Assessment of Conversion Technologies for Bioalcohol Fuel ...

CATEGORY XII–FERMENTATION OF SYNGAS FROM
THERMOCHEMICAL PROCESSES
Bioengineering Resources, Inc., Fayetteville, Arkansas
Organizational Background–Bioengineering Resources, Inc. (BRI) was formed to
commercialize a unique patented process that employs a bacterial culture to convert
synthesis gas into ethanol. Development of this process by University of Arkansas
researchers began some 18 years ago.
Technology Characteristics–The BRI technology, illustrated in Figure A23, uses an
enclosed two-stage gasification process to thermally decompose the carbon molecules
in organic feedstocks. A patented microorganism then reconstructs CO, CO2 and H2
into ethanol and water. Finally, anhydrous ethanol is produced by conventional
distillation followed by a molecular sieve. The microbiological conversion of hydrogen,
carbon monoxide and carbon dioxide to ethanol uses a strain of bacterium in the
clostridium family. BRI carried out pilot studies using a 2-foot reaction chamber in
which an aqueous solution of nutrients are added. Hydrogen, carbon monoxide and
carbon dioxide are added from gas cylinders. The bacteria convert these gases to
about 2-3% ethanol. Higher ethanol concentrations inhibit bacteria metabolism.
Products are continuously removed from the reactor and ethanol is recovered by
distillation. The synthesis gas exits the gasifier at temperatures of up to 2,350°F, and
must be cooled to about 98°F before being fed to the microorganisms. This cooling
process generates waste heat that can be used to create high temperature steam to
drive electric turbines.
Development Status–BRI reports that six years of testing at the company’s
laboratory and 1.5 ton-per-day pilot plant, both located in Fayetteville, Arkansas, have
successfully demonstrated that syngas with various impurities can be used.
Future Plans–BRI has formed a joint venture with a Florida land management
company, Alico, Inc. to apply the BRI technology in a project planned by Alico in
LaBelle, FL. In February 2007, Alico was awarded a U.S. DOE grant of up to $33
million for this project. This plant is intended to produce 13.9 million gallons of ethanol
a year and 6,255 kilowatts of electric power, as well as 8.8 tons of hydrogen and 50
tons of ammonia per day. For feedstock, the plant will use 770 tons per day of yard,
wood, and vegetative wastes and eventually energycane.
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