American Chemists Attempt to Hydrolyze Ethanol Byproduct to Improve Economics.

[NNadir]

The economics of biofuels depends intimately on having a place to dispose of the waste products. Currently the waste from the corn based ethanol in the United States is passed through cows and converted into cow shit. Apparently this market is approaching saturation, and so people are trying to find new ways of using the by product, known as DDGS.

Research suggest a possible solution.

The following is from the scientific journal Energy and Fuels (Energy & Fuels 2006, 20, 2732-2736)

There is considerable interest in using ethanol as an additive to gasoline and, ultimately, as a liquid fuel. Approximately 4 billion gallons of ethanol was produced in 2005, mostly from corn grain, an increase of 17% over the previous year and over twice as much as was produced in 2001.1 The Energy Policy Act, signed into law in August 2005, requires that 7.5 billion gal/year of biofuels, most notably ethanol, are to be mixed with gasoline by 2012.2 Several states in the Midwest have adopted or are considering more stringent renewable fuel standards. To meet this need, 29 new ethanol plants are under construction to add to the 95 plants operating as of January 2006.1 Thus, demand for ethanol in the United States is expected to continue
its rapid growth in the near future.

The dominant process for producing grain ethanol in the United States is the dry-grind process, which contributes about 79% of current ethanol production. During this process, distiller’s dry grain and solubles (DDGS) is created as a coproduct, and over 9 million metric tons of this material was produced in 2005.3 This residue has a high protein content and is currently used primarily as feed for the beef and dairy industry, while it is used only sparingly in the poultry and swine feed markets. However, as the supply of DDGS increases, its price is expected to decrease in relation to other feeds such as soybean meal.

Thus, it may be necessary to increase the value of DDGS in order to keep dry-grind ethanol plants cost competitive...

...Conclusion

Our experimental results show that the AFEX process is an effective pretreatment for the enzymatic hydrolysis of DDGS. Under mild conditions, glucose yields increased from 83% to 108% of the theoretical value after 72 h of hydrolysis, or 190. Furthermore, yields only decreased slightly at higher moisture content, indicating that this process may be effective without a costly drying step. Xylose yields were negligible even after the addition of xylanases. The low xylose conversion is consistent with FTIR analysis, as no evidence of hemicellulose hydrolysis is seen. Adding amylase did not improve glucan hydrolysis, most likely due to the fact that the cellulase cocktail used is already effective at breaking down starch.

These are encouraging results, indicating that hydrolysis of the fiber in DDGS may be economically feasible. This would not only increase the ethanol production in the plant but would also help offset the expected decline in value of DDGS by increasing its protein content.

The bold and italics are mine.