28 May 2009
Student project fueled by waste vegetable oil
A senior design project now allows for two pick up trucks to drive around campus fueled solely by bio diesel fuel.
The B100 biodiesel consists of waste vegetable oil (WVO) obtained from local restaurants and processed in a warehouse along Virginia Tech’s Plantation Road, surrounded by fields dedicated to farm animals. The team manufactured 200 gallons of biodiesel over the past two months, with processing equipment donated to the student team.
The project began in 2008 when the now senior team consisted of juniors. The first year consisted of planning, research, and obtaining the funding and needed equipment for the project. This year consisted of more research, design, construction of process equipment, and converting the WVO into biodiesel for consistent use. The group produces B100, or 100 biodiesel.
“In the summer, the viscosity of the 100% biodiesel is low enough to use,” said Christopher Block, of Lake Forest, Ill., who received his bachelor’s degree in mechanical engineering this spring. During winter months, certain biodiesels derived from animal fat can gel or freeze in the tank. Therefore, the fuel must mix with regular petroleum to operate properly. “We learned via emissions testing that the B20 and B50 blends produce more favorable emissions than the B100 fuel,” Block said, referring to mixes that use 80% petroleum and 20% biodiesel, and an even split, respectively.
The group limited its project to 200 gallons of biodiesel because of space limitations at the warehouse, but could produce more if needed. For now, the team can make up to 50 gallons at a time, so the potential for fueling a small fleet is possible. Already there are some takers.
“We are building a new team for next year who will take it to the next level,” said Foster Agblevor, associate professor of biological systems engineering for the College of Engineering and the College of Life Sciences and Agriculture. “Giles County Wheatland Eco-Park would like them to install the unit on their property for education and other purposes.” A company, whose name Agblevor would not disclose, wants to commercialize the project; while one source could be the university’s cafeterias, which would provide the waste grease product. “I will be encouraging the [biological systems engineering] department to start using our biodiesel on some of the equipment that runs on diesel fuel,” he said.
Block will remain on campus next year as he pursues a master’s degree in mechanical engineering. He hopes to continue with the biodiesel project, but they are looking for a permanent home for the operation.
The student team, in addition to Block, includes, Christopher Chelko of Huntersville, N.C., mechanical engineering; Matteo del Ninno of Alexandria, Va., mechanical engineering; Brian Eggleston of Blacksburg, Va., mechanical engineering; Blake Gordon of Bluefield, W.Va., mechanical engineering; Meredith Herrmann of Manasquan, N.J., industrial systems engineering; and Andrew Yard of Frenchtown, N.J., mechanical engineering.
The process of making the biofuel is straight forward.
They pre-filter the collected oil using a centrifuge unit to remove sediments and food debris. Oil that has been sitting is best. The filtering process continues as the oil pre-heats in a tank, and then is put through filter bags.
They determine the level of the oil’s acidity. This determines how much methoxide, a combination of potassium hydroxide and methanol, to add to the oil. The vegetable oil stays at roughly 140°F during this process.
They agitate the mixture for roughly eight hours at the same temperature. During the reaction stage, the catalyst, caustic potash, or Potassium Hydroxide, attacks the oil and begins breaking the molecules apart into glycerol and fatty acid chains. Just after the molecules break apart, the methanol begins to react with the fatty acid chains. Glycerin, a side product, results when the glycerol molecules separate from the reaction mixture.
They move the solution into settling tanks, where the glycerin settles to the bottom of the tank while the freshly made biodiesel remains at the top. They drain out the glycerin and use it for several purposes including composting or with animal feed.
They wash the biodiesel with water sprayed into the tanks containing the unwashed fuel. As the water falls, excess methanol and soap molecules dissolve in the water and settles in the bottom layer, thereby cleansing the biodiesel.
They drain the soapy waste water off the oil, leaving behind “wet” liquid biodiesel. To “dry” the fuel of water, they heat the biodiesel for several hours to evaporate the water.
The finished biodiesel pumps through a final filter into a diesel vehicle’s fuel tank.
For related information, go to www.isa.org/manufacturing_automation.