A Novel Sulfite Pretreatment Process (SPORL) for Efficient Biochemical Conversion of Woody Biomass to Bioethanol

The SPORL process consists of reacting wood chips with a solution of calcium, magnesium, or sulfite at elevated temperatures for a short time, and then size reducing the resulting material using a disk refiner to generate fibrous substrate for subsequent saccharification and fermentation. The work is a collaborative effort between industry, university, and federal agencies. Forest biomass is a very important feedstock for the future bioeconomy for the rural United States because of its availability in large quantities, flexible harvesting schedule that eases storage, and low cost for transportation due to high density and low ash content. About 30 percent of the projected annual sustainable available biomass is forest biomass based on the billion ton study. To meet local rural United States bioenergy needs and promote biodiversity, forest biomass will be an important integral part of the biomass feedstock supply. However, forest biomass, especially softwood, is very difficult to convert biochemically to fermentable sugars for cellulosic ethanol or biofuel production due to its strong physical integrity and chemical recalcitrance. The goal of this project in Phase II is to prove this commercially deployable technology for forest biomass bioconversion to produce cellulosic ethanol and lignin bioproducts at the pilot scale. The research proposed will create an opportunity for rural economic development through sustainable green energy production. While the commercial production of cellulosic ethanol is nonexistent currently in the United States, it expected that about 500 biorefineries will be built in the next 15 years to meet goal of 16 billion gallons of cellulosic ethanol set by the advanced fuel standard in the EISA of 2007. The development of this future biorefining industry will take place primarily in the rural areas where large quantities of biomass feedstock are available at a low cost. Producing ethanol from cellulose promises to greatly increase the volume of fuel ethanol that can be produced in the United States. That will not only benefit the United States, but could help poorer nations by reducing fuel cost. With the ever increasing occurrence and intensity of forest fires, large volume and high value utilization of forest thinning materials is critical to mitigate the very expensive cost for forest thinning operations to reduce fuel loadings. The woody biomass form forest thinnings meet the advanced fuel standard. The SPORL technology provides a viable avenue for utilization of the thinning materials, which makes thinning and healthy forest management operation sustainable. This will enhance our biofuel resource base by providing new feedstock. Therefore, the proposed research has the potential to enhance international competitiveness of American agriculture, enhance the competitiveness and sustainability of rural and farm economics, support increased economic opportunities and improved quality of life in rural America, and protect and enhance the Nation's natural resources base and environment.