IDTechEx projects that within the next few years that electric buses will represent the largest market for advanced and post-Li-ion batteries. With orders from over 30 transit agencies, one of the driving forces behind the demand for electric buses is Proterra. In part one of this two-part interview, Proterra CEO and president, Ryan Popple, discusses how electrifying a bus fleet cuts tailpipe emissions and positively impacts the energy grid while reducing life cycle costs.
Popple explains that today, the total acquisition costs for electric buses are similar to CNG (Compressed Natural Gas) and diesel hybrid buses. The acquisition costs include the underlying fueling infrastructure, which he indicates is much lower for electric buses than for liquid fuel technologies.
The operational cost of an electric bus is significantly less than the diesel or natural gas alternatives, as;
- the equivalent gas mileage is 21 MPG versus 3.27 to 4.58 MPG for CNG or Diesel-hybrids, which translates into 19 cents per mile versus up to 74 cents per mile
- lower maintenance costs due to fewer parts – Proterra buses have a 200 pound sealed motor versus the typical 1,500 pound internal combustion engine with its filters and lubricants that need routine maintenance. Maintenance is a significant expense, as Popple estimates that, on any given day, 10 to 20% of the 70,000 public buses in the U.S. are idle because of maintenance.
Popple indicates that the infrastructure for charging electric buses allows for scaling from one to many buses, with this metaphor about the chicken and the egg,
“Our fleets can buy exactly the number of chickens and exactly the number of eggs they need.”
It scales well because of the relatively low cost of a charging station, which can be as little as $20,000; compared to a CNG infrastructure which represents a huge upfront cost measured in the millions for the first bus.
The speed of the charge and the type of charger is a function of the application. For circulator routes, which are short and well-defined (e.g. campus), the battery storage requirements are relatively small and the charging is done in route in as little as three to four minutes. Other applications, such as traditional in-town bus routes, have larger battery packs (up to 660 kWh) and are designed for overnight charging that takes from four to eight hours. Proterra has shown that their electric bus can travel 600+ miles on a single charge.
He explains that they are using the SAE J-1772 CCS (Combined Charge Standard), which is a universal standard that car manufacturers are adopting for electric vehicles (see this article explaining how it works). By adopting this approach, cities can amortize infrastructure over many uses. As an example, Popple suggests that a Park and Ride parking lot could provide an electrical charge to cars by day and to buses at night.
Improving local air quality (see American Lung Association’s list of worst air pollution) is another factor that plays into local transit agencies’ decisions to shift from diesel to electric propulsion. Popple is seeing agreement across party lines regarding the need to cut soot and particulates from diesel engines. As such, some of the early adopters are in locales where pollution is the worst.
He gives an example of how one of Proterra’s early adopters in San Antonio has been able to gain the advantage of storing some of the almost 2,000 surplus Megawatts generated at night from West Texas wind farms. This results in electricity charging costs of as low as a penny per Kilowatt-Hour; increasing the MPG-equivalent to as much as 45 MPGe. He suggests that areas with abundant wind and hydropower, such as Wyoming and the Pacific Northwest, are great candidates for this synergy between mobile energy storage and peak electricity production.
As a pioneer in the electrification of wheeled transit, Popple indicates that Proterra has a responsibility to help grow the market. He explains that commercial vehicles represent the broader market for Proterra, which opens up the possibilities of licensing the underlying drive-train, battery and control technologies to other manufacturers.
In part 2 of this interview, Popple talks about how autonomous features play into the future of Proterra and transit in general.