KILMARNOCK, Scotland Is this a sign of the times, an indication of things to come, or just a half-witted idea?

Stagecoach Group, the parent company of Coach USA, has launched a program in the United Kingdom that encourages customers to exchange used cooking oil for discounted bus travel.

For its part, Stagecoach calls it a ground-breaking environmental initiative. Judge for yourself.

Eight Stagecoach buses being operated in Kilmarnock will run on 100 percent biodiesel manufactured from used cooking oil and other food industry by-products. The result, says Stagecoach, is an expected 82 percent cut in carbon dioxide emissions.

The biodiesel to be used in the buses is produced from tallow and used cooking oil, "both of which are sustainable sources that do not involve the destruction of natural habitats or compete with the human food chain," Stagecoach noted in an announcement.

All households on the route where the buses operate, which runs from Stewarton to Darvel via Kilmarnock, and carries around 15,500 passengers a week, will receive a free container to recycle their used cooking oil.

The oil can then be taken to a local recycling plant, entitling customers to a voucher for money off bus travel.

The buses involved in the trial are Alexander Dennis models equipped with MAN engines. They also have dual fuel tanks with a capacity for 184 litres of biodiesel and 40 litres of mineral diesel.

For the start-up each day, the buses will run on mineral diesel until the normal engine operating temperature is achieved -- a process that takes roughly 10 minutes. The system then switches automatically to biodiesel, which powers the vehicles the rest of the day.

Brian Souter, Stagecoach Group chief executive, said: "This innovative project is a great opportunity for our customers to play their part in saving the planet by recycling household products that would otherwise go to waste. I'm sure the idea of cheaper travel in exchange for the used contents of your chip pan (think fish and chips) will capture people's imagination."

The biodiesel for the six-month trial is coming from the UK's first large-scale biodiesel plant.

Stagecoach currently uses a blend of 5 percent biodiesel in more than 4,300 of its vehicles, or around 60 percent of its UK bus fleet.