Alternative fuels such as Compressed Natural Gas (CNG), Liquefied Natural Gas (LNG), Liquified Petroleum Gas (LPG), and alcohol fuels (methanol and ethanol) are already being used in commercial vehicles and transit buses in revenue service. Hydrogen, which has better air quality characteristics as a vehicle fuel, is being used in research demonstration projects in fuel cell powered buses, as well as in internal combustion engines in automobiles and small trucks. At present, there are no facility guidelines to assist transit agencies (and others) contemplating the use of hydrogen as an alternative fuel. This document addresses the various issues involved. Hydrogen fuel properties, potential hazards, fuel requirements for specified levels of bus service, applicable codes and standards, ventilation, and electrical classification are indicated in this document. These guidelines also present various facility and bus design issues that need to be considered by a transit agency to ensure safe operations when using hydrogen as an alternative fuel. Fueling facility, garaging facility, maintenance facility requirements and safety practices are discussed. Critical fuel-related safety issues in the design of the related system on the bus are also identified. A system safety assessment and hazard resolution process is also presented. This approach may be used to select design strategies which are economical, yet ensure a specified level of safety.
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