From wood to fuels: Integrating biofuels and pulp production

Abstract

Bioethanol currently contributes ∼2% to the total US transportation fuels mix, and another ∼0.01% is based on biodiesel. To make a substantial contribution to the United States' energy portfolio, biofuels production needs to grow substantially over the next decade by a factor of 10 or more. Although the contribution of agro-energy crops and agriculture waste for biofuels production is being intensively developed, the potential of the forest products industry to contribute to this effort has been generally underestimated. The forest products industry is one of a few nationally based industries that have the necessary skill set and infrastructure available to process sufficient biomass for the rapid short-term development and commercialization of biofuel and biochemical technologies. On an annual basis, the US pulp and paper industry collects and processes approximately 108 million tons of wood for the production of pulp and paper in a sustainable manner. Wood extractives from pulping provide approximately 700 million liters of turpentine and tall oil annually that could be employed for biodiesel applications. Wood chip preextraction technologies could make available to the biofuels industry about 14 million tons of hemicelluloses annually while at the same time enhancing the production of kraft pulps. This review highlights the chemical resources available from wood and summarizes which biomaterials are needed for pulp production and which could be utilized for biofuels, with a special emphasis on select hemicelluloses that are currently degraded during kraft pulping that could be utilized for bioethanol production. The review further describes the operational considerations by which the biofuels and pulp manufacturing industries could synergistically operate together.