A single-step technique for the conversion of ethanol-water mixtures into transportation fuel blendstocks can Block flow diagram illustrating (top)) water removal from wet ethanol vapor above the feed tray to produce pure fuel grade ethanol or (bottom) CADO of the same wet ethanol to fungible blendstocks. Source: Hannon et al.lower processing costs and shrink the fuel production environmental footprint associated with traditional three-step methods. A techno-economic and life-cycle analysis of the consolidated alcohol dehydration and oligomerization (CADO) technology advanced by Vertimass LLC can reduce greenhouse gas emissions between 40% and 96%.

The CADO scheme combines dehydration, oligomerization and hydrogenation in a single reactor system using a metal exchanged zeolite catalyst. Process conversion costs and emissions were contrasted with those estimated for current ethanol production processes based on sugarcane, corn and other raw materials.

Hydrocarbon blends produced by the CADO conversion process reduced greenhouse gas emissions by up to 96% depending on the feedstock: Reductions of 40%, 70% and 70% to 96% were documented for corn grain, sugarcane juice and sugarcane straw and corn stover, respectively. By processing vapor containing about 40% ethanol in water that is released when fermentation streams are volatilized, overall CADO costs for conversion of wet ethanol into hydrocarbon blendstocks are estimated at $2.00/GJ with the potential to drop to $1.44/GJ in the near future.

Researchers from Dartmouth College, Boeing, Argonne National Laboratory, National Renewable Energy Laboratory, U.S. Federal Aviation Administration, Brazilian Bioethanol Science and Technology Laboratory, Brazilian Center for Research in Energy and Materials, Oak Ridge National Laboratory, Pennsylvania State University, Imperial College London and University of California-Riverside also contributed to this study, which is published in Proceedings of the National Academy of Sciences.

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