Two organizations with a focus on green transportation teamed with three United States school districts to evaluate operational needs and provide detailed plans outlining resources and decisions necessary to transition to an all-electric school bus fleet.
The Center for Transportation and the Environment (CTE) and World Resource Institute’s (WRI) Electric School Bus Initiative prioritized partnerships with school districts in historically underserved communities, based on air quality, income and racial demographics, or tribal status. The fleets considered varied operationally, geographically, and in fleet size.
“The diversity of fleets allowed CTE and WRI to identify challenges and offer findings and solutions as guidance to other school districts interested in electrifying their fleets,” a news release stated.
The chosen districts included:
- Yakima School District No. 7 (Yakima, Wash.)
- Reading School District (Reading, Penn.)
- The Chickasaw Nation (Ada, Okla.)
Despite each district facing different needs, CTE and WRI reported four lessons learned that proved common:
Most Districts Don’t Need Shared 50kW Chargers
The organizations found that a 50kW DC fast charger shared across two buses isn’t much faster than two separate 19kW Level 2 AC chargers, but it’s more expensive to purchase, install, and manage. Relying on fewer chargers also may require manually moving charger cables or vehicles to ensure adequate charging is provided.
“Unless a 50kW DC fast charger answers a specific need, the extra benefit may be overshadowed by the additional costs,” the CTE reported.
Level 2 AC Chargers Work for Much of a District’s Needs
Most bus routes analyzed for this project were well covered by charged with a single 80A 19kW Level 2 AC charger. Some exceptions exist, and some fleets have routes that need larger batteries or high-power midday charging. Rural fleets and fleets consisting mostly of Type A school buses can expect greater challenges with longer routes and smaller batteries, increasing the need for higher-power charging.
“Finding the right balance between infrastructure cost and operating constraints is critical, but most school bus fleets can work with mostly Level 2 charging,” the CTE stated, “and this is likely a good place for many fleets to start.”
Field Trip Routes Might Require Additional Charging Upgrades
Extracurricular field trip routes may be too long for a single Level 2 charge given range limitations of current electric school bus technology. This may require mid-day charging or DC fast-charging, which would call for additional infrastructure, utility investments, and skilled technicians.
“This may be especially challenging for rural districts (that) are more geographically isolated and require longer travel to and from extracurricular events,” according to the CTE.
Consider Discrepancies Between Projected Costs and Construction Estimates
Charging infrastructure costs vary greatly depending on many factors.
“CTE provided a high-level cost estimate for each fleet based on assumptions from WRI research and other CTE projects,” the organization reported. “In CTE’s experience, a cost estimate from a design-build firm can be much higher than this early estimate. A school district considering ESBs should engage a design-build firm early in the process to gather more concrete cost information that will help in determining necessary funding.”
Detailed cost estimates also help a district plan a phased approach over time to work with its overall operation and procurement schedule.
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