Alternative Fuel Sources - Hydrogen and Fuel Cells: Advances in Transportation and Power - page 86

SYNTHESIS GAS FUEL
Biomass can be converted to synthesis gas (syngas), which consists
mainly of carbon monoxide (CO 2 ), carbon dioxide (CO 2 ), and hydrogen
(H 2 ), using the gasification process. Gasification technology has been in
a period of intensive development in the last few decades. Large-scale
demonstration facilities have been tested and some commercial units are
in operation. The problems with the application of gasification have been
economic and not technical.
In the past, the product from gasification has been electricity or heat
and the value of these products has not been adequate to justify the capi-
tal and operating costs. However, if gasification is combined with the pro-
duction of higher value liquid fuels, it can become a more viable alterna-
tive energy technology. After gasification, anaerobic bacteria are used to
convert the CO, CO 2 , and H 2 into ethanol.
Bioengineering Resources, Inc. (BRI) has developed syngas fermen-
tation technology that can be used to produce ethanol from cellulosic
wastes with high yields and rates. The process of combined gasification/
fermentation has been under development by BRI for several years. The
feasibility of the technology has been demonstrated and the yields can be
high because most of the raw material, except for the ash and metal, is
converted to ethanol. BRI's bioreactor systems for fermentation have re-
tention times of only a few minutes at atmospheric pressure and less than
a minute at elevated pressures. These retention times mean very reason-
able equipment costs. The biocatalyst is automatically regenerated by the
slow growth of the bacteria in the reactor.
BIOFUELS
By 2006, the U.S. had 77 ethanol plants producing more than 3 bil-
lion gallons of ethanol per year. Canada produced an additional 60 mil-
lion gallons. Corn was the feedstock in 62 of the 77 U.S. plants. Other
feedstocks included seed corn, corn and barley, corn and beverage waste,
brewery waste, cheese whey, corn and milo, corn and wheat starch, po-
tato waste and various sugars. The U.S. had 11 additional plants under
construction and 55 proposed. West Central Soy processes soybeans to a
food grade oil. Alcohol and a catalyst are then used to produce biodiesel
fuel and glycerin.