Cellulosic ethanol: status and innovation

• Cellulosic biofuels are becoming a commercial reality but are still expensive.
• Cost-lowering innovations can involve established or new paradigms.
• Consolidated bioprocessing with cotreatment (CBP-CT) is a new paradigm example.
• CBP-CT has potential for radical cost savings compared to the current paradigm.
• Cellulosic ethanol is important as a proving ground for new technologies.

Although the purchase price of cellulosic feedstocks is competitive with petroleum on an energy basis, the cost of lignocellulose conversion to ethanol using today’s technology is high. Cost reductions can be pursued via either in-paradigm or new-paradigm innovation. As an example of new-paradigm innovation, consolidated bioprocessing using thermophilic bacteria combined with milling during fermentation (cotreatment) is analyzed. Acknowledging the nascent state of this approach, our analysis indicates potential for radically improved cost competitiveness and feasibility at smaller scale compared to current technology, arising from (a) R&D-driven advances (consolidated bioprocessing with cotreatment in lieu of thermochemical pretreatment and added fungal cellulase), and (b) configurational changes (fuel pellet coproduction instead of electricity, gas boiler(s) in lieu of a solid fuel boiler).

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