BANGOR – Small towing tractors have been used for years at Bangor International Airport to tug airplanes across the tarmac, but now one of them will plug into an electrical socket instead of a diesel pump to refuel.

Mechanics from the airport’s ground support equipment team gutted the engine and motor from one of the tugs and replaced it with an electric battery, making for a more environmentally friendly machine that can tow just as much as

its diesel counterparts.

“This is a trend that a lot of airports are moving toward,” Tony Caruso, airport assistant director, said Thursday, standing next to the 3,000-pound machine.

The tractor can pull about 5,000 pounds, he said.

A small, three-pronged outlet has taken the place of the diesel tank door, and a battery meter now sits where the gas gauge once was.

The frame is the same, although it has been touched up with a fresh coat of white paint. The machine looks somewhat like a souped-up riding lawnmower.

The tractor, known affectionately as “ET One”, or electric tug one, is the first of the airport’s six tractors to be converted. Up next is a belt loader, which is used to unload luggage from the airplanes.

The air pollutants generated by the tractor will all but disappear, and carbon dioxide levels will drop by 40 percent, according to airport officials.

A diesel-powered tractor lasts about three to five years, while the converted version should be usable for up to seven years.

It cost about $6,000 to convert the tractor, but the machine should be cheaper in the long run to operate because it doesn’t require diesel, oil, transmission fluid and other maintenance, Caruso said.

“Preventive maintenance is really minimal,” he said.

A brand new diesel tractor that the airport purchased in 2002 cost approximately $50,000, Caruso said.

The estimated cost to run the converted tractor is about 10 cents per hour. It takes about eight to 10 hours to charge, which is necessary every two to three days, Caruso said.

So far, the airport’s ground crew is happy with the tractor’s performance, he said.

“It’s a new toy,” Caruso said.