E PA-420-S-85-100
r-'RC'1'' . i Of
NATIONAL ViErllCLE AND FUEL EMISSIONS
LABORATORY LIBRARY
2000 TRAVERWOOD DRIVE
ARBOR. Ml 48105
THE ENVIRONMENTAL PROTECTION AGENCY VIEW OF METHANOL
AS A TRANSIT BUS FUEL
Presented at the Headway '85 Transit Conference
in Kansas City, Missouri on November 4, 1985
Jeff Alson
Assistant to the Director
Emission Control Technology Division
Office of Mobile Sources
Environmental Protection Agency
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Environmental Protection Agency (EPA) interest in transit
buses has increased significantly in the last few years.
Concerns over existing diesel bus pollution and enthusiasm over
the potential of methanol to alleviate these concerns have both
contributed to this increased interest. This paper will give
an overview of the transit bus issue from an EPA perspective,
summarizing our current outlook on diesel buses, discussing
methanol as a general motor vehicle fuel, and focusing on the
benefits of methanol as a future transit bus fuel.
A Reassessment of Diesel Bus Pollution
Historically, transit buses have not been considered to be
a significant environmental problem. In any urban area, the
number of transit buses is only a minute fraction of the total
number of motor vehicles. Powered by diesel engines, which
inherently produce low levels of hydrocarbon (HC) and carbon
monoxide (CO) emissions, total mass emissions of most
pollutants from transit buses are dwarfed by aggregate
emissions from passenger vehicles, large trucks, and stationary
sources such as power plants and factories. In addition, from
a technical perspective, there has not been a promising bus or
truck alternative to the diesel cycle engine operated on diesel
fuel. Accordingly, EPA regulation of heavy-duty trucks and
buses has lagged behind that of passenger cars and light
trucks, and current EPA standards require only token control
measures on new heavy-duty diesel engines.
A number of developments have forced EPA to reexamine the
diesel bus issue. As EPA has reduced emissions from other
sources (for example, new passenger car HC and CO emissions
have been reduced by over 90 percent in the last fifteen
years), bus emissions have become proportionally more
important. Public health concerns with diesel particulate
matter (PM) and oxides of nitrogen (NOx) emissions have
increased, the former because of evidence that it contains
carcinogenic compounds and the latter because air quality
projections show that certain areas of the country will exceed
EPA's ambient standard during the 1990s, and both of these
pollutants are emitted in relatively large amounts by diesel
engines. As our ability to analyze motor vehicle emission
impacts has become more sophisticated, we have determined that
public exposure to transit bus pollution is much higher than to
many other pollution sources, on a per unit mass basis: buses
are operated exclusively in urban areas, typically over the
busiest roadway corridors with maximum population exposure, the
pollution is emitted at ground level directly into the human
breathing zone, and EPA and local environmental officials
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receive a high frequency of complaints about bus pollution and
odor. Finally, recent EPA testing has indicated that actual
diesel bus emissions of certain pollutants, such as CO and PM,
are much higher than previously thought.
Table 1 lists the current and future emission standards
which have been established for new engines to be utilized in
transit buses, as well as ranges for the emissions of current
technology engines. It can be seen that current diesel bus
engines are comfortably below the current HC and CO standards
of 1.3 and 15.5 grams per brake horsepower-hour (g/bhp-hr) ,
respectively, and that these standards are not expected to
change in the future. The situation with NOx and PM standards
is in a state of flux, however. We currently have a NOx
standard of 10.7 g/bhp-hr, which represents very little
control, if any, and no PM standard (there is a smoke standard
which constrains PM emissions somewhat). On March 15, 1985,
EPA promulgated new rules which will, for the first time,
require meaningful NOx and PM reductions from heavy-duty diesel
truck and bus engines. Interim standards beginning in 1988
will require minor improvements on some engine models. By
1991, new diesel bus engines will be subject to a NOx standard
of 5 g/bhp-hr, similar to a standard already in effect in
California. This will require some type of engine modification
on most new bus engines. Also beginning in 1991, new bus
engines will have to meet a 0.1 g/bhp-hr PM standard. This is
a very significant reduction in allowable PM emissions, and
will likely require the application of trap oxidizers, exhaust
aftertreatment devices which continuously filter and
periodically oxidize PM.
The lower diesel bus emission standards in 1991 have
certainly contributed to the interest of diesel engine
manufacturers in alternative fuels. The application of trap
oxidizers and NOx controls will undoubtedly raise the initial
purchase price, and probably the fuel consumption as well, of
transit bus engines. A second motivation is simply the
realization that we will not have abundant supplies of cheap
diesel fuel forever, and that an alternative fuel will
ultimately be necessary.
Methanol; The Transportation Fuel of the Future
Whether examined from an energy, environmental, or
economic standpoint, methanol is a very promising alternative
motor vehicle fuel. Of course, the historical -context for
interest in methanol, and all alternative liquid fuels,
involves the oil price shocks of the 1970s. American society
had prospered on cheap and plentiful oil, and it was only after
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the OPEC oil embargo of 1973-74 that we realized that petroleum
was a finite and valuable resource. Our vulnerability with
respect to energy security was reinforced in 1979-80 when a
relatively minor cutoff of crude oil from Iran caused major
havoc with world oil prices. Prices rose from $3 per barrel in
the early 1970s to nearly $40 per barrel in 1981. Oil import
payments, which peaked at $80 billion in 1980, became a major
drain on American capital, and contributed to a decline in our
international trade balance.
Although the present world oil price and supply situation
is much improved, with plentiful supplies and falling prices,
we cannot afford to become overconfident. Domestic oil
production, which has been constant for several years, is
projected to decline in the late 1980s, as shown in Figure 1.
The combination of lower domestic oil production and increased
economic growth is expected to significantly increase our
appetite for imported oil. In addition, world economic
recovery and growth and falling crude production in other
non-OPEC areas are expected to significantly increase world oil
prices in the 1990s. It is expected that our oil import bill
will exceed $100 billion per year by the early 1990s if a
satisfactory liquid fuel substitute is not found. Figure 2
indicates that our cumulative international trade deficits are
increasing at a high rate, due to record merchandise trade and
current account deficits in 1984. Higher oil import bills in
the 1990s can only worsen our trade difficulties. Since, as
shown in Figure 3, approximately 60 percent of U.S. petroleum
consumption is in the transportation sector, it is clear that
the U.S. will ultimately require a liquid fuel alternative to
petroleum which can be produced from domestic energy resources.
From an energy perspective methanol is an attractive
alternative. It can be produced in very large volumes from a
variety of domestic feedstocks such as natural gas, biomass,
and, most importantly, all types of coal. Our huge domestic
reserves of coal, evidenced in Table 2, will undoubtedly be a
feedstock for alternative liquid fuels in the future. The
production technology for coal-to-methanol plants is
technologically proven as both the coal gasification and
methanol synthesis processes are in use today. The fact that
coal would go through a gasification step would permit any
sulfur in the coal to be easily removed allowing the use of
high-sulfur coal. As a liquid fuel, methanol would generally
be compatible with existing vehicle and distribution systems.
Finally, it has been known for decades that methanol- is a very
efficient, high-octane motor vehicle fuel. From an overall
energy efficiency perspective, methanol would likely provide
the maximum number of vehicle miles per ton of coal feedstock.
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Methanol has always been considered to be a very
clean-burning fuel; in fact, its low emissions, especially of
nitrogen oxides, was a primary impetus for many of the initial
methanol research projects of the early 1970s. Of course, we
now have much more stringent passenger car emission standards,
and sophisticated emission control technologies have been
developed to control emissions from gasoline-fueled cars.
Compared to gasoline-fueled vehicles, methanol vehicles would
likely emit lower levels of reactive hydrocarbons, leading to a
projected decrease in photochemical oxidant levels. Engine-out
nitrogen oxide levels would also be lower, though whether
vehicle emission levels would be lower would depend on the
emission control system used (i.e., manufacturers might choose
to use a lower cost catalyst) .
The environmental benefits of methanol are most evident
when considered as a substitute for diesel fuel. Diesel
engines inherently emit high levels of particulate and nitrogen
oxide emissions, and trucks and buses are major sources of
these pollutants in many urban areas. Methanol engines tend to
emit very low levels of both of these pollutants. Methanol
substitution for diesel fuel would also reduce reactive
hydrocarbon and sulfur dioxide emissions as well. From an
environmental perspective, the use of methanol provides the
opportunity for vehicle manufacturers and consumers to achieve
the energy efficiency of a diesel engine but with exhaust
emissions comparable to or better than the cleanest gasoline
engine. Bus emissions will be discussed in more detail later
in this paper.
Of course, fuel economics will be vital to the viability
of any alternative liquid fuel. EPA has studied this issue
extensively and concluded that methanol would be the most
cost-effective liquid fuel, on a dollar per mile basis, of any
of the candidate fuels which can be produced from coal. When
methanol would be competitive with petroleum fuels is very
dependent on world oil prices. Our studies indicate that
methanol would be competitive with gasoline from $35 per barrel
oil and competitive with diesel fuel when crude oil prices
reach $45 per barrel. Even assuming that there will be no
world oil supply disruptions, most forecasts are that world oil
prices will rise above these levels in the 1990s.
There is a growing consensus that methanol is our most
promising alternative transportation fuel. Both Ford and
General Motors have active methanol vehicle -development
programs and various foreign manufacturers are also involved in
the area. Many energy and chemical industry firms have studied
the economic feasibility of coal-to-methanol production plants,
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though plans are presently on hold due to the large methanol
surplus and falling world oil prices. Methanol vehicles are
currently being evaluated by private and public sector fleet
operators throughout the U.S., such as the Bank of America and
the California Energy Commission.
Interest in methanol development has reached the highest
levels of our federal government and both major political
parties. The Administration has formed a Methanol Working
Group composed of representatives of 15 different executive
agencies and White House staffs. The primary purpose of the
working group is to review regulatory requirements which might
inhibit consumer use of methanol. Various pieces of proposed
legislation have attracted bipartisan support in Congress
including federal fleet demonstrations, explicit appropriations
for methanol bus purchases, the establishment of a formal
interagency commission on methanol, and changes in methanol
fuel taxation. Given the interest by high-ranking members of
both parties, it is expected that such proposals will continue
to be considered.
Thus, with respect to environmental, energy, and economic
considerations, we believe methanol is the most promising
alternative transportation fuel. The conversion of our
national vehicle fleet to pure methanol could eliminate our
need for oil imports with concomitant benefits such as an
improved balance of trade, insurance against the economic
dislocations caused by another oil price shock, and increased
national security. The redirection of the U.S. wealth now
going for oil imports into domestic coal-to-methanol production
could increase domestic economic growth and employment and
would provide a needed market for high-sulfur coal. And, at
the same time, the use of methanol in motor vehicles would
improve urban air quality.
The Potential for Methanol as a Transit Bus Fuel
While we believe methanol has the potential to ultimately
displace petroleum fuels in all motor vehicle applications, it
is particularly attractive at the present time for use in
transit buses. There are several reasons why methanol transit
buses could be implemented much more easily than could a
general fleet transition to methanol. First, because most
transit authorities are public agencies, they should be
sensitive to public complaints about the environmental problems
of diesel buses and the benefits to be gained from- operating
methanol buses. Transit agencies typically receive operating
subsidies from local units of government, and this provides a
leverage point for citizens interested in reducing air
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pollution. Even more directly, since the federal government
provides up to 80 percent of the funds used to purchase new
urban buses, it could directly promote interest in methanol
buses by providing financial inducements for technology
transfer or by simply requiring that all federal monies be used
for methanol bus purchases. Second, transit authorities have
centralized fueling sites which could be modified to store and
dispense methanol fairly easily. This means that a methanol
bus implementation program would be largely immune from the
distribution problems which would be associated with the
widespread transition to a fuel like methanol, with its
different chemical properties, requiring that scores of
thousands of private service stations be capable of storing and
dispensing it. Finally, because transit systems also have
centralized maintenance facilities, there would be far fewer
concerns over the proper maintenance and repair of a "new" or
at least different engine technology. Thus, urban buses are
probably the most appropriate vehicles to be initially fueled
with methanol.
Several heavy-duty engine manufacturers are now involved
in methanol research programs. Despite the fact that research
into the use of methanol in diesel engines is a fairly recent
phenomenon, manufacturers have already achieved considerable
progress. Three manufacturers have developed methanol-fueled
diesel-cycle bus engines: M.A.N., Mercedes-Benz, and General
Motors. M.A.N.'s involvement in the German Alcohol Fuels
Project led them to modify an existing 11.4-liter,
six-cylinder, direct-injected, naturally-aspirated, four-stroke
diesel engine for pure methanol combustion. The two key
aspects of the modification were the addition of spark ignition
and the functional separation of fuel injection and mixture
formation through wall deposition of the methanol. M.A.N, is
now developing a turbocharged version of this same methanol bus
eng ine.
Mercedes-Benz has designed a 11.4-liter, six-cylinder,
spark-ignited engine to operate on gaseous methanol, in order
to take advantage of methanol's relatively low boiling point
(permitting vaporization) and high heat of vaporization
(increasing usable energy). The engine, adapted from a design
originally intended for operation on natural gas and propane,
features a fuel vaporizer which utilizes heat energy from
engine cooling water.
General Motors has only recently become involved in
methanol bus engine research. GM selected its 9.0-liter,
six-cylinder, direct-injected, turbocharged, two-stroke diesel
engine, used in most new U.S. transit buses, as its baseline
engine. It was found to be surprisingly easy to autoignite
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pure methanol ia the two-stroke engine at normal engine
operating temperatures by controlling the exhaust gas
scavenging process to produce the requisite in-cylinder
conditions at the time of fuel injection. In effect, much of
the exhaust gas is maintained in the cylinder thus providing
sufficient temperatures for methanol ignition. Glow plugs were
added to the engine for use in cold starting and light-load
operation.
Each of these three manufacturers now has methanol buses
in various demonstration programs throughout the world.
Prototype methanol buses are now operating in revenue service
in San Francisco (GM and M.A.N.), Berlin (M.A.N, and Mercedes),
Auckland, New Zealand (M.A.N, and Mercedes) , and Pretoria,
South Africa (Mercedes) . Each bus has had some problems, but
none appear to be insurmountable. Both the engine
manufacturers and the demonstration sponsors have been pleased
with each of the programs.
The most critical ongoing demonstration program for U.S.
policymakers, both because of the manufacturers involved and
its accessibility, is the one in San Francisco sponsored by the
California Energy Commission. Two GM and M.A.N, methanol
buses, which went into service for the Golden Gate Bridge,
Highway, and Transportation District in January and July of
1984, respectively, will be operated in normal revenue service
until the end of 1985, at which time it is likely that
additional funding will be sought to continue the
demonstration. The program has been designed to provide
important information with respect to operating cost, fuel and
oil consumption, emissions, maintenance, driveability,
durability, and consumer and driver reaction. Experience
gained from this program will be very helpful in planning for
more comprehensive demonstrations in the future. In general,
the San Francisco demonstration has been very successful in
proving the feasibility of methanol transit buses. The M.A.N,
bus has been particularly impressive with very few maintenance
problems and an energy efficiency equivalent to its diesel
counterpart both in service and on track fuel economy tests.
As of October 1985, the M.A.N, bus had accumulated 37,000
miles. The GM bus was b.eset with some problems early in the
program, but is now running well and has accumulated 27,000
miles. The GM bus has not yet reached an energy efficiency
equivalent to the diesel. Both of the buses have exhibited
performance equivalent to diesel buses. For more detailed
information on this program, the reader should consult Society
of Automotive Engineers paper number 850216.
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A second U.S. demonstration, sponsored by the Florida
Department of Transportation and UMTA, is also ongoing. Its
purpose is to determine the costs and benefits of retrofitting
in-use GM 71-series diesel bus engines to methanol. Three
engines have been converted in 1985 and will be put into
service in Jacksonville, Florida for six months in early 1986.
This program is more fully described in Society of Automotive
Engineers paper number 841687.
Based on the promising results to date, additional
demonstrations, involving larger numbers of buses and the
active interest and participation of individual transit
authorities, are being planned. Seattle Metro Transit has
signed a contract to purchase 10 M.A.N, methanol buses,with
delivery expected in late 1986. The Southern California Rapid
Transit District is expected to solicit bids for 30 methanol
buses in the near future. Officials in several other cities,
such as New York and Denver, have also expressed interest.
It is becoming increasingly clear that environmental
considerations comprise the primary driving force toward the
use of methanol in transit buses. While interest in
alternative fuels is generally a function of oil prices and
availability, the enthusiasm for methanol buses has grown
significantly in the last two years despite a world oil glut
and falling oil prices. Our discussions with local
environmental officials and individual transit authorities have
indicated that there would be a high value associated with a
transit bus fuel which was cleaner than diesel fuel. What
would be the environmental implications of substituting
methanol buses for diesel buses?
EPA has tested many diesel bus engines down through the
years. Until very recently EPA has relied exclusively on
engine dynamometer testing which simplifies the laboratory
expense of characterizing an engine which may be used in a
number of truck and bus chassis applications. In addition, an
engine dynamometer can be smaller and cheaper than a chassis
dynamometer. Data collected prior to the late 1970s was
generated over steady-state engine testing which is not
considered to be very representative of in-use transit bus
operation. Much of the more recent data was generated over the
EPA heavy-duty transient engine test procedure, which is used
for official EPA certification purposes. This involves
operating an engine over a test cycle that consists of engine
speed and load transients which were designed to simulate
intercity truck usage (truck operation was selected for the
cycle design because trucks outnumber buses). The first column
in Table 3 gives the average engine emissions data for three
new diesel bus engines which EPA has tested over our
certification transient engine test cycle.
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Of course, the relevant information for air quality models
is the grams per mile (g/mi) that a vehicle is emitting.
Historically, EPA has typically used a "conversion factor" of
between 3 and 4 to convert engine emissions in g/bhp-hr to
vehicle or chassis emissions in g/mi. Recently, EPA has tested
7 diesel buses pulled directly from operating service and
operated on a chassis dynamometer over emission test cycles
designed to simulate transit bus operation. Three of these
buses were GMC RTS II buses from the Houston bus fleet which
were equipped with DDAD 6V-92TA diesel engines. Four GMC RTS
II buses with DDAD 6V-71 diesel engines from the San Antonio
transit authority were also tested. These buses had
accumulated between 55,000 and 247,000 miles prior to testing.
Two chassis test cycles were used, an EPA bus driving cycle and
the central business district phase of the SAE Type II Fuel
Consumption Test Procedure for buses. Both of these chassis
cycles involve transient operation with low average speeds and
high acceleration rates, and both cycles have yielded fuel
economy values which correlate well with field data. The
second column in Table 3 gives the average emission data for
these 7 buses. It can be seen that multiplying the engine data
by a conversion factor of 3 or 4 is pretty reliable for HC and
NOx emissions, but that this methodology does not hold for CO
and PM emissions. The CO and PM emissions for in-use diesel
buses were much higher than predicted by the engine data. The
discrepancies reflect some combination of engine aging and
wear, maladjustment, or more realistic test cycles. In any
case, EPA has concluded that previous projections of diesel bus
emissions have been underestimates, and that chassis testing is
necessary for accurate quantification of bus emissions.
Nevertheless, until recently there was no methanol bus
chassis data, only methanol engine data. Table 4 compares the
diesel bus engine emissions data from Table 3 with engine
emissions data for the M.A.N, and GM methanol engines. All of
these engines were new or nearly new. The M.A.N, methanol
engine was tested by the Southwest Research Institute under
contract to EPA. The engine was equipped with an oxidation
catalytic converter and tested over the EPA transient engine
test cycle. The GM methanol engine was tested by GM over the
older EPA 13-mode steady-state engine cycle. It did not
utilize a catalytic converter. As can be seen, CO and HC
emissions were not reported by GM.
The engine data in Table 4 show clearly that methanol,
because of the absence of carbon-carbon bonds" and fuel
impurities such as lead and sulfur, produces very low levels of
PM. Besides being a critical environmental benefit in and of
itself, the low particulate levels also permit the utilization
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of catalytic converters which, as shown by the M.A.N, data,
reduce total organics and CO levels as well. The NOx data is
mixed. While methanol is considered a low-NOx fuel because of
its low flame temperature, the M.A.N, methanol engine actually
emitted slightly more NOx than the diesel engines. On the
other hand, the NOx emission level from the GM methanol engine
is the lowest ever reported to EPA for a heavy-duty engine.
One of the most interesting issues with respect to
methanol fuel is organic (or fuel-related) emissions. Organic
emissions from diesel (and gasoline) vehicles are comprised
almost exclusively of HC compounds (with small amounts of other
compounds such as formaldehyde), and EPA regulates these with a
single HC standard. Organic emissions from methanol combustion
are typically 90 percent (or more) unburned methanol with the
remaining fraction being primarily formaldehyde with low levels
of HC. As the data in Table 4 show, methanol engines emit
considerably lower HC emissions, much greater methanol
emissions, and similar levels of formaldehyde compared to
diesel engines. Even if overall mass organic emissions were
similar, methanol is considered to be less photochemically
reactive than most HC compounds. Thus, methanol substitution
could reduce the photochemical reactivities of urban
atmospheres, resulting in lower ozone levels. Preliminary
computer modeling simulations have projected reduced
reactivities, and EPA is now in the process of validating these
results with smog chamber research.
Just this last summer EPA completed a comprehensive
methanol chassis emission test program at Southwest Research
Institute with the M.A.N, and GM methanol buses from the San
Francisco demonstration program. This is the first such
testing of methanol buses anywhere in the world and permits us
to directly compare diesel and methanol bus emissions. This
comparison is given in Table 5. The diesel bus data, involving
7 in-use GM buses with both 71-series and 92-series engines,
are repeated from Table 3. All of these buses were operated
over the EPA bus and SAE central business district test
cycles. The M.A.N. methanol bus utilized a catalytic
converter, while the GM methanol bus (and, of course, the
diesel buses) did not. The chassis data in Table 5 generally
confirm the engine data in Table 4. The methanol chassis
emissions data are particularly impressive for PM and NOx, the
two primary pollutants of concern from diesel buses. Both
methanol buses yielded PM and NOx reductions compared to the
diesel baseline, with the M.A.N. bus especially low on
particulate and the GM methanol bus very low on NOx. The
M.A.N, bus also emitted low levels of CO and organics as well,
due to both an efficient combustion process and the presence of
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a catalytic converter. Of particular significance is that
aldehyde emissions from the M.A.N, bus were lower than from the
diesel buses. The GM methanol bus produced extremely high CO
and organics emissions,with the very high methanol (i.e.,
unburned fuel) emissions an indication that there is still the
need for considerable fundamental engine design work to be done
with this engine. This should not be surprising since this is
the very first methanol bus built by GM. The application of a
catalyst would also lower CO and organics emissions (and likely
PM as well, since most of the particulate is organic, formed by
the combustion of small amounts of lubricating oil).
In summary, initial tests of methanol-fueled diesel
engines and buses confirm theoretical expectations that the
substitution of methanol for diesel fuel could provide
significant emission benefits. PM emissions would be greatly
reduced, and would likely be near zero for some engine designs.
NOx emissions would be reduced by at least 50 percent.
Methanol engines would likely be able to meet any future, more
stringent, PM and NOx standards without requiring additional
emission controls. Assuming the use of an exhaust catalyst,
which EPA believes should be mandatory, methanol engines would
also provide reactive HC reductions, with concomitant
improvements in atmospheric ozone levels, and CO reductions as
well. Present data indicate that catalysts would reduce
aldehyde emissions to levels equivalent to or below those of
current diesel engines. The only pollutant which would be
increased would be unburned methanol although catalysts would
reduce it to acceptable levels.
Of course, whether methanol buses become a realistic
alternative is in large part dependent upon fuel costs. It is
very difficult to project the future operating costs for
methanol and diesel buses with a high degree of confidence.
Prices for both fuels are currently depressed because of excess
capacities, though it is unclear how long these surpluses will
continue. Diesel fuel prices are particularly difficult to
project given their dependence on world oil prices.
Nevertheless, given the vital importance of fuel costs in the
operation of a transit authority, it is important to have some
idea of the relative operating economics of methanol and diesel
fuels.
EPA has performed an analysis to determine when methanol
fuel might become competitive with diesel fuel for use in
transit buses. Our analysis utilized the" following
assumptions: 1) Methanol buses will need only the addition of
a catalytic converter to meet the 1991 emission standards, 2)
The addition of a converter and a larger fuel tank will raise
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the cost of a methanol bus by approximately $1000, 3) Methanol
buses would achieve energy efficiencies equal to today's
uncontrolled diesel buses, 4) Delivered methanol fuel cost to
transit authorities in the 1990s would be $0.60 per gallon,
based on the large surpluses projected to exist, and 5) Diesel
buses would require particulate traps and NOx emission controls
to meet the 1991 standards, which will raise the cost of diesel
bus engines by $1000 to $3000 and will decrease fuel economy by
from 3 to 9 percent.
Based on these assumptions, the "break-even" diesel fuel
price would be in the range of $1.23 to $1.33 per gallon. In
other words, if diesel fuel cost more than $1.33 per gallon,
then methanol fueling would be cheaper. If diesel fuel cost
less than $1.23 per gallon, then diesel would continue to be
cheaper. Average diesel fuel prices between $1.23 and $1.33
per gallon could result in either methanol or diesel fueling
being more efficient depending upon various factors. Energy
experts still expect world oil prices to climb in the early
1990s, and diesel fuel prices could certainly exceed $1.33 per
gallon by the mid 1990s.
Conclusion
Evidence is mounting that diesel transit bus emissions are
of much greater public health concern that previously
believed. In view of the relatively high public exposure of
urban residents to diesel bus emissions, as well as
Congressional directives to control such emissions, EPA has
promulgated much more stringent emission standards to take
effect in 1991. For the first time, there is a real
alternative to the diesel bus which offers several
environmental advantages. It appears that methanol buses would
provide significant reductions of particulate, smoke, and NOx
emissions, and would likely reduce the ozone-formation
potential of urban atmospheres. Methanol bus engine
efficiencies are expected to equal, and possibly exceed, those
of diesel bus engines, and based on current energy price
projections methanol buses could be cheaper to operate by the
mid 1990s. EPA supports methanol bus research by the
automotive industry and strongly urges that transit authorities
consider methanol as one alternative for the 1990s.
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FIGURE 1
Million b/d*
U.S. Oil Supply
Domestic Production
1960
—, > 1 i
1965 1970 1975 1980
Million bid'
Imports
- 20
- 15
- 10
Area of
Uncertainty
- 5
0
1985 1990 1995 2000
* Million barrels/day
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FIGURE 2
Cumulative U.S. International Transaction Balances
Since 1972
Billion
1984 $
-500
-400
-300
-200
-100
0
+ 100
Merchandise
Trade
Current
Account
1972 73 74 75 76 77 78 79 1980 81 82 83 84
Year
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FIGURE 3
U.S. Petroleum Consumption
by Sector, 2000
Residential Electricity
and Commercial
Industrial
Transportation
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Table 1
EPA Transit Bus Engine Emission Standards
(g/bhp-hr over EPA transient engine test)
Current engines
1985-1987 standard
1988-1990 standard
1991 and later standard
HC
CO
NOx
PM
0.5 to 1.0
1 to 5
5 to 9
0.4 to 0.8
1.3
15.5
10.7
none
1.3
15.5
6.0
0.6
1.3
15.5
5.0
0.1
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Table 2
Recoverable Fossil Fuel Resource Distribution in the United States
Percentage of Total Percentage of Total
Recoverable Fossil Recoverable Fossil
Resource Fuel Energy* Fuel Energy-f
Coal 91.2 81.7
Oil Shale 2.8 12.9
Crude Oil 2.2 2.0
Conventional Natural Gas 2.2 2.0
Unconventional Gas 1.6 1.4
~Including only those oil shale resources containing over 30
gallons of oil per ton.
+Including only those oil shale resources containing over 15
gallons of oil per ton.
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Table 3
Diesel Bus Engine vs. Chassis Emissions
{EPA transient test procedures)
New Diesel In-Use Diesel
Bus Engines Bus Chassis
Pollutant (g/bhp-hr) (g/mile)
HC 1.51 3.35
CO 3.22 51.9
NOx 6.25 26.1
PM 0.57 5.52
\
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Table 4
New Diesel vs. Methanol Bus Engine Emissions
(g/bhp-hr)
Pollutant
PM
NOx
CO
Organics
HC
Methanol
Aldehydes
Diesel
Bus Engines
0.57
6.25
3.22
1.61
1.51
0
0.10
MAN Methanol
Bus Engine
0.04
6.60
0.31
0.68
0.001
0.68
0.001
GM Methanol
Bus Engine
0.17
2.20
1.28
1.13
0.15
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Table 5
In-Use Diesel vs. Methanol Bus Chassis Emissions
(g/mile)
Diesel Bus MAN Methanol GM Methanol
Pollutant Chassis Bus Chassis Bus Chassis
PM 5.52 0.09 1.09
NOx 26.1 13.6 7.90
CO 51.9 0.65 107
Organics 3.88 1.40 120
HC 3.35 0.09 1.15
Methanol 0 1.16 116
Aldehydes 0.53 0.15 2.33
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About Cars/Marshall Schuon NVT p$6
Engine Adjusts to Use Methanol or Gasoline
The car looks much like any other
black Lumina Euro sedan There is
the red stnpe along the lower body,
the spoiler on the trunk, the molded
alloy wheels But there are differ-
ences For one thing, there is that out-
rageous red and white legend on the
front doors, the one that screams
Gasolme/Methanol' GM'
And there are the innards, stain-
less-steel this and noncorrosive that
The car is a variable-fuel vehicle,
one of 2,220 that will go to California
in the next two years in a major as-
sault on the tyranny of foreign oil and,
perhaps, as a warnor in the battle for
cleaner air
Right now, though, the gleaming
1990 Chevy four-door lives in my
driveway, and it is an interesting ani-
mal Under the hood, there is a 3 1-
liter V6, and the engine's thirst is
satisfied equally by methanol or by
gasoline
That is the meaning of "variable
fuel," and the heart of the system is a
sensor that detects the amount of
methanol or gasoline in the line and
sends its message to a computer The
computer then alters the engine to op-
erate on what it is being fed
Methanol, a form of alcohol
produced from natural gas or from
coal, has been getting a lot of atten-
tion as a fuel that can supplement do-
mestic supplies in the event of a pe-
troleum cutback, and California is
making a big push for that and for an
end to pollution But, as always, there
are problems
For example, methanol is less vola-
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messuHC regulator
Alcohol-resistant materials allow Chevrolet's variable-fuel vehicle to
run on methanol or gasoline. The combustion mixture is regulated by a
computer that receives signals from the fuel sensor
tile than gasoline, which gives it poor
starting characteristics in cold
weather And it has only about half
the energy of gas, meanmg that it
takes twice as many gallons to get
from here to there
Worse, it costs more — on the order
of $1 50 a gallon And it is devilishly
corrosive
Because of its low volatility, it can
also form a flammable mixture in the
tank at normal temperatures, and
when it burns in an open area under
bright sunlight, it has a nearly invis-
ible flame There are safety concerns
But David Dimick, executive engi-
neer of the General Motors advanced
engineering staff, believes that the
glitches can be worked out, and that
the West Coast experiment will be a
big step forward
"The State of California intends to
buy these cars and to incorporate
them into regular fleet use," he said
"They will be used by utilities and by
government employees, and eventu-
ally will find their way into private
fleets We have some Chevy Corsicas
out there now, and we're learning a
lot "
One of those things is just how cor-
rosive methanol is
The cars' tanks, with built-in flame
arrestors, are made of stainless steel
There are Teflon hoses, special fuel
pumps and anodized fuel-injection
systems But Dimick said G M has
discovered that even the nickel-
plated filler necks were disintegrat-
ing And the gas caps were turning to
lace "We've had to replace the pipes
and the caps with stainless steel," he
said
Another difficulty is methanol's
Methanol is so
corrosive that the gas
caps were turning to
lace.
electrical conductivity, which has
been creating shorts in sender units
and other engine components And
Dimick said, there have been prob
lems with the fuel injectors them-
selves
Then, too, there is methanol's own
problem of pollution While it emits
fewer hydrocarbons than gasoline, it
produces more aldehydes and un
burned fuel So the air-quality benefu
depends on the degree to which those
factors are controlled
"We recognize there's a strong in-
terest in getting the level down,"
Dimick said, "and our intent is to get
significantly lower aldehyde num-
bers on some of those California
cars "
The Lumina in the driveway, mean-
while, seems to run very well indeed,
whether on methanol or on gasoline
And it is hard to tell the difference, al-
though the alcohol fuel does seem to
make the car feel its oats •
That has been proved in testing,
'Dimick said, and the V6's Q5 horse-
power jumps by about 7 percent when
the car is running on methanol
That fuel, incidentally, is rarely 100
percent alcohol Because of the inher-
ent dnveability and cold-start prob-
lems, a small amount of gasoline
(about 15 percent) is added
While the California cars will have
dashboard gauges to indicate the
exact percentage of alcohol running
through the engine, the gauge is miss-
ing on this car and a fill-up with gaso-
line made the mix only roughly 50-50
The nice thing of course, is that you
can put any mix of gas or alcohol into
the tank and the car will do the rest
The bad thing, and one of the major
stumbling blocks in the alternative-
fuel effort, is that methanol stations
are so few and far between
Chevrolet was taking no chances on
that count, however The engineers
filled the car in Detroit and brought u
to New York on a flatbed truck
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