An Analysis of Shutdown for an Operational Fuel Cell Transit Bus 2001-01-2778

The shutdown process of an operational phosphoric acid fuel cell transit bus has been investigated. The bus employs a hybrid arrangement of a 50 kW Phosphoric Acid Fuel Cell (PAFC) engine in parallel with Nickel-Cadmium batteries on a 30-foot heavy-duty transit bus chassis manufactured by Bus Manufacturing Inc. The bus uses methanol as the primary fuel, which is processed through a steam-reformer to produce hydrogen used in the fuel cell. Rapid cooling of PAFC power plants will induce component damage. Shutdown of the fuel cell bus is defined as the time that is required for the controlled reduction from operating temperatures within the fuel cell stack and reformer to minimize component degradation. While in general fuel cell vehicles produce low emissions and are very efficient while operating, shutdown of the fuel cell bus represents a significant time requirement, power and fuel consumption, and considerable pollutant emissions with no usable output power. A description of the shutdown procedure for the bus, fuel and power usage, average time required, and analysis of emissions data are presented.