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EV Articles by Paul Gipe

March 5, 2016
Paul Gipe

Proterra Demos Bus for Bakersfield’s GET Transit

Proterra, the high-tech startup, demonstrated its all-electric bus for Golden Empire Transit (GET) staff today. The company hopes to sell GET, the transit company serving Bakersfield, two electric buses.

GET’s fleet is currently powered with Compressed Natural Gas (CNG).

Like Electric Vehicles (EVs), which upon closer examination are just cars, electric buses are just buses. They ride like buses—rough. But unlike conventional buses that use an Internal Combustion Engine (diesel, gas, or CNG), Proterra uses a series of traction batteries that power a heavy-duty electric motor.

Decades ago GET converted from diesel to CNG as part of cleaning up emissions from heavy vehicles in the San Joaquin Valley. This was avant-garde in its day and the only way then to reduce emissions from transit buses.

EV technology has rapidly advanced and now fleet managers are taking a serious look at EVs for transit and delivery vehicles. United Parcel Service is already running a number of battery-powered delivery trucks in the Bakersfield area—the whine of their electric motors is becoming a common urban sound in our neighborhood, for example.

Like Nissan and the development of its Leaf, Proterra designed a purpose-built vehicle from the ground up or what the company calls a “clean sheet” design.

Backed by big name venture capitalists, Proterra builds the bus primarily from composites for 5,000 pounds less than a conventional steel and aluminum chassis. Less weight means the bus can travel farther or carry more passengers for the same charge.

Proterra’s current buses are built in a non-union shop in South Carolina. However, the company has set up corporate offices in Burlingame just outside California’s Silicon Valley. They are also building a new assembly hall in the City of Industry near Los Angeles where they will employ 70 and build up to 140 buses per year.

Again, like the current crop of EVs, the buses are more expensive than conventional buses, but Proterra claims the operating costs are significantly less. Savings accrue from less and simpler maintenance and the use of electricity instead of CNG or diesel fuel to power the vehicles.

Each bus costs about $750,000.

The company offers buses in a 35-foot and a 40-foot length. The longer bus will carry 40 seated and 37 standing.

They also offer two models for different service requirements: a fast charge version and an extended range version. The fast charge version is equipped with a 105 kWh battery pack beneath the floor of the bus. The vehicle is charged in 4-6 minutes from a 500 kW catenary boom that attaches to a fin on the top of the bus. The extended range version has 300 kWh of packs underneath the bus and charges at 200 kW from a conventional SAE J1772 CCS connector.

Proterra says the packs should last 6-8 years. No Proterra buses have been in revenue service for that long yet.

The multiple battery packs are liquid cooled from a chiller on the roof of the bus. The chiller also powers the bus's air conditioning of the passenger compartment.

Several transit companies around the continent are using Proterra buses. The largest, most visible fleet is that operated by Foothill Transit in Pasadena. Foothill Transit introduced the first three Proterra buses on Line 291 between La Verne and Pomona in 2010. In 2014, Foothill expanded the Proterra fleet to 15 vehicles. Foothill has since bought 13 of the extended range models. With the addition of the new buses, nearly 10% of Foothill’s fleet will be battery-powered.

Bakersfield’s GET will likely use state or air district funds for reducing heavy-vehicle emissions in the polluted San Joaquin Valley if they purchase the Proterra buses.

The demonstration bus was clean, quiet, and solidly built.

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