When it comes to alternative fuels, there are typically two options: biodiesel and waste vegetable oil. Both require a diesel engine, but biodiesel can run on a diesel engine as-is. Veggie oil, on the other hand, requires a conversion process, which includes the addition of a second tank and two heat exchangers connected to the engine.   

This conversion can cost anywhere from $500 (if you find a reasonably priced conversion kit and do it yourself) to a couple thousand dollars (if you pay a professional with a kit to convert it for you). However, once your car is converted, running it on veggie oil is cheaper than running it on biodiesel.

Biodiesel is simply vegetable oil combined with ethanol. This combination makes the oil less viscous, or sticky, so it can then run in a normal diesel engine. Biodiesel also completely replaces diesel as a fuel source, whereas veggie oil is intended mostly for longer trips. A veggie oil engine must be purged with either diesel or biodiesel at the beginning and end of a trip, because veggie oil is so viscous. The oil must be heated to the right temperature in order to successfully run through a diesel engine, and it isn’t hot enough when the car is first turned on.

DieselGreen Fuels is a company in Austin dedicated to educating the public on alternative fuels and providing the Austin community with biodiesel and filtered vegetable oil. At DieselGreen, waste vegetable oil can be purchased for $1.99 per gallon and biodiesel can be purchased for $2.99 per gallon. Though these prices are higher at the pump than filling up at a gas station, they are actually much lower than gas prices when the external costs of relying so heavily on gasoline are taken into account, says Chris Continanza, general manager at DieselGreen. DieselGreen’s alternative fuels can also be purchased at Ecowise, Oaxacan Tamaleo and El Sol Logistics Inc.  

For those most concerned with the price on their receipt, there is an option that currently is more economic than gasoline, while also friendly to the environment—it just requires some work on your part. Step one: purchase a veggie oil converter kit online for about $500, follow the directions closely and do it yourself. Step 2: purchase a veggie oil filtering kit on your own (for about the same price as a converter kit), so that all you need to supply in the future is the waste vegetable oil. Step 3: scour the area and find your own waste vegetable oil that can be obtained for free (or very close to it). This is best achieved if you can find one local restaurant that will agree to be your loyal provider. Restaurants must pay someone to dispose of the oil for them, so you are providing them a service as well.

This method is employed by David Cole, a resident of Waco who often makes trips to Austin to see family and friends. Cole has been filling his veggie oil tank for free at Busch’s Chicken, a small local chain restaurant, for more than three years. Regular diesel (or biodiesel) must be purchased at the beginning and end of a long trip running on veggie oil to cleanse the system, but the price in the long run is hard to beat.