specif ically, there are three primary components of biomass -- cellulose, hemicellulose and the polymer lignin which fills the remaining spaces in the plant cell wall. plants evolved so that these materials would last a long time and be chemically difficult to break down, making the biomass conversion process challenging. nrel has created a pilot plant to test ways to improve the process of breaking down the cellulosic material and make the sugars available for fermentation. the first step in the process is pretreatment. aden: nature has really made these materials to be resistant to being broken down. so that's why we have to do some preprocessing to break apart the cellulose and the hemicellulose from the lignin. and that's what happens in the pretreatment part of the process. we start to use acid as a chemical hydrolysis agent -- hydrolysis really means adding water to a reaction -- to begin to break down the biomass into its individual pieces and get some of the those sugars into solution. narrator: this pretreatment process releases the sugars in the hemicellulose. but the cellulos