Several cities in Minnesota, including Duluth and the Twin Cities of Minneapolis and St. Paul, embarked on an ambitious journey to transition their public transit systems to zero-emission electric buses. However, the road to eco-friendly transportation is proving to be a bumpy one, especially in the face of harsh winter conditions.
The electric buses, which were part of a larger initiative to reduce carbon emissions, have encountered significant operational challenges in subzero temperatures, a common feature of Minnesota winters. Despite the promise of a 150-mile range per charge, the reality has been starkly different.
In the Twin Cities, Metro Transit spokesperson Drew Kerr revealed to MinnPost that while using electric buses, the range further drops in colder conditions.
“Using garage chargers alone, electric buses can remain in service for 70 to 75 miles before needing to return to the garage; with on-route chargers, electric buses were scheduled to be in service for up to 90 miles before returning to the garage,” Kerr said.
In Duluth, the situation is no less challenging. The city’s spokesperson, Dave Clark, pointed out numerous issues with the charging stations, including frequent malfunctions and glitches. These problems have been compounded by the buses’ inability to provide adequate warmth for passengers during winter, a critical failure in a region known for its frigid temperatures.
“They would fail, they would not perform, they would experience malfunctions, glitches. They were extremely problematic right out of the gate,” said Clark.
Electric vehicles (EVs), including buses, are affected by sub-zero temperatures in several key ways. Firstly, the efficiency of lithium-ion batteries, which power most EVs, decreases in cold weather. This is due to the slowing down of chemical reactions within the battery at lower temperatures, resulting in a reduced ability to hold a charge and, consequently, a decreased range.
In cold conditions, a significant amount of the battery’s energy is diverted to heating the vehicle’s cabin, further reducing the available power for driving. This need for additional heating not only impacts the driving range but also influences the overall energy consumption of the vehicle. Another factor is the increased rolling resistance caused by colder and potentially snow-covered roads, which demands more power from the vehicle to maintain the same level of performance.
The regenerative braking system, a key feature in EVs for energy efficiency, may be less effective in cold temperatures. This is because the battery’s reduced efficiency at lower temperatures limits its ability to accept charge generated from braking. However, advancements in EV technology, including improved battery chemistry and thermal management systems, are continually being developed to mitigate these challenges and enhance EV performance in cold climates.
The transition to electric buses has not only been hindered by climatic challenges but also by technical and vendor-related issues. Metro Transit had initially planned to acquire a fleet of electric buses from Proterra, a company that later filed for bankruptcy. This left the agency without a reliable vendor and raised questions about the sustainability of relying on a single supplier for such a crucial public service.
Despite the setbacks, they remain committed to their approach. As cities like Duluth and the Twin Cities navigate these challenges, their experiences offer lessons for other regions considering similar transitions.