1a. Objectives (from AD-416)
The overall objectives of this project are to develop economically viable technology to allow production of fuel ethanol from "Generation 1.5" regional non-corn feedstocks such as winter barley, that are grown outside the Corn Belt on fallow land or land that does not compete with food production. Evolve these ethanol plants into multiple product biorefineries, producing high value food and feeds and then into multi-feedstock biorefineries that can accept fermentable sugars from local lignocellulosic feedstock to produce additional ethanol and valuable coproducts. 1. In conjunction with CRADA partners and other collaborators, develop technologies that enable (1) commercially-preferred processes for converting winter barley into fuel ethanol in ways that significantly reduce biorefinery water usage and (2) commercially-viable, value-added co-products from barley-based biorefineries. 1a: Develop commercially-preferred processes for converting winter barley into fuel ethanol and improved DDGS in ways that increase ethanol yield and significantly reduce biorefinery water usage. 1b: Develop commercially-viable, value-added carbohydrate based co-products from barley kernels, hulls, and/or straw in barley-based biorefineries. 1c: Develop commercially-viable, value-added lipid based co-products from barley kernels, hulls, and/or straw in barley-based biorefineries. 2. In collaboration with NCAUR, develop technologies that enable the commercially-preferred conversion of barley hulls and/or straw into sugar-containing make-up water, allowing the production of ethanol from both starch and cellulose in a barley grain-based biorefinery.
1b. Approach (from AD-416)
In conjunction with CRADA partners and other collaborators, develop technologies that enable commercially-preferred processes for converting winter barley into fuel ethanol and improved DDGS in ways that increase ethanol yield and significantly reduce biorefinery water usage. Develop commercially-viable, value-added carbohydrate based co-products from barley kernels, hulls, and/or straw in barley-based biorefineries. Develop commercially-viable, value-added lipid based co-products from barley kernels, hulls, and/or straw in barley-based biorefineries. In collaboration with NCAUR and other partners, develop technologies that enable the commercially-preferred conversion of barley hulls and/or straw into sugar-containing make-up water, allowing the production of ethanol from both starch and cellulose in a barley grain-based biorefinery.
3. Progress Report
Sub-Objective 1a: Developed a high-solid fermentation process for barley ethanol production. This process uses the native enzymes that are present in the barley grains during a short incubation period (2 hours) at low temperature (60oC) to reduce the viscosity of the mash and allow use of high solid concentrations. We were able to use 35% solids (dry basis) and achieve almost 19% ethanol by volume (150 g/liter). Used our new precision barley de-hulling process and a roller milling process as a way to potentially remove mycotoxins like deoxynivalenol (DON) from barley kernels prior to making fuel ethanol. If this is effective, it will result in improved DDGS that contain low enough levels of toxins to be fed to animals rather than being land filled or incinerated. Sub-Objective 1b: Determined the sugar composition of arabinoxylan (AX) and cellulose rich fractions (CRF) from barley hull and straw to determine their structure, composition and potential new uses. Water binding studies of CRFs indicated that they have very high water holding capacity useful for the food industry. Sub-Objective 1c: Developed a process to isolate a very pure germ fraction from hull-less barley using a comminuting mill. The goal was to produce fractions of barley that are enriched in health-promoting tocotrienols and other phytonutrients. This barley germ fraction contains up to 16% hexane extractable oil, which is higher than the amount of oil in barley germ obtained by hand dissections and higher than the amount of oil in commercial wheat germ. Objective 2: Developed a process for obtaining fermentable sugars from barley hull and integration of these sugars in a barley biorefinery for production of ethanol by yeast (from glucose) and value-added co-products such as astaxanthin (from other sugars such as xylose). Also, in experiments with Iowa State University a new and highly effective Low Moisture Aqueous Ammonia (LMAA) process was developed for pre-treating cellulosic biomass before cellulosic ethanol production. The process appears to have advantages over the state of the art. An invention report and a manuscript were written
1. New process to simultaneously make cellulosic and starch ethanol from barley. ARS researchers at Wyndmoor, PA, collaborated with researchers at Iowa State University to develop a new process to simultaneously generate fermentable sugars from starch and cellulose that are present in hulled barley kernels. The process does not require any grinding or removal of the barley hull that is used in conventional processes to convert barley to sugars and fuel ethanol. Instead, the whole barley kernel is subjected to cooking at low pH and moderate pressures before being exposed to commercial enzymes that break down both starch and cellulose simultaneously into sugars that can be fermented by brewer’s yeast into fuel ethanol. The result is the first process to make fermentable sugars from both cellulose and starch in the same process from barley and the process can be extended to corn, sorghum, triticale and rye. Use of this published and patent pending process will allow the production of more ethanol per bushel of grain feedstock and may also result in ethanol with low enough lifecycle green house gas emissions (relative to gasoline), to qualify as an advanced biofuel as defined by the Environmental Protection Agency.
2. Completing an economic analysis of a new barley fuel ethanol process. ARS researchers at Wyndmoor, PA, compared the cost of making fuel ethanol from barley in a conventional process to the cost of using a new ARS “EDGE” (enhanced dry grind enzymatic) process that uses a special enzyme to ease processing and increase ethanol yields. To do the comparison, the researchers built a techno-economic computer model that simulated the conventional barley to ethanol process then they modified the model to represent the new EDGE process. When the models were compared, it was found that if barley prices were less than about $2.00 per bushel, the EDGE process was not economic. However, with barley prices at the current level of $4-$6 per bushel and with present costs of the enzyme, the EDGE process results in significant savings over the conventional process. Companies using barley to produce fuel ethanol in North America and Europe can use this recently published information to determine which process they will use in their facilities.
3. New process to remove mycotoxins from barley grain while simultaneously making fuel ethanol. Barley grown in seasons with high rainfall is sometimes contaminated with toxins produced by fungi that grow in the field on the moist barley kernels. These “mycotoxins” are toxic to humans and animals and thus barley grain contaminated with them cannot be used for food or feed. ARS researchers at Wyndmoor, PA, collaborated with researchers at Virginia Tech to develop a new yeast strain and showed that it can convert barley to fuel ethanol and simultaneously convert the mycotoxin called deoxynivalenol (DON) into less toxic forms so that the resulting ethanol coproduct, distiller’s dried grains with solubles (DDGS) can be fed to animals. This is the first work of its kind and it has potential to allow use of contaminated barley in fuel and feed markets which will help farmers and ethanol producers avoid crop and product losses. The work has been published and covered in numerous press releases around the world.
Kim, T., Nghiem, N.P., Taylor, F., Hicks, K.B. 2011. Consolidated conversion of hulled barley into fermentable sugars using chemical, thermal, and enzymatic (C.T.E.) treatment. Applied Biochemistry and Biotechnology. 164:534-545.