Agricultural residues can provide an attractive feedstock for cellulosic ethanol production in the near term because of their current availability, and many with high cellulose and hemicel — lulose content are amenable to conversion to ethanol with high yields. However, in estimating potential contribution to large — scale fuel production, consideration must be given to how much can be removed without problematic environmental consequences such as depletion of soil carbon and soil erosion. In addition, the cost of gathering and transport must be factored in, and collection strategies should be employed that minimize collection of dirt and stones. Storage techniques must also be developed that are low in cost but result in little degradation of the feedstock. And we must be sure that the sugars can be extracted from the carbohydrate fractions with high yield.

Because of the large impact feedstocks have on overall costs, selection of low-cost residues can be particularly important for overcoming the many obstacles to implementa­tion of cellulosic ethanol technology for the first time in the near term including perceived risk and the associated high rates of return on capital, overdesign to compensate for risk, suboptimal facility sizes that keep investment costs lower but fail to capitalize on econo­mies of scale, and other disadvantageous burdens. For example, cutting the cost by $30/ dry ton can reduce cash costs by over $0.35/gal of ethanol produced. However, even then taking advantage of other economic levers such as integration into an existing fermentation or power facility to reduce capital costs; production of valuable coproducts from lignin, minerals, or other components; and use of low — cost debt financing through partnerships with municipalities or others can have a tremendous impact on commercial success (Wyman and Goodman 1993) . Unfortunately, given the great fluctuations in petroleum prices, all of these factors may not be enough to overcome the huge obstacles facing first-time implementation, and government policy would make a major impact on bringing the tech­nology into play before dire economic situations make it sufficiently profitable for the first projects to be successful (Wyman 2007). Although such assistance could take many forms, it must be structured in a manner that will not strand huge investments by the private sector while still ensuring rigorous due diligence that will result in economically viable projects. For example, government investments as an equity partner would buy down the high capital costs of first projects, show the private sector of the government’s seriousness, and provide a payback to the government. Once in place, significant learning curve improve­ments and technology advances will lead to lower costs that can compete without govern­ment support. However, because huge lead times are needed to build up meaningful capacity, such a commitment must be made sooner rather than later if we really hope to reduce our mounting dependence on oil imports and have any hope of affecting buildup of CO2 and other GHGs. Otherwise, we will continue to twiddle our thumbs while glaciers melt and coral reefs die.