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A converted diesel Westport Innovations bus

(CNN) -- For decades, fuel-efficient and mechanically simple diesel engines have powered heavy-duty vehicles and machines around the world. They have also been pumping out major pollutants.

A Canadian company called Westport Innovations hopes to sell diesel engine users on a conversion kit, which enables the same engines to run on natural gas.

The company projects that it will eventually capture almost a third of the $70 billion global diesel engine market, as nations turn to new technology to meet more stringent clean-air standards.

"At the moment, we have a very big atmospheric pollution concern, so we feel we have a very good product to step into an existing market on a short-term basis," said Patric Ouelette, chief scientist at Westport Innovations.

A diesel engine converted to burn natural gas
RELATED AUDIO Ouelette comments on the atmospheric pollution problem 119K/10 sec. AIFF or WAV sound Brad Douville explains the benefits of a converted diesel engine 94K/10 sec. AIFF or WAV sound

Patented method

Westport said its patented method converts a diesel-burning engine into one that burns almost all natural gas, after using just enough diesel to start the combustion cycle.

The conversion kit contains injectors capable of handling both diesel fuel and natural gas, as well as other components that store the natural gas at the high pressure necessary for efficient burning.

Westport said a converted engine emits half the pollution a conventional diesel engine does. The company also says natural gas is about 30 percent cheaper than diesel fuel, so bus and truck companies can recoup the cost of each $20,000 conversion kit within a few years.

One bus with a converted diesel engine is already shuttling college students around Berkeley, California.

"It handles real good, real good," said bus driver Sharon Woodbush. "I get a better ride out of this because you get more power -- especially on the takeoff."

Correspondent Rick Lockridge contributed to this report.