Two methods are currently used to produce ethanol from grain: wet milling and dry milling. The adjectives ‘wet’ and ‘dry’ describe the method, not the product. The different methods affect both the profitability and logistics. Dry mills produce ethanol, distillers' grain and carbon dioxide (Figure 1). The carbon dioxide is a co-product of the fermentation, and the distillers’ dried grain with solubles (DDGS) is a non-animal based, high protein livestock feed supplement, produced from the distillation and dehydration process. If distillers' grains are not dried, they are referred to as distillers' wet grain (DWG). Wet mill facilities are ‘bio-refineries’ producing a host of high-valued products (Figure 2). Wet mill processing plants produce more valuable by-products than the dry mill process. For example, in wet mill plants, using corn as feedstock, they produce: ethanol; corn gluten meal (which can be used as a natural herbicide or as a high protein supplement in animal feeds); corn gluten feed (also used as animal feed); corn germ meal; corn starch; corn oil; and corn syrup and high fructose corn syrups.
Number of Pages
Ethanol, Grains, Carbon dioxide, Profitability, Production costs
Department of Agriculture and Food, Western Australia. (2006), Ethanol production from grain. Department of Agriculture and Food, Western Australia, Perth. Report.