(9a) An Overview of Biofuels Process Development in South Carolina

The South Carolina Bio-Energy Collaborative, composed of Arborgen, Clemson University, Savannah River National Laboratory, and South Carolina State University, is working with Dyadic, Fagen Engineering, Renewed World Energies, and Spinx to develop bio-fuels production processes that are efficient and economical, that are integrated from biomass production to market, and that can utilize crops that grow well in the southeastern United States.

At the present time, a switchgrass-to-ethanol process is undergoing intense study. In this process, switchgrass is harvested, chopped, ground, and pre-treated in order to separate the lignin content from the cellulose in the switchgrass. The pre-treated switchgrass is hydrolyzed, and the sugars produced are fermented to make ethanol. Lignin separated during the pre-treatment step is precipitated and purified so that it can be used for other purposes. With minor modification, the process may be adapted to utilize other crops, and the application of the process to sweet sorghum and wood from trees (i.e., loblolly pine, eucalyptus, populus)is of great interest to the Collaborative. All process work is currently at the bench-top scale, but efforts are underway to secure funding for a pilot plant that will be capable of producing up to approximately 80 gal/day ethanol from switchgrass.

Algae, due to its enormous growth rate and ability to make oils and lipids, is also of great interest for the production of diesel fuel, jet fuel, and gasoline. Process development work is underway on closed algae growth systems and methods for recovering the desired fuel products from the algae. In related work, algae species are being screened to determine the strains most suitable for fuels production in South Carolina under salt water and fresh water conditions.

This paper provides an overview of the switchgrass-to-ethanol process steps, and discusses some of the key technical points that are being refined in order to help make the process economically viable. Potential variation of the process to handle multiple cellulosic feed materials is described. Algae growth and processing is discussed as a separate topic, and the current status of this work in South Carolina is provided.