As the trend toward transit electrification continues to accelerate, new battery electric bus (BEB) models are coming with bigger and bigger promises: greater range, faster charging, longer-lasting batteries. With these advancements and increasing goals for emissions reduction, more agencies are seriously considering significant BEB deployments.
In practice, tracking and utilizing operational data from an electric bus is more difficult than on a diesel bus. While something like the odometer might be familiar, the nuances of electricity usage bear little resemblance to the simple tank-and-fuel models of diesel and natural gas buses. BEBs require advanced telematics systems to measure anything with confidence, and interpretation of the data is rarely straightforward. Yet for any transit agency hoping to add BEBs to its fleet, a firm grasp of this data is crucial to a successful deployment.
Electric bus energy use is driven by advanced components, each with a unique relationship to the battery and external operating conditions like weather and traffic. These complexities are not trivial. Dispatchers want assurance that their buses will not get stranded due to a battery depleting with a cabin full of passengers. Yet a route that uses half the battery one day might use three-quarters the next. Range anxiety can often leave agencies sending out their BEBs for only a fraction of the service of which they’re truly capable.
Unlike internal combustion engine buses, which have predictable fuel economies and can reliably achieve the necessary range on most routes, electric bus performance can vary based on the skill of the driver, temperature and snow cover outside, traffic conditions and passenger loads of the day, the overnight storage environment, and the speed and hilliness of the route. The better the agency understands the impact of these variables, the less serious the range anxiety and the more use they can get out of their vehicles
That understanding matters from an investment perspective, too. Electric buses promise a cost trade-off: Agencies will pay more upfront but save on fuel and maintenance long-term. It is because of these high fixed costs that transit agencies have a strong interest in running their BEBs as much as possible. The marginal cost of running a BEB an extra mile may be far lower than its diesel and CNG counterparts. With a solid grounding in data, operation and planning teams can save money for their agency without sacrificing the quality of their service.
But the relationship between electricity cost and utilization can be complicated. The simple dollar-per-gallon value of traditional fuels rarely has an analogue in the world of BEBs. Utility bills can swing considerably from one month to the next despite no uptick in charging—the unfortunate effect of a steep demand charge or an unexpected change in seasonal rates. Many locations around the country find charging to be more expensive than current diesel costs. A thorough analysis of route feasibility, utility rate structures and potential charging strategies can equip a transit agency with the tools to avoid such unwelcome surprises.
The Center for Transportation and the Environment (CTE) is already working with transit agencies across the country to collect data on their electric buses and interpret it to actionable ends. As a national nonprofit devoted to helping fleet operators deploy green vehicles, CTE is an industry leader in solving difficult problems such as measuring battery capacity, predicting operating range under a host of conditions, and making sense of volumes of bus and charger data. CTE is developing innovative new tools to help transit agencies collect and analyze data, allowing them to make the best deployment and procurement decisions for their organization, city and ridership.
It is hard to say what exactly the BEB market will bring in the coming years; all signs point to exciting new technologies that will make public transportation a cleaner sector fit for the21st century. What’s clearis that a data-driven understanding of those technologies will be what provides their maximum value to the agencies and passengers who use them every day.
Erik Bigelow is a senior engineering consultant and the director of Midwest Operations leading the CTE office in St. Paul, Minn.
Greg Olberding is a lead associate at CTE who specializes in vehicle performance monitoring and key performance indicator reporting.
