Bourbon creating biofuels as a byproduct?

[Bourbon Boiler]

Maybe this has been discussed previously, but I saw this today.

http://www.newenergyworldnetwork.com/renewable-energy-news/by_technology/biofuel_biomass/edinburgh-napier-university-looks-to-bring-whisky-biofuel-to-the-pump.html

Supposedly the product made from waste in a whiskey making process would not require any engine alterations to be used by a typical motor vehicle. I couldn't find a more technical article that didn't require a subscription. I would be interested if anyone has any knowledge of the processes involved.

[cowdery]

Pot ale, I believe, is another name for tails. The other by product they use is the spent mash, which is sometimes dried for livestock feed but also flushed away as waste. more here.

If you want to search for more the search term you want is "butanol fermentation."

It's not new science but nobody has figured out how to do it economically.

[ODaniel]

Wouldn't this essentially be the "ethanol" they advertise? Alcohol + spark = combustion. Nothing new. Don't the distillers use the tails in the next run? Or is that just moonshiners?

[harshest]

Wouldn't this essentially be the "ethanol" they advertise?

I'll tell you what, I was recently at an ethanol plant here in Michigan and the first thing I said when I opened my truck door was, "This smells just like the Jim Beam distillery." There can't be a whole of difference between an ethanol plant and distillery...

[dgonano]

You should note that the process of mashing and distilling malted barley is quite different than that of our Bourbon industry.

They use hot water to cook the mash and only the liquids (wash) enter the pot still. No solids enter the still.The pot ale is the liquid remaining after distillation. The undistilled solids from the mashing(draff) probably have some unfermented qualities.

[cowdery]

An ethanol plant is a distillery. The only difference is the proof of distillation. Ethanol is vodka. There's virtually no difference between a whiskey distillery and an ethanol plant.

The experimental stuff is not the distillation nor even the fermentation. It's the conversion of starches into sugars. Some starches convert easily, others don't. Some dissolve but don't convert hence don't ferment (that's probably what's in the pot ale), others don't even dissolve. A big part of that is cellulose, which is still a starch which, theoretically, can be converted to sugar. They can do it in the lab but not on a production scale economically.

[Gillman]

Chuck, I was talking to a distiller recently (non-American) who told me a hallmark of a column still, in his experience, is that congeners are drawn from the column at different levels, to adjust the character of the final spirit. We have all seen diagrams of such equipment showing vaporisation temperatures of various congeners and thus the position (tray) in the columns where the draws take place. My understanding of the column stills used for bourbon is that no such draws are made, whether at the beer stripping level or subsequently. Is this your understanding too? I have always thought that what comes out of the doubler is what went in to the column less only what is in the spent beer, but I don't think I've ever read or been told that that is so as such.

Gary

[cowdery]

People who say what your (non-American) correspondent did are either simply ignorant or they are being deliberately disparaging. Your correspondent described fractional distillation, which is practiced in various kinds of non-alcohol distillation, most notably the refinement of oil. This is not done in alcohol production (either beverage or industrial) as anyone who purports to be a distiller should know because alcohol distillation does not produce multiple products. All you are trying to do is separate water and alcohol and, in the process, destroy or discard a few undesirable congeners, which exist in very minute quantities and which are not captured but, as I said, simply discarded or destroyed. This whole thing of equating column stills with oil refineries is a bit of a slur on North American practice so the next time someone says that to you, be offended.

[Gillman]

Draws from different sections of a column still are made for some rum, tequila and grain whisky, I have read this in the literature. Condensed co-products, e.g., aldehydes, can be removed from plates to adjust the character of the final spirit as I said earlier. In some cases they are re-cycled in the distillation process. These are not used to make separate alcohol products, nor was that suggested in the discussion I had with this person (and the oil industry never came up).

But in any case, I was asking about bourbon production, and you have confirmed my understanding. It makes sense too because this aligns more to a batch process of production, along the older pot still lines; the character of bourbon is in that tradition. He wasn't being disparaging, nor did he suggest draws are used in bourbon production (he didn't know), we were simply discussing the production of different spirits.

Gary

[Gillman]

I found these references, which give the same answer, but in an increasing level of technical detail:

http://www.ibdasiapac.com.au/asia-pacific-activities/convention-proceedings/2006/Papers%20&%20Presentations/Robson%20Frank%20Paper.pdf

http://www.hotelmule.com/management/html/96/n-1796-12.html

In the second link, page 12 together with page 18 shows that in the production of high quality (high ABV) spirit, such as vodka but extending to light rum, the base used for some tequila, and grain whisky, propanol, Butanol and amyl alcohol are removed in what are termed side streams from the rectification column. Perhaps not invariably, and producers surely must differ in their techniques, but clearly much alcohol in these classes is made this way. The undesired co-products are collected from plates below that where the spirit in its best quality (as explained in the article) is taken off. There is some alcohol in these fusels, separated in a fusel oil column and returned to the final spirit. It is interesting that alcohol is not collected on plates above the collection plate for spirit albeit at a higher ABV, since it contains certain low-volatile (high boiling) co-products although as explained this alcohol ultimately is retrieved too (probably refluxed back). These collections do not, or such is my understanding from these papers and Chuck's comments, occur in bourbon production, which is partly why white dog distillate has much higher levels of fusel oils and other co-products than pure spirit diluted to the same distilling-out proof.

I never really thought of this issue before, nor do I think it is anything other than a matter of tradition for bourbon to be made this way. Apologies for diverting the thread somewhat, but it was thinking of the differences between industrial and beverage alcohol production that prompted these thoughts. I am now thinking though, for the purposes of non-beverage GNS production, does it matter really whether these co-products are in the product or not? Perhaps fuel or other uses of such alcohol requires such purity, but I don't know.

Gary

[cowdery]

Ah. Now I see the difference. This is a common misunderstanding that happens when people try to equate bourbon column stills with the grain whiskey stills in Scotland. The stills in Kentucky are much smaller. Some 'products,' if you want to call them that, are vented away at the top of the still, in some set ups, but otherwise nothing is removed except by the process itself. The difference is that the rum, tequila, and vodka stills are much, much bigger and they're removing everything.

This is not strictly a function of through put. An American whiskey distillery will have multiple stills rather than one enormous one. They're trying to craft a taste, not remove all taste.

I get it now, I can see how in an ethanol plant you would produce enough of these what I would call distillation by products to make it worthwhile to capture them.

So, no, for all intents and purposes there is no fractional distillation going on in bourbon production.

[Gillman]

That's it, I think the larger number of plates, spaced closer too in the big towers used to produce grain whisky etc., facilitates taking off all the non-ethanol by these deliberate draws from the plates in the columns. Whereas in the smaller American columns, the separation is achieved just by what is left in distiller's beer as compared to what goes to the doubler. It's more rough and ready, as a pot still is in terms of what it separates in the multiple runs. Further reading has suggested to me that the removal is done, both to reduce the amount of fusel oils in the final spirit and increase output.

Gary