McAloon et al. [97] studied the cost of ethanol production from lignocellu — losic materials in comparison to that from corn starch. As properly pointed out in their study, the cost comparison was made between the mature corn — ethanol industry and the emerging lignocellulosic-ethanol industry. Based on the fixed price of the year 2000, the cost of fuel ethanol production from lignocellulose processes was determined to be $1.50/gal, whereas that from corn processes was $0.88/gal [97]. Needless to say, the cost values deter­mined in 2000 cannot be considered valid for the current year, due to signifi­cant changes during the period in infrastructural and raw material costs as well as variable operating costs. In order to make lignocellulosic biorefinery technology a success, the following must be resolved.

1. The lignocellulose feedstock collection and delivery system has to be established on an economically sound basis. Feedstock prepara­tion also becomes an issue.

2. Each step of the process technology needs to be separately inves­tigated for various options and the interactions and connectivity between the steps must be completely evaluated. Interactive effects between stages become very important, because one stage’s product and by-products may function as the next stage’s inhibitors.

3. A thorough database for a variety of different feedstock must be established. A different feedstock can be chosen as a model feed­stock for different countries and regions, depending upon the local availability, logistical constraints, and infrastructural benefits. Furthermore, conversion technologies should be readily adaptable to other lignocellulosic feedstock and agricultural residues [93].

4. Large-scale demonstration is crucially important for commercial operational experience as well as to minimize the risk involved in scale-up efforts. In addition, such an operation on a large scale helps demonstrate environmental life-cycle analysis whose results are more meaningful.

5. Low-cost but highly efficient enzymes for the technology must be developed in order to reduce operational cost and improve produc­tivity. Current efforts by the National Renewable Energy Laboratory, Genencor International, and Novozymes Biotech are very significant and noteworthy in this regard. Further advances will make the full- scale commercialization of cellulosic ethanol closer and more eco­nomically feasible.