It is brewed with an extended mashing time, in which the carbohydrates are broken down into simplesugars that are then fermented into alcohol and carbon dioxide.
He admits that it is not simple to pull the sugars out of non-food material like pulp or wood waste, but says that even factoring in the extraction process, the final cost should be lower than using corn starch or sugar cane, both of which are much higher-priced commodities.