This bus runs entirely on electricity. (Foothill Transit)

Next year, nearly 10 percent of Foothill Transit’s buses are expected to be running on electricity.

The bus operator in the San Gabriel and Pomona Valleys outside Los Angeles is at the forefront of transitioning its fleet away from fossil fuels. It’s already shifted away from diesel buses and largely uses buses running on natural gas.

On Wednesday, it announced another order of electric buses from manufacturer Proterra. In 2016, 30 of Foothill Transit’s 320 buses will run on electricity. Foothill first experimented with three buses in September 2010 and has gradually expanded since then.

“The electric buses are demonstrating that they can meet the duty cycles at least in certain segments of our industry,” said Doran Barnes, executive director of Foothill Transit. “As we learn more and the comfort level increases, the potential for more electric deployments are definitely there.”

Barnes says that operating and maintaining electric buses is less expensive than other types of buses. But it’s still unclear if shifting the entire fleet to electric buses would be more cost effective. Proterra’s electric buses are more expensive in initial costs, with a price of about $775,000.

A saving that doesn’t readily show up in dollar signs is the positive impact on the environment.

“We’re in an air basin that historically has been very challenged with pollution. A lot of efforts have been made to try to improve the air quality,” Barnes said. “There were days in the past when the foothills that are about 15 miles from our office, you couldn’t see them through the haze. Now virtually every day you can.”

Currently Foothill Transit has all its electric buses operating on one of its 36 lines, which accounts for 5 percent of its customer boardings. There is a charging station halfway along the route where buses stop for four to five minutes every two hours to  get extra power to make it through the day. (Its current buses only have a range of 30 miles. The new buses will have a range of 100 miles.)

Proterra chief executive Ryan Popple says he is confident electric buses have a bright future.

“Based on the cost curve that I’m looking at — especially in batteries — this vehicle is going to get to the point where it’s going to wipe fossil fuel vehicles out of urban transit use,” said Popple, who called a city bus route the worst route you could task an internal combustion engine with due to the stop-and-go driving and slow speeds.

Proterra also announced Wednesday it has received a $3 million grant from the California Energy Commission to fund a new facility in San Gabriel Valley for manufacturing its buses.

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