At the conclusion of the 1985 blockbuster movie, Back to the Future, Doc Brown (Christopher Lloyd) puts food scraps into the gas tank of his DeLorean time machine, boasting to Marty McFly (Michael J. Fox) and his girlfriend, Jennifer Parker (Claudia Wells), that gasoline is unnecessary in the future. Marty and Jennifer curiously look at each other because in 1985 the notion of fueling a vehicle with last night's leftovers was laughable.
Welcome to the future.
While they aren't stuffing wilted lettuce leaves and banana peels into gas tanks, students with ISU BioBus recycle waste vegetable oil from the Union Drive Community Center (UDCC) into biofuel to supplement the diesel fuel used to power CyRide bus No. 18.
ISU BioBus, a student entrepreneurial organization created about three years ago as part of a Live Green! initiative, currently has about 100 members -- 25 who actively convert the vegetable oil into useable fuel. You don't have to be a chemistry major to join; the group welcomes students from all disciplines.
David Correll, a Ph.D. candidate in the College of Business and one of the founders of ISU BioBus, says the organization is a good fit for students concerned about the environment.
"We're engaging students to reduce the carbon footprint of their own community," Correll said. "We want to show it's possible to do without a lot of money."
From French fries to fuel
Several students meet twice each week to convert the vegetable oil into biofuel using a process called transesterification, a chemical process that permanently thins the vegetable oil. First, the students retrieve the oil from UDCC using a contraption they built themselves -- the Super Sucker. It holds 60 gallons of vegetable oil. From there, they transport the vegetable oil to their lab in the BioRenewables Research Laboratory where the transesterification process begins.
The students mix methanol and potassium hydroxide into the vegetable oil in a large tank and heat it to 140 degrees. These chemicals remove the stickiness (glycerin) from the oil to create a higher quality fuel. After the oil sits for a few hours, the glycerin falls to the bottom of the tank, leaving the biodiesel on top. The biodiesel is drained and washed with water to purify it further. Finally, the oil is heated again to evaporate the water. The process yields about 50 gallons of biofuel.
How well does it work?
It's hard to comprehend that standard vegetable oil, which once cooked French fries and chicken strips, can power a bus. But it seems to works pretty well, according to James Rendall, maintenance coordinator at CyRide.
"CyRide has been using fuel from BioBus since last spring," Rendall said. "We haven't seen any issues arise due to the BioBus fuel."
ISU BioBus creates the biofuel, but leaves blending up to the CyRide staff. For example, more biofuel can be added to regular diesel during warmer temperatures.
"All biodiesel is susceptible to 'gelling,' which starts to occur around 30 degrees," Rendall said. "If you keep the percentage of biodiesel low, under 10 percent, the effects of gelling are greatly minimized."
That means CyRide uses less biofuel during winter than summer. Last summer, Correll said the blend used in bus number 18 was up to 22 percent biofuel.
But does the bus's exhaust smell like French fries?
"Yes, it can," Correll said. "It's not as noticeable with the CyRide bus because [the fuel] is a blend."
Future looks bright
ISU BioBus is in the process of developing a comprehensive business plan to increase the number of CyRide buses that use biofuel. While the club's goal is to reduce the community's carbon footprint, outreach to the campus community and beyond also is a top priority.
"My hope is to see more biobuses driving around," Correll said. "I also want to see [ISU BioBus] continue so that students get experience in making biofuel and being entrepreneurs."