To be sure, no one is pretending that waste-to-energy projects will become a major part of the larger natural gas vehicle market. But supporters say it could provide additional incentive to make biogas systems, which have lagged behind other sustainable energy solutions, more commercially viable.

“You’re essentially harvesting manure,” said Erin Fitzgerald, a senior vice president at the Innovation Center for U.S. Dairy, who says that farmers across the country are starting to think about whether the model tried at Fair Oaks will work for them. “It’s not glamorous. It doesn’t really catch your eye like wind and solar.”

Mike McCloskey, a co-owner of Fair Oaks, said he first started looking into renewable energy options for the farm more than a decade ago, when the smell of manure, used as fertilizer on his fields, started drawing complaints from some neighbors.

Today, the farm is running sophisticated $12 million “digester” facilities that process its overabundance of manure, capturing natural gas that runs electric generators or is pumped underground to a fueling station. The leftover byproduct is still spread on the fields as fertilizer.

While Mr. Corbett would not divulge how much money the farm saves by its switch to biogas fuel, he said the gas stations had already brought in new revenue from other trucking fleets.