These are four charging stations for Proterra electric buses. (Photo provided)

Duluth, Minn.

Duluth just completed a trial year of running some Proterra buses and has had some challenges. Phil Pumphrey, general manager of Duluth Transit Authority, said Duluth was named in one poll as the fifth coldest city in the U.S. It sits at the west end of Lake Superior and runs east and west with steep elevation climbs from the lake to about 800 feet.

These factors are why the FTA’s low-no emission vehicle grant program and partner Proterra wanted to see how the buses would perform.

Pumphrey said the authority received its first electric buses in the summer of 2018, and they were put into service by the end of that November. This first group included seven Proterra extended range buses with 440 KW and two-speed transmissions.

Duluth’s buses have supplemental diesel-fueled heaters in their cabins.

“The manufacturer was skeptical that we needed it because the bus has a HVAC system, but we told them we had to have it,” Pumphrey said.

Because of the battery drain caused by Duluth’s extreme extended periods of cold — often with temperatures of 20 below zero — the supplemental diesel heater became the primary heat supply.

“The cold decreases the ranges significantly. When the temperature hits below 20 degrees, it has a real impact — the buses can only run six to six and a half hours in the winter,” Pumphrey said. “A diesel will run all day so it’s not a one-for-one replacement for the buses.”

The city of Duluth operates its buses about 20-21 hours a day. “We have a lot of ridership — about 2.7 million a year,” Pumphrey said.

The authority has contracts with the universities in town to provide service, and a lot of lower income residents ride the buses. So Pumphrey said knowing the electric buses only run six hours makes a big difference in how and where the authority can utilize those buses.

“There have been savings promised, but they’re gone depending on how long you can run the buses,” he said.

Duluth has run hybrids, too, and have had some of the same issues. “I think it’s the weather,” he said.

The seven electric buses are about 10% of the fleet, and in hindsight, Duluth Transit Authority would have gotten fewer to start, but Pumphrey said the decision was made before he entered his current position. He said the buses cost about $900,000 each, not including the infrastructure and backup generator.

“After the bus has been discharged, we can recharge 10% in an hour on a fast charge so it takes about seven hours to fully charge.”

Duluth has experienced squealing power steering since the electric buses don’t provide residual heat in the engine compartment. This was among other “hiccups that we worked through,” according to Pumphrey.

Duluth also gets a break on the cost of electricity from their electric company but not until after 10 p.m.

Pumphrey said he thinks the electric buses would be ideal for their school districts because they run for a couple of hours in the morning and can be recharged before going out in the afternoon.

He said the passengers do like the buses because they are very quiet.

For other municipalities looking at electrification, he said he wouldn’t recommend “going whole hog — just get a couple.”

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