Huh? What’s an “all-electric” hybrid?

Now on the streets—you might find yourself aboard one of our newest all-electric hybrids! This next-generation of hybrids is designed to be our most efficient for fuel and emissions.

Thanks to a $2.5 million federal grant, we were able to purchase four of these buses, which are similar to a Toyota Prius—just a smidge bigger. Here’s how they work: a diesel engine powers a generator, which starts the bus and electrifies the energy storage system. The electric-traction motor then turns the wheels.

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It’s a hybrid—but electric!

“All-electric hybrid” may sound contradictory. These hybrids, though, are different and have even more awesome features than the last four we launched into service in 2012.

Everything on them can be electrically powered 100 percent—and for up to two miles! (Our older hybrids can’t do this because the diesel engine powers the hydraulic steering and air compressor.) If there’s not enough energy stored in the battery, the generator starts and uses the diesel engine, which also recharges the battery.

Another cool feature is what’s called Stop/Start Drive. As the bus slows to about 8 mph—and as long as the lithium-ion battery has enough juice—the engine shuts off and the battery takes over.

During shut-off, the bus’ accessories—such as the lights, air compressor, hydraulic steering and air conditioning—are battery-powered. As the bus leaves a stop and moves faster than 10 mph, the engine starts again.


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These buses use regenerative braking, too. This means when the brakes are applied, kinetic energy is captured and can be used immediately or stored in the battery for later use. The batteries also provide acceleration power.

Good gas mileage, low emissions

We won’t know until they’ve been in service for a while, but we expect these new hybrids to get at least 6 miles per gallon … just like our other four hybrids. In comparison, our newer fleet of standard buses get between 4.5 and 5 miles per gallon. In a 50,000-mile stretch, our all-electric hybrids would use about 1,719 fewer gallons of fuel when compared to our standard diesel buses. At over 50,000 miles, this saves about $4,000 worth of fuel!

The diesel engines on our newest hybrids also run even cleaner, as they comply with 2013 EPA regulations as opposed to the less-strict standards from 2010.

We’re often asked about getting more hybrid, electric, biogas or compressed natural gas (CNG) buses. We’re considering all of these quickly-evolving technologies, but as we test them, we look for cost-effectiveness of a bus’ entire lifecycle before making wholesale changes to the fleet.

Shhhhh …

And they’re quieter than our other buses. They’ll still make some noise, but we’ve never put a bus on the streets that’s basically as loud as a typical passenger car. Folks who are visually impaired will still be able to hear it.

Down the road

We’ll watch how our newest hybrid buses perform on the streets to see if we’ll buy more of them. Battery technology continues to improve and buses are being tested that can go 200 to 300 miles (wow!) without a recharge. These hybrids just may be great transition toward all-electric buses in the future.

Andrew Longeteig

Andrew Longeteig

I’m TriMet’s Communications Coordinator. I share what’s happening at the agency with the media and general public. When I’m not working, I’ll either be watching the Blazers or at a rock concert.

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