What is cellulosic ethanol?by Mark Steil, Minnesota Public Radio
Most ethanol is currently made from corn. But as demand goes up, other types of plant materials may become sources for ethanol production. Here's how the process works.
There are two ways to make cellulose ethanol. The first is a biological process which separates sugar from plant fiber. Virtually any type of plant material can be utilized. Wheat straw, corn stalks, switchgrass and wood chips are all on the list.
The material is chopped into pieces two inches or less in length. The chopped-up vegetation is soaked into a mud-like consistency. Next, enzymes are added to the solution. Enzymes force a chemical reaction in the solution, converting certain molecules into another type of molecule.
Finding the right types of enzymes is an important part of the development of cellulose ethanol. That is the focus of an extensive research program linking government, academic and private business researchers. The enzymes attack the plant matter and turn it into glucose, a sugar. The sugar is then fermented into ethanol.
The second method of making ethanol from plant fiber is non-biological. Instead, it uses available gasification technology. Under high pressure and high temperatures, cellulose is converted into a gas. The gas is then run through a special type of catalytic converter. The converter combines the molecules in the gas to make ethanol.