There are more than 30 gas stations within a four-mile radius of N.C . State, but only one of those offers something different apart from cigarette deals—local biodiesel.

Biodiesel, unlike other types of biofuels, is made from used vegetable oil. Any diesel engine can run off it without any conversions, according to Chris Jude, Piedmont Biofuels design-build project manager. Unlike corn or sugarcane ethanol, biodiesels  are derived from ubiquitous restaurant grease, which, with a little bit of chemistry, can turn into fuel with almost the same potential energy as traditional diesel.

“It’s pretty simple—biodiesel is compatible with any diesel engine,” Jude said. “If you have a diesel engine, you can just fill up. You can fill up completely on biodiesel or even mix it with regular diesel.”

Piedmont Biofuels distributes their converted vegetable oil to their co-op members at a pump near the Five Points district, and the biodiesel they sell is cheaper than their competitors diesel prices by 15 cents.

“A gallon of biodiesel is $3.75,” Jude said. “The average for diesel fuel is about $4.00.”

According to Larry Larson, co-op member and biodiesel proponent, there is little noticeable performance difference when his car is running on diesel or biodiesel. Larson, owner of coffee roaster Larry’s Beans, lets Piedmont Biofuels distribute their biodiesel by his warehouse on 1509 Gavin Street.

“Sometimes I might think there is a little more pep with regular diesel,” Larson said. “The biggest difference would be the smell. It does smell like the midway at the fairgrounds. Sometimes it’s a little french fry-y or Chinese restaurant-y, but I don’t mind it.”

But biodiesel consumers can’t stop by any french fry joint or Chinese restaurant to get their fix. According to Jude, there are four essential steps to turn vegetable oil into fuel.

1. Collection

Piedmont Biofuels gathers restaurant oil from a 100-mile radius around its headquarters in Pittsboro , NC, according to Jude.

“We collect our oil from restaurants in the Triangle,” Jude said. “We pay for the grease of the businesses we collect from.”

The co-op equips its clients with bins and dumpsters that a tanker collects on a consistent basis and transports back to the processing plant in Pittsboro .

2. Filtering and purification

After use in restaurants, the vegetable oil must be filtered before it can be converted into biodiesel.

“We filter out the water and fried bits from the oil,” Jude said. “You don’t want that in your engine.”

Before the processors can start converting the triglicerides of vegetable oil into the methyl esters of biodiesel, the grease must be as clean as possible.

3. Transesterification

Vegetable oil is a plant-based form of triglyercides , but to mimic petrodiesel , it must go through a process in which it’s converted into a fatty acid methyl ester, getting rid of a glycerol group.

This process involves adding methanol, a type of alcohol, to the vegetable oil. To speed up the reaction, the mix must be heated just under 158 degrees, the evaporation point of alcohol. The addition of a strong base, like sodium hydroxide or sodium sodium methoxide will catalyze the reaction, lowering the amount of energy required to covert the mix into fuel.

“The transesterification causes the glycerin from the oil molecule to drop out, leaving the fatty acids to bond to methanol,” Jude said.

4. Lab testing

Before Piedmont Biofuels distributes its biodiesel, it takes the new product to the lab to test for quality and purity.

“We want to make sure everything is working right before you pump it into your car,” Jude said. “A gallon of our biodiesel has 120,000 BTUs per gallon. Regular diesel is 130,000 BTUs.”

One BTU, British thermal unit, is the equivalent of the amount of energy required to raise the temperature of one pound of water from 39 to 40 degrees.

Debunking the myths

There is a common misconception that biofuels like ethanol and biodiesel are more expensive to produce than petroleum-based fuels, but according to Jude, gasoline and diesel are the least efficient of the bunch.

“On the spectrum, petroleum ranks pretty low,” Jude said. “Now, they do produce more energy per unit, but they consume a lot more during their refining and distribution. Gas and diesel are at about .83 units of energy output per one unit of energy input.”

Despite the energy involved in fertilizing, cultivating, harvesting and processing grain ethanol, the energy output per unit input is only 1.2, according to Jude.

Biodiesel tops the list at 3.5 units of energy output per one unit of input.

“Let’s say you’re growing a virgin soy bean crop—not being used for restaurant grease,” Jude said. “If you trace the energy from planting, fertilizing, harvesting, pressing it and distributing it, it’s still cheaper than petroleum.”

Despite the benefits of biodiesel, they still emit greenhouse gasses, like any other combustible fuel.

But according to Larson, biodiesel plays a part in a more sustainable future.

“Biofuels are part of the equation, they’re not the answer,” Larson said. “If we collected every bit of vegetable oil waste in NC and converted it to fuel, we would only have 4 days worth. But we have the power to make our own sustainable choices and we just want people to start thinking about their own role too.”