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SUMMARY OF SELECTED LITERATURE ON
LAND-USE TRANSPORTATION INTERACTIONS AND
ALTERNATIVELY FUELED BUSES
Volume 2: Alternatively Fueled Buses
EPA Contract Number 68-DO-0124
Work Assignment Number 1-119
SYSAPP-92/126b
30 September 1992
Prepared for
Valerie Broadwell
Policy Development Section
Ozone/Carbon Monoxide Programs Branch
Air Quality Management Division
Office of Air Quality Planning and Standards
U. S. Environmental Protection Agency
Research Triangle Park, NC 27711
Prepared by
Barbara S. Austin
Lori L. Duvall
Julie K. Morgan
Systems Applications International
101 Lucas Valley Road
San Rafael, CA 94903
(415) 507-7100
K2610 92117
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DISCLAIMER
This report has been reviewed by the Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, and has been approved for publication as received
from the contractor. The contents reflect the views and policies of the Agency, but any
mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
92117.01
ii
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Contents of Volume 2:
Alternatively Fueled Buses
1 ALTERNATIVE FUELS IN BUSES 1
2 BIBLIOGRAPHY OF MATERIAL ON ALTERNATIVELY FUELED . . 2
3 GLOSSARY 32
4 REFERENCES . . . 34
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INTRODUCTION
Continuing challenges in attaining National Ambient Air Quality Standards and the
passage of the Clean Air Act Amendments of 1990 have inspired renewed efforts to
identify and implement innovative new control strategies. In most urban areas, motor
vehicles contribute approximately 50 percent of emissions involved in ozone and
approximately 90 percent of carbon monoxide nonattainment problems. Increased
reliance on alternative fuels, increased understanding and use of the interdependence of
land use and transportation, and alternative technologies such as electric vehicles are
among the many innovative strategies under discussion. This volume provides a
preliminary bibliography of literature relating to alternatively-fueled buses. Volume one
of this set provides a review of literature relating to land use/transportation/air quality
interactions.
It is important to note that there is a specific focus for each subject area and that the
scope of this bibliography is not intended to cover either the vast body of related research
(i.e. alternative fuels in general), or to comprehensively review all material relating to
alternative fuels in buses. Rather it is intended to provide a source of information on the
scope and nature of current research. State and local agencies wishing to use such
strategies should also plan to draw on sources other than those reviewed here.
The remainder of this report is organized as follows: (1) a summary discussion of the
importance of land use/transportation interactions and examples of research relating to
strategies utilizing these interactions, (2) bibliography of land use/transportation material,
including brief abstracts (one to two paragraphs) of each reference, (3) summary of
alternatively fueled buses, and (4) bibliography of alternatively fueled bus studies,
including abstracts. Items one and two are included in volume one; items two and three
are included in this volume. Each volume is separately bound.
ALTERNATIVE FUELS IN BUSES
This section of the draft bibliography presents the results of a search of a number of
potential data sources related to the use of alternative fuels in heavy-duty applications,
more specifically in buses. An on-line search of the TRIS database, which lists
transportation-related documents, was conducted and almost one thousand references
provided by that search have been examined. In addition, numerous individuals engaged
in research on this topic have been contacted, including those in the academic community
as well as in government and private industry. Table 2 summarizes a number of key
observations from this review.
The materials provided here consist mainly of scientific papers from the academic and
consulting sectors in which one aspect of alternative fuel use in heavy-duty vehicles is
explored. For instance, several papers discuss the design and testing of engines for use
with alternative fuels (Chandler, et al, 1991; Gilbert and Gunn, 1991; Wachter, 1990).
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Others focus on how diesel fuel can be used more cleanly in heavy-duty applications
(Giuliani and Murphy, 1991; Small, 1988; Unnasch, 1986). Dual-fuel vehicles are
discussed in a few of the papers, although it is generally concluded that dedicated fuel
vehicles provide greater environmental and economic benefits (EPA, 1990a; Klausmeier
and Draves, 1991).
A number of transit agencies in the U.S. and in other countries have experimented with
alternatively fueled buses, and their experiences could prove to be extremely valuable to
those agencies currently exploring the possibility of purchasing such buses. Thus, several
reports which could be classified as case studies are also provided in this bibliography,
including reports from fleet operators in Denver, Seattle, Tulsa, Southern California,
New York and Ontario. Table 3 is excerpted from one such report, "Summary of
Alternative Fuel/Clean Air Technology Buses in North American Transit Use" (Meloche,
1990), and includes the names of transit systems currently (as of April 13, 1990) using
alternatively fueled vehicles, the alternative technology employed, fleet size, and vehicle
manufacturer.
It is clear that methanol and compressed natural gas are the alternative fuels that have
received the most attention from researchers and that have been chosen most often by
transit agencies for demonstration projects. Both of these fuels produce significant air
quality benefits, and the conversion costs are usually not as high as they are for ethanol
or other types of fuels. Diesel fuel is rarely included in the category of "alternative
fuels" unless its use has been modified in some way, usually through the installation of
particulate traps. Studies are included here which compare the emissions and cost
effectiveness of these traps with other forms of alternative fuels.
Most of the reports included in this bibliography discuss the costs associated with
converting bus fleets to alternative fuels. While the direct cost of using alternative fuels
is almost always significantly higher than the cost of diesel or gasoline, many of the
analyses included here fail to quantify the social benefits expected from the use of
alternative fuels. As pointed out in the paper by R.F. Webb Corporation (1990), the
economics of large-scale conversions of transit buses to alternative fuels will be favorable
only when benefit calculations include social benefits such as emissions reductions and
energy security. Clearly, these considerations should be treated as important factors in
any cost/benefit analysis, because they are the major reasons for encouraging the use of
alternative fuels in the first place.
Bibliography of Material on Alternatively Fueled Buses
Bol, M. A. and G. B. Hamilton. 1989. "Economic Life Cycle Costs of Methanol in
Diesel Applications." Vin International Symposium on Alcohol Fuels.
Based on the experiences of the Canadian Methanol In Large Engines (MILE)
Project, this paper seeks to evaluate the projected economic life cycle costs of
methanol hi transit bus operation. This analysis addresses the major costs of
operating methanol transit buses, including methanol fuel price and distribution,
engine costs, maintenance and fueling operations. Estimates of life cycle costs for
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other emission reduction options such as paniculate traps and low sulfur fuel are
also provided. The time frame for the scenario addressed by this paper is 1991-
92, when it is assumed that methanol engines will be commercially available from
at least one supplier. A range of estimated costs is provided, depending on
whether one takes an optimistic or pessimistic outlook on the future development
of a commercial methanol market. For example, the estimated capital cost of
vehicle modifications ranges from $600 to $1,500 (Canadian dollars), and annual
maintenance costs are estimated at between $1,500 and $3,000. For methanol, the
cost of the fuel itself represents 75 % of the total costs even under the most
optimistic outlook for developing technology. Methanol could compete on a cost
basis if diesel fuel prices increased by 75%. However, no attempt is made to
assign monetary value to the air quality benefits associated with methanol use.
Booz, Allen & Hamilton, Inc. 1983. Evaluation of Alternative Fuels for Urban Mass
Transit Buses: Final Report. Prepared for U.S. Department of
Transportation/UMTA and Port Authority of Allegheny County, Pennsylvania
(UMTA-PA-06-0060-83-1).
The objective of this paper is to identify an alternative to the use of diesel fuel in
transit buses. The main focus of this analysis of several types of alternative fuels
is economic rather than environmental. The impetus behind this project appears to
be the great instability of oil prices during the previous decade, and the authors
suggest that transit operators should select an alternative fuel conversion approach
with low initial costs and the flexibility of converting back to diesel should that
fuel become significantly more cost-effective. A number of alternative fuels were
ranked by cost, availability, safety and technical feasibility for use in diesel
engines with limited modifications. The field was narrowed to six fuels
(ammonia, methanol, ethanol, hydrogen, natural gas and propane), all of which
were determined to assist in making the transit industry independent from
imported crude oil. Several types of engines were also studied, with the ignition-
assisted diesel engine identified as the most efficient and versatile. This engine
technology was then used to assess fuel cost and suitability factors for the six
potential fuels. The selection of the best fuel was based on the costs of the fuel in
use and the costs of technology needed to use the fuel. A detailed method is
presented for tabulating the presumed 12-year life cycle costs. Methanol is
identified as the fuel which best meets the economic and technical feasibility
criteria of this study. A detailed demonstration plan is then described to test
methanol buses in northern, cold climate cities.
Bush, J. L. 1992. "Natural Gas is Leading Contender for State School Bus Fleets."
School Bus Fleet. April/May, pp. 28-36.
This article addresses some of the practical aspects of converting school bus fleets
to alternative fuels. The experience of the Tulsa, OK school district with CNG
buses is used as an example of what costs, benefits, and potential problems school
districts can expect when converting a fleet to CNG. The District reports fuel
cost savings between $800 and $1,000 per bus based on an average of 15,000
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miles annually. Vehicle conversion costs range from $3,000 to $3,500, depending
upon the number of $1,000 fuel tanks needed. Refueling compressors range in
price from $47,000 to $58,000. Overall, the District has few problems to report,
although a lack of knowledge was cited as the cause of most problems that have
been experienced to date. This article also provides an outline of the companies
involved in alternative fuel technology. Tecogen of Waltham, MA currently
produces the only California Air Resources Board-certified CNG engine, but
Hercules Engine Co. of Canton, OH is also working on a CNG engine which it
hopes to certify soon. Detroit Diesel is also developing CNG versions of its DDC
6V-92TA diesel engine. The conversion of school buses to natural gas in the
Austin, TX school district is discussed, as an example of the cost effectiveness of
retrofitting existing diesel buses rather than purchasing new alternative fuel buses.
Chandler, K. L., T. C. Krenelka and N. D. Malcosky. 1991. CNG Bus Demonstration
Program Data Analysis Report. Prepared for U.S. Department of Transportation/
UMTA by Battelle, Columbus, Ohio (UMTA-OH-06-0056-91-10).
Two demonstration sites were selected to study the development of the Cummins
Engine Company's L10G-240 compressed natural gas (CNG) engine. The first is
operated by the Central Ohio Transit Authority and the second is used by the
Greater Cleveland Regional Transit Authority. This report covers the period from
February 1990 to October 1991. The report contains data collected from the two
transit agencies on fuel and oil consumption, unscheduled maintenance and other
operating factors. The second bus was also tested at the Transportation Research
Center of Ohio in August 1991, and data on fuel economy, acceleration, cornering
and noise are included from those tests. In general, the Cummins engine is
making rapid progress in reliability, with the latest engine configuration showing
substantial improvements. No safety problems or accidents occurred at either
demonstration site during the period of study. The track testing showed that the
bus was generally close to meeting all criteria established by the first Article
Transit Bus Test Plan (UMTA-IT-06-0219-09-1) and widely used White Book
specifications for an alternative power plant. Those criteria that were not met
were only missed by small margins, and the bus always met each criteria area at
least partially. No fundamental reasons were identified why the bus could not
meet all First Article criteria with further development expected in the foreseeable
future.
Craig, E., S. Unnasch and M. Cramer. 1991. Methanol-Fueled Transit Bus
Demonstration, Phase II: Final Report. Prepared for California Energy
Commission by Acurex Corporation, Mountain View, California (Acurex Report
90-109-ESD).
In 1982, the California Energy Commission, in conjunction with the Golden Gate
Bridge, Highway and Transportation District, began its first heavy-duty methanol
demonstration project. The goal of the project was to demonstrate the viability of
using 100 percent methanol, or M100, in transit applications. Two buses were
used in this project: a two-stroke converted diesel engine from Detroit Diesel, and
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a four-stroke converted diesel engine from the German company M.A.N. The
buses were placed in revenue service in 1984, following a period of route
selection and driver and mechanic training. This report focuses on the last 4-1/2
years of the demonstration, from November 1985 through July 1990. An earlier
report entitled "Phase I: Technical Analyses" describes the results from the
demonstration's first year. The Final Report includes an operating chronology
and a discussion of the buses' time in service, driveability in service, fuel
economy data and engine upgrades performed. The maintenance performed on
each bus is described, along with a component durability analysis and a summary
of the results of an engine teardown in 1988. A detailed cost analysis is
presented, and the cost of operating a fleet of methanol buses is estimated based
on expected maintenance requirements for commercial methanol buses and fuel
economy experience from the demonstration. Finally, the results of two rounds of
emissions testing are described, where the methanol buses demonstrated significant
improvements in emission levels over their diesel counterparts.
Environmental Protection Agency. 1990a. Analysis of the Economic and Environmental
Effects of Compressed Natural Gas as a Vehicle Fuel: Volume n -- Heavy-Duty
Vehicles. Office of Mobile Sources, Washington, D.C.
This is one in a series of EPA reports on the environmental and economic impacts
of a number of alternative fuels. The report begins with an overview of how
compressed natural gas (CNG) has been used in heavy-duty vehicles, and it
identifies applications where the most rapid growth of CNG would be possible.
One chapter is devoted to CNG engine technology and presents emissions data for
CNG heavy-duty engines. Costs associated with CNG are discussed, including
vehicle costs, fuel costs, and fueling station and maintenance costs. Finally, the
environmental benefits of CNG compared to gasoline and diesel are described,
focusing principally on the areas of ozone, air toxics and global warming and
showing that CNG has the potential to provide significant emissions benefits,
provided the technology experiences a greater degree of optimization than is
currently in use. Dual-fuel vehicles are discussed, but when considered from the
perspective of clean alternative fuels, dedicated CNG vehicles clearly assume a
dominant position. Such vehicles can be optimized to make use of the specific
combustion properties of CNG, and thus can potentially produce much greater
emission reductions and fuel consumption gains than their dual-fueled
counterparts.
Environmental Protection Agency. 1990b. Analysis of the Economic and Environmental
Effects of Ethanol as an Automotive Fuel. Office of Mobile Sources,
Washington, D. C.
Ethanol has a number of properties which make it a good motor vehicle fuel. Its
octane is higher than gasoline, its flammability is lower, and its vapor pressure is
much lower, resulting in lower evaporative emissions. Under an expanded ethanol
program as considered in this report, the wholesale cost range for ethanol
produced from com is estimated at $1.00 to $1.50 per gallon. Clearly, without
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some subsidies, ethanol could not compete with gasoline at current or most
projected prices. Ethanol-fueled vehicles are expected to emit more ethanol and
acetaldehyde than a gasoline-fueled vehicle, but possible counterbalancing effects
have not been explored. The impact of ethanol on urban ozone has not yet been
adequately studied, but preliminary calculations of the relative reactivity of ethanol
emissions suggests equivalent ozone benefits from ethanol and methanol. Ethanol
is expected to produce substantial air toxics benefits, but its global warming
impact will depend heavily on the efficiency of future ethanol production plants
and the efficiency of future corn production (7.4 million BTU of fossil fuels are
currently used to grow one acre of corn). An ethanol spill should not be as
hazardous as a petroleum spill, since ethanol is inherently water soluble and
biodegradable. In the U.S., much more vehicle development has been done for
methanol than for ethanol, and one chapter in this report discusses the
characteristics of methanol and the degree to which methanol development results
are applicable to ethanol in light of their similar engineering properties.
Environmental Protection Agency. 1989. Analysis of the Economic and Environmental
Effects of Methanol as an Automotive Fuel. Office of Mobile Sources,
Washington, B.C.
One in a series of EPA reports on various types of alternative fuels, this report
discusses several economic aspects of methanol use, including the cost of
methanol production, overseas transportation and U.S. port costs, and the
gasoline-equivalent price of methanol. At the time the report was written, the
average cost of gasoline was $1.12 per gallon. The gasoline-equivalent price per
gallon of dual-fueled vehicles (operating on gasoline, methanol or a blend of the
two) was projected to be between $1.05 and $1.09, while the price for a dedicated
methanol vehicle was estimated at $.85 to $.88 per gallon. Thus, methanol was
seen as an attractive alternative to conventional fuel. As for the ozone benefits of
methanol, the volatile organic compound (VOC) emissions from methanol vehicles
consist mostly of unburned methanol, which has a reactivity of only one-fifth that
of gasoline hydrocarbon emissions. Methanol flexible fuel vehicles are projected
to emit at least 30 percent less VOC than typical gasoline vehicles, while
optimized, dedicated methanol vehicles may emit 80 percent less VOC. The use
of methanol is also expected to have a beneficial impact on air toxics emissions,
while the effect of methanol on global warming depends to a large extent on how
the methanol is produced.
"Favorable Experiences Reported by Transperth Using Natural Gas for Buses." 1990.
Bus Ride. January, pp. 72-4.
The city of Perth in Western Australia is increasingly committed to the use of
non-diesel fuels in its transit bus fleet. Because the city is extremely remote and
the region has enormous reserves of natural gas, Perth has converted several buses
to run on compressed natural gas (CNG) and on liquid petroleum gas (LPG).
Thirty more buses are currently being converted to CNG hi order to assess all
operational aspects before proceeding with a full-scale conversion of the entire
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fleet. The project has been quite successful thus far. Drivers like the gas-fueled
buses because they accelerate better than standard diesel versions, and patrons
approve of the quiet and vibration-free ride. Refueling has been accomplished by
unskilled personnel after only brief training, and safety requirements have been
readily accommodated without much additional expense. These experiences have
been helpful to the Australian federal government, which is now actively
promoting the use of CNG buses in other cities.
Francis, G. A. and R. D. King. 1988. Proving Ground Comparison of M.A.N.
Methanol and Diesel Transit Buses. Prepared for U.S. Department of
Transportation/UMTA by Battelle, Columbus, Ohio (UMTA-IT-06-0322-88-4).
This comparison included cold and warm weather tests of three methanol and
three diesel M.A.N. transit buses taken from revenue service at Seattle Metro.
The first test was a new driveability test structured to evaluate abnormal responses
of bus propulsion systems in a carefully controlled environment. The cold starting
characteristics of the methanol engine were very poor during January, and were
better but not completely satisfactory during August. There was some hesitation
during acceleration of the methanol buses, while the driveability of the diesel
buses was almost flawless. The second test was an acceleration test, in which the
average times required for the methanol and diesel buses to reach a speed of 50
mph were almost equal. The third test was designed to compare interior and
exterior noise of the buses under different operating conditions. The methanol
buses had higher average noise levels than the diesel buses in all interior tests and
in the exterior idle and pull-away tests. However, the differences were so small
that they should not be significant to anyone purchasing transit buses. It must be
recognized that these tests compare fully mature diesel technology with emerging
methanol technology, so no firm conclusions should be based on these results
alone.
Garland Independent School District. 1990. Status Report: Compressed Natural Gas.
Garland Independent School District, Garland, Texas.
Recent legislation in the Texas Assembly requires all school districts with more
than 50 buses to purchase vehicles capable of operating on some type of
alternative fuel. Because more than one-quarter of all proven U.S. natural gas
reserves are located in Texas, compressed natural gas (CNG) is the alternative
fuel of choice for most Texas school districts. The Garland schools have been
operating CNG buses since 1983, and currently have a fleet of 81 such buses.
This document presents an overview of their experiences with CNG buses,
including the costs of conversion, fuel and maintenance, and the advantages of
slow fill stations.
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Gerndt, H. and R. Stellmacher. 1989. "Battery Powered Electric Buses."
Transportation Planning and Technology. 14:217-25.
This paper describes the current status of battery powered electric buses and
reports on the results of a five year demonstration project in Dusseldorf.
Seventeen buses were equipped with a lead acid battery permanently mounted in a
trailer attached to the rear of the bus. Basic charging is done overnight, with
intermediate charging coupling techniques having been tested successfully on three
different routes. Despite considerably higher coach weight, energy consumption
was reduced by more than 20 percent as compared to diesel buses. The feasible
range of operation is a maximum route length of 20 km, with a mean recharging
time of 0.8 minutes per travelled route kilometer. Currently, the overall costs of
battery buses are twenty-five percent higher than for conventional diesel buses, but
the project has succeeded in demonstrating the high reliability and technical
feasibility of battery operations. Technology developments, such as more efficient
energy storage methods, are expected to narrow the cost gap to the point that such
technology will be desirable in energy- and environment-sensitive situations.
Development of electric vehicles is fostered by the fact that electric drives are
functionally superior to internal combustion engines, and that traction energy
electricity in the long run will be more economic and safeguarded with respect to
availability than combustion fuels.
Gilbert, A. T. and R. Gunn. 1991. Natural Gas Hybrid Electric Bus. Society of
Automotive Engineers, Warrendale, Pennsylvania (SAE 910248).
A joint project of Unique Mobility, Inc. and Ontario Bus Industries, the purpose
of the hybrid electric bus project is to prove that a compressed natural gas (CNG)
internal combustion engine, augmented by storage batteries to provide peak period
power, will produce lower emissions and increased fuel economy than a
conventional diesel powered bus. A computer model called the Electric Vehicle
Computer Model has been developed to predict engine performance and to select
drivetrain components, and was used to select a 7.6 meter bus chassis and a 4.3L
V6 internal combustion engine converted to run on CNG for this demonstration
project. An Engine Management System controls engine speed and power output
with varying load conditions. The bus can operate in typical urban stop and go
driving cycles with no decrease in net battery energy. The engine provides steady
state power for operation up to 37 mph; for operation above 37 mph, or during
acceleration and grade climbing, a portion of the power needed to propel the bus
is provided by the storage batteries. Further research on engine emissions is
currently underway, but preliminary results indicate that emissions from the
demonstration bus are significantly lower than those from conventional diesel
buses. At the time of this report, the project was addressing detailed design and
construction issues.
Giuliani, C. and M. Murphy. 1991. Status of Paniculate Trap Developments Related to
the Transit Industry. Prepared for U.S. Department of Transportation/UMTA by
BatteUe, Columbus, Ohio (UMTA-OH-06-0056-91-6).
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The use of diesel-fueled transit buses with particulate emissions control devices is
an attractive alternative for achieving the standards set by the Clean Air Act
Amendments of 1990. The traps in use have many configurations and are made
of ceramic monoliths, ceramic foam, ceramic fibre or metal mesh. The traps
must be cleaned frequently to maintain engine efficiency, with the preferred
cleaning method being to oxidize the particles using exhaust or auxiliary heat.
Fourteen buses with particulate traps were being tested at the time of this report:
six in Los Angeles, three in Milwaukee, three in New York and two in Dayton.
More significant, 450 diesel buses with traps were ordered for delivery during
1991. Results from emissions tests on these buses vary widely, but all show
significant reductions in particulate emissions when traps are used. Tests by EPA
in 1990 show that it is possible to reach the emission standards of the Clean Air
Act with state of the art engine and trap technology. The major problem affecting
the functioning of trap oxidizers in transit buses is ensuring that exhaust
temperatures are high enough to incinerate the trapped particles. Exhaust
temperatures are a function of engine speed and load, and it is more difficult for a
transit bus to maintain high exhaust temperatures than it is for an over-the-road
truck. The experiences of a number of transit agencies with particulate traps are
discussed, and it is concluded that the transit industry is making good progress in
this area. However, a few problems remain to be resolved, including the high
cost of system components and the lack of long term data on reh'ability and
maintenance requirements.
Hargreaves, D. 1989. "Propane: Safe, Clean and Affordable." Community
Transportation Reporter. March, pp. 11-3.
The author is the general manager of the Manistee County Transportation System
in Manistee, Michigan. After learning that Michigan transit operators would be
faced with declining financial assistance from the state, this system decided to
convert gasoline-powered vehicles to propane motor fuel in order to solve their
growing budget problems. In the first year that propane vehicles were in
operation, the system saved 22 % in operating costs over the previous year. Since
1986, 19 of their 22 vehicles have been propane-powered, and operating costs
have remained constant. The advantages this system has recognized include:
easier starting in cold weather; consistently lower cost per gallon than gasoline or
diesel; naturally higher octane rating; reduced maintenance costs because of
propane's clean burning properties; easy conversion process; and much cleaner
exhaust, resulting in less downtime for emissions testing.
Harmelink, M. D. and O. M. S. Colavincenzo. 1990. The Development of Natural Gas
Buses in Ontario. Ontario Ministry of Transportation. Presented at Globe 90,
Vancouver, British Columbia, March 22, 1990.
The province of Ontario initiated a conservation and oil substitution program in
1980, as a result of concern for the environment and for the long-term quality,
supply and cost of diesel fuel. This initiative included an alternative fuel
technology development program which supported the development and
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demonstration of natural gas buses, beginning in 1985 in the town of Hamilton
and continuing in Toronto and Mississauga. Originally, six buses were converted
to natural gas, each with an estimated range of 250-350 km. A complete fuel
economy comparison was performed with a diesel and a natural gas bus. The
natural gas vehicle consumed 9 % more energy, but the power output was similar
(i.e. it climbed hills at the same speed as did the diesel bus). During the first few
months of the demonstration the expected fuel economy was achieved; however,
in later, colder months, the fuel economy of the natural gas bus deteriorated.
This may be attributed to cold weather conditions and/or to operation at non-
optimal air-fuel ratios. The three cities currently operate 55 natural gas buses,
most with large storage tanks on the roof in order to provide a larger operating
range and to insure safer operations, since the tanks are out of the usual impact
area in collisions and vapors are most likely to rise away from the passenger
compartment. Current areas of investigation include examining the modifications
to storage garages which may be necessary for safety.
Hull, R. W. 1987. Environmental Benefits of CNG-Fueled Vehicles. Prepared for the
Gas Research Institute by Southwest Research Institute, San Antonio, Texas
(Contract No. 5084-251-1101).
The objective of this paper was to identify significant environmental, safety and
economic benefits associated with CNG-fueled vehicles, relative to gasoline-,
methanol- and diesel-fueled vehicles. The ultimate purpose of this study was to
identify opportunities for CNG vehicles to penetrate the fleet vehicle market. A
number of research projects and demonstration programs were reviewed. It was
concluded that natural gas is a cleaner fuel than either gasoline or diesel, and can
be considered as safe or safer than gasoline. These benefits were compared with
methanol, another clean-burning alternative fuel, and recommendations were made
for future research and development to make CNG a more attractive option for
fleet operators, including better engine optimization and onboard fuel storage.
Urban transit bus fleets were specifically identified as providing excellent
opportunities for expansion of CNG usage, because of the need for transit
operators to meet the EPA's stringent emissions standards.
Hundleby, G. E. 1989. Low Emissions Approaches for Heavy-Duty Gas-Powered
Urban Vehicles. Society of Automotive Engineers, Warrendale, Pennsylvania
(SAE 892134).
Starting from the premise that current diesel technology probably will not be able
to meet air quality standards (most notably, the paniculate standard), this paper
attempts to identify the optimum approaches for achieving low emissions operation
with spark ignited natural gas engines. "Low emissions" vehicles are considered
to be those that meet the 1994 Federal heavy duty emissions limits. Several
operation scenarios are identified and contrasted, including lean burn open loop
control versus closed loop mapped control, and no catalyst versus a 2- or 3-way
catalyst. It is found that a combination of EGR dilution, advanced control and a
3-way catalyst produces the lowest achievable emission rates. A natural gas bus
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project sponsored by a consortium of five major Nordic transportation agencies is
currently underway using this combination of technology, and very low emission
levels are expected.
Indirect Source Control Committee. 1992. Procedure to Determine Emission
Reductions: School Bus Conversion. California Air Pollution Control Officers
Association.
This document provides a procedure to calculate potential emission reductions
achievable by converting gasoline-powered school buses to compressed natural gas
(CNG). This procedure involves four discrete steps: determining the life of the
emission source; calculating the baseline emissions over the life of the source;
calculating controlled emissions over the life of the source; and calculating net
emissions reduction. Emission factors for various pollutants are taken from the
California Air Resources Board's EMFAC model. Each step is treated in detail,
with equations provided for each calculation and example calculations completed
for a hypothetical fleet of 15 buses. Limited data is currently available for
emissions deterioration rates of CNG buses, so the deterioration rates are assumed
to be the same as for new 1991 gasoline-powered school buses. These rates
should be revised as new data becomes available.
Indirect Source Control Committee. 1992. Procedure to Determine Emission
Reductions: Transit Bus Replacement. California Air Pollution Control Officers
Association.
This document provides a procedure to calculate potential emission reductions
associated with replacing diesel powered transit buses with alternatively fueled
vehicles. The steps involved in this procedure are the same as those described in
"Procedure to Determine Emission Reductions: School Bus Conversion" (cited
above), and sample calculations are performed for a hypothetical fleet of 15 buses.
Because limited data exists on emissions from various alternative fuels, this
procedure assumes that emissions from alternatively fueled buses will be
equivalent to emissions from transit buses meeting the 1991 model year emission
standards. As more complete data becomes available for specific alternative fuels,
that data should be used with this procedure.
Klausmeier, R. F. and J. Draves. 1991. "Assessment of Environmental Issues Related
to the Use of Alternative Transportation Fuels Analysis of Recent Data." Air &
Waste Management Association Annual Meeting, Vancouver, British Columbia
(91-106.3).
The emphasis in this paper is on how methanol, compressed natural gas (CNG),
liquefied petroleum gas (LPG) and reformulated gasoline compare with gasoline
and diesel in the areas of ozone attainment, air toxics and global warming. Both
light- and heavy-duty applications of alternative fuels are considered. In general,
dedicated CNG vehicles appear to have the greatest ozone benefits, with LPG and
methanol vehicles also offering significant benefits. Dual-fuel CNG or LPG
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vehicles and M85 (85% methanol and 15% gasoline) vehicles may not be much
better than gasoline vehicles, because evaporative non-methane organic gas
emissions from storage of gasoline greatly increase their overall contribution to
ozone formation. Both dedicated and dual-fuel CNG vehicles emit much less CO
than gasoline vehicles; LPG also produces a CO benefit. Preliminary data show
that both M85 and M100 vehicles emit much more CO than CNG vehicles. CNG
vehicles have significantly lower emissions of air toxics than gasoline vehicles.
The use of methanol should lower tail pipe emissions of toxic hydrocarbon
compounds, but will increase emissions of formaldehyde, a known carcinogen.
Little information is available on the impact of LPG on air toxics, but it should
result in lower benzene and toluene emissions. Although they may produce more
methane, CNG vehicles emit 30 percent less CO2 than their gasoline counterparts,
thereby lowering their overall greenhouse gas emissions. The impact of methanol
on global warming depends on how the fuel is produced. Methanol made from
natural gas produces 6 percent less greenhouse gas emissions than gasoline
vehicles, while methanol made from coal will increase those emissions relative to
gasoline.
Krenelka, T. C. and M. J. Murphy. 1990. Methanol Status Report. Prepared for U.S.
Department of Transportation/UMTA by Battelle, Columbus, Ohio (UMTA-OH-
06-0056-90-2).
This report covers data collected from the beginning of Seattle's methanol
demonstration program in 1987 through February 1990, when methanol programs
had been added in New York, Denver and Los Angeles. This data base is derived
from almost two million miles of revenue operation of methanol demonstration
buses. The methanol buses were roughly 18 percent less fuel efficient, on an
energy equivalent basis, than their diesel counterparts. The methanol buses
required more frequent maintenance and more maintenance labor hours per mile
than the diesel buses. However, it should be noted that mechanics are generally
highly experienced with diesel buses, and have little methanol bus experience.
Two engine problems emerged as significant issues: short glowplug life, which
seems to have been solved by changes to the glowplug controller; and plugging of
fuel injectors in the Detroit Diesel engines, which is yet to be solved (although
this problem did not occur in the M.A.N. engines). No significant safety, health
or accident issues arose relating to the use of methanol during the period of this
study. Methanol vapor level measurements were made at Seattle Metro and in a
maintenance shop in Denver, and the results showed compliance with all pertinent
OSHA regulations and other recommended human exposure limits. Methanol
buses appear to be well accepted by drivers, mechanics and the general public
Leonard, J. H. 1989. "Activities of the South Coast Air Quality Management District to
Promote Alternatively Fueled Motor Vehicles." Air & Waste Management
Association Annual Meeting, Anaheim, California (89-63A.3).
This paper presents an overview of the alternative fuel projects undertaken by the
South Coast Air Quality Management District (SCAQMD) as part of its strategy to
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achieve the air quality goals set forth in the District's Air Quality Management
Plan. Because mobile source control in the South Coast Air Basin is perhaps the
nation's most difficult air pollution challenge, SCAQMD is actively promoting the
research, development, demonstration and commercialization of alternatively
fueled vehicles on many fronts. Several of these projects focus on reducing
emissions from transit buses and other heavy-duty vehicles. SCAQMD is
cosponsoring a project with ICI to evaluate the technical feasibility and emission
benefits of retrofitting diesel buses to operate on methanol, with Avocet as a
chemical ignition improver. SCAQMD is also cosponsoring a project to perform
a comparative evaluation of clean fuels in transit buses operated by the Orange
County Transit District. This project will provide direct comparison data which
does not currently exist about different types of alternative fuels. Finally,
SCAQMD is involved in a project to develop and demonstrate technology for fuel
cell/electric battery-powered urban buses. This technology has the potential to
meet the definition of Ultra Low Emitting Vehicles called for in the South Coast's
Air Quality Management Plan.
N.B. The annual report for SCAQMD's Technology Advancement Office, which
monitors the progress of these projects, is due to be released in late summer or
early fall 1992. That report will provide updated information on the status of
these programs.
Maggio, M. E., et al. 1991. Challenges for Integration of Alternative Fuels in the
Transit Industry. Transportation Research Board, Washington, D.C.,
Transportation Research Record 1308.
This paper provides some background information on several potential transit
fuels, including CNG, methanol, ethanol, LPG and reformulated fuels, and
presents an overview of the physical and handling properties, the health hazards,
and some of the supply issues related to these fuels. Differences between
properties of alternative and conventional fuels, and precautions that should be
taken to guard against risks of handling alternative fuels and maintaining
alternative-fuel engines, are identified. It is concluded that alternative fuels present
different risks than conventional fuels, but those risks are not necessarily greater.
The paper also counters some misconceptions about the hazards of integrating
alternative fuels into transit fleets. All fuels present significant health and safety
challenges, and experience has shown that with proper training, facility design and
safety precautions, alternative fuels can be handled safely by operations, service
and maintenance personnel.
Mathieson, M. 1991. "Alternative Fuels Applications for School Transportation."
National School Bus Report. December, pp. 16-7.
This article briefly discusses the views of Thomas Built Buses, a school bus
manufacturing company, on the feasibility of using various alternative fuels in
school bus applications. The main focus of the author is on safety, but economic
factors in school bus conversions are also discussed. Clean diesel is identified as
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the fuel of choice for this manufacturer, because it is a "familiar" technology that
can safely and economically meet government goals of reduced air pollution.
However, because emerging catalytic converter and particulate trap technology
will likely not be ready for use in time to meet the Clean Air Act's heavy-duty
emission reduction goals, Thomas Built is also evaluating other types of
alternative fuels. Methanol is not considered an acceptable fuel, due to reported
mechanical difficulties and the potential for highly increased aldehyde emissions.
Similarly, liquid natural gas (LNG) is classified as an unsuitable school bus fuel
for several safety reasons, such as the vulnerability of fuel tanks to accident
damage and the propane-like actions of LNG in a leak situation. Compressed
natural gas (CNG) is considered an acceptable school bus fuel, and Thomas Built
is in the process of constructing a prototype CNG-powered chassis for
demonstration purposes. CNG is relatively safe, as long as certain handling
procedures are followed, and Thomas Built recommends that CNG be approved
for school bus use.
Meloche, M. J. 1990. Summary of Alternative Fuel/Clean Air Technology Buses in
North American Transit Use. American Public Transit Association, Washington,
D.C.
This document, which is updated periodically, contains a listing of all alternative
fuel transit buses in operation in North America as of April 13, 1990. This
information is provided by transit professionals and the engine manufacturers.
Data listed include the operating agency, installation date, number of buses,
engine type, manufacturer, and contact name and telephone number. The types of
buses considered to run on "alternative fuels" include battery-powered, methanol,
ethanol, diesel with particulate traps, compressed natural gas, liquid natural gas,
liquified petroleum gas and trolleybuses.
Mueller Associates, Inc. 1986. Dual-Fuel School Bus Demonstration: Final Report.
New York State Energy Research and Development Authority, Albany, New York
(Report 87-17).
The overall objective of this project is to demonstrate the technology and
economics of using compressed natural gas (CNG) in transportation vehicles;
school bus fleets were chosen because of their large fuel use, advantageous usage
patterns, and the benefits which would accrue from reduced fuel use. Three New
York school districts participated, each converting up to 10 buses to use CNG and
allowing data to be collected from a similar number of gasoline and diesel fuel
control buses. The project lasted three years, beginning with the '83-'84 school
year. Data collected includes bus fuel economy, bus maintenance costs, refueling
station operating and maintenance costs, regulatory problems, safety and
community acceptance. No safety or community acceptance problems were
experienced in any school district. When tuned, the CNG buses performed very
well and drivers were happy with the improved driveability. On average, the
CNG buses achieved better fuel economy than their gasoline counterparts, though
the diesel buses' fuel economy was still the highest because they use much less
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fuel at idle than do spark ignition engines. Extended spark plug and oil change
intervals were experienced for CNG vehicles, but the project duration was too
short to assess the effect of CNG on engine or exhaust system lifetimes. Overall,
it appears that CNG fueling stations can be operated by typical maintenance
personnel with small amounts of training. Station maintenance does take time,
especially during the start-up phase, so it is suggested that fleet operators
recognize this and respond by providing additional maintenance personnel to
perform the required work. In addition, great emphasis should be placed on
vendor quality and reliability. Vendors should provide a strong warranty and an
extensive training program. In order to achieve positive annual operating savings,
it is estimated that the cost of gasoline should be $.30/gallon higher and diesel
$.50/gallon higher than the cost of the equivalent amount of natural gas. To be
competitive, natural gas must be priced so that when compression and equipment
maintenance costs are added in, savings still result. Overall, New York state
should benefit from the use of CNG in terms of improved air quality and reduced
expenditures for imported petroleum. This report establishes the current (1986)
technical and economic status of CNG vehicles, and sets the stage for exploration
of optimum, advanced CNG vehicle economics.
Murray, EL S., et al. 1986. DOT Fuel-Cell-Powered Bus Feasibility Study. Prepared
for U.S. Department of Transportation by Los Alamos National Laboratory, Los
Alamos, New Mexico (LA-10933-MS).
The purpose of this study was to evaluate and document the feasibility of
powering standard size and small buses with fuel cells. Specifically, the study
objective was to determine whether fuel-cell-powered buses could achieve
satisfactory performance on standard drive cycles and whether their life cycle
costs could be competitive with conventional diesel buses. The present status of
fuel cell systems was documented and expected fuel cell development over the
next five years was projected. Preferred propulsion systems consisting of pure
fuel cells and fuel cell/battery hybrids were identified. Performance modeling was
performed using DOT drive cycles for the standard bus and a Georgetown
University route for the small bus. A life cycle cost analysis was performed to
determine break-even costs for the fuel cell system compared to conventional
diesel-powered buses. It was concluded that a functional, hybrid fuel cell/battery
powered bus can be built with currently available technology to meet the
requirements of the reduced power DOT drive cycle and, with some lowered top
speeds, to meet the Georgetown University route requirements. To break even
with a diesel bus, fuel cell and reformer costs should be in the range of $200 to
$500 per kilowatt. Estimates for fuel cells in electric utility applications were
$1000/kW, but in mass production the $200-$500/kW cost may well be
achievable. No dollar value was placed on the fuel cell's low air and noise
pollution impacts.
O'Connor, M. 1991. Status Report on the Riverside Transit Agency Methanol Bus
Fleet. California Air Resources Board, El Monte, California.
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Since 1987, the Riverside (CA) Transit Agency (RTA) has been conducting a
demonstration program to assess the ability of methanol-fueled buses to operate
reliably and achieve very low emission levels. The RTA fleet consists of three
GM buses with Detroit Diesel engines converted to operate on neat methanol, and
three diesel control buses. The methanol buses initially experienced mechanical
problems, including loss of power due to problems with the engine control system
and low engine compression. Detroit Diesel (DDC) rebuilt the engines and
upgraded the engine control systems. Recent efforts by DDC have significantly
improved fuel injector durability and glow plug life, two major maintenance
problems experienced by RTA. The methanol buses have undergone four separate
emission testing procedures at the Air Resources Board's emission laboratory. It
was found that hydrocarbon and carbon monoxide emissions were higher in the
methanol buses than in the diesel, but paniculate and nitrogen oxides emissions
were much lower. These findings are consistent with previous tests of this type of
methanol engine.
Reese, J. J. et al. 1992. Comparative Evaluation of Clean Fuels. Prepared for Orange
County Transit District by Acurex Environmental Corporation, Mountain View,
California (Monthly Progress Report 6590-25).
The Orange County Transit District is evaluating the feasibility of using clean
fueled buses and other vehicles in transit service. Eight buses are currently being
evaluated: two each of methanol, compressed natural gas (CNG) and propane
(LPG) and two diesel control buses. These buses were placed in service in
August 1990, and they continue to serve a central business district route. This
monthly report covers activity during the month of February, 1992. Included in
the report are data on mileage accumulation, fuel economy, road calls and
maintenance labor hours, cost of replacement parts and fuel-related costs. The
diesel buses experience better fuel economy and lower energy consumption than
their clean fuel counterparts, and road calls are less frequent for the diesel buses.
Of the clean fuel buses, the methanol vehicles required the fewest maintenance
labor hours, although the cost of replacement parts for the methanol buses was
much higher than for the others. Acurex is working on scheduling emissions tests
for the buses, and plans to start testing by June 1992.
Regional Transportation District. 1992a. Compressed Natural Gas Program, Monthly
Report, April, 1992. Regional Transportation District, Denver, Colorado.
In 1990, Denver's Regional Transportation District converted five diesel buses to
operate on a combination of diesel and compressed natural gas (CNG). Five
diesel buses were used as controls. No routine maintenance procedures have yet
been established for the CNG buses, but that is expected soon. Several
maintenance problems have been experienced with the CNG buses, including hard
starting in cold weather, electronic control problems and defective gas injector
valves. Recent emission tests show that the buses will not meet EPA urban bus
engine emission standards, but the manufacturer is making significant
improvements in the electronic control program and engine calibration which will
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hopefully allow the engine to be certified later this year. During the month
covered by this report, the CNG buses experienced eight engine/fuel related
problems, while the diesel buses had one such problem. The CNG buses averaged
3.13 mpg during the month, using 53% CNG and 47% diesel. The diesel control
buses averaged 3.6 mpg. The total operating costs per mile were $.80 for the
methanol buses and $.42 for the diesel buses.
Regional Transportation District. 1992b. Methanol Program, Monthly Report, March
1992. Regional Transportation District, Denver, Colorado.
Denver's Regional Transportation District is conducting an alternative fuels
research program in which five methanol buses were purchased and put in revenue
service in 1989. Five diesel buses serve as the control group for this experiment.
The methanol and diesel buses operate on the same routes and are exposed to
similar schedule speeds, stops per mile and passenger loading. During the month
covered by this report, the methanol buses experienced four engine/fuel system
problems while the diesel buses experienced three such problems. Average fuel
consumption for the methanol buses was 1.61 mpg, with the diesel buses
recording an average of 3.53 mpg. The fuel and maintenance costs for the
methanol buses were twice as much as for the diesel buses, which is due in large
part to much higher fuel costs for methanol. This document contains graphical
representations of the preceding data, as well as spreadsheets which provide a
breakdown of fuel and maintenance costs for the program over the previous twelve
months.
R.F. Webb Corporation, Ltd. 1990. Chapter on Energy, Canadian Transit Handbook.
Prepared for Transport Canada.
Diesel fuel dominates the Canadian transit fuel market, but transit systems and
other petroleum product users are increasingly concerned about the stability of the
oil supply worldwide, as well as about selecting fuel and bus designs to meet
rapidly emerging and stringent environmental performance standards. This
portion of the Canadian Transit Handbook addresses issues of energy consumption
and conservation in the public transit sector, and a large section of the chapter is
devoted to an exploration of the role that alternative transportation fuels may play
in future Canadian transit decisions. This chapter focuses on the alternative fuels
CNG, propane and methanol, both because of their emissions performance and
because there can almost certainly be an uninterrupted supply of these fuels from
massive Canadian sources. Canada is currently a world-scale exporter of natural
gas and methanol, and has demonstrated the feasibility of alternatively fueled
buses by accumulating many bus years of revenue service using such fuels in
several transit locations. However, the economics of large-scale conversions of
transit buses to alternative fuels will be favorable only when benefit calculations
include social benefits such as emissions reductions and energy security. Propane
and CNG have begun to penetrate the market for light-duty vehicles, and so far
several Canadian transit agencies have taken part in alternative fuel demonstration
programs, which are briefly described in this chapter. The lowest cost option
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currently appears to be propane, due to low fuel cost and relatively low cost for
refueling system installation. CNG is attractive for its emission benefits, but the
cost of installing a CNG fueling system may confine the use of this fuel to those
locations where subsidies can offset the initial costs. Methanol is appealing
because it can be handled much like gasoline or diesel, but the disadvantages
include relatively high fuel costs, toxicity and high levels of formaldehyde
emissions.
Santini, D. J. and J. B. Rajan. 1990. Comparison of Emissions of Transit Buses Using
Methanol and Diesel Fuel. Transportation Research Board, Washington, D.C.,
Transportation Research Record 1255.
The results of several studies on the emission characteristics of methanol- and
diesel-fueled buses are summarized. To facilitate comparison, the emissions test
data at idle and in various driving cycles are presented on an hourly or per-mile
basis. The emissions of specific pollutants from methanol-fueled test vehicles
varied greatly with average speed and depended on the engine technology and the
emission control devices used. The results suggest that the substitution of
methanol-fueled buses for diesel-fueled buses is not likely to result in net air
quality improvements for very low speed bus operations in urban environments.
In many instances, emission reductions experienced with methanol buses occur
only at steady-state cruising speeds, not at idling speeds more common for city
transit buses. Under these conditions, the negative effects of increases in CO,
formaldehyde, and hydrocarbons may offset the positive effects of paniculate
reduction. In addition, catalysts in methanol-fueled buses must be maintained
scrupulously in order to provide the emission reductions expected. In this paper,
no attempt is made to weight emissions, estimate air quality, or quantify net
emissions effects.
Santini, D. J. 1988. "Environmental Quality Changes Arising from the Replacement of
Diesel Oil-Fueled Buses by Methanol-Fueled Buses." FISITA Conference,
Washington, D.C., September 30, 1988 (885168).
A number of issues related to diesel and methanol buses are explored, with the
goal of summarizing the considerations that a transit operator and a metropolitan
area should include when making decisions about purchasing methanol-fueled
buses. Topics covered include: occupational exposures of maintenance workers;
probable levels of urban-resident pollutant exposure; environmental consequences
of fuel leaks and spills; and air quality effects of in-use emissions. Previous
cost/benefit comparisons are analyzed in light of these issues, to determine what
the ratios of methanol and diesel fuel prices should be to make adoption of
methanol buses desirable. Presumed environmental advantages of methanol
engines, which have been estimated based on average driving cycles, are not
likely to be as great in heavy, slow traffic. Still, substituting new methanol
engines for old diesel engines will precipitate drops in NOX and paniculate
emissions and, if a catalyst were used in the methanol engine, reductions in CO
and HC as well. Several characteristics of methanol make changes in operating
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and handling practices necessary. Methanol is poisonous and colorless, is more
chemically reactive than diesel or gasoline, and has higher volatility and a wider
range of ignition temperatures than diesel. It is not more hazardous than gasoline,
but requires different precautions in handling. It is preferable to do all methanol
refueling outside the garage and to improve ventilation in maintenance pits,
because methanol is denser than air and vapors tend to accumulate near the floor.
Spill handling for methanol is similar to that for gasoline. Negative effects of
introducing methanol buses include reduced safety relative to diesel buses and
increased emissions of aldehydes and unburned methanol. However, with proper
steps to counteract these effects, the net environmental impact should be positive.
Schleyer, C. H. and W. J. Koehl. 1990. Comparison of Gasoline and Methanol Vehicle
Emissions Using VOC Reactivity. Society of Automotive Engineers, Warrendale,
Pennsylvania (SAE 902095).
A major air quality benefit attributed to methanol as a motor vehicle fuel is a
reduction in ozone concentrations in urban areas. This paper explores the mass,
composition and ozone reactivity of the emissions from gasoline and methanol
vehicles. Methanol vehicle emission performance based on mass emission rates
relative to gasoline is evaluated. The emissions from gasoline and methanol
vehicles are then compared by two methods, using a published reactivity scale and
an ozone air quality model. This analysis shows no significant difference in the
amount of VOC and other pollutants emitted by gasoline and methanol vehicles.
The ranges of reactivity for gasoline and methanol overlap, with methanol
reactivity the same or higher than gasoline reactivity when equivalent vehicles are
compared. In addition, the reactivity scales are compared with each other and
with the OZIPM computer model, with varying degrees of agreement. The paper
concludes that more work is needed to accurately evaluate measures of
photochemical reactivity.
Schmidtke, G. 1989. "Natural Gas Saves District Money on its Bus Fleet." School Bus
Fleet. August/September, pp. 61-3.
Since 1984, the Yelm School District in rural Washington state has converted
eleven buses to run on compressed natural gas (CNG), at a total cost of $70,000.
After five years, the savings in fuel costs (up to $1,000 per bus per year) have
more than paid for the initial expenditure. In addition, the oil change interval has
been doubled and analysis shows that engine wear is significantly reduced with
CNG use, thus reducing maintenance costs. CNG was chosen over diesel and
propane for several reasons; availability of the fuel, ease of choosing a dual-fuel
system, safety considerations and the reduced need for environmentally sensitive
underground storage tanks.
Small, K. A. 1989. Methanol Fuel for Los Angeles Area Transit Buses: Costs and
Benefits. Institute of Transportation Studies, University of California, Irvine (UCI-
ITS-RR-89-1).
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This project focuses primarily on the air pollution benefits of converting transit
buses to methanol fuel, using two different methods: cost/benefit analysis and
cost-effectiveness analysis. The cost/benefit analysis compares the cost of
converting the fleet and using methanol with the measurable health benefits from
reducing particulates and sulfur oxides. The costs were assessed over a range of
possible methanol prices. The results indicate that over a wide range of methanol
prices, benefits exceed costs, even though many benefits are omitted in this
somewhat narrow calculation. The cost-effectiveness analysis adds a number of
factors to the previous work. The clean-air potential of methanol is compared
with that of other strategies for reducing diesel emissions, and the comparisons are
made for three different pollution indices, each combining the effects of
particulates and sulfur oxides in a different way. In all, methanol conversion has
a higher cost per unit reduction in pollution than the other strategies. However, it
also produces a higher absolute reduction in pollution, thus requiring an
examination of the incremental cost of the additional reduction it brings about. In
addition, an analysis of energy supply suggests that the ability to rapidly convert a
substantial amount of the nation's fuel use to methanol could serve as an important
deterrent to a repeat of the oil price increases of the 1970s.
Small, K. A. 1988. Reducing Transit-Bus Emissions: Comparative Costs and Benefits
of Methanol, Paniculate Traps, and Fuel Modification. Institute of Transportation
Studies, University of California, Irvine (UCI-ITS-WP-88-1).
This paper investigates the cost-effectiveness of three strategies for reducing
particulate and sulfur-oxide emissions from diesel transit buses, including low-
aromatic fuel, particulate traps and methanol. Three alternate indices of emissions
are considered: one equal to total particulates (including those formed in the
atmosphere from emitted sulfur dioxide); one based on California's ambient air-
quality standards; and one based on statistically estimated effects on mortality. At
the fuel prices considered most likely, methanol is far more costly than other
strategies per unit reduction in total particulates. No seriously proposed estimate
of benefits would justify the incremental cost of $108 per kilogram of particulates
reduced by switching from particulate traps to methanol. However, the picture
changes when sulfur is taken into account. The incremental cost of using
methanol to reduce noxious sulfur emissions by the equivalent of one kilogram of
particulates is either $43 or $7.50, depending on which of two estimates of
sulfur's noxiousness one accepts. In addition, methanol achieves the greatest
absolute emissions reduction. Lowering the aromatic content of diesel has
promise for achieving modest reductions in particulates, especially since it
includes the possibility of immediate application to the entire vehicle fleet without
waiting for old vehicles to be replaced.
Southern California Rapid Transit District. 1992. Alternate Fuels Section Quarterly
Status Report. October-December 1991, Vol. 2, No. 3.
The Southern California Rapid Transit District has been actively testing and
developing clean air technologies which will be applicable to transit service in Los
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Angeles in the twenty-first century. Currently the methanol technology is the
most mature, and the District has decided to purchase over 300 methanol buses for
revenue service in late 1992. Compressed natural gas (CNG) and particulate trap
technologies are still being developed, and the District is also exploring electric
trolley and liquified natural gas technologies in order to comply with the region's
Air Quality Management Plan goals of 30 percent electric and 70 percent
alternative fueled urban transit vehicles by the year 2010. The District has
developed a cost model to monitor trends in fuel price and operational costs,
which will provide the District with information on the developmental process of
each technology and how it has been affected by (or has affected) the larger
market forces in the energy and transportation industries. This report specifically
discusses the operations of the District's various alternatively fueled buses during
the fourth quarter of 1991, providing data on fuel economy and maintenance
requirements. The report also summarizes project developments during the
quarter, and discusses the durability study currently underway to measure the wear
on engine components from the use of various types of fuels.
Sypher: Mueller International, Inc. 1990. Project MILE Report: A Report on the Use
of Methanol in Large Engines in Canada. Prepared for Energy, Mines and
Resources, Canada.
Project MILE (Methanol in Large Engines) was initiated in 1984 by Canada's
federal Department of Energy, Mines and Resources. It was intended as a long-
term trial of methanol-fueled compression ignition engines in trucks and buses.
Demonstration buses were included in the fleets of Winnipeg and Medicine Hat.
Each fleet had custom-built fueling stations, safety equipment, personnel training
and repair and service backup for support. By October, 1989, the demonstration
vehicles had covered almost one million km hi revenue service. Problems with
engine reliability were experienced, but continuing developments by the
manufacturers significantly unproved the mechanical operations of the buses. The
methanol buses eventually matched diesel buses in power, driveability and
monthly availability. Fuel consumption on an energy content basis did not equal
that of diesel. Some mechanical problems remain, such as fuel injector tip
blockage, glow plug durability and valve seat wear. However, it was found that
methanol buses can be operated with little disruption to normal servicing and
operating procedures. Methanol fueling could not compete economically with
diesel. However, large reductions in methanol production costs coupled with
increased prices for diesel engines and fuel due to more stringent emissions
standards could make methanol more cost effective in the future. This project
indicated that methanol is currently technically feasible as an alternative fuel, and
significant emission reductions are possible with its use. The demonstration was
so successful that the city of Medicine Hat plans to convert its entire transit fleet
to methanol.
Tulsa Public Schools Transportation Department. 1992. Compressed Natural Gas
Information Fact Sheet. Tulsa Public Schools, Tulsa, Oklahoma.
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This informal document outlines the Tulsa Public School District's experience
with school buses converted to run on compressed natural gas (CNG). The
District entered a pilot program financed by the state of Oklahoma in 1988, to test
the feasibility of operating a fleet of CNG vehicles. The Tulsa Schools now
operate 102 CNG buses, the largest such fleet in the nation. Of those buses, 67
have dual-fuel systems and 45 have dedicated CNG engines. The District
experiences fuel cost savings of between $800 and $1,000 per bus per year, as
well as maintenance cost savings due to less frequent oil changes and routine tune-
ups. The document includes information on fill station construction, fuel mileage
and mileage range, safety and fueling requirements, as well as a list of vendors
involved in the implementation of the CNG program.
Unnasch, S, et al. 1990. Transit Bus Operation with a DDC 6V-92TAC Engine
Operating on Ignition-Improved Methanol. Society of Automotive Engineers,
Warrendale, Pennsylvania (SAE 902161).
This paper describes the steps taken to retrofit three diesel-powered buses to run
on methanol. The buses are currently in use in the Southern California Rapid
Transit District in Los Angeles. The existing engine is modified by installing
higher compression ratio pistons and higher flowrate mechanical fuel injectors,
while the fuel system is altered to accommodate the properties of methanol. An
existing underground storage tank formerly used for leaded gasoline is converted
for methanol use. Different types of fuel pumps are described, as well as the fuel
supply and delivery system in the Southern California region. The operating
experience with the buses is fully discussed, including routes and schedules, the
training of drivers and maintenance workers, average fuel economy, engine and
component durability and operating costs. In general, methanol bus performance
compares favorably with diesel, although methanol buses consume about 2.5 times
as much fuel. The cost of methanol, therefore, remains an important concern as
this demonstration project continues.
Unnasch, S. et al. 1986. Emission Control Options for Heavy-Duty Engines. Society of
Automotive Engineers, Warrendale, Pennsylvania (SAE 861111).
While diesel is the fuel of choice for most transit buses and other heavy-duty
applications, environmental concerns about paniculate and NOX emissions from
diesel combustion are causing diesel manufacturers and operators to look for
effective control techniques. Controlling particulates without increasing NOX has
been difficult with combustion modifications alone. This paper evaluates practical
measures which can meet both the paniculate and NOX standards, including
paniculate traps, clean (low sulfur, low aromatics) diesel fuel, gasoline and
methanol. Measures are evaluated not only on the emissions reductions they can
produce but also on their incremental life cycle costs. In terms of total cost, a
long-life paniculate trap that does not require premium fuel has the lowest
incremental cost impact. If a trap does require premium fuel or does not reach its
target life expectancy, all the approaches have approximately the same cost
impact. However, in terms of overall air pollution control strategies, methanol
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gains an advantage because it produces more benefits than paniculate reduction
alone. Methanol shows good cost effectiveness when air quality goals include
substantial reductions in both particulates and NOX.
Wachter, W. F. 1990. Analysis of Transient Emission Data of a Modelyear 1991 Heavy
Duty Diesel Engine. Society of Automotive Engineers, Warrendale, Pennsylvania
(SAE 900443).
U.S. heavy duty emission standards are expected to force huge efforts in engine
design and production. In response, a research program was undertaken to
identify phases of the heavy duty diesel transient cycle (HDDTC) with the most
potential to reduce emissions. For each controlled pollutant, the researchers
identify the phases of the HDDTC where significant contributions to overall
emission were made. In addition, the effects of various operating conditions, such
as combustion system configuration and quality of lube oil and diesel fuel, are
quantified and analyzed, and suggestions are made as to the conditions most
suitable for optimum emission reduction. A warning is given that, although the
1994 limits can be met with a laboratory engine under certain conditions,
production scatter and deterioration of emissions over the life of the engine are
factors of great importance in the estimation of actual emissions, and are not yet
fully understood by manufacturers.
Zelenka, P. et al. 1990. Ways Toward the Clean Heavy-Duty Diesel. Society of
Automotive Engineers, Warrendale, Pennsylvania (SAE 900602).
A review of the current development of heavy-duty diesel engines is followed by a
discussion of the technologies necessary to meet the U.S. 1994 heavy-duty
emissions standards. One promising development is the application of an
oxidation catalyst as an efficient and cost-effective device for burning off such
pollutants as CO, HC, PAH and soluble particulates. Other benefits of the
oxidation catalyst include significant reduction of aldehydes, reduced system cost
and complexity, and a levelling of the usual production variability of hydrocarbon-
related emissions. However, the catalyst is only a feasible solution of low-sulfur
fuel is readily available. Challenges to reducing emissions even further after 1994
are discussed, with emphasis on the future development of a methanol diesel
engine for achieving greater NOX reductions.
92117.03
23
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GLOSSARY
BART Bay Area Rapid Transit
CAAA Clean Air Act Amendments of 1990
Caltrans California Department of Transportation
CBE Citizens for a Better Environment
CEQA California Environmental Policy Act
CNG Compressed Natural Gas
DOE Department of Energy
DOT Department of Transportation
EPA Environmental Protection Agency
GRI Gas Research Institute
ITE Institute of Transportation Engineers
LEV Low Emitting Vehicle
LPG Liquified Petroleum Gas
MAG Maricopa Association of Governments
MPO Metropolitan Planning Organization
NARC National Association of Regional Councils
NEPA National Environmental Policy Act
NTD Neotraditional Neighborhood Design
OSHA Occupational Safety and Health Administration
92117.04
32
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RTF Regional Transportation Plan
SAE Society of Automotive Engineers
SCAQMD South Coast Air Quality Management District
TRB Transportation Research Board
TRIS Technical Retreival Information Service
TSC Transportation Systems Center
UMTA Urban Mass Transit Administration
UTPS Urban Transportation Plannng System
VMT Vehicle Miles Travelled
VOC Volatile Organic Compound
92117.04
33
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References: Alternatively Fueled Buses
Bol, M. A. and G. B. Hamilton. 1989. "Economic Life Cycle Costs of Methanol in
Diesel Applications." VIQ International Symposium on Alcohol Fuels.
Booz, Allen & Hamilton, Inc. 1983. Evaluation of Alternative Fuels for Urban Mass
Transit Buses: Final Report. Prepared for U.S. Department of Transportation/UMTA
and Port Authority of Allegheny County, Pennsylvania (UMTA-PA-06-0060-83-1).
Bush, J. L. 1992. "Natural Gas is Leading Contender for State School Bus Fleets."
School Bus Fleet. April/May, pp. 28-36.
Chandler, K. L., T. C. Krenelka and N. D. Malcosky. 1991. CNG Bus Demonstration
Program Data Analysis Report. Prepared for U.S. Department of Transportation/ UMTA
by Battelle, Columbus, Ohio (UMTA-OH-06-0056-91-10).
Craig, E., S. Unnasch and M. Cramer. 1991. Methanol-Fueled Transit Bus
Demonstration, Phase II: Final Report. Prepared for California Energy Commission by
Acurex Corporation, Mountain View, California (Acurex Report 90-109-ESD).
Environmental Protection Agency. 1989. Analysis of the Economic and Environmental
Effects of Methanol as an Automotive Fuel. Office of Mobile Sources, Washington,
D.C.
Environmental Protection Agency. 1990a. Analysis of the Economic and Environmental
Effects of Compressed Natural Gas as a Vehicle Fuel: Volume n Heavy-Duty
Vehicles. Office of Mobile Sources, Washington, D.C.
Environmental Protection Agency. 1990b. Analysis of the Economic and Environmental
Effects of Ethanol as an Automotive Fuel. Office of Mobile Sources, Washington, D. C.
"Favorable Experiences Reported by Transperth Using Natural Gas for Buses." 1990.
Bus Ride. January, pp. 72-4.
Francis, G. A. and R. D. King. 1988. Proving Ground Comparison of M. A.N.
Methanol and Diesel Transit Buses. Prepared for U.S. Department of
Transportation/UMTA by Battelle, Columbus, Ohio (UMTA-IT-06-0322-88-4).
Garland Independent School District. 1990. Status Report: Compressed Natural Gas.
Garland Independent School District, Garland, Texas.
Gerndt, H. and R. Stellmacher. 1989. "Battery Powered Electric Buses."
Transportation Planning and Technology. 14:217-25.
Gilbert, A. T. and R. Gunn. 1991. Natural Gas Hybrid Electric Bus. Society of
Automotive Engineers, Warrendale, Pennsylvania (SAE 910248).
92117.06
34
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Giuliani, C. and M. Murphy. 1991. Status of Paniculate Trap Developments Related to
the Transit Industry. Prepared for U.S. Department of Transportation/UMTA by
Battelle, Columbus, Ohio (UMTA-OH-06-0056-91-6).
Hargreaves, D. 1989. "Propane: Safe, Clean and Affordable." Community
Transportation Reporter. March, pp. 11-3.
Harmelink, M. D. and O. M. S. Colavincenzo. 1990. The Development of Natural Gas
Buses in Ontario. Ontario Ministry of Transportation. Presented at Globe 90,
Vancouver, British Columbia, March 22, 1990.
Hull, R. W. 1987. Environmental Benefits of CNG-Fueled Vehicles. Prepared for the
Gas Research Institute by Southwest Research Institute, San Antonio, Texas (Contract
No. 5084-251-1101).
Hundleby, G. E. 1989. Low Emissions Approaches for Heavy-Duty Gas-Powered
Urban Vehicles. Society of Automotive Engineers, Warrendale, Pennsylvania (SAE
892134).
Indirect Source Control Committee. 1992. Procedure to Determine Emission
Reductions: School Bus Conversion. California Air Pollution Control Officers
Association.
Indirect Source Control Committee. 1992. Procedure to Determine Emission
Reductions: Transit Bus Replacement. California Air Pollution Control Officers
Association.
Klausmeier, R. F. and J. Draves. 1991. "Assessment of Environmental Issues Related
to the Use of Alternative Transportation Fuels Analysis of Recent Data." Air & Waste
Management Association Annual Meeting, Vancouver, British Columbia (91-106.3).
Krenelka, T. C. and M. J. Murphy. 1990. Methanol Status Report. Prepared for U.S.
Department of Transportation/UMTA by Battelle, Columbus, Ohio (UMTA-OH-06-
0056-90-2).
Leonard, J. H. 1989. "Activities of the South Coast Air Quality Management District to
Promote Alternatively Fueled Motor Vehicles." Air & Waste Management Association
Annual Meeting, Anaheim, California (89-63A.3).
Maggio, M. E., et al. 1991. Challenges for Integration of Alternative Fuels in the
Transit Industry. Transportation Research Board, Washington, D.C., Transportation
Research Record 1308.
Mathieson, M. 1991. "Alternative Fuels Applications for School Transportation."
National School Bus Report. December, pp. 16-7.
92117.06
35
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Meloche, M. J. 1990. Summary of Alternative Fuel/Clean Air Technology Buses in
North American Transit Use. American Public Transit Association, Washington, D.C.
Mueller Associates, Inc. 1986. Dual-Fuel School Bus Demonstration: Final Report.
New York State Energy Research and Development Authority, Albany, New York
(Report 87-17).
Murray, H. S., et al. 1986. DOT Fuel-Cell-Powered Bus Feasibility Study. Prepared
for U.S. Department of Transportation by Los Alamos National Laboratory, Los Alamos,
New Mexico (LA-10933-MS).
O'Connor, M. 1991. Status Report on the Riverside Transit Agency Methanol Bus
Fleet. California Air Resources Board, El Monte, California.
Reese, J. J. et al. 1992. Comparative Evaluation of Clean Fuels. Prepared for Orange
County Transit District by Acurex Environmental Corporation, Mountain View,
California (Monthly Progress Report 6590-25).
Regional Transportation District. 1992a. Compressed Natural Gas Program, Monthly
Report, April, 1992. Regional Transportation District, Denver, Colorado.
Regional Transportation District. 1992b. Methanol Program, Monthly Report, March
1992. Regional Transportation District, Denver, Colorado.
R.F. Webb Corporation, Ltd. 1990. Chapter on Energy, Canadian Transit Handbook.
Prepared for Transport Canada.
Santini, D. J. and J. B. Rajan. 1990. Comparison of Emissions of Transit Buses Using
Methanol and Diesel Fuel. Transportation Research Board, Washington, D.C.,
Transportation Research Record 1255.
Santini, D. J. 1988. "Environmental Quality Changes Arising from the Replacement of
Diesel
Oil-Fueled Buses by Methanol-Fueled Buses." FISITA Conference, Washington, D.C.,
September 30, 1988 (885168).
Schleyer, C. H. and W. J. Koehl. 1990. Comparison of Gasoline and Methanol Vehicle
Emissions Using VOC Reactivity. Society of Automotive Engineers, Warrendale,
Pennsylvania (SAE 902095).
Schmidtke, G. 1989. "Natural Gas Saves District Money on its Bus Fleet." School Bus
Fleet. August/September, pp. 61-3.
Small, K. A. 1989. Methanol Fuel for Los Angeles Area Transit Buses: Costs and
Benefits. Institute of Transportation Studies, University of California, Irvine (UCI-ITS-
RR-89-1).
92117.06
36
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Small, K. A. 1988. Reducing Transit-Bus Emissions: Comparative Costs and Benefits
of Methanol, Particulate Traps, and Fuel Modification. Institute of Transportation
Studies, University of California, Irvine (UCI-ITS-WP-88-1).
Southern California Rapid Transit District. 1992. Alternate Fuels Section Quarterly
Status Report. October-December 1991, Vol. 2, No. 3.
SyphenMueller International, Inc. 1990. Project MILE Report: A Report on the Use of
Methanol in Large Engines in Canada. Prepared for Energy, Mines and Resources,
Canada.
Tulsa Public Schools Transportation Department. 1992. Compressed Natural Gas
Information Fact Sheet. Tulsa Public Schools, Tulsa, Oklahoma.
Unnasch, S. et al. 1990. Transit Bus Operation with a DDC 6V-92TAC Engine
Operating on Ignition-Improved Methanol. Society of Automotive Engineers,
Warrendale, Pennsylvania (SAE 902161).
Unnasch, S. et al. 1986. Emission Control Options for Heavy-Duty Engines. Society of
Automotive Engineers, Warrendale, Pennsylvania (SAE 861111).
Wachter, W. F. 1990. Analysis of Transient Emission Data of a Modelyear 1991 Heavy
Duty Diesel Engine. Society of Automotive Engineers, Warrendale, Pennsylvania
(SAE 900443).
Zelenka, P. et al. 1990. Ways Toward the Clean Heavy-Duty Diesel. Society of
Automotive Engineers, Warrendale, Pennsylvania (SAE 900602).
92117.06
37
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