THORNTON, Colo. — Colorado’s first hybrid school bus went into service last week, shuttling a group of third-graders on a field trip to an environmental research center.

Adams 12 Five Star Schools acquired one of IC Bus’ diesel-electric hybrids with help from a state alternative-fuels rebate.

The bus is expected to reduce diesel consumption by 70 percent and carbon dioxide emissions by 40 percent.

David Anderson, director of transportation for the school district, said that the hybrid school bus will be the first to be tested at high altitude. The district, based outside of Denver, is about a mile high — 5,280 feet — and the bus will be driven into the nearby mountains, possibly as high as 12,000 feet.

The district and IC Bus will look at how the high altitude affects fuel economy and performance.

Teacher Sarah Hayden’s third-grade class from Hillcrest Elementary took the bus’ inaugural trip as they visited the National Center for Atmospheric Research in Boulder. The class has been studying climate and environmental topics, including hybrid technology.

As the students returned from the trip, they took part in a press conference at their school. School district and air quality agency officials were also on hand to discuss the hybrid school bus project.