When the Rochester City Council approved the purchase of 11 new diesel-powered buses earlier this month, council member Michael Wojcik said it could be the last time.

"My hope is going forward the era of the internal combustion engine in Rochester's transportation will be coming to an end," he said, noting price and performance are just shy of making the decision this year.

On Thursday, Rochester Public Transit and other city staff received a peek at what could be in the city's future if diesel-powered transit fades away. They received a presentation and ride from Proterra, using a model of the first bus designed specifically to run on batteries.

Here are a few things to know about the potential for electric buses on Rochester's streets.

1. The cost margin is narrowing.

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Michael Hennessy, senior director of national sales for Proterra, said a basic electric bus costs $699,000 with batteries, but the batteries can be leased separately, bringing the initial cost as low as $499,000.

The city's recent bus order called for paying $452,887 for diesel-powered buses, with the city paying 20 percent of the nearly $5 million cost for 11 buses and the state covering the rest.

Hennessy said federal incentives have encouraged some communities to make the switch based on cost savings.

2. The plan calls for electric bus orders as early as 2019.

Rochester Transit Manager Tony Knauer said the city's plan calls for purchasing electric buses in 2019 or 2020, which would include larger articulated buses.

He said the city council will decide later this year what steps to take as it discusses budgets. That could include moving to electric buses earlier.

"That's always the council's prerogative," he said.

Hennessy said it typically takes 12 to 14 months to deliver an electric bus once ordered.

3. The city will continue buying diesel fuel.

With the purchase of 11 new buses, set to be delivered within 20 months, Knauer said diesel-powered buses will remain on city streets for at least another 15 years, the average lifespan of a bus in Rochester's fleet.

"It's not going to change overnight," he said, noting what the city pays for diesel fuel each year would gradually decrease.

The city currently pays approximately $1 million each year to fuel its buses, Knauer said.

4. Power plan could be key.

The fuel savings connected to switching to electric power hasn't been fully analyzed yet, Knauer said, citing a variety of factors.

Key among them could be how the buses are recharged.

Two options exist: Using smaller batteries that quickly recharge throughout the day at select sites along routes or opting for larger battery packs that run for longer periods but can take hours to recharge.

Drew Larson, energy and environment adviser for Rochester Public Utilities, said the city could save on electricity costs by opting to recharge each night, since rates drop with lower demand between 10 p.m. and 10 a.m.

"There are some strategies we could likely work with them on," Larson said of creating a power plan for an electric bus fleet.

5. The natural gas option has dissipated.

Knauer said natural gas-powered buses have been studied but are likely off the table for future purchases, noting fluctuating fuel prices are a concern.

"The problem is the prices are a lot more volatile there," he said.

As he prepared to board the electric bus Thursday, he said the cost of power seems to be more stable, which makes it easier to predict costs for operators.

6. Duluth provides insights for council members.

The city of Duluth expects to have its first electric buses delivered from Proterra in March.

Rochester council member Mark Hickey said the experience on the North Shore could provide insight for local use, especially when it comes to winter months.

"Cold weather and batteries are an interesting combination, so it will be instructive to see how they do," he said.

7. Weights are similar.

While the Proterra bus tested Thursday is made of a lighter composite material designed to improve battery efficiency, an electric bus won't necessarily take stress off city streets.

Hennessy said bus weight fluctuates based on battery type, but a fast charge model with fewer batteries weighs about 27,500 pounds.

Knauer said Rochester's current diesel buses hit the streets at about 28,000 pounds.