Yale Shuttle Bus Powered by Cooking Oil

Shuttle bus at Commencement runs on biodiesel fuel made with cooking oil recycled from its dining halls.

Yale will run one if its shuttle buses at Commencement with biodiesel fuel made with cooking oil recycled from its dining halls, University officials have announced.

The University has been operating the bus for the past month with a test blend of fuel that is 50 percent biodiesel. The bus will be run for the first time solely on biodiesel at the 2006 Commencement.

“The experiment with 100 percent biodiesel complements Yale’s use of alternative fuels in the rest of its shuttle fleet,” said Associate Vice President for Administration Janet Lindner. “The University has converted all of its shuttle buses to biodiesel, in a blend with ultra-low sulfur diesel, as part of its commitment to a greener campus and cleaner air. We have been making use of alternative fuel vehicles, such as hybrids, within our fleet and this month we began using alternative fuel in all Yale shuttle buses. These efforts will help promote a healthier environment for the New Haven community.”

The project to recycle cooking oil originated when a student who wanted to power his automobile with vegetable oil approached David Johnson, a research scientist at Yale. Working together, they applied a catalyst to remove the glycerin in the cooking oil and separate out the biofuel. “By removing the glycerin from vegetable oil, we essentially reduce its flashpoint from 600 degrees to 300 degrees, which allows us to use it as heating oil,” Johnson said. “Any car, truck or bus will run on it, with minimal modifications.”

Because the oil is a natural byproduct of plants growing in the United States, there’s no negative effect on the atmosphere, said Johnson. “The plants pull carbon dioxide out of the air; burning the fuel puts it back into the air, thus the effect is neutral,” said Johnson. “Whereas with fossil fuel, which was trapped hundreds of years ago, there are no plants to pull the carbon dioxide out of the air, so burning those fuels raises CO2 levels, which in turn leads to global warming.”

The bus ran for the first time solely on biodiesel at the 2006 Commencement.

The use of biodiesel made in the United States can also help reduce dependence on foreign oil supplies. “If we put our heads together, we can put a dent in it,” Johnson said of dependence on foreign oil.

The biodiesel fuel is made in laboratories on the Yale campus. Oil used for frying in the dining halls is collected by Yale Recycling and delivered to Sterling Chemistry Laboratory, where Johnson works with students to turn the waste oil into biodiesel.

Donald Relihan, director of support services at Yale, said, “The ultra-low sulfur diesel (ULSD) combined with biodiesel runs much cleaner than conventional diesel fuel.” He said the sulfur content of ULSD is reduced from approximately 500 parts per million to 15 parts per million and can reduce particulate matter air pollution by up to 14 percent.  When combined with a 20 percent biodiesel (B20), particulate matter air pollution is further reduced 10–15 percent.  Relihan added,  “B20 is currently the most common form of biodiesel, derived from soybean oil, and requires no vehicle, equipment or infrastructure modifications to use.  In preparation for the switch, the Yale buses were recently retrofitted with oxygenating catalytic converters and specialized filters that capture crankcase emissions.”

“The conversion has been painless,” said Ed Bebyn, Yale’s manager of parking and transit. “We are happy to be out in the forefront with environmentally friendly fuels and vehicles.”

The use of biodiesel from recycled cooking oil is part of the University’s effort to support a greener, more sustainable community.  Use of ULSD B20 helps reduce the negative impact of diesel air emissions on campus.  In addition, B20 when combined with ULSD helps engines run more smoothly and last longer.

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Tom Conroy: tom.conroy@yale.edu, 203-432-1345