Report

Federal Alternative Motor Fuels Programs

Fourth Annual Report to Congress

July 1995

U.S. Department of Energy

Office of Transportation Technologies

Office of Energy Efficiency and Renewable Energy

T OF ENERGY

DEPARTMEN

U

E

NITED STAT S OFA ERICA

M
Federal Alternative Motor Fuels Programs

Fourth Annual Report to Congress

July 1995

U.S. Department of Energy

Office of Transportation Technologies

Office of Energy Efficiency and Renewable Energy

UNITED STATES OF AMERICA

• DEPARTMENT OF ENERGY •
The U.S. Department of Energy

gratefully acknowledges the cooperation of the participating

Government agencies in the

Alternative Motor Fuels Programs—

the General Services Administration,

the National Highway Traffic Safety

Administration, the Environmental

Protection Agency, and the many

other Federal agencies that are

operating these vehicles and supplying valuable information on their

operation. The Department also

acknowledges the participation and

cooperation of the vehicle and

engine manufacturers, fuel suppliers,

private fleet operators, and state and

local transit companies. All involved

have worked to make this program

a success.

ii

Acknowledgments

“. . . the displacement of energy

derived from imported oil with

alternative fuels will help to

achieve energy security and

improve air quality.”

— Alternative Motor

Fuels Act of 1988
Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Summary of Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Establishing the Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

The Program Partnership . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Light-Duty Vehicles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Performance and Reliability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Fuel Economy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

Transit Buses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31

Performance and Reliability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

Fuel Economy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

Heavy-Duty Vehicles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

Performance and Reliability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47

Fuel Economy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48

Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50

Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53

Safety Incidents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53

Infrastructure Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55

Refueling Sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55

Maintenance Facilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57

Vehicle Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57

Where We Are . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58

Vehicle Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59

Alternative Fuel Vehicles in Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59

Vehicle Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60

Information Dissemination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63

The Alternative Fuels Data Center . . . . . . . . . . . . . . . . . . . . . . . . . . . .63

Market Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64

Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

Contents

iii
Abstract

This annual report to Congress presents the current status of the alternative fuel vehicle programs being

conducted across the country in

accordance with the Alternative

Motor Fuels Act of 1988. These programs, which represent the most

comprehensive data collection effort

ever undertaken on alternative fuels,

are beginning their fifth year. This

report summarizes tests and results

from the fourth year.

Summary of Results

Light-Duty Vehicles

The test program for light-duty vehicles analyzes the emissions, performance and reliability, fuel economy,

and cost of passenger cars, minivans,

and light vans and trucks that run on

alternative fuels, and compares the

results to similar control vehicles

that run on gasoline. The alternative

fuel vehicles being tested run on

either alcohol fuels (ethanol or

methanol) or on compressed natural

gas (see sidebar, page 5). The alcohol vehicles are actually flexible-fuel

vehicles—they are designed to run

on various mixtures of alcohol and

gasoline or on gasoline alone. In

contrast, the compressed natural gas

vehicles tested this year are designed

to run only on their designated fuel.

In 1994, the program collected data

on 603 vehicles that operate on

alternative fuels and 243 control

vehicles that operate on gasoline

only. The models being tested

include Chevrolet Luminas, Dodge

Spirits, Ford Tauruses, Chevrolet C2500 pickups, Dodge B-250 vans,

and Ford Econoline vans. Of the

alternative fuel vehicles, 45 are

designed to run on E85 (a mixture of

85 percent ethanol and 15 percent

gasoline), 338 are designed to run on

M85 (a mixture of 85 percent

methanol and 15 percent gasoline),

and 220 are designed to run on compressed natural gas. 

Emissions

Using standard testing procedures,

the program tests and compares the

emissions of vehicles running on

alternative fuels to those of vehicles

operating on reformulated gasoline.

The emissions results are also compared to the 1996 Federal emissions

standards (known as Tier 1), which

mandate the maximum allowable

emissions for regulated pollutants on

a basis of grams per mile. The regulated pollutants are hydrocarbons,

non-methane hydrocarbons, carbon

monoxide, and oxides of nitrogen. 

Of the 279 vehicles to be tested in

Phase II, the program has tested 146

vehicles to date. The results of the

measurements made to date are summarized in Figure 1. With the exception of Ford Econoline vans running

on 85 percent methanol, the emissions for every kind of alternative

1

Executive Summary
fuel vehicle tested were below the

Tier 1 standards for every pollutant.

The emissions from the Ford

Econoline vans running on 85 percent methanol exceeded the standard

for oxides of nitrogen by only a

small amount. 

The results also show that, in general, the emissions from the alternative fuel vehicles were less than those

from the control vehicles operating

on reformulated gasoline. The nonmethane hydrocarbon emissions

from vehicles running on natural gas

were considerably lower. However,

total hydrocarbon emissions from

these vehicles were significantly

higher. Methane, which makes up

the difference, does not contribute

significantly to the formation of photochemical smog, but is a highly

active greenhouse gas. In addition,

oxides of nitrogen emissions from

vehicles operating on 85 percent

methanol were slightly higher.

Performance and Reliability

As expected, because the vehicles

operating on alternative fuels are in

an early phase of development, they

have suffered more reliability problems than have gasoline vehicles,

which have a long development history. Also as expected, as the testing

program has progressed and as the

manufacturers have changed their

vehicle designs based on earlier

experience, the new models of alternative fuel vehicles are achieving

a higher level of reliability than

earlier ones.

Fuel Economy

The program measures the fuel economy of light-duty vehicles in two

ways: by testing the vehicles in a

laboratory with a chassis dynamometer and by analyzing refueling

records. All figures are reported as

miles per gasoline equivalent gallon,

which is actually a measure of the

energy efficiency of the vehicle per a

common energy unit. The dynamometer tests are averaged for each

type of vehicle/fuel combination and

reported as a single point. The refueling records indicated a wide range

of miles per unit energy for each

type of vehicle/fuel combination; this

is understandable because the

records indicate “real world” driving

cycles in which the conditions vary

considerably. 

The results of both types of tests

indicate that, for all of the models,

the fuel efficiencies of alternative

fuel vehicles are very close to those

of gasoline vehicles. For example, in

2

Executive Summary

Figure 1. Emissions results for lightduty vehicles

NMHC

HC

NOx

CO

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Dodge Spirit-M85 Dodge Spirit-RFG

Chevrolet Lumina-E85

Chevrolet Lumina-RFG

Dodge B250 Vans-CNG Dodge B250 Vans-RFG

Ford Econoline Vans-M85

Ford Econoline Vans-RFG

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

g/mile
the dynamometer tests, the average

fuel economy for Dodge Spirits running on methanol was about 24

miles per gasoline equivalent gallon,

the same as the average for Dodge

Spirits operating on gasoline. In fact,

the greatest difference in the

dynamometer testing occurred

between pickup trucks running on

compressed natural gas, which

averaged 12 miles per gasoline

equivalent gallon, and those running

on gasoline, which averaged 14

miles per equivalent gallon. 

The greatest disparity for the “real

world” analyses occurred between

Chevrolet Luminas running on

methanol, which ranged between 10

and 29 miles per equivalent gallon,

and Luminas running on gasoline,

which ranged between 20 and 28

miles per equivalent gallon. But this

disparity is probably due to different

driving cycles and driving styles.

Cost

Generally, at this point, the total cost

of owning and operating an alternative fuel vehicle is slightly higher

than that of owning and operating a

vehicle that runs on gasoline. Total

vehicle cost includes costs for acquisition, maintenance, insurance, fuel,

and oil. 

For alcohol vehicles, fuel costs are

higher than those for gasoline vehicles, but the incremental cost of

acquisition is relatively low. For

vehicles that run on compressed natural gas, on the other hand, fuel costs

are lower than gasoline while incremental vehicle acquisition costs are

significantly higher.

Transit Buses

The test program for transit buses

analyzes the emission levels, fuel

economy, reliability, and operating

cost of a sample of transit buses currently operating on alternative fuels.

Currently, the program is testing 98

buses in 7 metropolitan areas. Forty

of these buses run on diesel fuel

using standard diesel engines from

Detroit Diesel Corporation and

Cummins Engine Company. Five use

standard diesel engines, but operate

on B20, a blend of 20 percent

biodiesel and 80 percent conventional diesel fuel. B20 is not considered

an alternative fuel under the Energy

Policy Act of 1992.

Twelve of the buses use diesel

engines with a particulate trap. And

40 use engines modified to run on

alternative fuels: liquefied natural

gas (dual-fuel engines that also operate on diesel), compressed natural

gas, 100 percent methanol, and 95

percent ethanol.

Emissions

Two types of tests are used to measure emissions. The first is an engine

dynamometer that tests only the

engine, to certify it for operating on

specific fuels. The second is a chassis dynamometer in which the entire

bus is tested in a laboratory according to a standard Central Business

District driving cycle. The buses are

tested for the same pollutants as are

the light-duty vehicles, as well as for

emissions of particulate matter, and

are compared to heavy-duty

standards.

At this time the program has used

the engine dynamometer to certify

3

Executive Summary
two versions of the Detroit Diesel

6V92TA engine: the standard engine

for operating on diesel and an engine

modified to run on methanol.

Certification data for the methanol

engine indicate that its emissions are

well below the standards set by the

Environmental Protection Agency

and that they are also generally well

below the emissions from the standard Detroit Diesel 6V92TA diesel

engine.

The initial results of the chassis

dynamometer tests for buses using

Detroit Diesel engines are quite variable and inconclusive. Nonetheless,

we can observe that buses using

alcohol generally emit fewer oxides

of nitrogen and less particulate matter, but more hydrocarbons and carbon monoxide than do buses using

diesel. 

Similarly, although buses running on

engines from Cummins Engine

Company may still be considered to

be demonstration units, we can make

the general observation that those

using compressed natural gas emit

less particulate matter and more

hydrocarbons than those using

diesel. The additional hydrocarbon

emissions from the natural gas vehicles are probably mostly methane,

which is not reactive. Plans are to

include the measure of methane in

future emissions testing.

Fuel Economy

The fuel economy of buses,

expressed in miles per diesel equivalent gallon, was measured in a fashion similar to that of light-duty

vehicles—with a chassis dynamometer (using a Central Business

District driving cycle) and by analyzing refueling records.

The results from the chassis

dynamometer tests indicate that there

is very little difference between the

average fuel efficiency of buses

using alternative fuels and those

using diesel. The greatest difference

occurred in Tacoma, Washington,

where buses running on compressed

natural gas averaged a little more

than 3 miles per equivalent gallon,

whereas those using diesel averaged

a little less than 4 miles per equivalent gallon.

The results from the refueling

records suggest that the fuel

economies varied from site to site,

that those sites with narrow ranges in

fuel economy for diesel engines

tended to have tight ranges for alternative fuel engines, and that fuel

economies of alternative fuel engines

were similar to those of diesel

engines for a given site.

Reliability

Using road calls per 1,000 miles as a

measure of reliability, no general

trend has emerged. We can note,

however, that the dual-fuel buses in

Houston that run on liquefied natural

gas and diesel required far more road

calls than the control buses running

on diesel. Much of this can be attributed to the buses running out of fuel.

If a fuel problem develops with the

liquefied natural gas, the dual-fuel

engines are designed to run on diesel

as a backup. In this case, the bus

runs out of fuel in a short time

because of the small size of the

diesel tank. We also note that the

ethanol buses in Peoria report slightly

4

Executive Summary
fewer road calls than their diesel

counterparts. For the buses tested in

the three other cities we can make no

confident conclusion because of the

small number of miles traveled by

the alternative fuel buses.

Cost

With the exception of the Tacoma

buses operating on compressed natural gas, alternative fuel buses tend

to have higher total acquisition and

operations costs than their diesel

counterparts, often appreciably higher. This can be attributed to higher

acquisition prices (because of the

modified, developmental engines and

fuel tanks), and to higher maintenance costs (for some of the engine

types). As more alternative fuel

engines are built and sold, and as

more experience is gained, maintenance costs and incremental engine

costs should decrease. 

In Tacoma, on the other hand, compressed natural gas is relatively

inexpensive and the maintenance

cost for buses that use the compressed natural gas is comparable to

that of the diesel controls.

Medium- and Heavy-Duty

Vehicles

The heavy-duty vehicle program

collects and analyzes data on the

emissions, fuel economy, and cost

of two types of vehicles: mediumduty commercial delivery vans and

large trucks. For large trucks, the

program also analyzes performance

and reliability.

The program currently tracks 134

Chevrolet, Dodge, and Ford delivery

vans from two commercial fleets: the

5

Executive Summary

The Alternative Fuels Being Tested

In all, the three programs being managed by the Department of Energy

are testing six kinds of alternative fuels: methanol, ethanol, biodiesel,

compressed natural gas, liquefied natural gas, and propane. What are

these alternative fuels and why are we testing them?

Methanol. Methanol is an alcohol derived primarily from natural gas,

but it can also be derived from biomass or coal. Thus the potential

domestic resource base for methanol is vast. Methanol’s combustion

holds the promise of producing less carbon monoxide and non-methane

hydrocarbons than gasoline and less particulate matter than diesel. It

may also be converted into methyl tertiary butyl ether and then used as

a high-octane, oxygenated additive with gasoline.

Ethanol. Ethanol is an alcohol derived from biomass (corn, sugar cane,

grasses, trees, and agricultural waste). The potential domestic resource

base for ethanol is also vast. Ethanol’s combustion promises emissions

similar to those from methanol. And, like methanol, it also can be used

to make a high-octane, oxygenated ether.

Biodiesel. As tested in this program, biodiesel is actually 80 percent

conventional diesel and 20 percent diesel derived from biomass,

microalgae, or agricultural waste. Although it has properties similar to

conventional diesel fuels, its potential value derives from the fact that

its production can be based on a domestic and renewable resource

base. 

Compressed Natural Gas and Liquefied Natural Gas. Natural gas is

primarily methane (approximately 93 percent) with a mixture of other

gaseous hydrocarbons. It is derived from gas wells or in conjunction

with crude oil production. The United States has proven natural gas

reserves of approximately 170 trillion cubic feet; current natural gas

consumption is primarily (89 percent) derived from domestic sources,

with the remainder coming mainly from Canada. Relative to gasoline,

the combustion of natural gas promises to cut emissions of carbon

monoxide and non-methane hydrocarbons. The difference between the

compressed and liquefied versions of natural gas lies in the phase in

which they are stored. To obtain the liquefied version, the gas must be

cooled considerably and stored in insulated tanks.

Propane. This is a gas composed primarily of propane and other

gaseous hydrocarbons. It is extracted from natural gas or refinery gas

streams. Its emissions are expected to be similar to those of natural gas.
Federal Express CleanFleet and the

United Parcel Service Fleet. Twenty

of these vans run on 85 percent

methanol, 20 on propane, 41 on

compressed natural gas, 21 on reformulated gasoline, and 32 (the control

group) on standard unleaded gasoline.

The program is also tracking 21

large trucks. Seven of these operate

on compressed natural gas, 8 on 95

percent ethanol, and 6 (the control

group) on standard diesel. Also, 7 of

the trucks are used for line haul, 5

for road maintenance, and 9 for

hauling garbage.

Emissions

Using chassis dynamometers and the

Federal Test Procedure, the program

is testing 36 of the Federal Express

CleanFleet vans for emissions of

hydrocarbons, non-methane

hydrocarbons, carbon monoxide, and

oxides of nitrogen.

With some variance, the vehicles

operating on alternative fuels generally emitted less carbon monoxide,

fewer non-methane hydrocarbons,

and more total hydrocarbons than

vehicles running on standard unleaded gasoline (Figure 2). In addition,

with few exceptions, the Dodge and

Ford vans operating on alternative

fuels met the Tier 1 emission standards for all pollutants. Chevrolet

alternative fuel vans, however, did

not consistently meet the standards

for all regulated emissions.

During 1994, the program also

devised a new driving cycle with

which to use a chassis dynamometer

to test the emissions of large trucks.

It is currently using the new cycle to

test the emissions from some of the

line-haul trucks in the program. The

results to date are preliminary, and it

is not yet known whether this new

cycle will become the emissions testing standard for large trucks. 

Performance and Reliability 

The program collects data on maintenance and repair records of the

large trucks and tests their performance on characteristics such as

acceleration, hill climbing, driveability, and driver acceptance. This part

of the testing program is in its preliminary stages, and the data

recorded thus far are serving primarily to identify issues and to help

manufacturers make design improvements in their engines.

6

Executive Summary

Figure 2. Emissions results from

the CleanFleet

NMHC

HC

NOx

CO

0

2

4

6

8

10

Ford Vans-M85

Ford Vans-Gasoline

Dodge Vans-CNG

Dodge Vans-Gasoline

Chevrolet Vans-Propane

Chevrolet Vans-Gasoline

0

2

4

6

8

10

g/mile
Fuel Economy

The program measures the fuel economy of trucks in two ways: by analyzing refueling records and by

performing chassis dynamometer

measurements. The fuel economy is

measured in terms of miles per gasoline equivalent gallon for delivery

vans and miles per diesel equivalent

gallon for large trucks.

For the large trucks, most of the fuel

economies for the alternative fuel

vehicles were comparable to those of

their diesel counterparts. However,

the fuel economy of a line-haul truck

using a Caterpillar 3406 engine modified for compressed natural gas was

considerably lower than its diesel

counterpart. The engine has recently

been retrofitted to address the discrepancy.

For the delivery vans, Dodges and

Chevrolets operating on compressed

natural gas and on propane tended to

have fuel economies that were 10

percent to 15 percent lower than

their unleaded gasoline counterparts.

All alternative fuel Ford delivery

vans, however, had fuel economies

comparable to their gasoline counterparts.

Cost

As with the buses and light-duty

vehicles, the cost to acquire, operate,

and maintain alternative fuel

heavy-duty vehicles tends to be

greater than that to operate and

maintain vehicles using conventional

fuel. This is largely because of the

additional vehicle acquisition cost

and the cost of fuel.

Summary

In summary, these programs have

made significant progress in comparing alternative fuel vehicle performance with that of their conventional

counterparts. The data gathered to

date clearly show the promise that

alternative fuel vehicles offer the

nation’s future in terms of economic

stability, energy independence, and

improved air quality. Widespread

acceptance and use of these vehicles

will reduce our dependence on

imported petroleum, enhance our

national security, improve environmental quality, and potentially create

thousands of jobs through the displacement of imported petroleum

with domestically produced alternative fuel. However, much work

remains to be done before this

promise becomes reality. We have

many more miles to go in these programs to increase the confidence

level of the findings and to fully

evaluate the true potential of these

vehicles.

7

Executive Summary
8
Establishing the Programs

In 1988, Congress passed the

Alternative Motor Fuels Act, Public

Law 100-94. Recognizing that the

displacement of energy derived from

imported oil with alternative fuels

will help achieve energy security and

improve air quality, the lawmakers

designed this legislation to encourage the development of vehicles that

could run on alternative fuels, such

as methanol, ethanol, and

natural gas.

Public Law 100-94 amended Title III

of the Energy Policy and Conservation Act (the Act) by adding a part

(Part J) that directed the Department

of Energy to cooperate with other

agencies to acquire and operate vehicles that use alternative fuel (42

U.S.C. 6374, et seq.). The amendment also required the Department

of Energy to conduct a study of the

performance, fuel economy, emissions, and costs of these vehicles in

comparison with those that run on

conventional fuels, and to provide to

Congress an annual report of that

study (see sidebar, page 11). This is

the fourth annual report on the study

program set up by the Department of

Energy.

The Programs

In 1990, under the provisions of the

Act, the Department of Energy cooperated with other Federal agencies to

establish three programs of study:

• The Alternative Fuel Light-Duty

Program. In this program, established under section 400AA of the

Act (42 U.S.C. 6374), the General

Services Administration annually

purchases a practicable number of

passenger cars and light-duty

trucks and vans for use in the

fleets of various agencies of the

Federal Government. The

Department of Energy cooperates

with vehicle manufacturers, vehicle dealerships, government agencies, test laboratories, and others

to collect and analyze data on a

selected subset of these vehicles

and compares these data with data

collected from vehicles operating

on gasoline. The vehicles are

operated at various locations

across the nation (Figure 3) to

capture the effects of climatic conditions and altitude on vehicle

operation and maintenance.

This program studies vehicles that

operate on methanol, ethanol,

compressed natural gas, and gasoline. Those operating on methanol

or ethanol are actually flexiblefuel vehicles, which means that

they can operate on their

designated alcohol, on gasoline, or

on any mixture of the alcohol (up

to 85 percent) and gasoline. Those

operating on compressed natural

gas or gasoline are dedicated vehicles, which means they operate

only on the fuel for which they

are designated. Those dedicated

9

Background
vehicles operating on gasoline are

control vehicles that serve as a

baseline for comparison.

• The Alternative Fuels Transit Bus

Testing Program. In this program,

established under section 400CC

of the Act (42 U.S.C. 6374b), the

Department of Energy cooperates

with test laboratories, engine and

chassis manufacturers, government agencies, transit authorities,

and others to test the operation

and maintenance of alternative

fuel buses in seven municipalities

across the nation. 

The program tests vehicles with

engines and fuel systems modified

to run on methanol, ethanol, liquefied and compressed natural gas,

and biodiesel. The buses running

on conventional diesel fuels are

used as a basis for comparison.

The buses in the program running

on liquefied natural gas also

require diesel fuel as a pilot ignition source. All the other types of

alternative fuel buses in the program are dedicated to run on the

fuel for which they are modified. 

The bus test program should

prove quite valuable for transit

authorities. This is because,

according to a survey conducted

by the American Public Transit

Association, the bus sector of the

market is well ahead of other sectors in the market penetration of

alternative fuel vehicles.

Approximately 50,000 transit

buses in the United States run on

alternative fuels; this represents

about 5 percent of the bus market.

But until the inception of this program, no systematic data were

collected on the operation and

maintenance of these vehicles.

Also, a transit bus is an ideal

application of alternative fuels

because the buses are centrally

refueled (requiring less infrastructure development), and because

extra space is generally available

on a bus to store the sometimes

bulky fuel tanks. This makes it

possible that the market for alternative fuel vehicles could grow

faster for buses than for smaller

vehicles, a possibility that makes

good data all the more crucial.

• The Alternative Fuels Truck

Commercial Application Program.

Also known as the alternative

fuels heavy-duty vehicle program,

this program was established

under section 400BB of the Act

(42 U.S.C. 6374a). Under this

program, the Department of

Energy is cooperating with municipalities, state and local governments, other Federal agencies, and

private fleet operators to test the

real-life operation and maintenance

of two types of vehicles running

10

Background

Figure 3. Under the programs established by the Act, alternative fuel

vehicles are being tested at a variety of

locations across the United States.
on alternative fuels: commercial

delivery vans and heavy trucks. 

The program tests trucks and vans

running on methanol, ethanol, compressed natural gas, and propane. (In

general, the vehicles are dedicated to

running on a specific type of fuel.)

It compares the data from these vehicles with data from control vehicles

operating on unleaded or reformulated gasoline for the delivery vans and

diesel fuel for the heavy trucks.

Because large trucks are typically

very expensive, the program shares

the cost of the test vehicles with private fleet owners or state or local

governments. The program’s heavy

test trucks are modified to run on

methanol, ethanol, compressed natural gas, or biodiesel. The goal of

this part of the program is to test as

many of the currently available alternative fuel engines as possible and to

compare the cost and performance of

these engines with that of standard

diesel engines. 

For commercial vans, the program is

tracking two delivery fleets: the

Federal Express CleanFleet, and the

United Parcel Service Fleet. The

Federal Express CleanFleet includes

vehicles operating on compressed

natural gas, propane, and 85 percent

methanol. The only alternative fuel

used by vehicles in the United Parcel

Service fleet is compressed natural

gas. The program collects data from

these vehicles and compares the

information to that collected from

vehicles using similar engines but

operating on unleaded gasoline or

reformulated gasoline. 

The Program Partnership

Although the Act assigns to the

Department of Energy the responsibility for testing the vehicles and

reporting the results to Congress,

these programs are truly a partnership among a variety of parties ranging from automobile manufacturers

to Federal agencies to national laboratories to cities to private fleet operators. Each has an important role to

play and a vested interest in seeing

the job come to a successful conclusion:

• The Department of Energy manages the programs and cooperates

with other Federal agencies, state

and local governments, and private companies to ensure the

smooth operation of the programs.

• The National Renewable Energy

Laboratory is the field manager

for the testing programs. The laboratory coordinates the testing

efforts, collects all the data at its

Alternative Fuels Data Center,

analyzes and summarizes the data,

and makes the information available to all interested and qualified

parties.

• The General Services Administration purchases many of the

vehicles to be used in the programs and then distributes them to

the various Federal agencies, who

use them in their fleets and participate in the testing programs.

• The Environmental Protection

Agency sets regulations for

emissions and defines standard

methods for measuring those

emissions. 

11

Background

The Alternative Motor

Fuels Act of 1988

Congress passed the Alternative

Motor Fuels Act to encourage—

(1) the development and widespread use of methanol,

ethanol, and natural gas as

transportation fuels by consumers; and

(2) the production of methanol,

ethanol, and natural gas powered motor vehicles.

The Act directs the Secretary of

Energy to cooperate with the

Environmental Protection

Agency and the National

Highway Traffic Safety

Administration to conduct a

study of alternative-fueled vehicles, which shall address—

(i) the performance of such

vehicles, including performance in cold weather and at

high altitude;

(ii) the fuel economy, safety, and

emissions of such vehicles;

and

(iii) a comparison of the operation and maintenance costs

of such vehicles to the operation and maintenance costs

of other passenger automobiles and light-duty trucks.

The Act also directs the Secretary

of Energy to provide a report on

this study to the Committees on

Commerce, Science, and

Transportation and Governmental

Affairs of the Senate, and to the

Committee on Commerce of the

House of Representatives, within

one year after the first such vehicles are acquired, and annually

thereafter.
• Original equipment manufacturers—such as General Motors,

Chrysler, Ford, Detroit Diesel

Corporation, and Cummins—

design and modify engines and

vehicles to operate on alternative

fuels. They also help to test the

engines and vehicles and collect

data, which they send to the

Alternative Fuels Data Center.

• Automobile dealers keep records

on the maintenance and repairs

they perform on light-duty vehicles in the test program. These

records are forwarded to the

Alternative Fuels Data Center for

compilation; they are also used by

the program and by the vehicle

manufacturers to help determine

the redesigns that may be necessary to overcome recurrent problems with vehicle types. 

• Several municipal transit agencies

take part in the transit bus program, maintaining, refueling, and

repairing buses that run on alternative fuels. They then forward

their records on bus operation and

maintenance to the Alternative

Fuels Data Center. The transit

agencies also cooperate with test

laboratories that visit their facilities to measure the emissions and

fuel economy of the buses.

• Some municipalities cooperate in

the program for testing heavyduty vehicles by, for example,

operating and maintaining garbage

trucks that run on alternative

fuels. They forward all records to

the Alternative Fuels Data Center

for compilation. Many municipalities are interested in exploring

options to relieve pollution and

thus help prove and test the

vehicles.

• A variety of Federal agencies also

cooperate with the Department of

Energy and the General Services

Administration by planning the

purchase of alternative fuel vehicles for their fleets and then using

some of these vehicles in the test

programs. 

• The program for heavy-duty vehicles collects data from two companies that use alternative fuel

delivery vans in their commercial

fleets.

• Private test laboratories in several

states have contracted with the

Department of Energy to test the

emissions and fuel economy of

vehicles being used in the program. They use dynamometers to

perform standardized tests; collect, analyze, and reduce the data;

and send the data to the

Alternative Fuels Data Center for

compilation and further analysis

and reduction. 

• West Virginia University travels to

the various municipalities, taking

part in the programs for heavyduty vehicles and transit buses.

The university uses its transportable chassis dynamometer to

measure the emissions and fuel

economy of the trucks and buses.

• The University of Missouri gathers data on the operation and

maintenance of the buses in

St. Louis running on biodiesel and

transfers the data to the

Alternative Fuels Data Center.

12

Background
• Drivers of many of the test vehicles also gather data on refueling,

mileage in real-world situations,

and problems encountered.

13

Background
14
Overview

The test program for light-duty vehicles was designed to respond to the

requirements of section 400AA of

the Energy Policy and Conservation

Act to study emissions, maintenance,

safety, and fuel economy on passenger cars, minivans, and light vans

and trucks that operate on alternative

fuels. The Alternative Motor Fuels

Act directs the General Services Administration to purchase these vehicles from manufacturers that make

the original vehicles. The General

Services Administration is the

Federal agency primarily responsible

for purchasing alternative fuel vehicles for use in the Federal fleet. 

Alternative fuel vehicles built by the

manufacturers are either “flexiblefuel” or “dedicated.” Flexible-fuel

vehicles can run on more than one

fuel type or a mixture of fuel types.

All alcohol vehicles currently in the

program are flexible-fuel vehicles—

they are able to run on gasoline

alone or on various mixtures of gasoline and the alcohol fuel for which

they are modified (ethanol or

methanol). Relatively minor design

modifications are needed to turn a

gasoline vehicle into a flexible-fuel

alcohol vehicle. Changes include

using alcohol-resistant materials in

the fuel system, adding a fuel sensor,

and replacing the engine microprocessor with one designed specifically

for flexible-fuel control.

The compressed natural gas vehicles

in the program are dedicated

vehicles—they can operate only on

compressed natural gas. Because a

gaseous fuel is used, these vehicles

require more modifications than the

flexible-fuel alcohol vehicles. The

fuel tank is replaced by high-pressure

gas cylinders, which require a fuel

pressure regulator. Other changes

include adding a fuel temperature

sensor, a pressure relief device, and a

new fuel induction system.

The models

available from

the manufacturers

change each

year, and the

General

Services

Administration

purchases

replacement

vehicles yearly.

The agency

strives to purchase as many alternative fuel vehicles as budget and availability will

allow. The General Services

Administration leases the vehicles to

Federal agencies and their contractors, who operate the vehicles in

standard Federal work duty.

Table A-1 in the Appendix lists the

42 Federal agencies participating in

the program.

Refueling a flexible-fuel 85 percent

methanol Chevrolet Lumina

15

Light-Duty

Vehicles
16

Figure 5. Locations of light-duty

test vehicles

Figure 4. Vehicles in the

1994 test fleet

The Act requires data collection on a

representative subset of the alternative fuel vehicles in the Federal fleet.

Of several thousand vehicles in the

Federal fleet, the program is collecting data on 603 vehicles that operate

on alternative fuels and on 243

that operate on gasoline only,

which serve as a control group

(see Figure 4). Also, because

emissions, maintenance, safety,

and fuel economy can be

affected by climatic conditions

and altitude, the program

collects data on different

types of vehicles at various

locations around the country

(see Figure 5).

Each year, the program adds

vehicles to its data collection effort

only if the vehicles differ in design

from those already in the program.

This year the program added 1994

Dodge minivans (dedicated compressed natural gas), 1994 Dodge B250 vans (dedicated compressed

natural gas), and 1994 Ford Tauruses

(flexible 85 percent ethanol).

The General Services Administration

usually requires passenger cars to be

removed from service after 3 years

and vans and trucks to be removed

after 7 years. Accordingly, this year

the program removed from service

its 1991 Ford Tauruses and its 1991

Chevrolet Luminas (both are flexible

85 percent methanol). The 39 Ford

Tauruses were converted to dedicated gasoline vehicles and sold at a

General Services Administration

auction. Five of the Chevrolet

Luminas were moved to the National

Renewable Energy Laboratory for

additional testing. The other 20

Luminas were sold at a General

Services Administration auction.

The program also removed its 1992

Chevrolet C-2500 pickups from service (dedicated compressed natural

gas). Although these pickup trucks

were not scheduled to be removed

from service for several years,

General Motors recalled them

through a repurchase program after

two vehicles (outside the Federal

fleet) experienced fuel-tank failures. 

Since the program’s inception in

1991, experience with alternative

fuel vehicles has grown steadily.

This can be seen in the cumulative

miles traveled by vehicles in the

program (see Figure 6). Table A-2 in

the appendix summarizes the status

of the current test fleet.

To fulfill the requirements of the Act,

the program collects data from

drivers, maintenance facilities, the

General Services Administration, and

emissions laboratories. Drivers

report mileage, fuel usage, and

performance problems. The program

collects maintenance data from

General Services Administration

records, which it supplements with

repair invoices from the service

Light-Duty Vehicles

Gasoline

243 vehicles

Methanol flexible-fuel

338 vehicles

Compressed

natural gas

220 vehicles

Ethanol flexible-fuel

45 vehicles
17

Figure 6. Light-duty vehicle mileage

accumulation

departments of vehicle dealerships.

Periodically, the program removes a

subset of the vehicles for emissions

testing; this testing is performed by

laboratories approved by the

Environmental Protection Agency. 

The following sections analyze

the emissions, performance and

reliability, cost, and fuel economy of

light-duty vehicles in the test program.

Emissions

Emissions measurement is the single

most comprehensive part of the test

program for light-duty vehicles. The

effort extended here is also the most

extensive and carefully controlled

study of emissions of alternative fuel

vehicles in the world. The data

collection activities, which are essential to fully ascertain the long-term

emissions of light-duty vehicles

operating on alternative fuels, may

be divided into two parts: Phase I

and Phase II.

Phase I Emissions Testing

Phase I testing began in 1991 and

lasted through 1994. The program

tested 18 vehicles during this

phase—7 flexible-fuel Luminas, 2

gasoline Luminas, 7 flexible-fuel

Tauruses, and 2 gasoline Tauruses.

Each vehicle was tested at odometer

readings of 4,000 and 10,000 miles,

and subsequently at 10,000-mile

intervals. Nationally recognized

facilities tested the vehicles using

chassis dynamometers (see sidebar,

page 18) to measure emissions

according to the Federal Test

Procedure - Code of Federal Regulations, Title 40, Part 86,

Emissions Certification and Test

Procedures.

The program stopped testing these

vehicles when the General Services

Administration removed the vehicles

from its fleet. The National

Renewable Energy Laboratory,

however, obtained several of the

original vehicles to continue the

emissions tests at higher mileage

levels.

Last year, the Third Annual Report to

Congress presented the detailed

emissions results from Phase I.

Because of the small number of

vehicles tested, the availability of

only 85 percent methanol vehicles,

and the variability of results in

Phase I, the conclusions presented

were limited. Phase II was designed

to address the problems encountered

in Phase I.

Phase II Emissions Testing

To achieve a higher level of statistical certainty and to obtain results

from a wider range of alternative

Light-Duty Vehicles

9,000,000

8,000,000

7,000,000

6,000,000

5,000,000

4,000,000

3,000,000

2,000,000

1,000,000

Jan-91

Mar-91

May-91

Jul-91

Sep-91

Nov-91

Jan-92

Mar-92

May-92

Jul-92

Sep-92

Nov-92

Jan-93

Mar-93

May-93

Jul-93

Sep-93

Nov-93

Jan-94

Mar-94

May-94

Jul-94

Sep-94

Controls M85 E85 CNG

Mileage (millions of miles)

Abbreviations

CNG = Compressed natural gas

CO = Carbon monoxide

HC = Hydrocarbons

LNG = Liquefied natural gas

NMHC = non-methane hydrocarbons

OMNMHCE = Organic material

non-methane hydrocarbon equivalent

NOx = Oxides of nitrogen

PM = Particulate matter

RFG = Reformulated gasoline

E50 = 50 percent ethanol

E85 = 85 percent methanol

E93 = 93 percent ethanol, 5 percent

methanol, and 2 percent kerosene

E95 = 95 percent ethanol

M50 = 50 percent methanol

M85 = 85 percent methanol

M100 = 100 percent methanol
18

Light-Duty Vehicles

Emissions Testing Procedures

Before testing begins, the laboratory puts each vehicle through a detailed preconditioning procedure. This

ensures that the vehicle is running only on the test fuel and that each car tested has the same recent driving history. The vehicle is then allowed to cool for 12 to 36 hours before testing. The Federal Test Procedure includes

three tests: an evaporative emissions test while the vehicle is cold, a tailpipe emissions test while the vehicle is

going through a driving cycle, then another evaporative emissions test after the vehicle has gone through the driving cycle and is at operating temperature.

For the evaporative emissions tests, operators put the vehicle in a sealed enclosure and measure the hydrocarbons that leak from the vehicle. Tailpipe emissions are measured while the vehicle is on a chassis dynamometer,

a system that uses rollers to simulate driving conditions within a laboratory. This test lasts about 40 minutes.

Beginning with a cold start, a driver closely follows a predetermined speed versus time curve while the

dynamometer puts varying loads on the tires. This simulates the loads on a car during actual driving. After about

22 minutes, the driver turns the car off for 10 minutes, restarts it, and then follows another speed versus time

curve while the dynamometer again varies the load on the tires. During the test, the system automatically

measures emissions and fuel economy.

Immediately following

this test, the laboratories

subject the vehicles to an

inspection and maintenance 240 procedure to

test emissions. This is a

chassis dynamometer test

similar to the Federal

Test Procedure, except

that it lasts for only 4

minutes. Originally

designed for private

vehicles, this test is done

with the vehicle at operating temperature

because cars will be

warmed up when they

come in for emissions

testing. To determine the

value of the inspection

and maintenance 240 test

for low-emissions alternative fuel vehicles, the

program is correlating its

results with those of the

40-minute test.

With a chassis dynamometer, the drive wheels of a test vehicle are supported by rollers that

simulate driving conditions. Fuel economy and emissions are measured while driving on

the dynamometer.
fuels, the program initiated Phase II

emissions testing in 1994. This phase

calls for testing 279 vehicles; 146 of

these are already being tested.

For this phase, the program used a

competitive procurement to select

the laboratories that were to perform

emissions testing. The selection

criteria included technical expertise

(including experience in testing alternative fuel vehicles) and cost. The

program selected Environmental

Research & Development to test

vehicles from the Washington, D.C.,

and New York regions; Automotive

Testing Laboratories, Inc. to test

vehicles from the Detroit and Chicago

regions; and ManTech Environmental to test vehicles from the

Denver region. The Denver test site

will yield a high-altitude comparison

on emissions performance.

The laboratories test the vehicles at

the same odometer readings as in

Phase I, using chassis dynamometers

and the Federal Test Procedure. In

addition, they are also using the

Environmental Protection Agency’s

inspection and maintenance 240 test

procedure (see sidebar, page 18).

Phase II is also different from Phase

I in that the program is now testing

several types of vehicles: flexiblefuel vehicles running on 85 percent

ethanol; flexible-fuel vehicles

running on 85 percent methanol;

dedicated vehicles running on compressed natural gas; and vehicles

running on reformulated gasoline.

The reformulated gasoline,

California Phase II Certification Fuel

(see sidebar on page 25) is used to

make a comparison to alternative

fuels.

To compare emission levels at different fuel-mixing ratios, the program

tests the flexible-fuel vehicles on

three fuels: a mixture containing

85 percent alcohol and 15 percent

reformulated gasoline, a mixture

containing 50 percent alcohol and

50 percent reformulated gasoline,

and 100 percent reformulated gasoline. The kind of alcohol used in the

mixtures depends on whether the

vehicle is designed to run on ethanol

or methanol.

For vehicles dedicated to operating

on compressed natural gas, the

program tests them on natural gas

blended from tightly controlled

constituent gases (93.05 percent

methane, 3.41 percent ethane, 0.65

percent propane, etc.); this is

designed to represent an industryaverage fuel.

The program also compares the

emissions of alternative fuels and

those of reformulated gasoline to the

Federal emissions standards, which

mandate the maximum allowable

emissions from vehicles on a grams

per mile basis. The regulated emissions, called criteria pollutants, are

hydrocarbons, carbon monoxide, and

nitrogen oxides. Between 1994 and

1996, new standards are being

phased in. The new standards regulate both total hydrocarbons and

non-methane hydrocarbons for gasoline vehicles and organic material

non-methane hydrocarbon equivalents (which include aldehydes and

unburned alcohol) for alcohol vehicles. Methane is not included in the

hydrocarbon regulations because it is

non-reactive; therefore, it does not

add to photochemical smog.

19

Light-Duty Vehicles
By 1996 the previous standards,

known as Tier 0, will be completely

replaced by the new standards,

known as Tier 1. Figure 7 shows the

Tier 0 and Tier 1 emissions standards

for light-duty cars and trucks.

Phase II Preliminary

Emissions Results

During fiscal year 1994, the program

performed 259 emissions tests on 75

alternative fuel vehicles and 102

emissions tests on 71 gasoline control

vehicles. Table A-3 in the Appendix

lists the number of each vehicle

model included in the program and

the number of tests done on each

model. In fiscal year 1995, the program will perform more emissions

tests on these vehicles, as well as on

new vehicles. Once the new data are

added to the data already gathered,

the program will have the information needed to compare, with a high

level of confidence, the emissions

from vehicles running on reformulated gasoline to those from vehicles

running on alternative fuels. To date,

the program has completed about

half of its planned agenda for testing

emissions; the results presented

below for each vehicle, therefore,

are preliminary.

Results from Dodge Spirits 

To date, the program has done the

most extensive testing on Dodge

Spirits, performing 172 emissions

tests on 44 methanol flexible-fuel

models and 61 tests on 43 standard

gasoline models. As shown in Figure

8, all the results from these fourcylinder passenger cars are well

below the Tier 1 standards for nonmethane hydrocarbons, carbon

monoxide, and oxides of nitrogen.

When the flexible-fuel vehicles were

tested on 85 percent methanol or 50

percent methanol, they emitted

between 12 percent and 16 percent

less carbon monoxide than the

20

Light-Duty Vehicles

Figure 8. Emissions results

from Dodge Spirits

0

0.5

1

1.5

2

2.5

3

3.5

HC NMHC CO NOx

Emissions rate (g/mile)

Tier 1 M85 M50 RFG

Figure 7. Tier 0 and Tier 1 emissions

standards for light-duty cars and trucks.

(Note that NMHC is not regulated in

the Tier 0 standards.)

0

2

4

6

8

10

HC NMHC CO NOx HC NMHC CO

Tier 0 (g/mile) Tier 1 (g/mile)

Light-duty cars Light-duty trucks

Standard (g/mile)

NOx
flexible-fuel vehicles did when tested

on reformulated gasoline. Yet the

flexible-fuel vehicles emitted 10 percent to 15 percent more carbon

monoxide running on alcohol than

did the dedicated gasoline Dodge

Spirits running on reformulated

gasoline.

The emissions of non-methane

hydrocarbons and oxides of nitrogen

were not significantly different

between alcohol and reformulated

gasoline for the flexible-fuel vehicles, but were significantly higher

than emissions from dedicated gasoline Dodge Spirits running on reformulated gasoline. Note, however,

that the emission level of nonmethane hydrocarbons represents a

class of pollutants rather than one

specific compound. Therefore, the

constituents of the non-methane

hydrocarbon emissions from different vehicles may be quite different.

For example, research presented at a

recent conference of the Society of

Automotive Engineers found that

hydrocarbon emissions from the

methanol fuel vehicles tested contained higher levels of formaldehyde

than gasoline vehicles tested.

However, the hydrocarbons from the

gasoline vehicles contained higher

levels of toxics such as benzene than

the hydrocarbons from the alcohol

fuel vehicles (Vaughn Burns et al.,

“Emissions with Reformulated

Gasoline and Methanol Blends in

1992 and 1993 Model Year Vehicles,”

SAE 941969, October 1994).

Results from Chevrolet Luminas

The average results from the sixcylinder Chevrolet Luminas were all

below the Tier 1 emissions standards

(see Figure 9), although results from

individual tests may have exceeded

the standards. With the exception of

hydrocarbons, for the flexible-fuel

vehicles, the emission levels from

the alcohol tests were significantly

lower than those from the tests for

reformulated gasoline; the emissions

of hydrocarbons among fuel types

showed little variation.

When compared to the standard

Lumina running on reformulated

gasoline, however, the emissions

from the flexible-fuel vehicles were

far lower on all counts.

For the flexible-fuel vehicles, typically, the lowest average results

came from the 85 percent ethanol

tests, followed by the 50 percent

ethanol tests, and then by reformulated gasoline. The standard Lumina

showed the highest average emissions for every category of

pollutant.

Results from Dodge B-250 Vans 

Nearly every individual emissions

data point collected so far for the

21

Light-Duty Vehicles

Figure 9. Emissions results from

Chevrolet Luminas

Tier 1 Standards E85 E50 RFG

Emissions Rate (g/mile)

0

0.5

1

1.5

2

2.5

3

3.5

HC NMHC CO NOx
dedicated vans operating on compressed natural gas met the Tier 1

standards, and all the average results

are well below these standards. In

contrast, individual results from the

gasoline vehicles and even some of

the averages did not meet Tier 1

standards (although they met the less

stringent Tier 0 standards). The

average results for the Dodge vans

along with Tier 1 standards for lightduty trucks are shown in Figure 10.

Because several of the vans using

compressed natural gas have arrived

at the emissions laboratories with

fuel system leaks, test procedures

have been modified to include a leak

test similar to the evaporative tests

performed on liquid fuel vehicles

(see sidebar on page 18). These tests

will show the extent of leakage from

the compressed natural gas systems.

Results from Ford Econoline Vans

The methanol flexible-fuel Ford

Econoline Vans are a relatively new

addition to the emissions testing program. By the end of fiscal year 1994,

18 tests had been completed on 5

vehicles. The initial data points indicate a potential for reduced emissions when the vehicles operate on

alcohol fuels (see Figure 11). Further

testing will determine if these early

results can be shown to be statistically significant.

Performance and Reliability

In the United States, manufacturers

have produced alternative fuel vehicles for only a few years. In contrast,

they have produced gasoline vehicles

for more than 8 decades. The classical development curve for any technology shows that early in a

product’s development stage, problems with reliability tend to be very

high, but these problems decrease

dramatically as the product matures.

We should expect, therefore, that the

new kinds of vehicles in the program

will experience more reliability problems than those with a long history

of development.

22

Figure 11. Emissions results from Ford

Econoline vans

Light-Duty Vehicles

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

HC NMHC CO NOx

Tier 1 standards M85 M50

Emissions Rate (g/mile)

RFG

Figure 10. Emissions results

from Dodge B-250 vans

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

HC NMHC CO NOx

Tier 1 standards CNG RFG

Emissions Rate (g/mile)
23

Figure 12. Methanol vehicle repairs

reported: February 1991-August 1993

Light-Duty Vehicles

These classical expectations are

being borne out for the light-duty

vehicles being tested. Early in the

test program, the alternative fuel

vehicles experienced more reliability

problems than comparable gasoline

vehicles. However, as data begin to

accumulate on the newer models of

the alternative fuel vehicles, a different picture is emerging (see

Figure 12). The newer models seem

to have achieved a higher level of

reliability and performance than the

earlier ones. This improvement

probably results from making

changes in the vehicle design and

from basing service on experience

with the earlier models. Changes

made include:

• Fuel system materials that are

more compatible with alternative

fuels now being used.

• The programming of the control

computer for the engines of

alternative fuel vehicles has been

improved.

• The refueling connectors for

compressed natural gas have been

redesigned. (These connectors are

now standardized.)

• The fuel-type sensor for the

engine computer has been

improved.

• More durable fuel injectors and

fuel pump speed controllers are

being used. (The Chevrolet

Lumina uses a two-speed fuel

pump.)

• On-line service information is

now available to the repair

technician.

The fuel system parts replacements

from earlier and later model alternative fuel vehicles are tabulated in

Table A-4 in the Appendix. The

repair data collected indicate that

repair technicians misdiagnosed

problems in several instances. In

some cases, various parts were

replaced until driver complaints

eventually stopped. In most cases,

repairs were covered by the manufacturer’s warranty, so excess downtime, not cost, was the burden

presented to the fleet operator.

Misdiagnoses and downtime for

repairs may be reduced as repair

technicians become familiar with

alternative fuel vehicles. This

familiarization process will take time

because technicians are exposed to

relatively few alternative fuel

vehicles.

Fuel Economy

The program measures the fuel economy of the vehicles in the test fleet

in two ways: by testing the vehicles

on a chassis dynamometer and by

0.1

0.0

0.2

0.3

0.4

0.5

0.6

Maintenance/

Feb Apr Jun Aug Oct Dec Feb Apr Jun Aug Oct Dec Feb Apr Jun

1000 miles

1991 1992 1993
24

Light-Duty Vehicles

analyzing refueling records. All figures are reported as miles per gasoline equivalent gallon, which

expresses the fuel economy on an

equivalent energy basis. This compensates for differences in the energy

content of each fuel type and uses

the average energy content of

unleaded gasoline as the basis for

comparison—115,000 Btu per gallon

(see Figure 13). One gallon of

unleaded gasoline has the same

energy content as 1.77 gallons of

85 percent methanol, and as 1.42

gallons of 85 percent ethanol.

During emissions testing, the chassis

dynamometer tests provide information on fuel economy. The fuel economy tests provide a single number

that is based on a specific “city”

driving cycle. Closely controlling the

fuel and operating conditions, the

test laboratories take measurements

on a number of like vehicles, which

are then averaged into a single value.

The dynamometer results are shown

as points in Figure 14.

The program calculated the actual inuse fuel economy for the light-duty

vehicles by using the 27,900

refueling records currently in the

Alternative Fuels Data Center.

During actual use, the fuel economy

varies considerably because of factors such as driving cycle (stop-andgo city driving, highway driving,

deliveries, or a combination of all

three) and individual driving styles.

An individual vehicle/driver combination generally has a fairly consistent fuel economy, but wide

variations in fuel economy occur

from vehicle to vehicle, site to site,

and driver to driver. 

Analysis of the in-use fuel economy

is further complicated by the fact

that the alcohol vehicles are flexiblefuel vehicles and may be fueled with

gasoline at any refueling. This

Figure 13. Energy content comparison

Unleaded gasoline

E85

M85

0 20,000 40,000 60,000 80,000 100,000 120,000

Btu/gallon

Figure 14. Fuel economy by

vehicle type

0 10 20 30 40

Fuel economy (miles per gasoline equivalent gallon)

▲

E85 Lumina

M85 Lumina

Gasoline Lumina

M85 Taurus

Gasoline Taurus

▲

▲

▲ ▲

M85 Spirit

Gasoline Spirit

▲

M85 Econoline ▲

Gasoline Econoline

▲

▲

CNG pickup

Gasoline pickup

▲

▲

CNG van

Gasoline van

▲

▲

In-use fuel economy from refueling data

Fuel economy measured with a chassis dynamometer during emission testing
gasoline then mixes with the alcohol

fuel left in the tank to create some

unique mixture of alcohol and gasoline. To compensate, the program

bases its fuel economy calculations

only on instances where alcohol

fuels were used for three consecutive

refuelings. The range of results for

in-use fuel economy for each vehicle

type is shown as a line in Figure 14. 

The figure shows that, on an equivalent energy basis, vehicles operating

on alternative fuels have about the

same fuel economy as those operating on reformulated gasoline.

Cost

Total cost for owning and operating

a light-duty gasoline vehicle may

generally range from 25 to 40 cents

per mile. Total vehicle costs include

costs for acquisition, maintenance,

insurance, fuel, and oil. Results from

the Federal alternative fuel fleet test

program indicate that, for current

prototype vehicle technologies and

the immature fueling infrastructure,

the costs for alternative fuel vehicles

are slightly higher than the cost for

gasoline vehicles. In the case of

alcohol vehicles, the fuel costs are

higher than gasoline, but the incremental cost for vehicle acquisition is

relatively low. For natural gas vehicles the fuel costs are lower than

gasoline, but the incremental cost for

purchasing a natural gas vehicle is

significantly higher.

Additional Acquisition Cost

The additional acquisition cost is the

difference between the cost of a

stock gasoline fueled vehicle and

that of an alternative fuel vehicle.

Currently, the modifications needed

for alcohol vehicles add between

$0 and $800. Compressed natural

gas vehicles may add as much as

$4,800 to the vehicle’s cost. Typical

vehicle modifications for alcohol

vehicles include plastic or stainless

steel fuel tanks and lines and special

gaskets. High-pressure tanks and

tubing are required for compressed

natural gas vehicles. Some of the

additional acquisition cost may be

recovered when the vehicle is sold,

but this depends on its final

25

Light-Duty Vehicles

Reformulated Gasoline

Spurred by the need for cleaner air and lower vehicle emissions,

and working in concert with the automotive industry, refiners

created a cleaner burning gasoline late in the 1980s. The term

“reformulated gasoline” was coined in 1989 in response to

proposals to include clean fuels requirements in the Clean Air Act

Amendments. Today, the sale of reformulated gasoline is mandated

in the nine smoggiest cities in the country, plus any cities that

voluntarily opt in to the program.

Compared to standard gasoline, reformulated gasoline has a lower

organic sulfur content, reduced aromatic concentrations, and a

lower vapor pressure. It also has added oxygenates, which reduce

carbon monoxide emissions while improving the octane quality of

the gasoline. The most common oxygenates are ethanol, methyl

tertiary butyl ether (a methanol-based ether), ethyl tertiary butyl

ether (an ethanol-based ether), and tertiary amyl methyl ether. 

To compare alternative fuels to clean-burning gasoline, reformulated gasoline was used as the base case in the emissions study. Both

the State of California and the Federal Government have issued

standards for reformulated gasoline. California-certified reformulated gasoline is used for the emissions testing presented in this

report.
26

Light-Duty Vehicles

application and whether the alternative fuel is locally available. 

Fuel Cost

Fuel cost varies greatly across the

country, depending both on wholesale fuel cost and local tax treatment

of the fuel. Wholesale fuel cost

varies about 20 cents per equivalent

gallon among cities. State and local

tax treatment can vary by as much as

40 cents per equivalent gallon.

Variations include taxing only the

gasoline portion of an alcohol fuel,

offering ethanol incentives of up to

40 cents a gallon, and taxing the

entire fuel as if it were gasoline. This

disparity in tax treatment has an

impact on each fuel’s ability to compete in the marketplace. In

September 1994, retail fuel prices

were approximately $1.10 to $1.50

per equivalent gallon for 85 percent

ethanol, $1.20 to $2.00 for 85 percent methanol, $0.60 to $0.90 per

equivalent gallon for compressed

natural gas, and $1.00 to $1.30 for

unleaded gasoline. Several industry

newsletters, such as Clean Fuel

Vehicle Week, Oxy-Fuel News, and

21st Century Fuels, track both the

wholesale costs and the tax treatment

of various fuels on a weekly or

monthly basis.

The regional variations in fuel cost

combine with the fuel economy variations from vehicle to vehicle to produce a wide range of fuel costs per

mile driven. Figure 15 shows the

range of fuel cost per mile for alternative fuels and gasoline sedans and

vans in the Federal fleet. 

Oil Cost

Oil cost depends on recommended

oil change intervals and the price of

oil. Because alcohol vehicle manufacturers recommend more frequent

oil changes, the oil cost for these

vehicles is generally higher than for

gasoline vehicles. Typical oil costs

are about 1.3 cents per mile for alcohol fuel vehicles, and 0.7 cents per

mile for gasoline vehicles. In some

cases natural gas vehicles may have

extended oil change intervals, which

results in lower oil costs for natural

gas.

Maintenance Costs

Most maintenance on the Federal

test vehicles has been done under

warranty at no cost to the fleet operator (except for lost time in service).

Thus, the maintenance cost per mile

is not available. In general, maintenance costs are expected to be marginally higher for alternative fuel

vehicles than for gasoline vehicles

Figure 15. Range of fuel costs per

mile, based on large regional variation in fuel cost and driver-reported

miles per gallon

Ethanol

Methanol

Gasoline

Compressed

natural gas

Gasoline

Sedan Van

0 0.05 0.10 0.15 0.20

Fuel cost (dollars/mile)
for several reasons. Parts costs are

higher for vehicles in limited

production. Experience with the test

fleet has also indicated that some

maintenance costs are unique to the

alternative fuel vehicles. Although

fuel pump and injector problems

have been common, they are

decreasing as manufacturers gain

experience with alternative fuels.

These factors lead to the expectation

that the long-term maintenance costs

of alternative fuel vehicles should,

with time, approach those of gasoline vehicles. 

Fuel Cost per Mile Traveled

The average fuel cost for operating a

vehicle can be determined by using

the national average fuel cost and the

average fuel economy based on controlled dynamometer testing.

However, these figures will not necessarily apply directly to vehicles in

use, but will provide a good relative

comparison. The cost per mile for a

specific vehicle will be strongly

affected by factors that affect fuel

economy (see previous section) and

by the local fuel cost.

Figure 16 presents the average fuel

cost per mile for alternative fuel

sedans and vans.

27

Light-Duty Vehicles

Figure 16. Average fuel cost per mile in

1994 for the light-duty alternative fuel

vehicles in the program

0 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20

E85

M85

Gasoline

CNG

Gasoline

Sedan

Van

Dollars/mile
26
29

Overview

The transit bus program is designed

to provide a comprehensive study of

the alternative fuels currently used

by the transit bus industry. The study

focuses on the emissions levels, fuel

economy, reliability, and operating

costs of the various fuels and

engines.

To obtain the detailed information

needed for the study, the program

selected transit agencies that met the

following criteria:

• The transit agency must have test

buses that represented the most

current technology available at the

time.

• The transit agency must have

available control buses identical to

the alternative fuel buses except

for the fuel they use.

• The transit agency must be willing

to supply detailed data on the

vehicles for several years.

Using these criteria, the program

chose to test buses in seven metropolitan areas: Houston, Texas;

Miami, Florida; Minneapolis,

Minnesota; New York, New York;

Peoria, Illinois; St. Louis, Missouri;

and Tacoma, Washington (see

Figure 17). By design, these areas

are located around the country, so

that the buses can be tested while

operating under different climatic

conditions. The program is testing

five alternative fuels—compressed

natural gas, liquefied natural gas,

methanol, ethanol, and B20, a blend

of 20 percent biodiesel and

80 percent conventional diesel fuel.

B20 is not considered an alternative

fuel under the Energy Policy Act of

1992. Figure 18 shows the number

of test buses of each fuel type. At

two of the sites, buses will be run on

diesel with engines equipped with

particulate traps, which will be compared to buses running on diesel

without traps. The goal of the program is to test, at each location, a

minimum of five buses running on a

single alternative fuel and at least

five control buses running on diesel.

For example, in St. Louis the program is testing five buses running on

biodiesel and five running on standard diesel. Table A-5 in the

Appendix provides a summary of the

transit buses in the program.

Transit Buses

Figure 17. The program tests alternative fuel buses in seven municipalities

across the nation.
A subcontractor collects data

on maintenance, fuel, and

added oil from each transit

agency. The subcontractor then

processes the data, converts

them into a standard form for

submission to the Alternative

Fuels Data Center, and analyzes the results. The

Alternative Fuels Data Center

then makes the information

available to the public through

a series of data base queries

designed to present the data in a concise and logical format.

In addition to the operating data collected from each site, West Virginia

University personnel visit each of the

sites and conduct emissions tests on

the buses using the university’s

transportable chassis dynamometer

(shown in the photo).

With the exception of the biodiesel

test buses, the alternative fuel buses

in this program use the most common alternative fuel engines available from the heavy-duty engine

manufacturers. These engines are:

• Detroit Diesel 6V92TA methanol

engine

• Detroit Diesel 6V92TA ethanol

engine

• Detroit Diesel 6V92TA pilot ignition natural gas engine

• Cummins L10 natural gas engine.

The biodiesel buses use biodiesel

fuel in an unaltered Detroit Diesel

6V92TA engine. Each of the engines

has a horsepower rating between 240

and 280. Buses in the program are

35-foot and 40-foot models manufactured by Mercedes, Flxible,

Gillig, TMC, and BIA.

Detroit Diesel Corporation and

Cummins have made extensive

efforts to develop heavy-duty

engines that run on alternative fuels

and to introduce them into the transit

bus market. The earliest of these

engines were placed in the field as

demonstration units to prove the

concept of operation on the alternative fuels, and to identify areas for

improvement. Since that time, both

companies have improved their

engines and emission control

systems.

30

Transit Buses

Figure 18. The number of test

buses of each fuel type

West Virginia University uses its

transportable chassis dynamometer

to conduct emissions tests at each of

the sites.

LNG/diesel dual fuel

10 buses

CNG

10 buses

M100

10 buses

E93 or E95

10 buses

Biodiesel

5 buses

Diesel

32 buses

Diesel with

particulate traps

12 buses
Emissions

West Virginia University’s

Department of Mechanical and

Aerospace Engineering designed and

constructed a transportable chassis

dynamometer to test emissions levels

from heavy-duty vehicles. The ability

to transport this chassis dynamometer allows the program to perform

a large number of on-site emissions

tests on buses and heavy-duty vehicles around the country. Before the

unit was built, other options were

considered, such as transporting

vehicles to existing stationary

dynamometers, or removing engines

and transporting them to existing

facilities. Both options were rejected

because of expense and vehicle

downtime.

West Virginia University has available a detailed description of the test

procedures and the facility design.

Typically, the transportable chassis

dynamometer is set up on the

grounds of the test fleet or local transit agency and the selected heavyduty trucks or buses are tested using

the fuel in the vehicle at the time of

the test. The dynamometer may be

set up to operate inside or outside

depending on the space available at

the transit agency. Samples of the

fuels (both alternative and diesel)

being used at the site are collected

and sent to a laboratory for analysis.

The fuel analysis data are then sent

to the Alternative Fuels Data Center.

The first transportable unit was built

in 1991. The unit has tested transit

buses and other heavy-duty vehicles

nationwide since early in 1992. In

1994, a second unit was built; it will

begin testing vehicles in 1995.

In 1994, personnel from West

Virginia University’s Department of

Mechanical and Aerospace

Engineering traveled to Miami,

Minneapolis, Peoria, and St. Louis to

perform emissions tests on 38 buses

using DDC 6V92TA engines—

engines designed to operate on 100

percent methanol, 95 percent

ethanol, diesel, or biodiesel (no

changes were made to the diesel

engine for operation on biodiesel).

They also traveled to Miami and

Tacoma to perform emissions tests

on 25 buses using Cummins L10

engines—engines designed to operate on compressed natural gas or

diesel. They tested all the buses with

the transportable chassis dynamometer using the standard Central

Business District test cycle, a driving

cycle devised to simulate the speeds,

loads, and conditions experienced by

buses during a typical route through

a city’s Central Business District. A

summary of the results of the emissions tests for each engine type is

provided below.

Detroit Diesel 6V92TA

Separate versions of the DDC

6V92TA engines are certified by the

Environmental Protection Agency

for operation on methanol and diesel.

To run on methanol, the standard

engine is modified to include a

higher compression ratio, higher

flow fuel injectors, the Detroit Diesel

Electronic Controller, and methanolcompatible materials. This engine

can be configured to run on 100 percent methanol, 85 percent methanol,

or 95 percent ethanol; but the

Environmental Protection Agency

has not yet certified the engine for

31

Transit Buses
operation on ethanol. Certification

data for the methanol engine (Figure

19) show that the engine’s emissions

are well below the standards set by

the Environmental Protection

Agency. 

The engine certification data are

taken using an engine dynamometer

and are therefore independent of the

vehicle application. In contrast, the

chassis dynamometer tests emissions

from the vehicle over a specific

driving cycle. The results of chassis

dynamometer emissions tests on

buses powered by DDC 6V92TA

engines are shown in Figure 20.

These are early test results and the

data from the alcohol-fuel buses are

quite variable from site to site and

bus to bus. Nonetheless, we can

make some general observations—

buses running on alcohol emit far

fewer nitrogen oxides and less particulate matter but significantly more

hydrocarbons and carbon monoxide

than do buses running on diesel.

Note, however, that the hydrocarbon

data for the alcohol-fuel buses are

reported as organic material hydrocarbon equivalent, which includes a

fraction of the unburned alcohol and

aldehydes measured. The program is

investigating several reasons, including whether the catalytic converters

are functioning properly, for the

increased emissions levels. Detroit

Diesel Corporation has made recent

improvements to the fuel injectors,

which also may help improve emissions levels. 

Figure 19 (above). Certification data

from the DDC 6V92TA engine modified

for methanol operation Figure 20 (below). Emissions results

from buses with DDC 6V92TA engines

2

CO HC NOx

80

60

40

20

0

g/mile

g/mile

4

3

1

0

PM

32

Transit Buses

0

1

2

3

4

5

CO HC

0

PM

0.04

0.08

0.12

0.16

0.2

0.24

Standard: 15.5 g/bhp-hr

Grams per brake horsepower-hour

Grams per brake horsepower-hour

M100 (1993)

Diesel (1991)

Diesel with trap

M85

EPA Standards

NOx

Average result

100 percent methanol

95 percent ethanol

Biodiesel

Diesel with particulate trap

Diesel
Cummins L10

The Cummins L10 buses tested so

far in this program were demonstration units that were not certified by

the Environmental Protection

Agency. Cummins has since made

several improvements to enhance the

performance of its engines, and to

reduce their emissions levels. The

later versions of this engine have

been certified by the California Air

Resources Board and will be included

in future testing.

Nonetheless, West Virginia

University did perform chassis

dynamometer tests on compressed

natural gas and diesel control buses

powered by Cummins L10 engines

(Figure 21). As with the tests on the

Detroit Diesel engines, these are

early results and no definite conclusions can be drawn. But again, we

can make some general observations.

First, emissions levels from the

diesel control buses appear to be

more consistent from bus to bus than

results from the buses running on

compressed natural gas. 

Second, as expected, the emissions

of particulate matter from buses running on compressed natural gas are

much lower than those from the

diesel buses.

Third, some of the buses operating

on compressed natural gas have far

lower emissions levels of carbon

monoxide than do the diesel buses.

This may be partly because those

buses with the low emission levels

had odometer readings less than

20,000 miles, but the diesel controls

for these vehicles are 2 years older

with much higher odometer readings. 

Finally, the compressed natural gas

buses tended to have higher emission

levels of hydrocarbons. It is likely

that this difference in hydrocarbon

emissions results primarily from

methane emissions, which were not

separately measured at the time of

the tests. Because methane is considered to be nonreactive in forming

ozone in the atmosphere, however,

the Environmental Protection

Agency has written new regulations

in terms of non-methane

hydrocarbons. West Virginia

University plans to incorporate

methane analyzers in the future. 

Future Activities in

Emissions Testing

The preliminary data on bus emissions have raised several questions:

• Why are the chassis dynamometer

emissions so highly variable?

• What role does the condition of

the bus/engine play in emissions?

33

Figure 21. Emissions results from

buses with Cummins L10 engines

Transit Buses

50

CO HC NO x PM*

0

10

20

30

40

g/mile

*CNG values are negligible

CNG Diesel
• What is the cause of the relatively

high carbon monoxide and hydrocarbon emissions levels?

• How can these high levels be

corrected?

In September 1994, the National

Renewable Energy Laboratory

brought together a panel of experts

from the engine manufacturers and

others in the field of testing the

emissions of heavy-duty vehicles.

The panel reviewed the procedures

followed by West Virginia University

and the results seen so far. West

Virginia University is already implementing some of the panel’s recommendations. Representatives from

Cummins and Detroit Diesel

Corporation agreed to assist in the

program by helping to identify the

appropriate vehicles for testing, and

by providing technical expertise

when high emitters are encountered. 

Performance and Reliability

One measure of reliability in a bus is

the number of road calls that are

required for every 1,000 miles that

the bus travels. When the driver is

prevented from completing his or her

route because of a problem with the

bus and calls for a replacement bus,

a road call is recorded. Road calls

encompass all types of events from

an engine failure to simply running

out of fuel.

The road calls per 1,000 miles of

operation for the various buses at

the different sites are shown in

Figure 22.

Figure 22 indicates that the dual-fuel

buses in Houston running on liquefied natural gas and diesel are experiencing considerably more road

calls than the diesel controls. These

road calls are largely due to the

buses running out of fuel or to the

system detecting a fuel leak and

shutting down the bus. Note that the

dual-fuel buses have a very small

diesel fuel tank. If a fuel problem

develops with the liquefied natural

gas, the dual-fuel engines are

designed to run on diesel as a backup.

In this case, the bus would run out of

diesel in a short time—the diesel fuel

tank alone is not large enough to run

the bus independently. The dual-fuel

buses experienced more than four

times the rate of road calls for “out

of fuel” as did the diesel controls.

In the future, the program will add

an additional site for buses running

on liquefied natural gas. In this case,

though, the buses will have different

engines, to see if they have similar

problems.

1 The diesel control buses in Miami are older than alternative fuel buses and have

considerably more miles on the vehicles. Insufficient data are available to characterize the Minneapolis buses running on 95 percent ethanol and the St. Louis

buses running on biodiesel.

34

Transit Buses

Miles To Go Before We’re Done 

The goal of the program is to

gather sufficient data on 10 buses

for each fuel type, with five buses

at one site and five at another. At

this time, the program is approximately half complete. Some sites

have reported a substantial number of data; others have just started to report data. Significant

differences often emerge between

sites as a result of different previous experience with the buses,

different operating conditions,

and different reporting procedures. Care should be taken in

drawing conclusions from the

program at this time. In the next

report to Congress, the number of

data available for analysis will

more than double, and this will

substantially raise the confidence

level of the findings.

Figure 22. Road calls per 1,000 miles

of operation1

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0.55

0.6

LNG/diesel Miami-CNG Tacoma-CNG Peoria-E95 Miami-M100

Alt fuel Diesel

Road calls per 1000 miles
Buses running on compressed natural

gas experienced a higher rate of road

calls than their diesel controls at

Miami, but a lower rate at Tacoma.

However, total mileage accumulated

on the Miami compressed natural

gas buses is quite limited at this

time. This also points out the need

for two sites per alternative fuel and

the need to average data over many

miles. 

Road calls for the Peoria buses running on 95 percent ethanol appear

comparable to the diesel control

buses with particulate traps.

Data from the Miami buses running

on 100 percent methanol show a

higher rate of road calls than their

diesel counterparts. This difference is

primarily because of problems with

fuel systems and with stalling

engines. However, these data are

based on a total of less than 200,000

miles traveled. More miles are needed

to confirm the results. The program

has recently added a second site—

New York (Triboro)—at which to

test more buses running on 100 percent methanol. Data from the new

site will be compared to the Miami

results.

Fuel Economy

Fuel economy and fuel costs are

very important to transit agencies

because these costs represent a large

portion of the operating cost of a

transit bus: approximately half of the

operating cost of a diesel bus, and

more than half for some alternative

fuel buses.

The fuel economy from engine

dynamometer tests and the range of

in-use fuel economies is shown in

Figure 23 for each site. Expressing

the fuel economy in miles per diesel

equivalent gallon allows for a direct

comparison of the relative energy

efficiency of the various alternative

fuel engine technologies.

Variability of fuel economy is different for each site. This variability may

result from differences in driving

cycles from bus to bus and from site

to site. In general, sites with a tight

range of fuel economies for the

diesel buses also have a tight range

for the alternative fuel buses. The

dynamometer results (which were all

obtained using the Central Business

District driving cycle) are relatively

consistent throughout the test fleet.

This strongly indicates that the variations in the in-use results are probably due to driving cycles. Because

the dynamometer results are

35

Transit Buses

Figure 23. Bus fuel economy, expressed

as miles per diesel equivalent gallon 

0 5 10

Fuel economy (miles per diesel equivalent gallon)

▲

St. Louis-Biodiesel

St. Louis-Diesel ▲

Peoria-E95

Peoria-E93

Peoria-Diesel ▲ ▲ ▲

Minneapolis-E95

Minneapolis-Diesel ▲

▲

▲

Miami-M100

Miami-Diesel

▲

▲

Miami-CNG

Miami-Diesel

▲

▲

Tacoma-CNG

Tacoma-Diesel

▲

In-use fuel economy from refueling data

Fuel economy measured with a chassis dynamometer during emission testing
36

Transit Buses

consistently below the average inuse results, the Central Business

District driving cycle may not be

representative of the actual driving

cycles of the test buses.

The liquefied natural gas engines at

Houston operate on a compressionignition cycle; the diesel fuel is used

as a “pilot ignition” source to ignite

the natural gas. An average fuel

economy for these buses was calculated by summing the amount of

liquefied natural gas (in diesel equivalent gallons) and diesel burned in

the buses over time, and dividing

that sum by the total miles logged.

The average fuel economy for the

liquefied natural gas buses (3.1 miles

per diesel equivalent gallons) was

approximately 14 percent less than

that of their diesel counterparts. Part

of this reduction may be attributed to

the approximately 860 pounds of

extra weight of the liquefied natural

gas/diesel dual-fuel buses, but the

majority is most likely attributed to

the engine design or factors such as

differences in driving cycles. It is

interesting to note that when the

dual-fuel buses were operating in

their “backup” mode of diesel only,

the fuel economy was within 1 percent of that of the control buses. This

shows that the extra weight of the

dual-fuel buses does not make a

major contribution to the difference

in fuel economy.

The compressed natural gas engines

at Miami and Tacoma are sparkignited throttle engines; the diesel

engines are unthrottled compressionignition engines. When a diesel

compression-ignition engine is

redesigned into a spark-ignition

engine running on natural gas (as is

the case with all the compressed natural gas engines in the program),

there is an inherent loss of efficiency

because of pumping losses. Pumping

losses represent the amount of energy

required for the engine to draw in air

during the intake cycle. An unthrottled diesel engine has minimal

pumping losses, whereas a sparkignited engine with a throttle has significant pumping losses. Also, the

compressed natural gas engines have

a lower compression ratio than their

diesel counterparts: 10.5:1 for the

compressed natural gas engines versus 16.3:1 for the diesel engines.

An additional disadvantage for the

compressed natural gas buses is their

weight—they weigh about 3,900

pounds more than their diesel counterparts. This weight penalty can

largely be attributed to the weight of

the compressed natural gas tanks,

and results in about a 15 percent

increase in the curb weight of a bus

(the diesel control buses have a curb

weight of approximately 27,000

pounds). These three factors led to

the expectation that energy efficiency might be significantly

reduced. A difference in the fuel

economy of the compressed natural

gas and diesel buses was observed in

the average results and in the

dynamometer results. The fuel economy of the compressed natural gas

buses was about 10 percent to

20 percent lower than that of their

counterparts.

The alcohol buses also suffer from

weight penalties. The alcohol option

results in a weight penalty of

between 1,000 and 1,500 pounds,

depending on the tank’s capacity. In

addition, the alcohol buses at the
Miami site have an additional weight

penalty of 1,200 pounds, which is

attributed to options and specifications unrelated to the alcohol fuel

engine. This extra weight was

expected to reduce the fuel economy

of the alcohol buses. 

In addition, the alcohol buses have

very high compression ratios (more

than 20 to 1), which were expected

to lower fuel economy because of

friction losses such as piston side

loading. The results to date, however, indicate that the alcohol fuel

buses at all the sites are performing

very well, delivering fuel economy

comparable to that of the diesel control buses. The weight and compression ratio penalties may not be as

significant as the pumping losses

caused by throttling. Both the 95

percent ethanol and the 100 percent

methanol engines at Peoria,

Minneapolis, and Miami are unthrottled compression-ignition engines,

meaning that they do not suffer from

the same pumping loss penalties as

the compressed natural gas buses.

Also, the diesel control buses at

Peoria are equipped with particulate

traps, which are known to lower fuel

economy slightly. 

Biodiesel buses exhibited approximately 7 percent lower average fuel

economy than the diesel control

buses, but the range of their fuel

economies overlapped considerably.

Because the fuel economies quoted

are already based on diesel equivalent gallons to eliminate any differences in fuel energy content, this

drop was not expected. Research to

determine the cause of this drop is

under way.

In summary, the fuel economy

results are in line with expectations

from the various engine technologies, with the possible exceptions of

the liquefied natural gas dual-fuel

engine, and the biodiesel buses,

where the reason for the lowered fuel

economy is not readily apparent.

Cost

The cost of operating alternative fuel

buses versus their diesel counterparts

can be broken down into three

primary categories:

• Additional acquisition cost

• Fuel cost

• Maintenance cost

Each component of the operating

cost is covered in the following

sections.

Because transit buses are stored and

refueled centrally in facilities owned

and operated by transit agencies, the

capital and operating costs for any

changes made to a facility to accommodate alternative fuel buses is also

an important part of the overall cost

of operating with alternative fuels.

The capital and operating costs for

new facilities or modifications to

existing facilities to accommodate

alternative fuel vehicles vary dramatically, even for one type of alternative fuel. These costs include

changes such as installing new

refueling equipment or installing

monitoring and ventilation equipment. The costs are affected by the

size of the agency and the state and

local building codes. The program is

currently evaluating representative

capital costs and will present them in

37

Transit Buses
38

Transit Buses

future reports. However, at this time,

compressed natural gas and liquefied

natural gas facilities appear to have

the highest capital costs.

Additional Acquisition Cost

At this time, buses running on alternative fuels tend to be more expensive than those running on diesel.

Higher engine costs represent a significant portion of this increased

expense. Because these engines are

developmental, the engine manufacturers charge about $25,000 to

$30,000 more for an alternative fuel

engine than for a diesel engine. We

expect that, as their production volume increases, the cost of alternative

fuel engines will begin to approach

those of their diesel counterparts.

There is, however, insufficient information to indicate if they will equal

the cost of diesel engines some time

in the future. Biodiesel buses are the

exception to the rule. Because the

buses running on biodiesel in this

program use conventional diesel

engines, there is no additional acquisition cost.

Also, alternative fuel buses are more

expensive because their fuel tanks

cost more. These additional costs can

run from $5,000 for a bus operating

on 95 percent ethanol to around

$20,000 for one operating on compressed natural gas. Again, fuel tanks

represent no additional expense for

buses running on biodiesel.

Fuel Cost

In September 1994 the price paid for

a gallon of diesel fuel by the transit

agencies varied from about 47 cents

to 65 cents. The price paid per

diesel equivalent gallon varied considerably for the alternative fuels.

The price paid for compressed natural gas was the lowest, at 58 cents to

69 cents per diesel equivalent gallon

(this price excludes the cost of the

electricity needed to compress the

fuel—the program is currently calculating these costs and will include

them in future reports). At $2.29 per

diesel equivalent gallon, 100 percent

methanol was the most costly of the

alternative fuels in the test program.

The price paid for 95 percent ethanol

was about $1.76 per diesel equivalent gallon. Early in 1994 the Peoria

Transit agency switched from using

95 percent ethanol to 93 percent

ethanol (93 percent ethanol, 5 percent methanol, and 2 percent

kerosene) to take advantage of a

43 cent per gallon “blenders credit,”

which lowered their fuel cost to

$1.19 per diesel equivalent gallon.

The biodiesel used in Missouri and

the combination of liquefied natural

gas and diesel used in Houston each

cost about $1.00 per diesel equivalent gallon.

In general, the prices of alternative

fuels have been more variable than

those of diesel fuel, both regionally

and over time. For example, compressed natural gas prices differ significantly from region to region and

methanol prices nationwide have

been volatile recently.

Maintenance Cost

Maintenance costs are being tracked

on all the buses. Copies of all the

work orders and parts replaced are

received from the transit agency.

The work performed and parts

replaced are coded by type of work
39

Transit Buses

(scheduled maintenance, unscheduled maintenance, road calls, and

configuration changes to the buses),

as well as by vehicle subsystem such

as engine and fuel system. 

A few words of caution are necessary in using the data. As more miles

are logged by the test vehicles, a better average maintenance profile

emerges from the data. Also, comparisons of maintenance data from

different agencies should not be

made because each agency has a

different system for recording and

submitting data. Finally, the maintenance cost data do not include warranty work performed on the buses

because the agencies do not bear the

cost of this work.

According to the limited number of

data available at this time, maintenance costs for the Houston buses

that run on liquefied natural gas and

diesel have been considerably higher

than for the control buses. This is

partly due to problems with the gas

injectors and with dirt in the fuel.

Both of these problems were being

rectified by the engine manufacturers

and by Houston Metro. Fuel system

leaks were also a source of

problems.

The Miami buses running on

methanol also have slightly higher

maintenance costs related to the fuel

system. These higher costs are currently being investigated. The addition of New York as a second

methanol site will aid in the cost

analysis of methanol buses.

Maintenance costs for Tacoma compressed natural gas and Peoria

ethanol buses are comparable to

those of the diesel controls.

Cost per Mile Traveled

Figure 24 shows the fuel and maintenance costs per mile traveled. The

fuel cost per mile was calculated

using the average in-use fuel economy and the actual fuel cost paid by

the transit agencies. The fuel and

maintenance cost per mile for test

buses running on compressed natural

gas has been about the same as those

for buses running on diesel fuel.

However, the analogous costs for all

of the buses using alcohol fuel and

buses using biodiesel have been

about twice as high as the costs for

buses using diesel. The costs for liquefied natural gas/diesel buses have

been about one and one half times

those for their diesel counterparts.

Figure 24. Bus fuel and maintenance

costs per mile traveled (assumes labor

rate of $15 per hour)

0 0.2 0.4 0.6 0.8 1

Houston-Diesel

Houston-LNG/Diesel

Miami-Diesel

Miami-CNG

Tacoma-Diesel

Tacoma-CNG

Peoria-Diesel

Peoria-E95

Peoria-E93

Minneapolis-Diesel

Minneapolis-E95

Miami-Diesel

Miami-M100

St. Louis-Diesel

St. Louis-Biodiesel

Fuel Maintenance

Cost (dollars/mile)
40
41

Overview

The heavy-duty program collects

data on two types of vehicles:

medium-size commercial delivery

vans and large trucks. Figure 25

shows the locations of the heavyduty vehicles in the test program.

Gasoline is the standard fuel for

commercial delivery vans; diesel is

standard for large trucks. The vehicles included in the program are listed

in Table A-6 in the Appendix. Figures

26 and 27 show the number of test

vehicles of each fuel type for large

trucks and delivery vans, respectively. The large trucks in the program

are used for various purposes such as

picking up garbage or transporting

goods over long distances (known as

line-haul operation). The trucks’

driving cycles are distinctly different,

depending on how they are used.

Figure 28 depicts the function of the

test trucks (called vehicle “vocation”).

The program has made an effort to

include in the testing as many typical

large truck vehicle vocations as

possible.

Because large trucks are usually very

expensive, the ability to test a particular vehicle vocation depends primarily on the availability of willing

cosponsors. Private fleet owners or

state or local governments are sharing the high cost of the test vehicles

in the program; on average, the program costs are being split

approximately evenly. 

As alternative fuels become more

widely used, state and local governments and private fleets are increasingly interested in sponsoring

alternative fuel vehicle programs.

The program goal is to

cosponsor the use of as

many of the large alternative fuel engines

(those that are now

commercially available

from original equipment

manufacturers) as possible, and to take data to

track the engines’ cost

and performance. The

sidebar on page 42 highlights the alternative

fuel engines currently in

production or preproduction by original

equipment manufacturers. In general,

these engines are dedicated to a speHeavy-Duty

Vehicles

Figure 25. Locations of heavy-duty

vehicles in the test program

Figure 26. Number of large trucks of

each fuel type

6

7

6

CNG

E95

Diesel Controls
cific fuel type. Therefore, by testing

a variety of engines, the program is

also testing a variety of alternative

fuels. 

The program collects data on the fuel

and oil consumption, maintenance,

performance, and emissions of alternative fuel vehicles and control vehicles of the same type that operate on

conventional fuels. The fleet operators provide all except emissions

data to the Alternative Fuels Data

Center. The vehicle emissions are

measured using the transportable

chassis dynamometer operated by

West Virginia University. These data

are also transferred electronically to

the data center, which makes the

information available to the public in

various ways, including via an

Internet option. 

The program is also currently tracking two commercial van delivery

fleets: the Federal Express

42

Heavy-Duty Vehicles

Heavy-duty Alternative Fuel Engine Availability

Three original equipment manufacturers—Detroit Diesel Corporation, Cummins Engine

Company, Inc., and Caterpillar Inc.—now have alternative fuel heavy-duty engines in

production. Below is a list of the engines made by each of these companies and their

use.

Horsepower

Manufacturer Model Fuel Range Vocations

Detroit Diesel 6V92 E95 250-300 Bus, large truck

Detroit Diesel 6V92 M85 250-300 Bus, large truck

Detroit Diesel Series 50 Natural gas 250-300 Bus, large truck,

garbage packer

Cummins L10 Natural gas 240-260 Bus, large truck,

garbage packer

Caterpillar 3306 Natural gas 250 Bus, medium truck,

garbage packer

The natural gas engines can be run on either compressed natural gas or liquefied natural gas.

In addition to the engines that are currently in production, each of these companies has

heavy-duty engines that are in the pre-production development and demonstration phase.

The pre-production engines are listed below. 

Horsepower

Manufacturer Model Fuel Range Vocations

Detroit Diesel Series 60 Natural gas 300-400 Large truck

Detroit Diesel Series 40 Natural gas 250-300 Medium truck

Detroit Diesel Series 30 Natural gas 200-250 Medium truck,

school bus

Cummins C8.3 Natural gas 250 Medium truck

Cummins B5.6 Natural gas N/A Medium truck,

school bus

Caterpillar 3406 Natural gas 350 Large truck

Most of these engines are designed to be used in transit buses or large trucks such

as tractor-trailer line-haul trucks or large municipal trucks (such as dump trucks

and plows). However, some engines (with the vocations labeled “medium truck”

above) are being targeted for the lighter end of the heavy-duty vehicle spectrum.

Representative vocations for these include delivery trucks, lighter municipal trucks,

and 20-foot box trucks. Some of these medium truck engines are also being built

for school buses.

A Quieter Garbage Truck

New York City has operated six compressed natural gas garbage packers

for more than 2 years with excellent results. Drivers appreciate the significantly lower engine noise levels of the compressed natural gas vehicles

compared to their diesel counterparts. These are the only garbage packers

in New York City where the driver and assistant can easily talk to each

other in the cab.

As a result of the excellent performance and driver acceptance, the New

York City Department of Sanitation has ordered ten additional compressed natural gas garbage packers. Five will be equipped with Detroit

Diesel Corporation Series 50 engines and five will be equipped with

Caterpillar 3306 engines. Detroit Diesel Corporation

methanol engine
CleanFleet, and the United Parcel

Service fleet. The Federal Express

CleanFleet uses several alternative

fuels (compressed natural gas,

propane, and 85 percent methanol);

the United Parcel Service uses only

compressed natural gas. Comparisons

are drawn between the alternative

fuel vehicles in these fleets and vehicles with similar engines that operate

on unleaded gasoline or reformulated

gasoline. 

In addition to the data collection

program described above, the

Department of Energy also manages

a grant program that supports states

in their purchases of alternative fuel

heavy-duty vehicles. The vehicles in

the grant program are located all

across the country; they represent

vehicle vocations that range from

street sweepers to school buses. The

program is collecting some data

from the grant program, which will

be added to the Alternative Fuels

Data Center. The locations of the

vehicles in the grant program are

shown in Figure 29, with additional

details in Tables A-7 through A-9 in

the Appendix.

Emissions

Federal Express CleanFleet

In the CleanFleet program, 36 vans

are undergoing emissions tests. The

first round of emissions tests was

performed after approximately 4,000

miles of driving. Figures 30 through

32 present the results. The program

has conducted two additional rounds

of emission tests: a second round of

tests after the vans have driven

approximately 14,000 miles and a

third round at the end of the project.

The results of these

additional rounds of

emissions tests are

currently being analyzed. The program

tested three vans from

each combination of

vehicle manufacturer

and fuel type.

The CleanFleet vans

use liquid and gaseous

alternative fuel technologies that were

available for commercial service in 1992,

met Federal Express

operations requirements, and had the

backing of the three manufacturers—

Ford, Chrysler, and General Motors

(Chevrolet). Aspects of the vehicle

technology pertinent to exhaust

emissions follow.

The propane gas vans from Ford and

Chevrolet were gasoline production

vans retrofitted to burn propane gas.

The Chevrolet vans were equipped

with a special catalytic converter

designed specifically for vehicles

operating on propane.

The Ford vans, however, used a catalytic

converter designed for

vehicles burning gasoline.

The compressed natural gas vans also represent a range of

technologies. The

Chevrolets are gasoline vans modified to

run on the gaseous

fuel and use an

Englehard catalyst

optimized for

43

Heavy-Duty Vehicles

Figure 27. Number of delivery vans of

each fuel type

Figure 28. Vocation of large trucks in

the program

85 percent

methanol

Reformulated

gasoline

41 21

20

20 32

CNG

Propane

Gasoline

Garbage

packers

7

5

Line haul

Road

maintenance

9
compressed natural gas. The Ford

vans have an engine optimized for

compressed natural gas and a catalyst system designed for gasoline

vehicles. The Dodge vans, which are

among the first production vans to

run on compressed natural gas, use a

catalyst system tailored for use with

natural gas vehicles.

The methanol vans are Ford flexiblefuel vans with a gasoline catalyst

system. During the CleanFleet

demonstration, the vans are run

strictly on 85 percent methanol.

The reformulated gasoline and control vans are standard, gasolinepowered, production vans.

The California Air Resources Board

conducted the emissions tests using a

chassis dynamometer running the

Federal Test Procedure. Within the

CleanFleet program, reformulated

gasoline was considered to be an

alternative fuel. Industry average

standard unleaded test gasoline

(RF-A) was used in the control vehicles for comparison to the alternative

fuel vehicles. 

Figures 30 through 32 show that several of the vehicles demonstrated statistically significant improvements

over the gasoline control vehicles.

The CleanFleet compressed natural

gas vehicles emitted an average of

65 percent to 80 percent less carbon

monoxide than vehicles running on

unleaded gasoline. These vehicles

also had 70 percent to 95 percent

lower non-methane hydrocarbon

emissions. Emissions of oxides of

nitrogen were mixed, ranging from

50 percent less than gasoline for the

Dodge vans to about 20 percent

more for the Ford vans.

As shown in Figure 32, the Ford

vans running on 85 percent methanol

had lower emissions of all four of

the measured pollutants—from about

20 percent lower oxides of nitrogen

emissions to about 50 percent lower

total hydrocarbon emissions.

The propane vans in the CleanFleet

emitted about 50 percent less carbon

monoxide but about 50 percent more

hydrocarbons than their

44

Figure 30. Emissions results for

CleanFleet Dodge delivery vans 

0

1

2

3

4

5

6

CO HC NMHC NOx

Emissions (g/mile)

Tier 1 standards CNG RFG RF-A

Heavy-Duty Vehicles

Figure 29. Locations of heavy-duty 

vehicles in the grant program

CNG

Ethanol

Methanol

LPG

SoyDiesel
gasoline-powered counterparts.

Emissions of oxides of nitrogen were

about 60 percent less than gasoline

vans for the Chevrolet vans, but

about 50 percent more for the Ford

vans. 

Because few of the vehicles in the

CleanFleet program were fully optimized for the alternative fuels, these

emissions results are encouraging.

Large Trucks

During fiscal year 1994, West

Virginia University used its transportable chassis dynamometer to

measure emissions from the New

York City Department of Sanitation’s

compressed natural gas garbage

packers, Archer Daniels Midland’s

95 percent ethanol and diesel control

line-haul trucks in Illinois, and

Hennepin County, Minnesota’s

95 percent ethanol and diesel control

snowplows. 

Emissions Results from Compressed

Natural Gas Garbage Packers

Compressed natural gas garbage

packers with Cummins L10 engines,

which operate in New York City,

have automatic transmissions and

were tested using the standard

Central Business District driving

cycle. The emissions results from

these vehicles were promising but

mixed.

Particulate matter emissions from the

compressed natural gas trucks were

very low—86 percent to 92 percent

less than emissions from comparable

diesel trucks. This appears to be an

inherent advantage of natural gas

fueled engines. More recent versions

of compressed natural gas engines

are attaining a 95 percent reduction

in particulate matter emissions when

compared to equivalent diesel

engines.

The emissions of oxides of nitrogen

from these uncertified prototype

compressed natural gas engines were

not as encouraging. The level of

oxides of nitrogen emissions was

approximately twice that from diesel.

However, it must be noted that these

45

Heavy-Duty Vehicles

Figure 32. Emissions results from the

CleanFleet Ford delivery vans

0

1

2

3

4

5

CO HC NMHC NOx

Emissions (g/mile)

Tier 1 standards CNG M85 Propane RFG RF-A

Figure 31. Emissions results for

CleanFleet Chevrolet delivery vans

0

2

4

6

8

10

CO HC NMHC NOx

Tier 1 standards CNG Propane RFG RF-A

Emissions (g/mile)
early engines had not yet been

developed for low oxides of nitrogen

emissions and later compressed natural gas engines are showing oxides

of nitrogen emission levels 50 percent

to 75 percent less than comparable

diesel engines.

The carbon monoxide emissions levels from the compressed natural gas

trucks showed wide variability during the tests. The emissions levels

ranged from 96 percent less to fourand-a-half times greater than from

comparable diesel trucks. These

compressed natural gas engines

depend on correct functioning of the

catalytic converter to achieve low

carbon monoxide emissions; therefore, a malfunctioning converter

results in very high emissions.

Failure in this type of converter can

be caused by incorrect air/fuel ratio

in the engine. Cummins engineers

have advised the program that these

prototype engines are known to have

a problem with air/fuel ratio drift,

which probably explains the high

levels of carbon monoxide being

emitted by some of the trucks. Later

certified versions of this engine are

showing consistently low carbon

monoxide emissions.

The hydrocarbon emission levels

from the compressed natural gas

trucks were about one to four times

higher than those from comparable

diesel trucks. The hydrocarbon emission levels measured were total

hydrocarbons, including methane;

therefore, higher levels are to be

expected (natural gas is mostly

methane). During certification emissions tests of later models of these

engines, non-methane hydrocarbon

levels were 70 percent less than

those of an equivalent diesel engine.

Emissions Test Results from

Ethanol Trucks

There is no industry standard test

cycle for chassis dynamometer emission testing of heavy-duty trucks.

The Central Business District cycle

is generally used for testing transit

buses and large trucks with automatic transmissions, but cannot be

followed with manual transmission

trucks. West Virginia University has

used a modified Central Business

District cycle, and, more recently,

has developed and applied a new

truck test cycle for our large trucks.

Work is ongoing to define a truck

test cycle (or cycles) that can be

adopted as the industry standard.

As there is no standard cycle, and

emission levels measured are very

cycle dependent, the absolute emission levels measured are not particularly meaningful. Fortunately,

46

Heavy-Duty Vehicles

Ethanol line-haul truck operated by

Archer Daniels Midland in Illinois
however, the relative emission levels

between alternative fuel trucks and

diesel trucks are less dependent on

the driving cycle. Therefore, we can

make meaningful comparisons of the

relative emission levels from alternative fuel vehicles and comparable

diesel control vehicles.

We have studied the emissions data

taken in fiscal year 1994 on 95 percent ethanol-fueled line-haul trucks

in Illinois and 95 percent ethanolfueled snowplows in Hennepin

County, Minnesota. All these trucks

use Detroit Diesel Corporation 6V92

engines. Particulate matter emissions

from the ethanol trucks were quite

low, averaging approximately

65 percent less than their diesel

counterparts. Emissions of oxides of

nitrogen were also lower, averaging

about 25 percent less than the diesel

trucks. In contrast, emissions of

carbon monoxide and hydrocarbons

from the alcohol trucks both averaged

several times higher than comparable

diesel trucks—about three times as

high for carbon monoxide and five

times as high for hydrocarbons.

The program has reviewed these

unexpectedly high carbon monoxide

and hydrocarbon emission measurements with Detroit Diesel Corporation engineers. The Detroit Diesel

experts were surprised by the high

carbon monoxide and hydrocarbon

emissions findings because they are

in sharp contrast to the engine emission certification results for this

engine (see the Transit Bus section

of this report for a discussion of the

engine certification results). They

noted that the carbon monoxide and

hydrocarbon levels are high as the

exhaust leaves the engine, but a catalytic converter is used, which brings

these emissions down to very low

levels. Therefore, an obvious explanation for the high carbon monoxide

and hydrocarbon emissions is that

the catalytic converters are not functioning properly in the field. Several

factors could cause this malfunction,

including failure of the converter

itself, engine faults causing abnormal

combustion (which could prevent

the converter from functioning

correctly), or failure of the converter

to “light-off” sufficiently during the

test driving cycles.

Whatever the explanation, the carbon

monoxide and hydrocarbon emissions levels were disappointingly

high when measured on test cycles

believed to be fairly representative of

in-city operation of large trucks.

Performance and Reliability

To track the performance and reliability of the test vehicles, personnel

at all the sites record the details each

time a vehicle undergoes maintenance or repair work. Extensive

information is already available for

the line-haul trucks operated by

Archer Daniels Midland in Illinois. 

Vehicle performance encompasses

factors such as acceleration, hill

climbing, driveability, and driver

acceptance. Data on vehicle performance are collected in two ways:

tests are conducted on parameters

such as acceleration, and driver feedback is also recorded. The sidebar on

page 48 highlights specific performance and reliability issues that have

surfaced at each program site. As a

direct result of this field experience,

47

Heavy-Duty Vehicles
the engine manufacturers involved in

these projects have already made significant design improvements to

their engines. For example, the

Caterpillar 3406 engine demonstration in California has led to the

development of a production version

of the engine. As data on each

engine type accumulate, the lessons

learned from these projects will further advance the development of

heavy-duty alternative fuel engines. 

The repairs on the Illinois line-haul

trucks running on 95 percent ethanol

and diesel are summarized in

Figure 33. There has been little difference in the number or type of

repairs done on the ethanol and on

the diesel trucks at this site.

Fuel Economy

Each time a truck is

refueled, the driver

records the quantity

of fuel put into the

truck and its odometer reading. From

these records, the

actual in-use fuel

economy of the

vehicle can be

calculated. In addition, when the

vehicle is tested for

emissions on the

transportable chassis

dynamometer, the

fuel economy is also

measured. 

The in-use fuel economy varies from

refueling to refueling

because of factors

such as variations in

driving styles and day-to-day duties.

The data from the chassis dynamometer, on the other hand, are

taken under tightly controlled conditions and therefore vary little. The

disadvantage of the dynamometer

tests is that the driving cycle used

during the tests may not be representative of the vehicle’s normal

operation.

Figure 34 presents the large truck

fuel economy data available to date.

In some of the sites, only in-use

results are available. All the results

are presented on a mile per diesel

equivalent gallon basis. 

For the Illinois line-haul trucks, the

fuel economy measured with the

chassis dynamometer is lower than

48

Heavy-Duty Vehicles

Heavy-Duty Vehicle Performance and Reliability Issues

Project Fuel Performance Reliability

Federal Express 85 percent methanol, Driveability and range Original equipment

CleanFleet compressed natural complaints (separate manufacturer engines

gas, liquefied reports available) generally better than

petroleum gas, conversions

reformulated gasoline,

electricity

Acurex/VONS Compressed natural Hill-climb test slower Numerous reliability

gas than diesel; problems indicate lack

acceleration of development

comparable to diesel

New York City Compressed natural Comparable One low-mileage

Sanitation gas performance; much piston failure

quieter

Illinois Energy and 95 percent ethanol Comparable Bearing failure caused

Natural Resources/ performance by operator error1

Archer Daniels Midland

Trucking Research 95 percent ethanol Performance Fuel pump failures

Institute/ complaints related to (under investigation)

Hennepin County fuel pumps; also coldstarting problems

1 A new operator thought that the DDC-required fuel additive was an oil additive and added it to the

crankcase. This diluted the oil and caused premature wear of the crankshaft bearings. Although this

was a simple mistake, it does point to the necessity of thorough training for operators of alternative

fuel vehicles.

Alternative Fuels in Action

During 3 years of operation, the four

95 percent ethanol line-haul trucks at

Archer Daniels Midland in Illinois

have accumulated more than 200,000

miles each. Maintenance and reliability have been comparable with

diesels, demonstrating that ethanol is

a viable choice of fuels for over-theroad trucking. Meanwhile, in

Hennepin County, Minnesota, two

ethanol-powered snowplows have

plowed through extreme conditions.

These snowplows, powered by

Detroit Diesel 6V92 engines running

on 95 percent ethanol, have endured

the harshest winter in many decades,

operating flawlessly in temperatures

that dipped as low as 25 degrees

below zero. During the summer, the

trucks were use for road maintenance and operated reliably in

extremely hot weather. The drivers’

weekly reports compared the ethanol

trucks quite favorably to their diesel

counterparts.
49

Heavy-Duty Vehicles

the in-use figures. This probably

results from the difference between

the dynamometer driving cycle and

the actual driving cycle. The West

Virginia University Truck Cycle,

which emulates city driving, was

used on the dynamometer; however,

the line-haul trucks typically drive

long distances on the highway. For

the New York City refuse packers,

which operate primarily on a

stop-and-go driving cycle, the

dynamometer results (using the

standard Central Business District

driving cycle) fall within the range

of in-use results for the compressed

natural gas trucks and close to the

range of in-use results for the diesel

trucks.

Most of the alternative fuel vehicles

demonstrated fuel economies comparable to their diesel counterparts.

However, the fuel economy of the

compressed natural gas line-haul

truck in California (with a Caterpillar

3406 engine) was significantly lower

than that of its diesel counterpart.

This may be attributed to factors

such as pumping losses (throttled

engine), lack of fuel system development, unnecessary operation of cooling fan, and exhaust back pressure.

(These vehicles were later retrofitted

with dual exhausts to lower exhaust

back pressure.) 

Significant quantities of data have

been accumulated for the commercial

delivery vans in the Federal Express

CleanFleet project. Figure 35 presents a summary of the in-use and

chassis dynamometer fuel economies

on a mile per gasoline equivalent

gallon basis. In general, all the

chassis dynamometer results show

higher fuel economies than the

in-use figures. This probably results

from the driving cycle of the urban

delivery vans. The vans spent more

stopping and idling time in use than

is included in the Federal Test Procedure driving cycle used in the

dynamometer tests. 

Figure 33. Number of repairs done

each month on 95 percent ethanol and

diesel line-haul trucks

0

2

4

6

8

10

12

Number of repairs per vehicle

Diesel Ethanol

Feb-92

Mar-92

Apr-92

May-92

Jun-92

Jul-92

Aug-92

Sep-92

Oct-92

Nov-92

Dec-92

Jan-93

Feb-93

Mar-93

Apr-93

May-93

Jun-93

Jul-93

Aug-93

Sep-93

Oct-93

Nov-93

Dec-93

Figure 34. Large truck fuel economy

0 5 10

Fuel economy (miles per diesel equivalent gallon)

Illinois, line haul-E95

Illinois, line haul-diesel

▲

▲ ▲

▲

Nebraska, road maintenance-E-95

Nebraska, road maintenance-diesel

New York, garbage packer-CNG

New York, garbage packer-diesel

California, line haul-CNG*

California, line haul-diesel*

* Only average in-use fuel economy figures were available at the time of this report.

▲

In-use fuel economy from refueling data

Fuel economy measured with a chassis dynamometer during emission testing
50

Heavy-Duty Vehicles

The Chevrolet propane and compressed natural gas and Dodge compressed natural gas vehicles show

about 10 percent to 15 percent lower

in-use fuel economy than the control

gasoline vehicles. The dynamometer

results mirror this difference. All the

Ford vehicles, which are operating

on compressed natural gas, propane,

and 85 percent methanol, have fuel

economies within a few percent of

their gasoline counterparts in both

the in-use and dynamometer data.

With all engine manufacturers working on increasing efficiency and

reducing emissions, fuel economy is

expected to improve for alternative

fuel and conventional fuel heavyduty engines. The manufacturers’

efforts have already paid off handsomely—for example, line-haul

trucks have exhibited a 40 percent to

50 percent improvement in fuel

economy in the past 10 years. These

improvements have come from

advances in electronic engine controls, as well as vehicle design and

aerodynamics. For alternative fuels,

most engine companies are in the

early stages of the development

curve. Therefore, there may be considerable room for further improvement.

Cost

Keeping operating costs low is critical to successful heavy-duty vehicle

operations. For example, the

American Trucking Association

reports that in line-haul trucking, the

profit margin is very tight—on the

order of 2 percent. This means that

any increase in operating cost either

makes the operation unprofitable or

must be passed on to the consumer.

Acquisition Costs

The additional acquisition costs for

the large alternative fuel trucks are

similar to those of the buses, as

described in the previous section.

Many of the engines are exactly the

same engines as those used in the

transit buses.

The Federal Express CleanFleet and

United Parcel Service Fleet vehicles

have engines similar to those of the

light-duty trucks, so their acquisition

costs are similar to those of the lightduty trucks.

Fuel Costs

Although alternative fuels enjoy

tax breaks in many states, high

Figure 35. CleanFleet fuel economy

results

Chevrolet-CNG

Chevrolet-Gasoline

5 10 15

Fuel economy

(miles per gasoline equivalent gallon)

▲

▲

▲

▲

▲

▲ ▲

▲

▲

▲

▲

▲

Dodge-CNG

Dodge-Gasoline

Ford-CNG

Ford-Gasoline

Chevrolet-Propane

Chevrolet-Gasoline

Ford-Propane

Ford-Gasoline

Ford-M85

Ford-Gasoline

▲

In-use fuel economy from refueling data

Fuel economy measured with a chassis dynamometer during emission testing
production costs for some alternative

fuels may offset the breaks. Figure

36 shows fuel cost per diesel equivalent gallon paid by the large truck

operators. The fuel cost per mile

traveled also depends upon the fuel

economy of each vehicle.

Maintenance Costs

In virtually all the current heavyduty alternative fuel projects, alternative fuel vehicles have cost more

to maintain. A probable cause is the

lack of development of the alternative fuel engines and fuel systems.

As alternative fuel engines attain

higher mileage levels, and manufacturers refine engine and fuel system

designs based on the experience

gained in this program, reliability

levels comparable to diesel engines

may result. The current generation of

diesel engines has achieved a high

level of reliability and longevity.

Engine manufacturers have reported

cases of diesel engines running more

than 1 million miles without an

overhaul. Alternative fuel engines

will have to log many more miles

before their longevity can be

evaluated fairly. 

51

Heavy-Duty Vehicles

Figure 36. Fuel cost per diesel

equivalent gallon

E95

CNG

Diesel

Fuel cost (dollars per diesel equivalent gallon)

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

United Parcel Service

Expands its Compressed

Natural Gas Fleet

Based on the excellent performance of the 20 dedicated compressed natural gas engines in

their Washington, D.C., fleet,

United Parcel Service has decided

to order 276 more of the Tecogen

4.3L compressed natural gas

engines and retrofit additional

vehicles with these engines. The

repowered vehicles will operate in

Connecticut and Southern

California. United Parcel Service

expects compressed natural gas

vehicles to play an important part

in its fleet operations in the future.
52
53

Safety Incidents 

In general, the test fleet has a very

good safety record. Safety incidents

involving the alternative fuel systems

have been rare. However, two sets

of incidents did occur: one with

compressed natural gas cylinders and

the other with methanol cold-start

injectors. The program has investigated the causes of these incidents

and has taken steps to prevent their

recurrence.

During the past year, there were two

serious incidents involving Chevrolet

C-2500 dedicated compressed natural

gas pickup trucks, but these trucks

were not part of the General Services

Administration’s fleet. Minnegasco

and Pacific Gas and Electric

Company owned and operated the

two vehicles. (The General Services

Administration had 600 of the same

model of vehicle in service.) The

high-pressure fuel tanks failed on

both vehicles. The equipment was

lost, but no one was seriously

injured.

Production Automotive Systems,

Inc., converted the two pickup trucks

for General Motors. The fuel tanks,

manufactured by Comdyne, Inc.,

were fully wrapped aluminum-lined

cylinders with an E-glass/epoxy

overwrap. Stress corrosion cracking

of the overwrap developed as a result

of exposure to acids, which caused

the cylinders to rupture during

refueling. The Gas Research

Institute sponsored an investigation,

which was conducted by Southwest

Research Institute. The investigators

recommended:

• Modifying the design of the stone

shield to prevent immersion of the

cylinder in trapped liquids.

• Improving cylinder design by

using coatings with proven acid

resistance.

• Training operators of existing natural gas vehicles to increase

awareness of the effects of acids

on uncoated, composite-wound

cylinders.

The Gas Research Institute also recommended that all natural gas vehicle owners immediately inspect

cylinders for stress corrosion cracking, that cylinders be inspected periodically, and that owners be

cautioned not to expose these cylinders to acids. The Gas Research

Institute is distributing safety guidelines on natural gas vehicles. The

Chevrolet C-2500 natural gas pickup

trucks are no longer being sold.

Inspectors found damage on two of

the compressed natural gas fuel tanks

on the line-haul trucks in California.

One was damaged by a leaking

exhaust system and could not be

repaired; the hot exhaust gases had

burned an area of the composite

wrap material on the outside of the

tank. The tank did not rupture.

When the damage was discovered,

Safety
54

the tank was replaced. The other

damaged tank showed a gouge. The

tank was repaired and the vehicle

was returned to service.

The National Renewable Energy

Laboratory funded an inspection and

study of compressed natural gas fuel

tanks on school buses sponsored by

the Department of Energy.

Inspectors checked 118 gas cylinders

and tagged 4 damaged cylinders.

The damaged cylinders were shut off

from the rest of the bus fuel system

and their pressure was reduced until

the cylinders could be recertified or

replaced. A full report of the

inspection results is available from

the National Renewable Energy

Laboratory. 

The Federal Express CleanFleet had

two fires on methanol-powered Ford

vans. One vehicle was repaired; the

other was a total loss. No one was

injured. Both fires were attributed to

fuel leaks at the cold-start injector.

Since the vehicles were built, Ford

has determined that this component

is not needed, and it has been

removed from the remaining

vehicles.

Safety
55

To meet the demands that the

increasing numbers of alternative

fuel vehicles place on the U.S. marketplace, an associated infrastructure

has developed. This infrastructure,

consisting of refueling sites and

maintenance and storage facilities, is

the fabric that holds together the

components of the alternative fuel

industry. The infrastructure’s growth

has been stimulated by various

incentives such as the Alternative

Motor Fuels Act of 1988, the Clean

Air Act Amendments of 1990, the

Energy Policy Act of 1992, and

Executive Order 12844 (Federal Use

of Alternative Fueled Vehicles, April

1993). 

Refueling Sites

Light-Duty Vehicles

Figure 37 illustrates the recent rapid

growth of compressed natural gas,

85 percent methanol, and 85 percent

ethanol refueling stations. The total

number of these refueling sites has

quadrupled in the past 4 years. More

than 90 stations offer 85 percent

methanol and about 30 offer 85 percent ethanol. The number of compressed natural gas sites has more

than tripled since 1990, growing

from 300 to more than 1,000. About

three-fifths of the compressed natural

gas sites are fully available to the

public or may be made available by

arrangement, usually with the local

utility company. As shown in

Figure 38, these sites are distributed

throughout the United States. The

3,300 liquefied petroleum gas sites

in the figure represent responses to a

1992 survey by the National Propane

Gas Association. However, the

Liquefied Petroleum Gas Clean

Fuels Coalition estimates that there

are now as many as 11,000 sites

where liquefied petroleum gas can

be obtained for use as a motor fuel. 

Buses and Heavy-Duty Vehicles

In general, transit bus agencies and

heavy-duty fleets install their own

fueling stations and do not use public

fueling stations. The refueling station for each alternative fuel poses

unique challenges both in terms of

set-up costs and safety considerations.

Infrastructure

Support

Figure 37. Estimated number of refueling stations by year and fuel type

Sources: 

1 National Corn Growers Association

2 Various state energy offices and the

Department of Energy

3 American Gas Association

1991 1992 1993 1994

0

200

400

600

800

1000

1200

Number of stations

Year

CNG3 M852 E851
For methanol and ethanol refueling

stations, it is relatively easy to install

a new in-ground or above-ground

fuel storage tank. However, because

the alcohol fuels have corrosive

properties, special attention must be

given to the choice of materials used

to make the tank and pump. For the

compressed natural gas refueling

infrastructure, various choices exist.

All options tend to be more expensive than the alcohol fuels. A slowfill system uses a small compressor

and has the lowest cost. In a slowfill system, the vehicles are hooked

up to a refueling hose overnight.

Typical refueling time is about 8

hours. At the other end of the

spectrum, a fast-fill system requires

a large and expensive compressor

station. These can typically refill a

vehicle with compressed natural gas

in about the same amount of time it

takes to refill with diesel or gasoline.

Most public access compressed natural gas stations are fast fill. These

stations can cost $200,000 to

$300,000 to build.

A persistent problem with the installation of alternative fuel refueling

stations is the lack of consistent zoning and safety requirements. Each

municipality has its own unique

requirements. This prevents the standardization of equipment and

56

Figure 38. Alternative fuel refueling

sites in each state

Infrastructure Support

M85 Sites

 LPG Sites

 CNG Sites

E85 Sites

16

85

1

20

45

6

104

63

1

118

214

3 42

48

11

19

38

222

3

47

80

1

6

20

2 10

23

165

6

4 108 1

39

124

2 12 38

9 35

14

44

12

2 25 21

2

6

12

41 12

29

182

1

16

125

75

10

83

11 48

10 47

4 8 20

1 31

18 36

15 46

42

100 7

72 8

5 17

53

98

2

48 56

4 21

1 51 133

2

5

3

43

6 5 24

6 80 2

1 77 202

48

20

1 33

25 39

1 30 37

2

22

139

19

33

1

1

8

District of

Columbia

West

Virginia

1

37

16

Alaska 8
installation procedures, which in turn

leads to higher costs.

Maintenance Facilities

Light-Duty Vehicles

Original equipment manufacturer

dealerships perform maintenance on

light-duty alternative fuel vehicles in

the test fleet. Dealership personnel

have been factory trained to service

the type of alternative fuel vehicles

the particular dealership carries.

They are particularly knowledgeable

about the vehicle’s fuel system and

electronics. The General Services

Administration reports that vehicle

maintenance was sometimes difficult

in the early years of the program

(1991-1992), but that it generally no

longer presents a problem. The dealerships now provide reasonable service for the vehicles they sell.

Converted vehicles can be returned

to the conversion shop for service.

To expand the pool of qualified technicians to service alternative fuel

vehicles that have been converted to

compressed natural gas or liquefied

petroleum gas, the Department of

Energy’s Office of Transportation

Technologies, in compliance with

Section 411 of the Energy Policy Act

of 1992, has funded a national program to certify training programs for

technicians who convert vehicles to

alternative fuels, and who maintain

and repair the vehicles and refueling

stations. This program is called

CHAMP (Certification of Higherlearning in the Alternative Motor

Fuels Program). The CHAMP team

is composed of 16 charter organizations that represent automotive vehicle manufacturing, education and

certification, alternative fuels production, vehicle conversions, automotive service, and the public. This

team will provide the guidance and

resources to aid the certification program’s development, implementation, and evaluation.

Transit Buses and

Heavy-Duty Vehicles

Generally, the transit agency or the

engine dealership performs maintenance on the alternative fuel buses in

the program. Because transit agencies usually have only one or two

central sites for maintaining their

entire fleet, these sites are outfitted

for the alternative fuels used by the

agency and the technicians at those

sites gain experience with the alternative fuel systems quickly. In contrast, there are often only a few

alternative fuel heavy-duty vehicles

at any given site. The lack of

trained maintenance technicians with

experience in alternative fuel technologies has been a problem at these

sites. In addition, many of the maintenance shops used by the heavyduty vehicles do not have adequate

ventilation and gas detectors to

safely work on gaseous fuel vehicles

indoors. Although both situations

are improving, progress is slow. A

maintenance facility may not be able

to justify upgrading equipment and

training its personnel to maintain

alternative fuel vehicles that often

number less than ten in a given site.

Vehicle Storage

Special precautions must be taken

before storing gaseous fuel vehicles

indoors. Indoor storage requires gas

detectors and adequate ventilation

57

Infrastructure Support
58

systems. Many underground parking

facilities do not currently permit

compressed natural gas or liquefied

petroleum gas vehicles. This

presents a problem for pickup and

delivery vehicles operating in urban

areas. In the long term, this issue

will need to be resolved if compressed natural gas and liquefied

petroleum gas are to gain widespread

use for this type of service.

Where We Are

The infrastructure for light-duty

alternative fuel vehicles appears to

be growing in pace with the number

of vehicles of this type being

introduced. No significant impediment to further expansion is evident.

The infrastructure for transit buses is

also developing along with the vehicles. However, there have been significant infrastructure problems with

alternative fuel use in large trucks.

Virtually every large truck project

has encountered problems with some

aspect of refueling, maintenance, or

storage. Continued government support of heavy-duty projects will

increase familiarity with the infrastructure issues associated with these

vehicles and help drive the private

sector to resolve these issues.

Infrastructure Support
59

Figure 39. Number of E85 vehicles in

U.S. fleets

Alternative Fuel Vehicles

in Use

Figures 39 through 41 give some

perspective on the number of Federal

and non-Federal light-duty alternative fuel vehicles in the United States

for the past 3 years. The figures also

present predictions on the number of

alternative fuel vehicles that will be

in operation in 1995. The

Department of Energy’s Energy

Information Administration estimated these numbers using the best

sources available. The number of

liquefied petroleum gas vehicles is

difficult to estimate because they are

almost all conversions. Current estimates put the number of liquefied

petroleum gas vehicles in operation

in the United States at approximately

186,000.

In February 1994, the American

Public Transit Association conducted

a survey of transit bus agencies. The

alternative fuel share of the U.S. bus

market at that time was about 2 percent of the approximately 50,000

buses on the road. The market penetration of alternative fuels in the bus

sector is substantially ahead of any

other transportation sector. A transit

bus is an ideal application for alternative fuels because the buses are

centrally refueled (requiring less

infrastructure development), and

extra space for larger fuel tanks is

generally available on a bus.

Vehicle Availability

0

100

200

300

400

500

600

700

800

900

1992 1993 1994 1995

Non-Federal Federal

Number of vehicles

Year

Figure 40. Number of M85 vehicles in

U.S. fleets

1992 1993 1994 1995

0

4000

8000

12,000

16,000

20,000

Non-Federal Federal

Number of vehicles

Year
60

Vehicle Availability

The sidebar on page 61 lists the

types of vehicles that were available

from the original equipment manufacturers in 1994 and those that are

planned for production in 1995. The

models offered in 1994 included

three compressed natural gas models,

four 85 percent methanol flexiblefuel models, and one heavy-duty liquefied petroleum gas truck. Models

to be offered in 1995 include two

flexible-fuel 85 percent methanol

vehicles, four dedicated compressed

natural gas models, two bi-fuel compressed natural gas models, and one

liquefied petroleum gas heavy-duty

truck.

The General Services Administration

has indicated that original equipment

manufacturer offerings in calendar

year 1995 may not be sufficient to

meet the purchase requirements of

the Energy Policy Act of 1992 and

Executive Order 12844. These mandates require the purchase of 15,000

alternative fuel vehicles for the

Federal fleet in 1995. They plan to

supplement original equipment manufacturer orders with purchases

made through qualified vehicle converters. A qualified vehicle converter is an original equipment

manufacturer-approved organization

that converts standard vehicles to run

on an alternative fuel.

In some cases, the supply of compressed natural gas vehicles offered

for purchase in calendar year 1995

may be delayed because of cylinder

supply problems.

Vehicle Availability

Figure 41. Number of CNG vehicles in

U.S. fleets

1992 1993 1994 1995

0

20,000

40,000

60,000

80,000

100,000

Non-Federal Federal

Number of vehicles

Year
61

Vehicle Availability

Alternative fuel vehicles offered by U.S. original equipment manufacturers

1994 Model Year Vehicles

Manufacturer Model Body Style Design Fuel Secondary Fuel

Chrysler - Dodge RAM van/wagon Full-size van Compressed natural gas

Chrysler - Dodge Spirit Compact sedan 85 percent methanol Gasoline

Chrysler - Dodge Caravan Minivan Compressed natural gas

Chrysler - Dodge Intrepid Mid-size sedan 85 percent methanol Gasoline

Chrysler - Plymouth Acclaim Compact sedan 85 percent methanol Gasoline

Chrysler - Plymouth Voyager Minivan Compressed natural gas

Ford Taurus Mid-size sedan 85 percent methanol Gasoline

Ford F600/700 Heavy-duty truck Liquefied petroleum gas

1995 Model Year Vehicles

Manufacturer Model Body Style Design Fuel Secondary Fuel

Chrysler - Dodge Intrepid Mid-size sedan 85 percent methanol Gasoline

Chrysler - Dodge Ram Van/Wagon Full-size van Compressed natural gas

Chrysler - Dodge Ram pickup Full-size pickup Compressed natural gas

Chrysler - Dodge Caravan Minivan Compressed natural gas

Chrysler - Dodge Dakota Mid-size pickup Compressed natural gas

Chrysler - Plymouth Voyager Minivan Compressed natural gas

Ford Taurus Mid-size sedan 85 percent methanol Gasoline

Ford F150/250 Full-size pickup Compressed natural gas Gasoline

Ford Econoline Full-size van Compressed natural gas Gasoline

Ford F600/700 Heavy-duty truck Liquefied petroleum gas
62
63

The Alternative Fuels Data Center,

where all data from the program are

collected, analyzed, and disseminated.

Information dissemination is an

important component of the

Department of Energy’s program.

Accurate, timely, and readily available information can only help to

hasten public acceptance and the

enthusiastic adoption of alternative

fuel vehicles. Programs to provide

information about alternative fuels

are mandated by the same Federal

legislation that affects other alternative fuels arenas: the Alternative

Motor Fuels Act of 1988, the Clean

Air Act Amendments of 1990, the

Energy Policy Act of 1992, and

Executive Order 12844. 

The Alternative Fuels

Data Center

To make the best possible use of the

information being collected through

the various programs, the

Department’s Office of

Transportation Technologies’ Office

of Alternative Fuels established the

data center (AFDC) at the National

Renewable Energy Laboratory. The

center serves as the focal point for

data generated by all the test fleets.

The center maintains information on

line in computerized data bases.

Hard copies are available as well,

and are distributed by personnel

manning the National Alternative

Fuels Hotline (1-800-423-1DOE).

The center’s engineers validate the

quality of the data they receive

through various computerized,

statistical, and manual procedures. If

the data meet these quality tests, they

are loaded into the production data

base. If the data do not meet the

quality standards, they are investigated to determine the error for possible

correction of the data and/or to

implement procedures to prevent

similar errors in future data. Once

loaded into the data base, the data

are analyzed and reports are developed. All information in the data

base is made available to other

researchers, private industry, and

anyone else interested in the information. Access is provided electronically via dial-up modem or through

the international computer network,

Internet.

Information

Dissemination

Report
64

Several methods of access are available. AFDC/View and AFDC/Menu

are two systems developed by the

data center’s engineers to allow users

quick and easy access to more than

300 predetermined queries. Users

generally specify vehicle models or

locations of interest and the system

returns raw and summary data. In

addition to these methods, the center

also provides access via systems that

allow the users to program their own

queries. These methods are recommended for the serious researcher,

not the casual user. Another method

of accessing the data on Internet is

via the World Wide Web (WWW),

using browsers such as Mosaic.

Because this graphical user interface

is very intuitive and user friendly, it

is gaining wide popularity. The

White House has just announced that

it has information available on

Internet via the World Wide Web.

The World Wide Web does not limit

access to raw data but also can

include complete reports, graphics,

photographs, sound, and even

movies. The center currently maintains maps of alternative fuel refueling sites, a data base of biofuels

literature, and the complete text of

the center’s quarterly newsletter.

This access method will be greatly

expanded in the coming year to

include Department of Energy alternative fuels reports and most program summary information.

The hotline staff maintains a large

inventory of information of interest

to the public as well as government

workers and researchers on alternative fuels and the supporting industries. Everyone is welcome to call

and have questions answered by an

informative operator. The hotline

operators have immediate access to

the center’s data bases, along with

information that has not yet been put

into the data base. They can answer

questions immediately, mail any

requested information, or provide

reference to other sources of

information.

The center is constantly producing

and updating a series of publications.

This year several brochures were

published, some of which covered

contacts in the alternative fuels

industry, facts about Federal legislation, facts about compressed natural

gas conversions, and maps of refueling site locations. In addition, the

center publishes a quarterly newsletter that currently has a circulation of

nearly 15,000 and is also available

electronically.

Data center personnel are aggressively pursuing establishing a comprehensive data base of research and

demonstration information on alternative fuels. Materials that are not

copyrighted will be available as

complete documents. Copyrighted

information will be maintained as a

literature citation. The hotline will

use this system. In addition, a new

interface is being developed to guide

on-line users through the maze of

information and point them to the

information they need. A prototype

version of this system will be available in 1995.

Market Research

In 1994, a subcontractor conducted

market research to obtain independent feedback on the types of information needed by prospective and

Information Dissemination Report
current users. The research consisted

of interviews with existing and

potential customers. It netted positive feedback, finding that the current hotline and data center service is

meeting expectations and that the

potential to convert hotline users to

data center users is high. Most

respondents were interested in lightduty vehicle data, and the greatest

interest appeared to be in compressed natural gas as a fuel. The

research determined that needs cannot be met with one presentation format; a broad mix of styles is needed.

The current approach to information

dissemination, as well as future

plans, tracks closely with these

findings.

65

Information Dissemination Report
66
A-1

Table A-1: Federal Agencies Participating in the Light-Duty Vehicle Program

Argonne National Laboratory Federal Emergency Management Agency

Bureau of Indian Affairs Federal Energy Regulatory Agency

Central Intelligence Agency Federal Aviation Administration

Colorado Army National Guard Federal Energy Regulatory Commission

Consumer Product Safety Commission Federal Highway Administration

Department of Agriculture Government Printing Office

Department of the Air Force Herbert Hoover National Historic Site

Department of the Army Library of Congress

Department of Commerce NASA Transportation Section

Department of Defense National Archives and Records Administration

Department of Energy National Credit Union Administration

Department of Health and Human Services National Guard Office

Department of the Interior National Park Service

Department of Justice National Renewable Energy Laboratory

Department of Labor Naval Petroleum Reserve

Department of State Office of Surface Mining

Department of Transportation Small Business Administration

Department of the Treasury South Dakota Urban Indian Health

Department of Veterans Affairs U.S. Bureau of Alcohol, Tobacco & Firearms

Environmental Protection Agency U.S. District Court

Federal Drug Administration U.S. Geological Survey

Appendix
A-2

Table A-2: Status of the Current Light-Duty Test Fleet

Vehicle Description Model Fuel Design Number Reported 

Year Type Number of

Miles

Dodge Ram Van 1992 CNG Dedicated 63 598,290

Dodge Ram Van 1994 CNG Dedicated 12 21,612

Dodge Spirit 1994 M85 Flexible 222 1,282,247

Chevrolet C-2500 Pickup 1992 CNG Dedicated 1451 407,492

Chevrolet Lumina 1991 M85 Flexible 251 666,729

Chevrolet Lumina 1993 M85 Flexible 21 104,500

Chevrolet Lumina 1992 E85 Flexible 32 213,552

Ford Taurus 1991 M85 Flexible 391 955,021

Ford Taurus 1993 M85 Flexible 17 96,072

Ford Taurus 1994 E85 Flexible 13 9,208

Ford Econoline Van 1992 M85 Flexible 14 66,933

Total AF Vehicles All 603 4,421,656

Total Control Vehicles All Gasoline 2432 1,820,752

Total AF and Control All 846 6,242,408

1 Removed from data collection in 1994 (except five 1991 Chevrolet Luminas)

2 Ninety-one control vehicles (all 1991 Tauruses, 1991 Luminas, and 1993 C-2500 pickups) were removed from data

collection in 1994

Appendix
A-3

Table A-3: Emissions Tests Completed on Light-Duty Vehicles in 1994

Vehicle Model Model Year Number Number

Type of Vehicles of Tests

Chevrolet C-2500 Pickup 1992 CNG 5 5 

Chevrolet C-2500 Pickup 1992 Standard 2 2 

Chevrolet Lumina 1992 E85 flexible-fuel 13 54 

Chevrolet Lumina 1992 Standard 14 19 

Dodge B-250 Van 1992 CNG 11 16 

Dodge B-250 Van 1992 Standard 9 14 

Dodge Spirit 1993 M85 flexible-fuel 44 172 

Dodge Spirit 1993 Standard 43 61 

Ford Econoline Van 1993 M85 flexible-fuel 2 12 

Ford Econoline Van 1993 Standard 3 6 

Total 146 361 

Appendix
A-4

Table A-4: Fuel System Parts Replacements on Light-Duty Vehicles

Vehicle Model Fuel Number Total Fuel-Related Repairs

of Vehicles

1991 Ford Taurus M85 38 55 fuel pumps 

47 processors

29 fuel injectors

30 methanol wiring harnesses

11 fuel pressure regulators

10 fuel tanks

13 mass air flow sensors

21 fuel sending units

Gasoline 9 No fuel-related parts replaced

1991 Chevrolet M85 33 16 fuel injectors

Lumina 7 fuel pump speed controllers

2 fuel pumps

Gasoline 8 1 open circuit to oxy. sensor

1 evap. solenoid/sensor

1 oxygen sensor

1 intake manifold gasket

1992 Dodge Ram Van CNG 42 4 oxygen sensors

3 fuel pressure sensors

2 speed sensors

11 sets of fuel injectors

7 check valves

4 fill valves

Gasoline 0

1993 Dodge Spirit M85 54 3 fuel flow sensors

3 flexible-fuel sensors

1 fuel pump

Gasoline 3 1 fuel sending unit

Appendix
Table A-5: Summary of the Alternative Fuel Transit Buses in the Data Collection Program

Site Fuel Number of Alternative Months Total Mileage on

Fuel Buses of Data Alternative Fuel Buses

Houston LNG/diesel dual-fuel 10 17 376,000

Miami CNG 5 12 66,000

Tacoma CNG 5 7 141,000

Peoria E95/E93* 5 21 357,000

Minneapolis E95 5 3 24,000

Miami M100 5 12 134,000

New York M100 5 0 0

St. Louis Biodiesel (B20) 5 4 75,000

* Peoria switched from E95 to E93 in March 1994 for financial reasons. Approximately 75 percent of the above

mileage had been accumulated when this switch was made.

A-5

Appendix
A-6

Table A-6: Summary of the Heavy-Duty Vehicles in the Data Collection Program

Project Fuel Engines Vocation Number of Sponsors Launched

Vehicles/Controls

Federal Express M85 Local 84/27 NREL, SCAQMD, CEC, 10/92

CleanFleet delivery Federal Express, OEMs,

Fuel suppliers

CNG

Propane

RFG

Trucking Research CNG Tecogen 4.3 L Local 20/5 NREL, UPS 09/94

Institute/United delivery

Parcel Service

Acurex/VONS CNG Caterpillar 3406 Line haul 1/1 NREL, SCAQMD, SoCal 10/92

Grocery Company Gas, CEC

New York City CNG Cummins L10 Garbage 6/3 NREL, NYC Department 11/92

Department of packer of Sanitation

Sanitation

Illinois Energy and E95 DDC 6V92 Line haul 4/1 NREL, Illinois ENR 10/92

Natural Resources/

Archer Daniels

Midland

Trucking Research E95 DDC 6V92 Dump truck/ 2/1 NREL, Hennepin County 10/93

Institute/Hennepin snowplow

County, Minnesota

Trucking Research E95 DDC 6V92 Dump truck/ 2/0 NREL, Nebraska 09/94

Institute/Nebraska snowplow

Trucking Research CNG DDC Series 60 City delivery 1/1 NREL, SCAQMD, SoCal, 09/94

Institute/Acurex Gas, CEC

Trucking Research Biodiesel DDC, Cummins, Line haul 6/3 NREL, Ag Products 10/94

Institute/Ag Products Mack

Appendix
A-7

Table A-7: Vehicles in the Heavy-Duty Grant Program: Phase 0 and 1 School Bus Grants

Phase Operating State Number Fuel Vehicle

Jurisdiction Type

0 Tulsa County Oklahoma 55 CNG School buses

0 Tulsa County Oklahoma 45 CNG School buses1

0 Town of Weston Massachusetts 3 CNG School buses

0 Town of Weston Massachusetts 2 CNG School buses1

0 Wood County West Virginia 2 CNG School buses

0 Wood County West Virginia 2 CNG School buses

0 Wood County West Virginia 4 CNG School buses1

1 Maricopa County Arizona 4 CNG School buses

1 Braxton County West Virginia 3 CNG School buses

1 Montgomery County Pennsylvania 1 Methanol School bus

1 D.C. Public Schools District of Columbia 4 CNG School buses

1 Springfield School District Missouri 4 CNG School buses

1 Jordan School District Utah 4 CNG School buses

1 University of Vermont Vermont 2 CNG School buses

1 Shenendehowa School District New York 2 CNG School buses

1 Marcus Whitman School District New York 2 CNG School buses

1 Albuquerque New Mexico 4 CNG School buses

1 Franklin County Kentucky 4 CNG School buses

1 Montgomery County Maryland 32 CNG School buses

1 Baltimore County Maryland 32 CNG School buses

Total 153

1 Conversion vehicles (all others are OEM vehicles)

2 Two of the vehicles were purchased with DOE funding; one was purchased with Maryland state funds.

Appendix
A-8

Table A-8: Vehicles in the Heavy-Duty Grant Program: Phase 2 School Bus

and Heavy-Duty Vehicle Grants

Phase Operating State Number Fuel Vehicle Type

Jurisdiction

2 Peoria Illinois 2 E95 Snowplow/construction trucks

2 Peoria Illinois 1 E95 School bus

2 Louisville/ Kentucky 3 CNG Municipal wreckers

Jefferson County

2 Mecklenburg County North Carolina 4 CNG School buses

2 State of Nevada Nevada 2 CNG 15,000-GVW Crew Cab

dump trucks

2 State of Nevada Nevada 2 CNG Tymco street sweepers

2 New York City New York 2 CNG Athey street sweepers

2 Bethlehem School 2 CNG Transit-style buses used

District, Albany County New York in school bus operation

2 East Providence Rhode Island 4 CNG School buses

2 Richland and South Carolina 4 CNG Heavy-duty trucks

Lexington Counties

2 Richmond, Virginia 3 LPG Class 7 (28,000-33,000 GVW)

Northern Virginia, dump trucks

and Suffolk

2 Virginia Beach Virginia 1 CNG School bus

2 Pleasants County West Virginia 2 CNG Transit-style buses used 

in school bus operation

2 Washington, D.C. District of 3 CNG Jet Vac machines

Columbia

2 Washington, D.C. District of 1 CNG 38,000-GVW dump truck

Columbia

2 Waco and Washington Iowa 4 Soydiesel* School buses

Community

School Districts

Total 40

*70 percent soydiesel/30 percent diesel blend

Appendix
A-9

Table A-9: Vehicles in the Heavy-Duty Grant Program: Phase 3 School Bus and Heavy-Duty Vehicle

Grants

Phase Operating State Number Fuel Vehicle Type

Jurisdiction

3 Washington, D.C. District of 4 CNG Ford E350s

Columbia

3 Boston Massachusetts 4 CNG Airport shuttles

3 Long Beach California 4 CNG Refuse haulers

3 State of Maryland Maryland 7 CNG Heavy-duty vehicles

3 Kenosha Wisconsin 3 CNG Refuse haulers

3 Kenosha Wisconsin 1 CNG Street sweeper

3 Chicago Illinois 7 Diesel, LPG, Refuse haulers

Ethanol, CNG

3 Las Vegas Nevada 2 CNG Street sweepers

3 Phoenix Arizona 2 CNG Tractor trailers

3 Phoenix Arizona 2 CNG Dump trucks

3 Phoenix Arizona 2 CNG Refuse haulers

3 State of Pennsylvania Pennsylvania 1 M100 School bus

3 State of Pennsylvania Pennsylvania 1 CNG School bus

3 Austin Texas 2 LPG Refuse haulers

Total 42

Appendix
T OF ENERGY

DEPARTMEN

U

E

NITED STAT S OFA

ERICA

M

Produced by the

Office of Transportation

Technologies of the U.S.

Department of Energy

July 1995

DOE/GO-10095-150

DE95004048

Printed with a renewable source ink on paper

containing at least 50 percent wastepaper,

including 20 percent postconsumer waste