Rudolph Diesel's 1897 engine was designed for peanut oil, the same fuel Brian Vaughan and Alex Roman are burning during their 5,800-mile migration from Anchorage, Alaska to Stowe, Vt., for Thanksgiving. The couple has a seasonal lifestyle working as trail builders and guides between adventures spent climbing, bicycling and skiing. They made a stop in Hailey this week to check in with their winter gig at Sun Valley Trekking and to filter more vegetable oil with an on-board centrifuge that takes out unwanted particulates the size of corn starch that can create havoc with a diesel motor.
Grease is what Vaughan and Roman call the fuel they collect from restaurants to burn in the engine of a 1997 Ford F250 that Vaughan bought in March 2009 for $7,000 and converted last winter while living in the Wood River Valley.
"I saw a movie called "Who Killed the Electric Car?" and that pushed me over the edge," Vaughan said. "There's useful grease out there. It's just another way of reducing our impact on the environment."
He said a converted diesel motor with heating elements can burn just about any oil, but not gasoline.
"There wasn't much sunlight when we were leaving Saturday," Roman said. "We started with 190 gallons to get through Canada."
She said they went through eight fuel filters because they didn't get the fuel clean enough before leaving.
"There's a lot of frustrating moments when it's not working very well. I was very nervous about messing something up when I first started driving, but it's worth the investment to get things up and running."
Vaughan said many of his clothes are greasy at this point in the learning process, including the truck conversion and installation of the portable centrifuge. One of his challenges was organizing additional fuel lines needed to switch between diesel and grease.
Unlike gasoline-powered vehicles, diesel motors return to the tank excess fuel not burned in the pistons.
"When I'm sitting in the back of my truck with it idling, I can hear (the fuel) dribbling back into the tank at a fairly consistent rate," Vaughan said. "I have three tanks—two 15-gallon tanks for diesel fuel and the 30-gallon tank for veggie oil. You have to start and stop [the engine] on diesel to clean out the fuel lines."
Vaughan explained that filtered straight vegetable oil also must be heated to 160 degrees before it combusts under pressure in a diesel engine.
He said it takes about four hours to filter 50 gallons of fuel, which leaves behind a small quantify of sludge, which can be composted.
"It's the same mileage, same power, same driving feel, same noise—different smell," Vaughan said. "My mom was like, "Are you making french fries out of the back?"
He said it's harder to get around on straight vegetable oil in Canada, where restaurants are more sparse.
"America's obesity is what keeps us going," he said. "There's a restaurant called the Bear's Tooth. It's a theater pub in Anchorage where we get grease. They use about 15 gallons a day in the kitchen. It's a super popular place in Anchorage."
The fuel source is free for the time being since most restaurants have little use for used fryer grease. But Vaughan figures that his investment, including the truck, will take him about 20,000 miles, or two roundtrips from Alaska to Vermont, to be paid off at 15 miles per gallon compared to the cost if he were using diesel.
Vaughan said the truck is dependable for long drives with enough clean grease, but added that it is not a practical system for driving between Hailey and Ketchum because it can take that distance to switch from diesel to grease and back. During the drive from Alaska, they switched to burning diesel for part of the journey.
"We bought about 50 gallons just to get through hard spots when we ran out of filters," Vaughan said.
They hope to make the final stretch to Vermont all on grease.
"I wanted to reduce my dependence on petroleum, but if we ran out of petroleum tomorrow, I couldn't go anywhere either," Vaughan said, pointing to the petroleum-based plastic buckets the couple uses to collect fryer grease—just one example of that dependence.