As the MBTA modernizes its vehicle fleet, it’s also looking to cut down on pollution. Diesel buses are some of the most notorious belchers, attributed to high asthma rates in urban areas. To begin replacing them, next month the T will receive its first battery-powered buses.
“Battery-powered buses is a technology we are looking at. We decided we’re not going to purchase any more diesel buses,” said Steve Poftak, general manager of the MBTA.
Electric buses that use overhead trolley wires have been around since the days of streetcars, but battery buses are a new thing. One place they’ll be deployed is on the Silver Line between South Station and Logan Airport, where specially made diesel-electric buses are powered by trolley wires for half the trip and diesel for the rest. The battery buses will eliminate that switchover — once they’re proven to work.
“We’re waiting for someone manufacturing electric buses at scale that can handle the demands of Boston and Greater Boston weather,” Poftak said.
A good place to test that is in Minnesota, where the winter is even harsher than Boston’s. The city of Duluth is testing seven battery-powered buses for the Federal Transit Administration.
One reason Duluth was selected for the test, said Phil Pumphrey, general manager of the Duluth Transit Authority, is its extremely cold climate.
Duluth hit 20 degrees below zero more than once this season, though Pumphrey said the coldest they ran the buses was 6 degrees above. Like a car or flashlight, the length of a battery charge varies depending on temperature.
“At about 15-degree temperature, were getting about six, six-and-a-half hours right now,” Pumphrey said. “That may go up.”
He said it takes about an hour more than that to charge the battery, which is done overnight.
The other reason Duluth was chosen for the test is its topography, with the city built on a hill going up 700 feet above Lake Superior. While that elevation is not as much a concern for Boston, it led to the buses being pulled for an adjustment.
“It’s called the hill-hold feature,” Pumphrey explained. “We have inclines of 9 percent out here. If the bus starts rolling back, you’ve got to stop it. You don’t want it to slip, slide back into cars behind you.”
Made by Proterra Corporation of South Carolina, the Duluth buses do use some diesel fuel to operate the heating system so that the battery isn’t overtaxed. It’s pretty much the opposite of the heater and power system for your car.
Though the T is watching the Duluth experiment, Boston is getting different buses, made by New Flyer of St. Cloud, Minn. The goal is to retire about 500 diesel buses, already being replaced by hybrid diesel-electric. Battery buses could also replace the trolley buses in Watertown and Cambridge.
So what do riders say?
“I think the thing that matters most to me would be pollution. Pollution and efficiency,” said Kersten Rapp of Cambridge, riding the Silver Line to Logan Airport. While he endorses an emissions-free Boston, he cautions that making batteries means creating pollution somewhere.
“It’s like anything with electric vehicles,” Rapp said. “You want to reduce pollution everywhere, not just locally, right?”
That would include his destination of Logan Airport — though battery-powered airliners haven’t arrived there yet.