Progress 06/01/06 to 05/31/07
The National Alternative Fuels Laboratory (NAFL) at the University of North Dakota Energy & Environmental Research Center developed and is optimizing electrochemical processes for producing nitrogen-based fertilizers from nitric oxide (NO), carbon dioxide, hydrogen, and electricity. An electrochemical cell was designed, fabricated, and used to produce ammonium nitrate (AN), ammonia, and urea from reagent-grade feedstocks. Data from these lab-scale experiments were utilized to assess the economics of the processes based on the use of NO recovered from electric utility coal combustion emissions and carbon dioxide generated as a coproduct of fuel ethanol production. The economic assessment indicated good potential economic viability for the AN process, primarily because of its low hydrogen input requirement. Ongoing AN process optimization work is focused on improving the catalytic activity of the electrodes utilized to drive the process. NAFL developed and is optimizing
a catalyst system for converting ethanol to butanol and other alcohols via a low-severity process that is compatible with integration at current and new ethanol production facilities. Using a carbon-based catalyst, a 40% conversion of ethanol to butanol was achieved. NAFL developed new synthetic methods for producing polymer products by substituting petroleum-derived ethylene oxide with hydroxyacetaldehyde (HA), a constituent of bio-oil generated via fast pyrolysis of lignocellulose. NAFL experiments indicated that HA can undergo a variety of reactions at its hydroxyl and aldehyde functionalities to yield large-market polyglycolamine products including latex paint dispersants and polymer-flood enhanced oil recovery agents. NAFL pursued development of a low-energy ethanol production route based on a continuous fermentation process that uses self-flocculating yeast and a specially designed suspended-bed airlift bioreactor (SBAB). A self-flocculating yeast strain was selected and
acquired from the USDA Culture Collection, and two SBAB fermenters for ethanol continuous fermentation were designed and constructed. Fermentation study was focused on cellulosic ethanol, with emphasis on development of a beer recycle process. Beer recycle is crucial for improved cellulosic ethanol economics because the low density of cellulosic biomass typically translates to a low-concentration sugar solution and subsequent low-ethanol titer, which results in a high per-gallon ethanol dehydration cost. Typical ethanol concentration in a cellulose fermentation broth is about 4%, versus starch-based ethanol titers that can range from 12%-17%. Initial testing utilized purchased cellulose and cellulase enzyme to yield an 8.5% glucose concentration hydrolysate, which was fermented to yield a clear beer with an ethanol concentration of 4%. This clear beer was recycled through a second hydrolysis to yield an ethanol concentration of 8%. Attempts to achieve a third recycle were unsuccessful
because of a reduction of cellulase activity by ethanol. During this project, an invention was conceived that comprises a method for the electrochemical production of ammonium nitrate from nitric oxide.
Commercialization of the NAFL electrochemical ammonium nitrate synthesis would result in cheaper fertilizer and turn coal-fired power plant NOx emissions into a revenue stream. Operating the process with wind-generated electricity would enable extracting value from wind energy without the need for additional transmission capacity and would promote rural economic development on the Great Plains. Because butanol is an excellent gasoline oxygenate with fuel properties that complement (rather than compete with) those of ethanol, commercialization of the NAFL low-severity process for conversion of ethanol to butanol represents a valuable product diversification option for current corn-based and future cellulosic ethanol plants. Because petroleum-derived ethylene oxide-based polymer production processes encompass large markets, commercialization of HA-based processes to produce these polymers will enable the replacement of oil with biomass in chemical markets and improve
biorefining economics. The commercial viability of the HA-based processes will depend to a large extent on the cost of lignocellulosic pyrolysis-based HA production and, ultimately, how this cost compares with the cost of ethylene oxide. Thus, HA-based products with the best potential viability are likely to be those with a sales price of greater than $0.50/lb.
- Liu, C.; Hu, B.; Chen, S.; Glass, R.W. Utilization of Condensed Distillers Solubles as Nutrient Supplement for Production of Nisin and Lactic Acid from Whey. Appl. Biochem. Biotechnol. 2007, 137-140 (1), 875-884.