Quite a lot of distillery tour guides will tell you of the happy cows which are fed the draff or spent grains left over from the mashing process. Glenfarclas also incorporates their pot ale or spent wash into the draff for livestock feed, a byproduct which has traditionally been disposed of by most (I'm guessing) distilleries. Bruichladdich is looking into the creation of methane from their pot ale, using it to help power the distillery. I'd like to think that waste heat recapture is high on the list of research into the further improvement of distilling efficiency. We humans are a wasteful lot, and must get to a point where the byproducts of human activity cease to be considered waste but moreso as raw material for some other industrial process or human endeavour. Every natural process is part of a closed cycle, and human industry should be no different...Am I grandstanding again?
The main use of heat in a distillery is, of course, to separate the alcohol from the rest of the liquid within the stills by evaporation. And in order for us to be able to drink it, it must be condensed into a liquid again. This is the job of the aptly named condensers, those big copper columns which are often seen standing beside and connected to the stills. In some distilleries they are situated outside, for lack of space or to keep them cooler (another guess there). The vapour coming off the still is sent through the condenser where it circulates around a series of smaller tubes running the length within it. These tubes hold cold water which takes the heat from the vapour allowing it to condense back into a liquid. This is one of the processes which we are unable to see happen during that tour of our favourite distillery.
However there is another, older technique for condensing the vapour coming off the stills and that is the use of wormtubs. The function is the same but the technology is a little less sophisticated (arguably?). The vapour passes through a tube which "worms" its way in a circular path down through a large "tub" of cold water, usually outside.
At the top are Kilchoman and Bunnahabhain. The third photo shows the wormtubs of Abhainn Dearg, which are inside and sit above the two stills. The last photo shows the outside tubs of Cragganmore. I bet these would make dandy hottubs during a chilly winter. Dram in hand, soaking in the soothing warmth while snowflakes gently caress your face...mmmmmmm.
Slàinte
