This all sounds fantastic – but will it work?

Celtic Renewables is halfway through its pilot programme that it hopes will produce 2,600 gallons of biofuel. The pilot should determine whether producing biobutanol from whisky’s waste is cost effective. The basic technology is well-established, having been invented prior to WW1 but, by using a new generation of ‘bugs’ developed by the company, it is hoped that a significant and commercially-viable industry can be quickly developed.

Apart from the potential benefit to isolated Highland and island communities, where the generation of biofuels from whisky’s waste could contribute to energy self-sufficiency, the potential exists to create larger scale facilities in areas such as Speyside, where whisky production is highly concentrated.

Fantastic as it may seem, it’s just possible that as Scotland’s North Sea oil runs out a new source of cheap energy could be found at every distillery gate.

Better not mention that to Scotland's government!