Next Stop: Clean Air

October 19, 2017IMG_4291

If you can’t hear a bus coming, is it still on time?

Not too long ago, Western Washington Clean Cities got a closer look at King County Metro’s electric battery buses. And what we saw made us excited for the future!

Over the past year, King County Metro has piloted three all-electric battery buses on routes 226 and 241 in Bellevue. So far, the buses have traveled over 150,000 miles and saved 24,000 gallons of diesel fuel!

Electric battery buses are still a relatively new technology, so bumps and bruises are inevitably picked up along the way. During a day-long showcase, King County, as well as other public transit authorities from New York City and Vancouver, presented to regional transit agencies the benefits and challenges of owning and operating a small fleet of electric buses. The showcase also provided an opportunity for local agencies to begin planning for transit electrification.

Here are three key things we learned:

1. Going electric is an investment.

The upfront costs of upgrading your fleet to electric power can seem daunting. A Proterra battery-electric bus can cost about $750,000 – about $250,000 more than a typical diesel bus. And that’s not counting the charging infrastructure (more on that later). But most fleet managers and procurement staff at King County Metro’s showcase agreed that purchasing an all-electric bus itself is not cost prohibitive. Once an electric battery bus is in service, the savings from operating it can be substantial. With Washington’s electricity among the cheapest in the nation, “fueling up” is a sure-fire way to recover some cost savings. Electric buses also don’t require oil changes or other routine maintenance associated with combustion engines – a significant savings that will continue to grow as the number of electric buses in a fleet increases.

In other words, transit agencies can think of electric battery buses as an investment by moving money from their operating budget over to their capital budget.

Another thing to consider is the possibility of purchasing an electric battery bus while leasing the battery itself. With battery technology quickly changing these days, leasing the battery instead of purchasing it could prevent transit agencies from being stuck with yesterday’s aging battery system.

Regardless, the benefits of electric battery buses extend beyond pure financial gains. Each battery bus saves thousands of tons of greenhouse gas emissions per month, and completely eliminates harmful diesel pollution. 


2. Slow charging or fast charging? It depends.

The ranges of electric battery buses vary based on the manufacturer and battery size. Some buses have a shorter range (25-50 miles) but can fully charge in just ten minutes. Others have a much longer range (125 miles or more), but require several hours to repower. Which option should transit agencies choose?  

The answer depends on what type of route the bus will service. Routes through urban areas, with lots of starting and stopping, may be more suited for shorter range buses that can benefit from regenerative braking, which can up to 30% of the power consumed!. Bus routes in suburban or rural areas, with more highway driving, are likely better for the buses with greater battery capacity.

Another possibility is choosing a combination of both options. Like King County Metro, the Metropolitan Transportation Authority (MTA) of New York is also testing out battery electric buses. One of their routes uses a longer-range battery bus to navigate across Manhattan to Brooklyn. At the end of each route, the bus “tops off” with a fast charger during a layover – also called opportunity charging – before restarting the route. Although the bus still has plenty of battery power once the route is completed, topping off allows the bus to eventually transition to another planned route later in the day.

Potential weather is also a factor worth considering. According to the MTA, the battery buses can end up using more energy for cabin comfort on hot or cold days than actual propulsion. Good thing we have a milder climate here in Washington!


3) It’s all about the infrastructure.

If there was one common theme from the battery bus showcase, it was “infrastructure, infrastructure, infrastructure.” Most transit agencies thinking of going electric recognize that the biggest issue they face is something completely foreign to them: setting up charging equipment.

Determining the charging equipment’s footprint, designing the site’s overall set-up (and potentially integrating it with the street), and scheduling construction of the electrical infrastructure are all outside of a transit agency’s typical purview.

Charging a bus – or, more likely, many buses – also puts a demand on the electric grid. Many showcase attendees wondered at what point they would need a transformer or electrical substation. If one was required, would the local utility help pay for its construction? And what would happen if there’s an electricity outage?

Much still needs to be worked out between transit agencies and utilities on this front, but regulations currently do not allow a utility to pay for additional infrastructure costs. Utilities might, however, reimburse the customer some of the upfront costs based on the amount of power used by the customer. Setting up bus charging infrastructure also requires a certain amount of redundant power sources, although no system will be able to combat a complete power blackout without an extra generator.

One thing that everyone can agree on is the need for a standardized set of chargers – regardless of which bus manufacturer you’re operating. Currently each bus manufacturer uses a different set of charging equipment, making the planning and procurement of various buses a tricky proposition. Although nothing has been resolved as of yet, most showcase speakers expressed confidence that a consistent format for bus charging will eventually be agreed upon.

Lastly, on the issue of bus infrastructure, agencies with plans to acquire battery buses in the future will need to think about distributing the buses in an equitable way. Everyone wants one of the brand new buses where they live. Should they be spread out throughout a jurisdiction among many routes or concentrated in a certain part of the region? In planning the next phase of their battery bus deployment, King County Metro is looking at air quality data in the county. Metro plans to focus the battery buses and their associated charging infrastructure in south King County, an area disproportionately impacted by diesel pollution and poor air quality.

Thanks to King County Metro for putting together their battery bus showcase. We’re already looking forward to the next one! If you have questions about electric transit – and what next steps to take – let us know. We’d be happy to help.