Achieving near-term economic competitiveness with gasoline and starch-based ethanol will enable a viable lignocellulosic ethanol industry. Ethanol from lignocellulosic feedstocks will then be able to join starch-based ethanol in providing a sustainable, renewable resource for the world’s transportation needs. However, market analysis (4) indicates that supplying a significant fraction of transportation fuel needs with ethanol for the long-term will require additional technology advancements in all areas of the biorefinery. This is predominately driven by the need to capture higher cost feedstocks to maximize the overall impact of the biorefinery.

Future R&D efforts will need to focus on four complementary approaches. Indepen­dently, the approaches will not be sufficient to meet the long-term goals of the biorefinery, but taken collectively they will combine revolutionary scientific breakthroughs with evolu­tionary process developments to maximize the potential of the biorefinery concept to supply a significant fraction of transportation fuel needs.

Some cost reductions will be achieved by continuous process improvements to near-term technologies. For example, the construction and operation of full-scale biorefineries will highlight opportunities for unit operation optimization and provide operational experience for process optimization and cost reductions. The accumulation of operating experience and engineering data will lead to larger-scale biorefineries, which will further reduce bio­fuels production costs by leveraging economies of scale. These are the evolutionary cost reductions. However, more dramatic cost reductions will be required from scientific break­throughs for biorefineries to reach their ultimate potential.

Earlier sections of this chapter described technologies for feedstock supply systems, bio­chemical conversion, and thermochemical conversion to accomplish near-term economic competitiveness. In the future, advances will be made in all three areas, and there will be opportunities for cost savings through integrating biochemical and thermochemical con­version technologies into larger facilities. The four areas of future technology advancement needed to accomplish the ultimate potential of biorefineries are as follows:

1 Advanced, large-tonnage feedstock supply systems

2 Systems biology to improve biochemical processing

3 Selective thermal transformation to improve thermochemical processing

4 Technology integration, economies of scale, and evolutionary process optimization.