In partnership with the U.S. Environmental Protection Agency’s webinars on the Clean School Bus Program, the National Renewable Energy Laboratory (NREL) shared information on the other key ingredient to alternative fuel/energy school buses: infrastructure.
NREL, a part of the U.S. Department of Energy (DOE), has been a key partner in evaluating electric school buses. The organization is working on creating a program for school districts looking into school bus electrification. A webpage provides resources as well as webinars to help school districts interested in implementing zero-emissions. Additionally, NREL and the DOE, as well as the EPA offer clean school bus technical assistance to school districts.
Lauren Lynch, the senior mechanical engineer for NREL, commenced the June 22 webinar by discussing how vehicle acquisition and infrastructure installation should be done in parallel. For districts applying to the Clean School Bus Program, she noted that engaging first with local utilities will help districts as they embark on a new electric bus implementation process. Utilities will be especially helpful with planning the best location of the chargers and designing the infrastructure space.
She noted that the installation of charging infrastructure includes an understanding of vehicle energy needs. Energy is dependent on how much the vehicle will travel and its operational efficiency, she said. For instance, she asked, what are your route requirements? How much energy would need to be recharged at the end of each day?
Meanwhile, power is how rapidly the unit can supply energy to the vehicle. The more power, the shorter time it will take the vehicle to charge. The power requirements of charging infrastructure first require school districts to understand the demand.
Lynch said NREL recommends that districts conduct a route analysis, which includes understanding route lengths, hours of service and weather or season the buses will be operated in. Plus, she added that the battery efficiency and range are affected by many factors, so understanding the route requirements will help directors choose the products that are best for them.
Jesse Bennett, an electrical engineer at NREL, added that working with utilities when deploying this equipment is paramount, especially as it could require upgrades to the electric utility grids as well as buildings.
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In addition to considering updates, Bennett said another consideration is optimal site layout, such as determining where and how the buses will be parked, where the panel is located, and minimizing the distance from the panel to the electric vehicle supply equipment (ESVE) to save money.
Meanwhile, John Gonzales, the senior engineer for the NREL, discussed propane and natural gas infrastructure. He noted there are two options with CNG fueling, time-fill stations and fast-fill stations, though most school districts choose time-fill.
Gonzales also discussed the costs associated with adding a propane station, and how these stations can be installed above or below ground and come in various sizes.