McCormick Students Help Shuttle Bus Go Green With A Little Help From French Fries

July 7, 2008

Every week, the dining halls on the Evanston Campus of Northwestern University produce nearly 170 gallons of waste vegetable oil. In the same amount of time, the intercampus shuttle uses anywhere from 200 to 300 gallons of diesel fuel — at five miles a gallon — to transport students and faculty between the Evanston and Chicago campuses.

The math and the logic lend themselves to an obvious solution — to have the shuttle buses run on vegetable oil instead of diesel fuel. But implementing such a change has been years in the making, and recently a group of Northwestern students found that even great plans take a lot of work.

The idea to have the buses run on the oil came two years ago to Engineers for a Sustainable World, a Northwestern student group that works to reduce poverty and improve global sustainability. In 2006, the group created a proposal to convert the buses in hopes of winning an MtvU grant. Though they didn’t win the grant, the proposal got the ball rolling, says Aaron Greco, a PhD student in mechanical engineering who now acts as the project’s adviser.

Greco can quickly list off the benefits of such a system — the emissions are cleaner, with no sulfur and fewer particulates, which can cause lung cancer. The process is mostly carbon neutral, and the net carbon contribution to the environment is 80 percent less than that of diesel fueled buses. Plus, the system would eliminate a campus waste stream and reduce the University’s demand for petro-diesel fuel, a non renewable resource.

“We hope that this project will ultimately bring awareness to sustainability and to how these solutions can benefit the environment and the university,” Greco says.

Since the idea first blossomed, students in both Engineering Design and Communication and Segal Design Institute classes — taught by both McCormick and Writing Program faculty —have worked on various aspects of the project, from oil quality testing to cost analysis. Though student teams got a good start on the project, many of their ideas, as often happens, just didn’t work out in the end. So this winter, a team made up of Charles Weschler, Rebecca Hoo, and Ji Hun Lee took on the project and came up with a whole new operation — from collection to filtration to distribution.

Their plan that works like this: each week, three students take a university-owned truck and drive around to gather the 55gallon drums of waste vegetable oil from dining halls. They then bring it to Ford Motor Company Engineering and Design Center (the temporary home of the filtration system) and pour the oil into a large barrel that acts as the first step of the filtration system. They let the oil settle for a week — allowing the large particles of food and sludge to sink to the bottom of the barrel — before pumping out the top oil through a small filtration system. What results is vegetable oil with no water and with particles less than five microns in size — clean enough to run a diesel engine.

In fact, the team created a prototype diesel engine that runs on vegetable oil, which, when running, gives off not the odor of diesel fumes but rather the scent of campus-staple french fries.

But what’s a little fried-food smell compared to a cleaner, more sustainable system?

“It still saves hundreds of dollars a week in diesel fuel,” Hoo says.

While developing the operation, team members say that, in addition to learning about the fine points of filtration, they learned more about dealing with systems and people.

“We learned how to create a system out of scratch,” Weschler says. “It was the first time I helped create something that was working in real-time and had a real-life application.”

The team learned about being compliant with regulations — like how only certain colored barrels can be used — and learned that the most important part of executing a plan is often not the plan itself.

“We ran into problems in terms of communications, so I think we learned how to better coordinate that,” Lee says. Coordinating the needs of the food service company, the bus company, and the university can be a job in itself, he says.

“It’s the coordination and cooperation that makes it difficult,” Weschler says.

Though the team was still ironing out the details of how to get the oil from the filtration system to the buses, and Greco says ESW will take on the plan from here in hopes of realizing the system in the fall.

“The main goal of this team was to develop the full-scale operation,” Greco says. “Now we’re ready to construct it and try it out.”

The last hurdle is converting the bus to run on the vegetable oil. The viscosity of the oil much thicker than diesel, so the bus would need a conversion kit that would use the waste heat of the engine to warm up the oil so it can easily run through.

“It’s actually not a major overhaul of the engine,” Greco says.

In the long run, the group hopes that the project will become part of the university, with students donating a few hours each week to make the system work. McCormick students will likely continue working on the project in order to optimize operations and teach them about sustainability, Greco says.

“I think this is always going to be used as an educational tool,” he says.