action to make it happen. But uncertainties about the regulatory environment, especially those arising from concerns of the general public, have the potential to raise storage costs above those cited in this study. Meanwhile, ultimate requirements for selection, design, monitoring, carbon accounting procedures, liability, and associated regulatory frameworks have yet to be developed, creating the possibility of delay in initiating demonstration projects and, later, in licensing individual commercial projects. Large-scale demonstrations and establishment of procedures for operation and long-term monitoring of CCS have to be actively pursued in the next few years if thermochemical conversion of biomass and coal is to be ready for commercial deployment by 2020.

Challenge 3

Cellulosic ethanol is in the early stages of commercial development. A few commercial demonstration plants are expected to begin operations over the next several years, and most process improvements will likely come from evolutionary developments, knowledge gained through commercial experience, and increases in scale of operation. Incremental improvements of biochemical conversion technologies can be expected to reduce nonfeedstock process costs by up to 40 percent by 2030. It will take focused and sustained industry and government action to achieve those cost reductions, but some key technical challenges remain:

  • Developing more efficient pretreatment to free up cellulose and hemicellulose and to enable more efficient downstream technology conversion. Improved pretreatment is not likely to reduce product cost substantially because the pretreatment cost is small relative to other costs.

  • Creating better enzymes, not subject to end-product inhibition, for facilitating the conversion process.

  • Maximizing solids loading in the reactors.

  • Engineering organisms capable of fermenting the sugars in a toxic biomass hydrolysate and producing high concentrations of the final toxic product biofuel; improving microorganism tolerance to toxicity is a key issue.

Challenge 4

If ethanol is to be used in large quantities in LDVs, an expanded ethanol transportation and distribution infrastructure will be required. Because ethanol cannot be



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