What is the difference between a wet and a dry mill ethanol plant?
The wet mill process soaks the grain kernels until a machine can separate the components. The germ is removed; the starch is removed for industrial or food uses or conversion into sweeteners, degradable plastics, proteins, pharmaceuticals and many other consumer products including ethanol. The remaining protein gluten meal and protein gluten feeds are sold on the protein market. The dry mill process grinds the grain to flour and the entire product goes through the fermentation procedure where the starch is converted to ethanol. After the ethanol is distilled off, the remainder is dried and sold as a protein product called Dried Distillers Grains with solubles (DDGs). There is a greater range of products that can be made in a wet mill than a dry mill, but the cost to build and operate a wet mill plant is much higher.
