Frank Ferrell is CEO of Ninth Street Bakery in Durham, but not long ago he happened upon an inspiration in Asheville:

A blue and white, 1971, 18-seat Mercedes 309D bus.

Ferrell and his wife were stopping into the French Broad Food Co-op to get some sandwiches, and there it was, just sitting on the street with a "For Sale" sign and only 27,000 miles on it.

A Biodiesel Bus. Ferrell was captivated. He bought.

"It's totally fringe," he said. Now, Ferrell's bakery is the sort of business that prides itself on making products from scratch with organic ingredients. Biodiesel -- i.e., a diesel engine operated on eco-friendly vegetable-based fuels -- appealed to his green streak.

At first, he planned to use it for the bakery. "A great kind of traveling billboard," he thought. But the seats didn't leave the load space he needed. "Then we just started thinking, Why don't we do our own tours?"

Gaia Bio Bus, as Ferrell tentatively named the business, would be a double-edge enterprise: touring, plus promotion for biofuels.

"Biodiesel burns really clean," he said. Moreover, since it can run on the used cooking oil from restaurants, "it's using all this energy that up to now has just been waste," he said.

"So to me, it's really exciting."

Ferrell waxed downright visionary. "It got me thinking about energy and my energy use," he said, and the costs, direct and indirect. Things like air quality and climate change, asthma and foreign wars and declining petroleum reserves.

"I just think when the supply starts going down, with all the demand ... it's going to get ugly. We're addicted to our high-energy lifestyle."

Ferrell had plenty of ideas for tours to sell for about $45 a head, including food stops along the way. Maybe one of old mill towns; to the area's coffee shops. Kickoff was going to be last weekend, traveling around to independent bookshops to promote the "buy local" theme.

Then, he loaned out the Bio Bus and got a call from the road. No start. No oil.

Ferrell said he had changed the oil about a month before, put in six quarts. But while nobody was looking, the Bio Bus' crankcase had run dry.

No tour. And as far as the bio-touring future was concerned, no telling.

For want of a nail, the shoe was lost, for want of a shoe, the horse ... Ferrell might have been remembering the old proverb as Bio Bus got towed to the shop.

Fortunately, the engine wasn't frozen, and by the middle of this past week Ferrell was feeling better. It's still a mystery where the oil leaked out, but repair parts are on the way from Oregon, and the Bio Bus will be hitting the road again.

But from now on, Ferrell said he's minding his crankcase.

There's a lesson in this for us all: no matter how visionary, no matter how green, no matter how fringe-y your intentions and your vehicle may be -- if you want to get anywhere, you better watch the dipstick.