Show More


Charlie Carlin '03 Writes of His Truck, Converted to Run on Used Vegetable Oil

June 5, 2016

"Running my truck on used vegetable oil won’t save the world," writes Charles R. "Charlie" Carlin in the journal Minding Nature. "It is, however, a solution to apathy, and it generates a vibrant community."

The 2003 DePauw University graduate's essay details how he converted a diesel pickup truck he's named "Elford" into a vehicle that runs on used vegetable oil discarded by restaurants, detailing the adventure as well as the lessons learned in the process.

"Here’s the deal. Vegetable oil and diesel fuel have about the same amount of energy stored in them; the difference is their viscosity. Vegetable oil is much thicker, but heated to 170 degrees or so, the oil thins enough that it can be sprayed through the fuel injectors, and then a diesel engine will treat it just like regular fuel. Fortunately, one of the main products of combustion is heat. That’s why cars have coolant, water pumps, and radiators -- to move excess heat away from the engine block. Vegetable oil conversions use the heat from combustion to warm and thin the oil so the engine can burn it. First you need to filter out the french fry bits and water, but that’s about it."

He notes, "Since 2008, I’ve traveled 105,000 miles on used oil. At fifteen miles per gallon, that adds up to seven thousand gallons of diesel that I have not burned. By comparison, a 747 burns that much fuel in two hours. With its afterburners on, an F-15 burns four gallons of fuel every second. I am no competition for the war machine. Plus, we can’t all burn used vegetable oil. Currently, the United States produces enough vegetable oil annually to meet about one percent of the nation’s fuel needs. As commercial biofuels producers have scaled up, competition for used oil has also increased. This is not a large-scale solution."

Carlin was an environmental politics major at DePauw, where he traveled to Ecuador to set up a human rights observer program. He went on to earn a master's in counseling and psychology from Prescott College and is now studying geography at the University of Wisconsin-Madison.

"The climate crisis often feels overwhelming, like nothing short of revolution or systems collapse will stop it. Experiments with EAST COLLEGE TOWER hdrliving outside the grips of the fossil fuel economy offer a window into already existing alternatives. I put a big sticker on Elford’s tailgate that reads, 'Powered by vegetable oil: clean, renewable, domestic.' Everywhere I go, folks strike up conversations with me. We make jokes about my truck smelling like french fries, talk about the money I’ve saved, and pillory energy companies. Each chat reinforces a sense of possibility that alternatives are not only imaginable but already in action."

Read the essay, "Travels with Elford," at the website of the journal, published by the Center for Humans & Nature.

Back