OMAHA, Neb. — The largest automotive carrier west of the Mississippi is exploring ways to make its locomotives more fuel efficient.

Union Pacific saved more than 20 million gallons of diesel fuel last year through a series of programs and locomotive acquisitions designed to improve its fleet's fuel efficiency.

It scheduled about 150 Genset Switchers to begin service last year. The Genset emits up to 80 percent fewer nitrogen oxides and particulate matter and is 16 percent more fuel efficient.

Union Pacific also tested a hybrid locomotive dubbed the Green Goat, which, like the Genset, reduces emissions of nitrogen oxides and particulate matter by up to 80 percent ans uses 16 percent less fuel.

More than 2,600 new fuel efficient long-haul locomotives have been added to its fleet while 1,700 older models were retired, and another 1,700 were overhauled or rebuilt.

The company conducted field tests on oxidation catalysts that could be added to older locomotives to reduce particulate matter emissions. A 3,800-horsepower locomotive built in 1992 is the first in North America to test the "Oxicat" converter.

The company also instituted a program to reward fuel-efficient locomotive engineers. Through its Fuel Masters program, the top 15 to 20 percent of engineers with the best fuel consumption performance in each territory receive $100 fuel cards.