Ethanol waste: it’s what’s for ... breakfast? 6

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1. 

   Sean Casten Posted 12:52 pm
   04 May 2009

   While this doesn't really refute your arguments, it's worth noting that many of the chemicals you cite currently come out of corn wet milling operations.  A corn dry mill (which is what most of the recent ethanol boom has been built around) differ from wet mills in many ways, but the most substantive is of sequence; where a corn wet mill grinds and fractionates corn, pulling out various food grade things on the front end (corn oil, protein, etc.) and then uses a sliver of the starch stream to ferment into ethanol, a corn dry mill runs the whole grain into a fermenter where the yeasts selectively ferment the starch in the kernel and then take the residual (the distillers grains, within which are all the proteins, oils and unfermentable sugars that the yeasts couldn't process) to go to other purposes.  So while we may not like the source of those chemicals in a before or after scenario, the after does have a lot of similarities with the before.As an interesting aside, I believe there were some folks several years ago looking to put a corn oil fractionation process on the front of ethanol dry mills, based largely around the fact that the FDA wouldn't allow you to sell oil fractionated on the back of that process as a food grade additive. (Some ethanol plants have recovered the corn oil on the back end as biodiesel, but that retails for just a fraction of food grade corn oil on a per gallon basis.)  I presume that these prohibitions would also apply to the removal of other food additives from the distillers grains - at least absent some regulatory change and/or new technology

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   Tom Philpott Posted 3:38 pm
   04 May 2009

   Hey Sean,Are you saying that wet-distilled doesn't have the residue problem, but dry-distilled does? That makes sense to me. Interestingly, if wet-distilled works better has human feed, it's a lot trickier as animal feed -- it goes bad faster, and has to be used soon after the processThe folks above are talking abput dry distillers grains, presumably because shelf-life issues.

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3. 

   Sean Casten Posted 4:16 pm
   04 May 2009

   No, a bit more subtle than that.  (Why do all my comments start that way?)The "wet" and "dry" monikers on corn milling processes are confusing, in the sense that both are pretty wet.  The real distinction between the two is the difference between a petroleum refinery and a lubrication oil factory.  A wet mill - like a petroleum refinery - takes an input material and converts it into a huge panopoly of products, with the ability to instananeously shift production from one feedtrain to another in response to variable market pricing.  It's an extremely efficient process, using everything from the tail to the snout, as it were.  It's also massively capital intensive (if you've ever been to Decatur IL, that's what a wet mill looks like).  A dry mill - like a lubrication oil plant - takes the same raw material as the wet mill, but only converts it into one product: ethanol.  It's much less efficient from a resource use perspective, and much more exposed to the economic vagaries associated with volatility in corn and ethanol pricing.  But it's great advantage is that it's much cheaper and quicker to build.  Ergo, in the big ethanol bubble that's now popping, we built lots of dry mills.  But we also made ethanol in existing wet mills, opportunistically as markets warranted.  (Interestingly, the historical "big boys" of corn milling - ADM and Cargill - were largely absent from the dry mill construction boom, suggesting that the smart money figured it was just as well not to build low-cost, low-efficiency, economically-volatile plants.)The only reason I brought that all up in response to your post is that those wet mills produce lots of the chemicals you mention from corn and from a processing perspective, it seems to me that if we're comfortable getting our lycopene from corn in a wet mill, the only reason we wouldn't be comfortable getting it from a dry mill is because of some technological constraint that forces various impurities / poisons / bad flavors / etc. into the fraction in a dry mill from which that lycopene might be recovered.Re: the specific wet / dry distillers grains issue, you're right about the rotting issue, but that doesn't necessarily affect food grade stuff.  Distillers grains are simply the goopy stuff at the bottom of a fermenter after the yeast have done their work.  (If you've ever made beer, think of the sludge left in the bottom of your fermenter after you've poured off the liquid to bottle.)  Since corn (carbohydrate + oils + proteins) went into the fermenter and the yeast can only ferment the carbohydrates (and only the 6-carbon ones, at that), the goop that you're left with is actually a pretty protein & fat rich food, with good nutritional value - assuming no contamination, of course.  The problem is that - as my compost pit knows well after I've made a nice batch of homebrew - pigs and cattle are far from the only thing that likes to eat it.  In other words, it rots quick.  The only way to prevent that is to dry it down in an evaporator - or to send it directly to feedlots from the fermenter bottom.  Since most of our ethanol mills aren't near feedlots, drying has become the preferred approach.  Ergo, "dried distillers grains".And - if only to tie this back to the energy nature of this website - ethanol plants use enormous amounts of natural gas drying those grains, such that it's only marginally economic for the mills themselves to sell the stuff.  Many that I've talked to wouldn't sell it at all, but for the fact that the BOD is too high to allow them to get a water discharge permit, so they instead by natural gas, dry it down and sell it at a marginal break-even or even loss.  Upshot of that is that many folks are looking at ways to get the value out of that material without using the natural gas - thus the many efforts to fractionate and sell bits and pieces into other markets before having to burn all that fuel.Make sense, or have I gotten off on too far a tangent?

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4. 

   Kiara Posted 11:43 am
   06 May 2009

   I could see contamination with pesticides and herbicides but where does the contamination with antibiotics come from?  Irrigation?

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5. 

   Tom Philpott Posted 6:33 am
   08 May 2009

   Kiara,Sorry not to respond sooner. Industrial-scale ethanol makers use antibiotics to control the fermentation process. Weird, huh?

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   1. 

      Sean Casten Posted 6:49 am
      08 May 2009

      Interesting, Tom - I didn't know that, but I'm not surprised.  My grad school thesis was working on technologies to make ethanol from cellulose, and I ruined many a good experiment when my feed lines got bacterially contaminated.  So I can understand the motivation to add antibiotics, although I didn't realize they needed it for yeast systems as well.  (Those yeasts can produce such high alcohol concentrations that they usually keep out any bacteria, at least in my subsequent home brew experience.)Perhaps the solution is an industrial lambic, following in the Belgian's footsteps, eh?

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