Cellulosic Ethanol

While many companies have attempted to produce ethanol from cellulosic (non-corn) waste feedstocks during the past 10 years, Raven has a proven technology that can successfully produce fuel-grade ethanol in commercial quantities. The process is known as “two-stage dilute acid hydrolysis.” Raven’s proprietary process works by breaking down biomass (agricultural waste products such as wood chips, corn stover and sugarcane bagasse) into three primary streams that are then converted into a suite of derivative chemicals, ethanol, and energy producing lignin. The chart below illustrates this process:

Two Stage Dilute Acid Hydrolysis Process

How it Works

STAGE ONE: After cellulosic feedstock is ground into a fine stream mass, it passes into a first stage acid hydrolysis process where it is treated with a weak sulfuric acid solution to separate residual xylose (C5 sugars). Since xylose does not easily ferment into ethanol, Raven’s patented process converts the xylose into a derivative chemical product (furfural) which can be sold into the petrochemical and biotechnology industries at significantly higher prices than ethanol.

STAGE TWO: The remaining feedstock is again treated with a sulfuric acid solution. The second stage acid separates glucose (C6 sugars) from the basic feedstock stream. The glucose is then subjected to a standard fermentation process which ultimately produces ethanol.

The final step in the process involves the utilization of lignin. Lignin is considered the “backbone” of all cellulosic waste material and represents only 15% by weight of the original feedstock, but contains about 80% of the heat energy content. Raven’s process takes advantage of this energy source by using high efficiency boilers to generate energy for the plant saving significant energy costs.