Note: For biofuels from fibers and wastes, converting cellulose to ethanol through enzymatic hydrolysis provides the greatest potential for reductions, but gasification and conversion to diesel and di-methyl ether (DME) provide similar reductions. For the advanced technologies, it is assumed that biomass provides both the feedstock and much of the process energy.
Analyses from many countries indicate that biofuels are currently a relatively expensive means of reducing GHG emissions relative to other mitigation measures, with the cost of CO2-equivalent emissions reductions exceeding €135 ($163) per tonne, according to estimates analyzed by Fulton et al. (2004). (See Figure 11.) The one exception is Brazil, where pure ethanol sold for nearly 40 percent less than the gasoline-ethanol blend in late 2005 (even accounting for the lower energy content in ethanol).