University of Kentucky
Bioenergy and Biofuels Research Topics
SURA Southern Energy Initiative
February 2007
Crops and Feedstock Production
The Science and Engineering for a Biobased Industry and Economy
This multi-state project is directed toward reducing the cost of handling biomass, and expanding the scientific knowledge leading to significant economic improvements in biobased products. The project intends to identify educational materials to train a workforce to support biobased industry. A website has been launched which serves as a clearinghouse for information related to research on biomass conversion. Contact: Sue Nokes (), Czarena Crofcheck, Mike Montross.
Collection and Characterization of Biomass for Fuel and Chemical Production
Corn stover is a potential feedstock for the production of fuels and chemicals that could generate additional farm revenue of $70/acre.Corn stover has been characterized to determine variations in composition so suitable equipment and processes can be developed. Collection of specific fractions of corn stover (primarily cobs and leaves) would increase the glucose yields from saccarification of the fractionated stover, while the stover left behind in the fields (primarily stalks) should provide sufficient erosion control. Collection of cobs, leaves, and husks could be accomplished with minor modifications to current combines, considering existing combines provide separation of corn from cobs, leaves, and husks. Based on recent results, the amount of glucose released from stover would increase by approximately 21% by selectively collecting cobs and leaves and leaving stalks and leaves in the field. Preliminary economic analysis indicates that the ethanol cost could be reduced by 17% if the glucose potential of the biomass feedstock was increased by selective fractionation.
Contact: Mike Montross (), Scott Shearer, Czar Crofcheck.
Biomass Processing and Conversion
Microbially-Based Biofuels and Bioproducts Research
Faculty from the UK College of Agriculture, in collaboration with other scientists, have been conducting basic research in the area of microbially-based biofuels and bioproducts since 1995. This research effort is based on the premise that structural plant carbohydrates (fibrous biomass) can be used as inexpensive and renewable feedstocks for biologically-mediated conversion processes. Our specific focus has been understanding and enhancing the use of thermophilic and anaerobic bacteria as bio-catalysts in the conversion of fibrous biomass to biofuels and other vendable chemicals. The major research thrusts include: biochemical and molecular characterization of sugar transport in anaerobic thermophiles, evaluation of thermophilic microbial metabolism at high pressure in supercritical solvents, development of solid-state culture techniques involving thermophilic bacteria and fibrous biomass for the production of thermo-stable enzymes, isolation of ethanol-tolerant strains and subsequent characterization of adaptation to ethanol using state of the art proteomic approaches, and characterization of cellular metabolism using metabolomic approaches. Contact: Herb Strobel (), Sue Nokes, Barbara Knutson, and Bert Lynn.
Indirect Thermochemical Conversion of Biomass to Fuels and Chemicals
Similar to coal, biomass can be converted into fuels and chemicals indirectly by gasification to syngas followed by catalytic conversion to liquid fuels, or directly to a liquid product. Syngas can be generated from many different biomass sources or used in blends with other hydrocarbon fuels using well established gasification technology. This synthesis gas can then be converted to liquid fuels and chemicals via the Fischer-Tropsch (FT) process. The FTprocess centers on the reaction of hydrogen with carbon monoxide, carbon dioxide or mixtures of these to yield one or more types of carbon compound, e.g., hydrocarbons, alcohols, esters, acids, ketones, aldehydes, etc. The purification, separation, conversion or treatment of one or more of the products resulting from the Fischer-Tropsch synthesis, such as by oxidation, adsorption, solvent extraction, etc., is also of paramount importance. The Center for Applied Energy Research operates the largest open-access FT testing and development laboratory in the world, currently operating 18 stirred reactors, 1 slurry bubble column reactor and several fixed bed reactors. We are exploring the use of both iron and cobalt based catalysts for syngas conversion to paraffin, diesel and jet fuels, as well as separation and upgrading of products. Contact: Rodney Andrews () or Burt Davis.
Biomass liquefaction
Oils produced by pyrolysis are less viscous, and have higher yields at lower cost when compared to the oils produced by high-pressure liquefaction. For this reason, pyrolysis is currently the expected route for the industrial conversion of biomass to fuels and chemicals. However, pyrolysis is unsuited for production of heavy liquid products due to operating conditions that primarily favor the formation of light oils and gases. A selective, low severity, non-hydrogenative process may prove to be an economical method for producing crude oils from biomass, especially when targeting on-site applications (e.g., at farms, lumber mills, forests, etc.). In this way, the crude bio-oil could be transported to a centralized facility for refining, making the crude bio-oil quite similar to crude petroleum, where several products are possible through the refining process. The process is similar to traditional pyrolysis with respect to the thermochemical processes taking place, but uses a liquid medium to act as a solvent, to extract formed products, to provide heat transport and mitigate localized hot spots, and to act as a carrier fluid for product separation. The concept of extraction-liquefaction was shown in previously for white oak conversion into a valuable product suite. We are investigating a novel liquefaction-extraction method for biomass conversion to crude bio-oil utilizing an extruder-reactor for on site densification of biomass. The proposed approach aims to utilize biomass on the farm for delayed transport to centralized bio-refineries. Given that biomass is expensive to transport, being able to pre-process and densify the biomass before transport to a centralized bio-refinery will save significant costs and potentially increase rural income. Contact: Rodney Andrews (), Czar Crofcheck, Kunlei Lui, Mark Crocker.
Biofuels Upgrading and Bio-oil Stablization
The crude bio-oils afforded by thermochemical conversion processes such as pyrolysis are chemically complex and are typified by a high oxygen content. The oxygenated compounds present in raw bio-oils impart a number of unwanted characteristics such as thermal instability (reflected in increasing viscosity upon storage), corrosivity and low heating value. This instability is associated with the presence of reactive chemical species, notably alkenes, aldehydes, ketones, carboxylic acids and guaiacol-type molecules. Upon prolonged storage, condensation reactions involving these functional groups result in the formation of heavier compounds.The quality of bio-oils can be improved by the partial or total elimination of the oxygenated functionalities present. In this context, we are studying new approaches for catalyst-assisted stabilization of crude biomass-derived pyrolysis oils, for the ultimate production of fuels and high value chemicals. This work is performed in collaboration with the UK Department of Biosystems and Agricultural Engineering. Contact: Czar Crofcheck () or Mark Crocker.
Biodiesel Production
The production of biodiesel from vegetable oil represents another means of producing liquid fuels from biomass, and one which is growing rapidly in commercial importance. Commercially, biodiesel is produced from vegetable oils, including rapeseed, sunflower and soybean oil, as well as from animal fats. These oils and fats are typically composed of C14-C20 fatty acid triglycerides. In order to produce a fuel that is suitable for use in diesel engines, these triglycerides are converted to the respective alkyl esters(with glycerol as a co-product) by base-catalyzed transesterification with short chain alcohols. Commercially homogeneous base catalysts are used, such as NaOH. However, solid base catalysts are attractive on the basis thattheir use should (i) result in a reduction in the amount of soaps and salts that need to be removed (thereby improving the quality of the glycerol co-product), and (ii) enable biodiesel production to be more readily performed as a continuous process. We are therefore studying the use of a variety solid base catalysts for this purpose, such as layered double hydroxides. Contact: Mark Crocker () or Czar Crofcheck.
Other work in the area of biodiesel production is focused on utilization of glycerin byproducts in plant heat and power operations. Novel burner designs are being developed to allow direct utilization of glycerin for the production of heat and electricity on site in more efficient manner than is currently available. Contact: Rodney Andrews () or Kunlei Lui.
Producer Gas from Biomass Gasification
An area of biomass utilization we would like to explore is the use of producer gas derived from biomass gasification as supplemental fuel for landfill gas fired power generation sets. Along with this, there is a great deal of interest from the electric power industry in the use of producer gas for use in coal fired power plants for reburn fuel to reduce NOx emissions. Contact: Kunlei Lui () or Jim Neathery.
Production of Biomass Briquettes as an Alternative Fuel Source
The numerous industrial and process heat boilers found at pulp mills, food plants, and other industrial sites are relatively small, often less than 25 MW units, which are essentially unregulated. The substitution of CO2-neutral biomass represents an attractive approach to decreasing the release of air pollutants such as SOx, NOx, and mercury, as well as reducing fossil energy consumption in this often overlooked, but significant industrial sector. One promising approach is to substitute a briquetted fuel manufactured from the agricultural or wood waste that is generated at or near the industrial site where the fuel is to be used. In addition to being sustainable and cleaner burning, such a briquetted biofuel can be more economically stored, conveyed, and processed in existing equipment. Further, the development of low-cost, briquetting binders from agricultural-processing residues would create a market for these low-value byproducts while decreasing the energy required for the briquetting process.The overall goal of the project is to produce a premium, durable briquetted biomass fuel from agricultural and wood wastes that is an attractive alternative energy source for coal-fired boilers. Specific objectives include: investigate corn stover, fescue, and wood waste as a briquetted-fuel source; assess the performance of inexpensive binders available from farms and agricultural-processing facilities (e.g., poultry litter, gum residue from soybean oil extraction, and distillers grain from ethanol production), determine the energy content, chemical composition, and strength and attrition characteristics of the biomass briquettes produced, estimate the economics and net energy balance for briquetted biomass fuels. Contact: Mike Montross (), Darrell Taulbee, Scott Shearer or Rodney Andrews.
Genomics and Plant Genetics
Renewable Fuels from Tobacco
This research is aimed at genetically engineering tobacco plants for the biosynthesis and accumulation of specialized branched-chain hydrocarbons known as triterpenes, targeted compounds with 30 to 34 carbon atoms. These triterpenes are considered the biogeochemical progenitors to the current day shale oil deposits and are readily converted to high-grade combustible fuels with current conventional processing methods. We have already created transgenic plants capable of accumulating 15 carbon terpenes (sesquiterpenes), and demonstrated that these compounds are derived directly from the action of photosynthesis and the direct funneling of photosynthetically fixed CO2 into the biosynthesis and accumulation of terpenes. These oils can be easily cracked into combustible grade fuels under standard conditions. Overall, 67% of the converted oil has been shown to convert to gasoline grade fuel, 15% to aviation turbine fuel, 15% to diesel fuel and a residual of only 3% in previously reported work. Contact: Joe Chappell ().
Policy, Commercialization and Relations
Kentucky Rural Energy Consortium
The Kentucky Rural Energy Consortium (KREC) is a partnership involving the UK College of Agriculture, College of Engineering, and Center for Applied Energy Research; UL Kentucky Pollution Prevention Center and J.B.SpeedSchool of Engineering; other KentuckyUniversities; the Kentucky Division of Energy and other key state agencies; and agricultural commodities groups and industry partners. KREC seeks to advance research on biomass, renewable energy and energy efficiency pertaining toKentucky agriculture, rural communities, and industries. KREC was established in 2005, and awarded 7 competitive research grants in 2006. Contact: Sue Nokes (), Don Colliver, Mike Montross, Czar Crofcheck, Rich Gates.
Biomass Education Modules
A workshop was developed for middle-school students to show that decisions related to renewable energy (or any energy policy for that matter) are not straight-forward. A learning module was developed for use in classrooms by teachers or as self-paced learning for students which includes power point slides, craft instructions, and an energy board game. The website can be accessed at Contact: Sue Nokes ()
Biodiesel and Ethanol Tours
State officials and citizens across the Commonwealth were educated about the production and utilization of clean/alternative fuels by means of guided tours of ethanol and biodiesel production facilities, and by the creation of companion “virtual” tours for both ethanol and biodiesel. The “virtual” tours, entitled The Kentucky Biodiesel Journey and the Kentucky Ethanol Journey, are both CD-based, movie-like journeys. A web site was created to distribute the virtual tours and addition information about Biofuels in Kentucky, Contact: Czarena Crofcheck ()
Commercialization
Many of the projects here, in particular FT catalysis, briquetted fuels, and biomass liquefaction, are carried out in collaboration with industry. These programs build on the long standing relationships between the College of Agriculture, the College of Engineering and the Center for Applied Energy Research in supporting the agriculture, chemical and power industries in Kentucky and the nation.