Utilization of Battery Electric Buses for the Resiliency of Islanded Microgrids

Abstract

During a grid outage, microgrids can benefit from energy resources that enhance the reliability and resiliency of serving critical loads and overall protection. The present study develops a methodology to assess the efficacy of battery electric buses (BEBs) as a microgrid resiliency attribute during islanded operations, and applies the methodology to an existing 20 MW-class microgrid equipped with a fleet of 20 BEBs. Each BEB comprises 324 kWh of stored energy and can charge/discharge at 80 kW which translates to 1.6 MW and the potential of 6.48 MWh of stored power and energy respectively depending on the state-of-charge of each bus. For the application evaluated, the methodology reveals that a BEB fleet can serve as a viable resiliency and flexible energy resource for an islanded microgrid by enabling Mobility Services+, examples of which include (1) deployment to serve critical loads within the microgrid (e.g., an emergency control center, shelter, clinic), (2) deployment to serve critical loads outside the microgrid (e.g., a hospital, fire station, grocery store), and (3) service as a blackstart resource should the microgrid prime power generator trip. In the present case, the BEB fleet has the ability to support a microgrid emergency center for at least 16 h, and serve as a blackstart resource with a probability of 100% by a combination of parked BEBs and BEBs recalled from on route transit service.