Tucked away in a corner of an empty warehouse at McDonnell Horticulture is a $500 homemade contraption that could save the business and its customers thousands of dollars.

The device is a biodiesel converter. It is a gently used water heater and two 55-gallon barrels connected with nongalvinized pipes, valves and tubing. There are a bubbler, a compressor, a heater and a motor.

The converter is a high school science fair project that earns a D-minus for appearance but an A-plus for effectiveness.

It converts old cooking oil that commonly comes from deep-fat fryers at local restaurants to biodiesel fuel for the 16 tractors at the 225-acre nursery on old U.S. 1 in Cameron.

Biodiesel is made by chemically altering the oil -- essentially thinning it down -- to allow it to run in an unmodified diesel engine.

Pat McDonnell, who owns the business, is an innovator who grows ideas as well as he grows plants. He challenges his employees through cutting-edge projects.

"I saw this as an opportunity to take the business to a new level," McDonnell said.

McDonnell, who also has a degree in chemistry, began kicking around the idea of building a biodiesel converter last year. He said it was not a dollars-and-cents decision.

"It started as a summer project for an intern, not as a way to make or save money," O'Donnell said.

In the process of pitching his idea to others, one name -- Daniel Dayton -- stuck out. Dayton was a recent college graduate who has a degree in sustainable agriculture from Warren Wilson College.

Learned on Internet

Smart and inquisitive, he had the right background, a genuine interest and limited time on his hands.

"He was ideal for me," McDonnell said. "Come June or July, I don't have a lot of work for extra people, so he was perfect for the job."

Dayton is a Peace Corps volunteer who leaves for Mali in West Africa this July. McDonnell describes the tall redhead as someone with "with a little mad scientist in him." Not surprisingly, Dayton took to the project right away.

He learned how to create the homemade device on the Internet. Hours of research and experimentation performed over several months were fraught with ups and downs, successes and failures, and some unintended outcomes.

"One time we made soap," Dayton said.

Soap is created when the chemicals are mixed in improper proportions.

During the process, McDonnell encouraged Dayton to experiment, but he also required him to write down everything he did so he could learn from it.

"We told him you have to be comfortable with failing," McDonnell said. "You have to be comfortable with innovating. I had to tell him it wasn't a failure if you learned something."

Persistence paid off two months ago when the device produced useable fuel in small batches.

"Its not a complicated thing, it just takes some practice," Dayton said.

The device takes about four days to convert the oil to diesel. The byproduct of the process is potash, which ultimately could be used as fertilizer.

Benefits Evident

Tractors in the nursery began using the biodiesel last week.

The benefit of biodiesel is evident to Melvin Thomas, who is the nursery operations manager. Thomas said the business uses 100 to 150 gallons of diesel fuel per week.

Last week, Thomas purchased a tanker load of regular diesel for $4.30 per gallon.

A gallon of biodiesel is made in 25-gallon batches. It costs an estimated $1.80 per gallon to make, Thomas said.

To make the fuel, employees collect used vegetable oil from restaurants in several North Carolina counties, including Moore.

"These restaurants, for the most part, are paying somebody to haul this off, and when you show up and offer to take it away for free they are a little skeptical," McDonnell said.

In addition to the cost savings, Thomas said, the fuel has other benefits.

First, it is cleaner-burning. It doesn't produce that thick, black smoke that typically comes from running vehicles on regular diesel, Thomas said. He said the tractors seem to get better gas mileage, but he didn't have the necessary data to prove that assumption yet.

There is one thing, however, that is taking some getting used to -- the smell.

"It has a unique smell," Thomas said of the new fuel. "When you burn it, it smells like French fries."

Contact Tom Embrey at 693-2473 or by e-mail at tembrey@thepilot.com.