Chemical Engineering Students Study Animal Fats

By Annel K. Greene, PhD
Center Director, Clemson University
Animal Co-Products Research and Education Center


Dr. Charles Gooding, professor of chemical engineering and a member of the Clemson University Animal Co-Products Research and Education Center (ACREC) team, challenged his senior design class to “develop and optimize a process to manufacture 100 million kilograms (kg) per year of biodiesel fuel.” He divided the class into nine teams. Four of the teams used rendered products as their feedstock and the remaining five teams used algae oil as their feedstock.

The class began by selecting team leaders via an election. These leaders then built their teams through a competitive draft similar to a professional sports draft except the order of selection was determined by lot.

Each team worked together to develop a process as demonstrated by a flow sheet and stream table. They sized all equipment using the best data and information derived from engineering resources. Finally, the students conducted an economic analysis of their designed process. Upon completion of the semester, the student teams made oral presentations on their projects. The panelists for the review included Clemson University faculty engineers and external reviewers. The external reviewers were commercial engineers, including Mike Dobeck from Darling International, Inc., and one very impressed microbiologist. Student teams submitted final written reports in addition to the oral presentations and were told that their audience members were somewhat knowledgeable about chemical processing and potentially interested in investing in a biodiesel plant.

Gooding further specified that the process must be able to handle a feedstock with 15 percent free fatty acids and that student teams should evaluate profitability if the feedstock cost $0.30 per kg (/kg) and $0.60/kg. The students were told to specify a minimum acceptable rate of return of 10 percent and to determine the corresponding wholesale, FOB price of the biodiesel. Gooding explained to the review panel that the reason for considering the higher price was to determine if it was possible that biodiesel production could raise the value of fat from the rendering industry. Results of the students’ projects indicated that the answer was no unless a dramatic change occurs in the wholesale price of fuel or tax incentives/credits are applied. In the study, however, students were instructed to not consider tax credits or any other government intervention.

The first team was comprised of Joe Johnson, Dick Pace, Sarah Rudy, and Robert Witt, who was team leader of the group. Their project was entitled, “Biodiesel Production from Low-cost Tallow Feedstock Through Acid-catalyzed Esterification and Base-catalyzed Transesterification.” Using the assumption that rendered fat feedstock contained 84 percent triglycerides, 15 percent free fatty acids, and one percent water, the Witt team approached the project from a conventional standpoint.

They designed a biodiesel production facility using acid-catalyzed esterification to convert the free fatty acids into methyl esters. The team used sulfuric acid catalyst and an excess of methanol in a continuous stirred tank reactor to convert 97 percent of the free fatty acids into methyl esters within 1.5 hours. The process followed with neutralization and methanol recovery steps and, subsequently, the remaining tallow and methyl esters were sent into a second reactor for a base-catalyzed transesterification reaction using sodium hydroxide. The calculated reaction produced a 98.5 percent conversion of triglycerides into biodiesel in one hour, and purification steps were incorporated post-reaction.

The Witt team determined that the fixed capital investment for this processing facility would be approximately $4.79 million. The economic analysis indicated that the cost of manufacturing would be $49.4 million for the $0.30/kg feedstock and $84.2 million for the $0.60/kg feedstock. Reporting annual cost of manufacturing, the students recommended selling the glycerin by-product at a conservative price of $0.10 per pound, yielding approximately $2 million per year. The team determined that the break-even selling prices of the final product would be $1.69 per gallon for the $0.30/kg feedstock and $2.90 per gallon for the $0.60/kg feedstock. The team further reported that the price of raw materials was the determining factor in profitability for this proposed biodiesel plant. They also reviewed waste treatment and safety issues and typical waste handling procedures were determined to be adequate. Safety risks centered on the exothermic reaction during the acid-catalyzed esterification processing and safety shut-off measures were designed into the system.

The second team presented their project, “Process Design of a Biodiesel Plant.” The team was comprised of Timon-Eddy Brown, Jenny DiNoto, Shaina Milleman, and Andrew McCord, who was the team leader. Using the same parameters for the size of the processing plant, team McCord chose to design a plant using sodium methoxide as the catalyst. The team determined that the fixed capital investment for this processing plant would be $7.35 million and the yearly cost of manufacturing for the lower cost feedstock ($0.30/kg) was $54.4 million whereas the higher cost feedstock ($0.60/kg) was $92.9 million.

The third student team was lead by Andrew Carter and team members were John Abramczyk, Michael DeWitt, and Tyler Williams. Their project was entitled, “Process Design for the Production of Biodiesel from Rendered Fat.” This team searched patents and determined a different approach to dealing with free fatty acids. They analyzed four different methods of catalysis: acid catalysis, base catalysis, silica chloride, and Esterfip-H. The team chose Esterfip-H as the catalyst for the transesterification process because this system is tolerant of water and generates high purity biodiesel and glycerol without additional purification steps. This catalysis method requires a feedstock without free fatty acids, therefore, the feedstock is pre-treated using potassium hydroxide and calcium chloride to remove the free fatty acids as insoluble fatty acid salts that the students proposed as dairy cattle feed. The triglycerides are used to form biodiesel and glycerol by reaction with excess methanol in the presence of the Esterfip-H catalyst. Centrifugation was employed to separate the glycerol from biodiesel. Using their process, the Carter team determined that the price of biodiesel would be $2.88 per gallon with the $0.30/kg feedstock and $4.49 per gallon with the $0.60/kg feedstock.

The fourth team was comprised of leader Brandon Tucker and teammates Nick Sturgis, Riann Vorster, and Matt Vyrostek. Their project was, “Design and Economic Evaluation of a Biodiesel Production Plant from Rendered Fats.” The Tucker team chose to design a process using acid catalyzed esterification with subsequent base catalyzed transesterification resulting in a triglyceride conversion rate of 97.9 percent. Using 18 unit operations, the team developed a process with a total fixed capital cost of $5.2 million. The $0.30/kg feedstock yielded a wholesale biodiesel price of $2.25 per gallon whereas the $0.60/kg feedstock was $3.85 per gallon.

From the students’ projects, Gooding concluded that the capital investment for a biodiesel plant is significant to an investor, but overall is not what determines the economics. He stated that the deciding factor in profitability is related to the price of biodiesel in the future and the incentives/tax breaks that may be provided via government programs. In general, he concluded that dividing the wholesale price per gallon of biodiesel by a factor of 10 will determine the price per pound of fat feedstock. In other words, Gooding states that “if biodiesel can be sold wholesale for $2.00 per gallon, then you can make a small profit by making biodiesel instead of selling your fat to somebody else for $0.20 per pound.”

In the fall semester, Gooding will teach approximately 60 sophomore level and 40 senior level chemical engineering students who will study the topic, “High Value Products from Rendered Fats, Oils, and Greases: Process Design and Analysis of Profitability.” In the courses, students will design chemical processes and evaluate the profit potential of converting rendered fats, oils, and greases into a variety of high-value products. After identifying potential end-products from rendered materials, the students will study product demand, product value, and the complexity of the conversion process. The students will develop process flow diagrams and stream tables for the most promising products, and estimate the required capital investment, cost of manufacturing, and profitability of each. This educational opportunity will be an opportunity not only for the students but also for the rendering industry.

The introductory sophomore course will concentrate on mass and energy balances and Gooding will assign the students the task of investigating the “chemical descendents of triglycerides and free fatty acids.” In the project, students will identify new end-products made from triglycerides or free fatty acids and thus will identify new potential markets for the rendering industry. The senior students will be given a similar assignment to identify chemical reactions and using chemical stoichiometry and market analysis, these students will identify the value of the starting materials and the products. Rendering industry experts will be consulted during this student assignment.

The main objective of the fall 2010 class projects is to evaluate products that may have a higher value than biodiesel with the overall goal of determining if there are more profitable markets for rendered animal fats. Both the sophomore and the senior classes will work on identifying and evaluating potential products and processes in the fall semester. In the spring 2011 semester, the senior class will conduct full process evaluations similar to the spring 2010 class biodiesel project. They will seek to determine if there are promising (and profitable) alternative products for using animal fats.

In addition to finding potential new markets for rendered animal products, the class will learn about the rendering industry and become a pool of 100 chemical engineers from which the rendering industry may seek to hire. From the Clemson University spring 2010 class, 37 newly graduated chemical engineers have just entered the work force. Of these, 16 new chemical engineers are now familiar with rendered products and biodiesel production. It is very likely these are the only recent chemical engineering graduates in the United States to have studied rendered animal fats in a class setting.

For further information on Gooding’s work, or to suggest course topics, e-mail him at chgdng@clemson.edu.


ACREC Solutions – August 2010 RENDER | back