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Zero Emission, All-Electric Buses Take To Louisville Streets

Louisville's new fleet of electric buses are lighter, quieter and cleaner than the old, carbon monoxide-emitting trolleys residents have grown accustomed to seeing (and perhaps riding) downtown.

The 10 new buses take to Louisville streets this week to begin transporting passengers for free along two routes in the downtown area. On Monday, the Transit Authority of River City and city officials officially unveiled the new buses.

The buses will save TARC about $300,000 a year in gas and maintenance costs, said Jon Reiter, a TARC spokesman.

“This is the most energy-efficient transit vehicle on the road, regardless of fuel type,” said Ryan Popple, president and CEO of Proterra, the bus manufacturer.

Popple said a traditional diesel-powered bus consumes 10-12 kilowatt hours of energy per mile. The new electric buses use less than two kilowatt hours of energy for each mile.

Three charging stations located at the fringes of downtown Louisville will provide electricity to the buses. With a roughly six to eight minute charge a bus can travel about 40 miles, Poppel said.

The cost of that electricity is “next to nothing” compared to the cost of diesel fuel, said Geoffrey Hobin, special projects manager for TARC.

Hobin said during recent testing sessions TARC racked up an electric bill of about $2,900 for the buses.

That breaks down to about eight cents a mile, Hobin said. But he said fewer charging sessions will be needed now that training has ended, meaning the cost will be split nearly in half.

Ideal cost structure for the electric buses would be about 10-15 percent of what is spent for diesel operations, Hobin said.

One of the reasons the buses are more efficient is the design, Popple said. The new electric buses weigh about 28,500 pounds—significantly lighter than the trolleys they replace, despite a capacity of about 10 more passengers.

Another way the buses are able to boost efficiency is by operating on routes with slow-moving traffic, Poppel said.

The ‘stop-and-go’ nature of downtown traffic allows the buses to recapture energy during deceleration, he said, which also increases longevity of the buses’ braking systems.

The buses’ electric motor generates 300 horsepower and 500-foot pounds of torque, Poppel said.  And it’s “about the size of a beach ball,” he added.

“A strong mechanic can take it out as a one person job,” he said.  That wouldn’t be the case with a traditional 8.9 liter diesel engine, which weighs hundreds of pounds, Poppel added.

A Proterra maintenance specialist will be stationed in Louisville to assist with bus upkeep, Poppel said.  Most maintenance efforts are focused on the bus battery.

“We want to make sure that the batteries perform in all temperatures, all climates,” he said.

And temperature is not expected to have much of an impact on battery performance, Poppel said. But colder temperatures could require slightly longer charge times, as the battery is working extra to operate a heater, he added.

So with an all electric bus the question arises, what happens during power outages?

Mike Segvich, a mechanic with Proterra, said the buses would be “slow charged” on a generator.  He said that would take about 45 minutes.

And Poppel added that if a sweeping power outage does occur the buses could potentially be used as an electricity provider—meaning the electricy put in to the buses could also be transferred to something else.

“As these vehicles are carrying more and more energy it’s possible for them to push the energy back to the grid,” Poppel said.  “In an emergency situation, instead of using all of your transit buses for transit service you might actually send them over to a hospital, and they would plug in and run critical building infrastructure.”

To pay for the buses, TARC received about $4.4 million from the Federal Transit Administration’s Clean Fuels Program in spring 2012. In fall 2013, TARC received the same amount from the state’s congestion mitigation program, Reiter said.

Louisville Metro government contributed about $500,000 to the $2 million “local match” that covers the rest of the cost, he added.

“Technology is at a point in time where we ought to take a chance,” TARC director Barry Barker said. “What we are trying to do is create some excitement, demonstrate that there are many roles for public transportation, economic development, environmental improvement and simply being there to improve people’s quality of life.”

What Now For The Trolleys

The trolley had the reputation as TARC's highest polluting vehicle—the five oldest trolley buses combined emit a total of about 1,135 pounds of carbon monoxide in a year. But they are not being totally removed from service.

The green Toonerville trolleys will be nixed from daily operations, but five will remain to operate during the Frankfort Avenue Trolley Hop on the last Friday of each month.

And the rest will be sold at public auction, which is in accordance with federal regulations.

Other public agencies or private companies still want the trolleys "because they are attractive," Hobin said.

"People love them for weddings," he said.


Jacob Ryan is the managing editor of the Kentucky Center for Investigative reporting. He's an award-winning investigative reporter who joined LPM in 2014. Email Jacob at jryan@lpm.org.