Armijo Reflects on LNG Decision
This article is part of an ongoing series of reports by U.S. transit professionals who
have participated in leadership development missions to Europe, Asia, Canada, and South
America through the International Transit Studies Program. The program was established in
1994 by the Transit Cooperative Research Program--a cooperative undertaking of the Federal
Transit Administration, the Transit Development Corporation, and the Transportation
Research Board--to provide an international dimension to the development of transit
managers and to expand the network of contacts available for advice and problem solving.
Orange County Transportation Authority Director of Operations David Armijo participated
in the study mission in the spring of 1997 that included meetings with operators and
technical inspections of bus and rail fleets in Helsinki, Finland; Stockholm and
Gothenburg, Sweden; Copenhagen, Denmark; and Stuttgart, Germany. Armijo was involved in
OCTA's liquefied natural gas decision, and he shares with readers how the study mission
influenced the direction of several transit projects in Orange County.
By David Armijo
Director of Operations
Orange County Transportation Authority
Orange, Calif.
In 1992, the Orange County Transportation Authority began a five-year demonstration
project to test the effectiveness of operating buses with methanol, compressed natural
gas, and propane. Initial results favored propane. As a result, OCTA joined the Southern
California Air Quality Management District and several transit agencies to sponsor
development by Detroit Diesel Corporation of a Series 50 propane fueled engine.
The expectation was that, once developed, the California Air Resources Board would
certify the DDC as an ultra low emission bus engine (2.5 grams per Bhp-hr) and begin
production. In the summer of 1997, however, DDC announced that, due to limited product
demand, it chose not to produce the Series 50 propane bus engine.
As a result, OCTA staff began re-examining available alternative fuels. Consideration
was given to fuel availability, engine availability and reliability, capital, operating
and maintenance costs, the experience of other transit operators, and lessons learned in
Scandinavia, one of the earliest adopters and testers of alternative fuels.
The city of Stockholm, Sweden, operates 1,600 buses. Most of these are diesel powered,
although the city is testing the use of seven hybrid-electric buses. The city also
operates 130 buses using ethanol--an alcohol-based fuel mix that, in Scandinavia, includes
excess Italian red wine that had evidently flunked the taste test. Although unusual as a
fuel source, wine-based ethanol represented an abundant commodity that required minimal
maintenance and infrastructure to support.
Transit staff in Stockholm included professors from the University of Stockholm and
Lund Institute of Technology. While their approach to alternative fuels is no less
academic than that found in the United States, the Scandinavian transit system appeared to
be focused on long-term solutions to pollution problems. They also exuded great confidence
that hybrid and fuel cell technology are the next generation. The question is not if, but
when.
Stockholm is the first city in the world to have six hybrid buses on one inner-city
route with their own onboard electricity supply. An automobile engine is used to provide
power for an electric generator, which feeds the electric motors that drive the bus. The
engine can operate on either ethanol or diesel and is fitted with a three-stage catalytic
converter, which provides a high level of exhaust gas cleaning. Surveys indicate that most
bus patrons like the new hybrid-electric buses, although some passengers complain about
noise and limited space for children's strollers.
In Orange County, the factors that affected the eventual recommendation for liquefied
natural gas as a preferred fuel choice include cost, safety, maintenance, and reliability
factors. OCTA staff determined that the best alternative to diesel fuel is natural gas.
For the past 30 years, natural gas has sold for 20 percent to 60 percent less per unit of
energy than crude oil. It satisfies public health concerns by having low-pollution
characteristics and emitting significantly less carbon monoxide, carbon dioxide, and
reactive hydrocarbons.
A comparison study was conducted between CNG and LNG. During the past five years, CNG
and LNG engine and fueling technologies have matured. Advancements in bus engine
technology allow natural gas storage on the bus as either CNG or LNG, with little or no
cost differential between the purchase price of either a CNG or LNG bus.
For larger fleets, LNG fueled buses are less costly to operate and maintain. CNG
fueling infrastructure is by far more costly. A 1996 study conducted for the Phoenix
transit system demonstrated that the annual cost to operate a fleet of 200 CNG-fueled
vehicles would be $60,000 to $100,000 more costly than a similar-sized LNG-fueled fleet.
In addition, LNG fueling and storage infrastructure is easier to install, operate, and
maintain. It is relatively simple and efficient compared to the CNG system. For example,
Houston's Metropolitan Transit Authority of Harris County can fuel four LNG buses
simultaneously at a rate similar to diesel fuel.
LNG has fewer safety concerns than CNG, and the supply of fuel is more reliable. LNG is
dispensed at low pressure and an LNG bus weighs about 1,000 pounds less than a CNG bus. In
the event of an emergency, LNG, like diesel, is stored on the transit property and will
have several days of available supply.
LNG is a flexible alternative fuel choice. As hybrid-electric technology evolves,
LNG-fueled engines will be available to drive the electric generators and emit ultra-low
levels of nitrogen oxide emissions.
LNG is also a good hydrogen source for fuel cell technology. Transitioning to LNG fuel
will allow OCTA to use new bus propulsion systems as they go into production during the
next decade.
OCTA is just one of a growing number of transit systems that are choosing LNG fuel,
including Houston, Dallas, El Paso, Phoenix, and Copenhagen, Denmark. Copenhagen Public
Transit Authority will operate a fifth of its bus fleet with LNG this year, a total of 180
buses.
OCTA will order 186 LNG buses this spring. Two hybrid-electric buses are scheduled for
delivery this June; OCTA will operate them in revenue services and will evaluate their
cost effectiveness.
OCTA's future plans include the first purchase of articulated buses to be added to a
growing fleet; new contracted services for fixed route, rail feeder, and paratransit
services; and implementation of Intelligent Transportation System projects, including a
new digital communication system that will use Global Positioning System technology in
fixed route and paratransit services. While many of these programs and projects were
established prior to my involvement in the international studies mission, the opportunity
to experience the innovations of other transit systems was invigorating and served as a
challenge to influence and bring to fruition many of OCTA's projects.
Return To International Focus
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