In 2000 the Zero-Emission Bus (ZBus) regulation was established. Its intentions were to develop a Californian transit system made up of 15% zero emission buses. This formation of this regulation would also meet California’s air quality, greenhouse gas, and energy security goals.
Source: Zero-Emission Bus Design
Zbus’ produce zero smog pollutants and when compared to diesel-fueled
buses, is predicted to reduce greenhouse gases by 46 percent. They have
centralized fueling that allows one station to serve several buses.
Additionally they can provide fuel for passenger vehicles.
Source: Zero-Emission Bus centralized fueling station