Promoting Sustainability, Dartmouth’s “Big Green Bus” Goes On A Road Trip

Dubbed the “Vehicle for Change”, Dartmouth’s “Big Green Bus” has departed for its seventh annual summer road tour. The former Greyhound bus converted to run on vegetable oil will be home and headquarters for 13 Dartmouth students specially chosen to head this year’s campaign to raise environmental awareness and promote sustainability.

The 11-week tour will span over 31 states. At each of the communities being visited, students will discuss and listen to sustainability success stories of local residents, business owners, and officials. These stories will be shared with the different communities the students visit. Additionally, each of the students play a unique role as part of the team, ranging from technically inclined engineers to public relations experts.

The current bus is actually Big Green Bus #4 and this year will be its first summer in operation. Donated by Greyhound, the bus was gutted and modified by Dartmouth students for maximum environmental friendliness.

The Big Green Bus has a Detroit Diesel 8V92TA engine converted to run on waste vegetable oil; typically, oil that was used for deep frying food. Because vegetable oil is much thicker than diesel fuel at lower temperatures, the so called “Frybrid” system on the bus uses diesel fuel until the engine and vegetable oil is warmed up to operating temperatures. Once the engine is warmed up and the vegetable oil reaches about 180 degrees Fahrenheit, the engine runs completely on vegetable oil. To cool the engine down, the system is purged to prevent vegetable oil from thickening and clogging the engine and fuel injectors.

The bus has one 220 gallon tank for diesel fuel and two 290 gallon tanks for vegetable oil. One of the 290 gallon tanks is for dirty oil, containing food pieces and other debris, and the other is for “clean” oil. Jules Valenti, who graduated Phi Beta Kappa from Dartmouth with a bachelor’s degree in mechanical engineering, explains how the dirty oil is cleaned: by letting it sit, food debris in the oil settles to the bottom of the tank and is drained from the tank. Afterward, the oil is transferred to the “clean” tank.

The Frybrid system on the Big Green Bus allows vegetable oil to get the same fuel economy as diesel fuel. Says Morgan Curtis of the engine’s fuel filtration system, “Functioning properly, the engine will get about the same mileage out of vegetable oil — about 1,000 miles on 300 gallons — that it would get on diesel fuel.”

The bus used in this summer’s tour has a host of other sustainable features besides the ability to run on vegetable oil. The solar panels attached to the bus’s roof provide enough electricity to run several on-board appliances and electronics including computers, a refrigerator, lighting, television, air conditioning, and the pumps that pump the vegetable oil.

The bus is lined with sustainable bamboo flooring. The bamboo was harvested in compliance to Forest Stewardship Council (FSC) standards. The wood has comprehensive documentation, from the time it was harvested to when it was purchased by a customer. Some of the excess flooring was used to build cabinets in the bus.

On tour, the students have to plan carefully where to source used vegetable oil. Due to the rising popularity of used vegetable oil as a fuel source, restaurants are increasingly making contracts with grease rendering companies. The Big Green Bus crew says they will rely on smaller restaurants for fuel because of the likelihood that those restaurants do not have contracts.

As the Big Green Bus tours the country, leaving behind an exhaust smelling like deep fried food, its crew hopes to share environmental success stories with each of the communities it visits, meant as an inspiration and a “Vehicle for Change.”

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