International Fuelcellbus Collaborative

Terminology Definitions

Bus Manufacturer: Each bus project includes a bus original equipment manufacturer (OEM) that supplies the basic framework for the bus chassis and conventional bus components.  The OEM works with the fuel cell provider and integrator to equip the bus with the novel hydrogen and fuel cell systems.

Demonstration Status: This website characterizes projects as ACTIVE, PLANNED, and COMPLETED. ACTIVE projects are those where the bus has been constructed and delivered to the deployment site.  Thus an ACTIVE project has the bus at the deployment site although it might be undergoing final testing and/or training before beginning full operations.  Likewise, a PLANNED project is one that has been initiated and the bus is in the pre-development, development, or construction phase but has not been delivered to the deployment site.  COMPLETED projects are those where the operational phase has ended.

Energy Storage Type: Hybrid fuel cell buses utilize energy storage devices to buffer peak power loads and allow for regenerative braking.  Current bus designs use batteries, super capacitors, or a combination of the two. The type of battery is determined by what compound the battery uses as the electrolyte.  The most common types used in fuel cell buses are Lead Acid, Lithium Ion, Lithium Titanate, Nickel Metal Hydride, or Molten Salt batteries. 

Fuel Cell Manufacturer: The fuel cell manufacturer designs and builds the fuel cell, and will often times work with the bus manufacturer and integrator to install the fuel cell system into the bus.

Fuel Cell System Architecture: The hydrogen buses employ various power configurations.  These include Fuel Cell Hybrid, Fuel Cell Direct, Fuel Cell APU, and Hydrogen Combustion Engine (HICE).  Fuel Cell Hybrid buses can be built with either a battery dominant or fuel cell dominant powertrain architecture.  Battery dominant means a bigger battery is the prime mover of the bus, while the fuel cell feeds electricity to the battery and acts as a range extender.  In fuel cell dominant hybrid powertrains, the fuel cell produces the power to move the bus and power electrical devices, while a smaller battery provides transient power.  Fuel Cell Direct vehicles do not have a hybrid drive, meaning all of the bus’ power comes from the fuel cell.  Fuel Cell Auxiliary Power Unit (APU) buses use fuel cells to power bus functions other than propulsion.  Hydrogen Combustion Engine vehicles are different than hydrogen fuel cell vehicles because they burn hydrogen the same way gasoline is burnt to propel a vehicle.

H2: Hydrogen

H2 Provider: This website defines H2 Provider as the primary organization responsible for either producing hydrogen to fuel the buses and/or delivering the hydrogen for use.  H2 Partners: In addition to the primary Hydrogen Provider, this website shows H2 Partners as those organizations who provide and/or assist with the hydrogen storage and dispensing infrastructure.  Because hydrogen infrastructure is developing rapidly, the line between H2 Provider and H2 Partner is fluid and often difficult to define in a broad manner.

H2 Source: This website details if the hydrogen was generated on-site or off-site. If produced on-site, the website further defines if production is via electrolysis or reformation. Electrolysis is the process of using an electric current to separate ions. In this case, the ions of water are separated and the resulting hydrogen is collected.  Hydrogen reformation refers to reacting some hydrocarbon, usually natural gas, with steam at elevated temperatures and pressures to produce a synthesis gas, which if combined at the right ratios will be mostly hydrogen gas.

HICE: Hydrogen Internal Combustion Engine

Hydrogen Off-Site Production:  Hydrogen can be produced through a number of renewable or nonrenewable pathways.  Most of the world’s transportation hydrogen is generated in centralized locations and then transported either as a liquid or gas to refueling sites.

Integrator: The integrator is responsible for ensuring the bus and fuel cell system function together to give power to the bus.  The integrator is often times the bus manufacturer, sometimes in collaboration with the fuel cell and/or drive system supplier.

Sponsor: Public funding has supported all fuel cell bus deployments to date.  The largest contributor is listed herein with additional sources also displayed as information is available.

Transit Operator: The transit agency or other organization responsible for operating the bus(es) during the demonstration periods.

High V.LO City:  A European program involving deployment of fuel cell buses in Italy, Scotland and Belgium.

HySUT: A program begun in 2009 in Japan with the goal to establish hydrogen supply infrastructure and to improve the hydrogen business environment.

IFCB Workshop: International Fuel Cell Bus Workshop.  This is the annual gathering of the fuel cell bus working group initiated by the FTA and DOE in 2003.



AC Transit Alameda Contra-Costa Transit District
BP British Petroleum
CARB California Air Resources Board
CHIC Clean Hydrogen in European Cities Project
CMRTA Central Midlands Regional Transit Authority
CNG  Compressed Natural Gas
CTE Center for Transportation and the Environment
CTTRANSIT Connecticut Transit
CUTE Clean Urban Transport for Europe, 2001 – 2006
DDOT District Department of Transportation
DGE Diesel gallon equivalent
DOE U.S. Department of Energy
DOT U.S. Department of Transportation
ECTOS  A partner of the CUTE Project in Reykjavik, Iceland
EU  European Union
FCEB Fuel cell electric bus
FTA Federal Transit Administration
GEF Global Environment Facility Implementing Agency
GHG  Greenhouse Gases (mainly Carbon Dioxide & Methane)
HyFLEET:CUTE An extension of the CUTE Project, that added additional sites and time to demonstrations.  HyFLEET is an abbreviation for “Hydrogen Fleet”
JHFC Japan Hydrogen & Fuel Cell Demonstration Project
MOU Memorandum of Understanding
NAVC Northeast Advanced Vehicle Consortium
NFCBP US National Fuel Cell Bus Program
NREL US National Renewable Energy Laboratory
OSU Ohio State University
PEM Proton Exchange Membrane (also known as Polymer Electrolyte Membrane)
STEP  A partner of the CUTE program in Perth, Western Australia
SFMTA San Francisco Municipal Transportation Agency
UNDP UN system’s development program
ZEBA Zero Emission Bay Area