On December 2, 1997, Cummins

Engine Co., Inc. of Columbus,

Indiana, announced that its B5.9LPG

is the first dedicated heavy-duty

propane gas engine to receive certification to the 1999 Environ-mental

Protection Agency (EPA) Clean 

Fuel Fleet Vehicle (CFFV) Low

Emissions Vehicle (LEV) standard.

This spark-ignited power plant features advanced electronic engine

management, closed-loop air/fuel

ratio control, lean-burn technology

and integrated subsystems. The technology and subsystem are common

with the current Cummins B5.9G,

C8.3G and L10G natural gas engines.

The B5.9LPG is the first dedicated heavy-duty propane engine

available for bus and truck markets.

The engine is rated at 195-horsepower and 420 lb-ft peak torque. Its leanburn technology gives a thermal 

efficiency that is much higher than

propane stoichiometric gasoline

engine conversions. Production

began in September at the Rocky

Mount, North Carolina manufacturing plant where the B5.9 and C8.3

diesel and natural gas engines are

also built.

Like the Cummins B5.9 natural

gas engine, the propane version is

based on the heavy-duty B5.9 diesel

platform and designed for high durability at a low cost. The B5.9G natural gas engine has been in production

since 1994 and can be purchased

through more than 30 vehicle manufacturers. A few critical parts from

the B5.9G engine were optimized 

for operation with HD-5 LPG 

vehicle fuel.

Cummins has 7 years of experience with spark-ignition, lean-burn

engines for bus and truck fleets. 

The company's alternative engines 

currently power more than 2,400

vehicles in various fleet applications

with operations covering more than

150 million miles in revenue service.

Cummins received support to

develop the B5.9LPG engine from

various industry stakeholders including the National Renewable Energy

Laboratory/Department of Energy,

Natural Resources Canada, Propane

Vehicle Council, Propane Gas

Association of Canada, South Coast

Air Quality Management District and

Superior Propane, Inc. Further information on the B5.9LPG is available

from Cummins by phone at 1-800-

343-7357, by e-mail at powermaster@cummins.com, or on the World

Wide Web at www.cummins.com.

Volume 6, Number 4

Warren Gretz\PIX04762

INSIDE THIS ISSUE

Gasalarm Systems Introduces Series GS2000 Gas Monitor..................2

Lessons Learned from the Ontario, California, LCNG Station.............2

EPA Finalizes Heavy-Duty Diesel Engine Emissions Standards...........4

The Cryenco TADOPTR Program..........................................................6

Cummins’ Heavy-Duty Propane Engine Receives

1999 EPA CFFV LEV Certification

The Cummins B5.9LPG engine
2 Alternative Fuels In Trucking—Volume 6, Number 4

One major challenge that must be

overcome before building an alternative-fuel storage and dispensing station is surmounting all the administrative and legal hurdles. Experience

in the city of Ontario, California,

where a liquefied and compressed

natural gas (LCNG) station was

recently built illustrates the importance of meeting these challenges in

the planning phase. The building

contractors for the site encountered

unexpected administrative problems

with city officials that caused many

delays. They learned that erecting an

LCNG fueling station takes very

careful planning, not just in design

and construction, but in understanding and adhering to regional and

local code regulations.

Foremost, all the necessary permits must be obtained and every

detail considered before construction

can begin. To illustrate, in mid-April

of 1997, the city of Ontario approved

the foundation plans for the LCNG

tank pad. However, the city withheld

an operating permit for the liquefied

natural gas (LNG) tank and dispenser

because more detailed design drawings were necessary. In addition, the

drawings had to be signed by a

licensed California engineer. After

the contractor provided the needed

information, there was an additional

administrative processing delay,

causing the completion date for the

station to be pushed back.

Gasalarm Systems has introduced

a combustible gas monitoring system

that can help advance alternative fuel

vehicle use in the trucking industry.

The SERIES GS2000 monitor is

designed to detect methane, propane,

and butane fumes in such areas as the

fuel tank, engine compartment, and

vehicle cab. With the new system,

the trucking industry can safeguard

operators while increasing productivity, improving customer service, and

conforming to the recommended

practices set up by the Society of

Automotive Engineers (SAE) in

J2343, Recommended Practices for

LNG Powered Heavy Duty Trucks.

Article 4.9 of SAEJ2343 recommends that trucks have a warning

system for potentially dangerous gas

fumes in the cab and in the engine

compartment. The SERIES GS2000

monitoring system is designed to

detect these fumes. The system 

controller features three alarm settings and a separate diagnostic for

detecting faults in the system itself.

Because the controller SERIES

GS2000 is small (approximately 4 

in. long, 1 in. high and 2.5 in. wide),

it fits easily into the dashboard. It

consumes very little power, and does

not require frequent calibration or

maintenance. The sensor(s) for the

SERIES GS2000 can be mounted in

the engine compartment, fuel tank

space, or cab, and has mud/splash

guards. Each sensor has a miniature

2-20 milli-amp transmitter with a 

life expectancy of 1 to 2 years in 

continuous operation. 

The system’s separate alarms 

activate at varying levels of gas

fumes. At standard factory settings,

an alarm goes off if fumes exceed

15% of LEL, causing the yellow A1

LED to light up and the buzzer to

beep slowly. Beyond a 30% LEL, 

the amber A2 LED illuminates and

the buzzer beeps slightly faster. After

the LEL exceeds 45%, the red A3

LED lights up and the buzzer beeps

very quickly. The alarm controller

has an auxiliary relay that also can 

be used to energize beacons or external horns. The relay activates if 

the LEL exceeds 45%. Users can

adjust the alarm systems from 0% 

to 100% LEL.

For more information on

Gasalarm Systems' SERIES GS2000,

call Gasalarm Systems Company,

Inc. at (281) 364-1988, fax them at

(281) 364-1987, or e-mail them at

gasalarm@compuserve.com.

Gasalarm Systems Introduces 

Series GS2000 Gas Monitor

Lessons Learned from the Ontario, California,

LCNG Station
Alternative Fuels In Trucking—Volume 6, Number 4 3

The station’s compressed natural gas

(CNG) dispensers were installed in

October. However, coordination difficulties arose with the electrical

inspectors which caused delays in

obtaining operating approval for

CNG service. The engineers working

on the LNG service of the station

also experienced delays caused by a

late shipment of the nitrogen needed

to test the pressure and electricity.

Once the nitrogen was delivered, the

vessel pressure tested well, but one

unit experienced electrical problems.

Solving these problems caused additional delays that, in turn, caused

postponing of scheduled training for

the station operators.

Clearly, getting an LCNG station

constructed and running is no simple

task. Contractors have many legal

obstacles to overcome before an

LCNG station is operational. They

must understand all aspects of the

permitting process and obtain all 

the necessary permits before construction begins. Time should be

included in construction planning to

allow orderly permitting to occur. A

good plan should also include time

allotted for the unexpected, such as

material delivery delays and debugging of systems. Building in the flexibility to be able to manage the unexpected is a vital component of the

planning process.

Refueling a compressed 

natural gas Dodge 

Caravan SE.

Warren Gretz\PIX02488
4 Alternative Fuels In Trucking—Volume 6, Number 4

On October 21, 1997, the U.S.

Environmental Protection Agency

(EPA) issued new emissions standards for heavy-duty diesel engines.

They will take effect in Model Year

(MY) 2004. The EPA emphasized

further reductions in oxides of nitrogen (NOx), which are key components in tropospheric ozone (smog)

formation. On a national level,

roughly 50% of NOx emissions

come from mobile sources, and the

EPA wants to cut these emissions

from heavy-duty vehicles.

The new EPA emissions standards

cover engines used in urban buses

and in highway trucks weighing

more than 8,500 pounds and represent a 50% reduction in NOx levels

below the standards in force today.

These new standards do not apply to

off-road vehicles, marine vehicles, or

locomotives. Under the new rules, 

all engines certified during and after

MY 2004 must meet either (1) a

combined non-methane hydrocarbon

(NMHC) plus NOx standard of 2.4

grams per brake-horsepower hour

(g/bhp-hr) or (2) a combined NMHC

plus NOx standard of 2.5 g/bhp-hr

with no more than 0.5 g/bhp-hr of

NMHC emissions. The current rules

governing particulate matter will

remain the same (0.1g/bhp-hr for

trucks and 0.05g/bhp-hr for buses).

The EPA expects that the diesel

engine manufacturers can meet these

standards. However, the agency 

has established backup regulations

that can be set up if engine manufacturers have problems adapting to the

new standards.

Besides establishing new rules on

highway diesel engine emissions, the

EPA also modified the averaging,

banking, and trading (ABT) programs; clarified responsibilities of

parties rebuilding or repowering

engines; and adopted new in-use

emissions control provisions.

The ABT program modifications are meant to add flexibility 

and encourage engine manufacturers

to make cleaner burning engines

before 2004. New trading procedures

would eliminate current credit 

discounting and life limits.

Manufacturers can also generate

credit for natural gas engines to 

offset diesel engine emissions. 

Although the EPA issued these

new regulations for highway diesel

engine emissions, they are holding off

on issuing new standards for highway

Otto-cycle (spark-ignited) engines,

most of which use gasoline. The

agency is currently reviewing proposals and looking for better technology

that could further control emissions

from heavy-duty gasoline engine’s.

For a summary of EPA emissions

standards contact Jennifer Barker,

U.S. EPA, Office of Mobile Sources,

2565 Plymouth Road, Ann Arbor,

MI, 48105, (313) 668-4510 or visit

the World Wide Web site http://

www.epa.gov/OMSWWW/

nonroad.htm

EPA Finalizes Heavy-Duty Diesel Engine Emissions 

Year

1990

1991-93

1994-97

1998+

2004+

10/96

10/98

1987-90*

1991-93*

1994+*

1994-95*

1996+*

CO

(g/bhp-hr)

15.5

15.5

15.5

15.5

15.5

3.0

15.5

15.5

15.5

15.5

15.5

Idle CO

(percent exhaust

 gas flow)

0.5*

0.5*

0.5*

0.5*

0.5*

0.5*

0.5*

0.5*

0.5*

0.5*

Federal Proposed federal European Union California

Heavy-Duty Highway 

*This refers to a note concerning this entry. For 
Alternative Fuels In Trucking—Volume 6, Number 4 5 

Standards

NMHC + NOX

(g/bhp-hr)

2.4 or 2.5 with a limit 

of 0.5 on NMHC (ABT)

NOx

(g/bhp-hr)

6.0 (NCP)

5.0 (ABT, NCP)

5.0 (ABT, NCP)

4.0 (ABT, NCP)

5.2

6.0

5.0

5.0

5.0 (0.5-3.5*)

4.0 (0.5-2.5*)

PM

(g/bhp-hr)

0.60 (NCP)

0.25 (ABT, NCP), 0.10*

0.10 (ABT, NCP), 0.07*, 0.05*

0.10 (ABT, NCP), 0.05*

0.10 (ABT, NCP), 0.05*

0.19

0.11*

0.60

0.25*/0.10*

0.10

0.07*

0.05

Smoke*

(percentage)

20/15/50

20/15/50

20/15/50

20/15/50

20/15/50

42/2.26*

100/1.459*

200/1.065*

20/150/50

Useful Life

1990-97+ for HC, CO, and PM:

LHDDE: 8years/110,000 miles

HHDDE: 8 years/185,000 miles

HHDDE: 8 years/290,000 miles

1994+ urban buses for PM only:

10 years/290,000 miles

1998+ for NOx:

LHDDE: 10years/110,000 miles

HHDDE: 10 years/185,000 miles

HHDDE: 10 years/290,000 miles

LHDDE: 10years/110,000 miles

HHDDE: 10 years/185,000 miles

HHDDE and urban buses: 435,000 miles, 

13,000 hours, or 10 years (but not less 

than 290,000 miles)

LHDDE: 8 years/110,000 miles

HHDDE: 8 years/185,000 miles

HHDDE: 8 years/290,000 miles

Warranty Period

5years/1000,000 miles

(but not less than the 

basic mechanical warranty

 for the engine family)

5years/1000,000 miles

(but not less than the 

basic mechanical warranty

 for the engine family)

5 years/1000,000 miles. or 

3.000 hours (for 1994 and 

earlier engines greater than

8,500 lbs and for 1995+engines

 greater than 14,000 lbs)

HC

(g/bhp-hr)

.3*

1.3

1.3

1.3

0.8

1.3/1.2*

1.3/1.2*

1.3/1.2*

1.3/1.2*

1.3/1.2*

Engines—CI and Urban Buses

the full text of this chart please see the EPA’s Emissions Standards Reference Guide for Heavy-Duty and Nonroad Engines.
For any alternative fuel to succeed in today’s market, it must be

economically competitive with its

fossil fuel counterpart. With heavyduty vehicles, the standard fossil fuel

is diesel. The only competitively

priced, alternative fuel in today’s

heavy-duty market is natural gas

(LNG). Liquefying rather than compressing the natural gas allows more

fuel to be stored on a truck.

From an operator's point of view,

however, the fuel price is only one

component of the total cost of using

the fuel. Let us use liquefied natural

gas (LNG) as an example. LNG is a

cryogenic liquid and is stored at about

-270°F. As it warms, it begins to boil.

This means that if the fuel is not used

quickly, some of it may be lost

through "boil off." This potential fuel

loss increases the cost of LNG and

reduces its economic competitiveness.

One solution to the problem is to

install a device that could reliquefy

boil-off gas. Although the technology

to liquefy gases is not new, most systems must convert massive quantities

of gas to be cost effective. Using

existing technology to liquefy very

small amounts of gas is too expensive. Now, technology is emerging

which promises to solve the problem.

In 1994, Cryenco obtained the

rights to develop a new cryogenic

refrigeration technology called thermoacoustically driven orifice pulse

tube refrigeration, or TADOPTR. The

unique process refrigerates, and thus

liquefies, industrial and natural gases

for a variety of purposes, including

fueling trucks with LNG and compressed natural gas (CNG). The technology is well suited for small liquefaction capacities of roughly 500 to

10,000 gallons per day (GPD).

In 1989, scientists from the Los

Alamos National Laboratory (LANL)

and the National Institute of

Standards and Technology (NIST)

first demonstrated TADOPTR. That

demonstration was the joining of two

separate, but synergistic technologies—the thermoacoustic driver

(TAD) and orifice pulse tube refrigeration (OPTR)—neither of which uses

any moving parts. LANL patented

the TADOPTR system, and in 1993,

Cryenco entered a licensing agreement with LANL to further develop

the technology for liquefaction of

gases.

6 Alternative Fuels In Trucking—Volume 6, Number 4

The Cryenco TADOPTR Program

Burner

system

OPTR (orifice pulse tube refrigerator) liquefies the remaining natural gas using acoustic energy.

TAD (thermoacoustic driver) burns some natural gas to generate acoustic energy.

Resonator

(8 in. dia.)

This TADOPTR prototype system currently liquefies about 150 gallons of LNG per day.
Alternative Fuels In Trucking — Volume 6, Number 4 7

Cryenco has divided the 

TADOPTR project into two

phases. Phase I involves developing a system with a liquefaction capacity of approximately

500 GPD. Phase II involves

developing a system with a

capacity of 5,000-10,000 GPD.

Both systems will be designed to

fit on a standard, flat bed truck.

The TADOPTR system consists of three major components.

The first is its power source, a

natural gas burner. Next is the

TAD, which is a converter that

changes the thermal input power

to acoustic power, like a pressure

oscillation. The third component

is the OPTR, another convertor

that changes the acoustic power

into heat removal, or thermal

extraction power. One end of the

TADOPTR is heated to 3400°F,

while the other end gets cooled

to 2240°F. The working gas, 

typically helium, is the only thing

that moves within the system.

Creating a large temperature difference across a short section of 

a pipe filled with a working gas 

causes the gas to go into spontaneous

pressure oscillations. By using the

continuous input of heat from a 

burner to maintain the required temperature difference, the oscillations

are sustained.

The OPTR operates on a modified Stirling refrigeration cycle, but

the cold displacer in a Stirling system

is replaced by a gas column (or pulse

tube), an orifice (or opening), and a

reservoir. These are all static components that cycle the working gas

between a cold, heat-extracting heat

exchanger when the TAD cools and

expands the working gas, and a

warm, heat-rejecting heat exchanger

when the TAD compresses and heats

the working gas. In this way, the

OPTR pumps thermal energy from a

cold reservoir to a warm reservoir.

The three components of a

TADOPTR each have a characteristic

dimension. The OPTR is a 500-GPD

unit that has dimensions of only a

few feet. The burner is about 5-10

feet long. The TAD is roughly 40

feet long and a couple of feet wide.

As the photo above illustrates, the

OPTR is the front vertical section,

the TAD is the long tube in the 

middle, and the natural gas burner

is at the back. The unit pictured

is designed to produce about 100

GPD of LNG.

Cryenco raised private venture

capital funds to support the initiation

of Phase I of the TADOPTR project

and invested considerable internal

funds in support of the program.

In May 1995, Cryenco received a

federal contract from the U.S.

Advanced Research Program

Agency, most of which also was

directed toward supporting Phase

I of the project. The U.S.

Department of Energy provides

funding to LANL to pursue fundamental research on thermal acoustics in parallel with Cryenco's

commercialization efforts.

Cryenco is currently investigating several potential markets

for the TADOPTR. The potential

uses include natural gas liquefaction at remote gas and oil wells,

natural gas liquefaction at offshore oil wells, natural or industrial boil-off gas reliquefaction 

at large scale storage facilities,

and others. Each of these markets

has its own unique criteria and

operating conditions that should

be addressed. 

For the natural gas liquefaction applications in particular, an

attractive feature of the technology is

that it uses natural gas as a power

source. However, Cryenco has

expanded its program to include

smaller scale, OPTR-based, refrigeration and liquefaction systems that use

an electrical power source. The electrical systems, orifice pulse tube

refrigeration liquefiers (LOPTRs),

will have liquefaction capabilities

from roughly 10 to 500 GPD,

although there are no technical limits

on going to larger sizes. The LOPTR

systems are expected to address markets which require cryogenic liquids. 

Cryenco’s evolving technology

holds great promise for solving the

LNG boil-off problem. Work is

underway to set up a field experiment to determine if the promise will

become a reality.

OPTR 

uses

acoustic 

energy for 

liquefaction

Piston driven

by a linear

electric motor 

to generate

acoustic energy

A linear motor driven OPTR
Volume 6, Number 4

René Howard, Editor

Lisa Shertz, Graphic Designer

Alternative Fuels in Trucking is published quarterly

by the National Renewable Energy Laboratory

(NREL), a U.S. Department of Energy (DOE) 

national laboratory. The newsletter is written by 

the American Trucking Association Foundation’s

(ATAF’s) Trucking Research Institute.

The aim of Alternative Fuels in Trucking is to

inform fleet owners and operators, equipment suppliers, government officials, and other interested parties

about important developments in the use of alternative

fuels in heavy-duty trucks. Suggestions and comments

are welcome and may be directed to the National

Alternative Fuels Hotline at 800-423-1DOE. Views

expressed by guest authors are their own, and not

those of ATAF, DOE, or NREL.

NREL/BR-540-23965

June 1998

Printed with a renewable-source ink on paper

containing at least 50% wastepaper, including

20% postconsumer waste

UNITED S AT

FO SET

MA

ER

CI A

• DEPAR MT

FOTNE

NE ERGY •

U.S. Department of Energy

Office of Energy Efficiency and Renewable Energy

Office of Transportation Technologies

How to Reach Us

• The AFDC World Wide Web 

address is 

http://www.afdc.doe.gov

• The Alternative Fuels in

Trucking newsletter is available

on the WWW at http://www.

afdc.doe.gov/1/trknews It is

available on-line 2 or 3 weeks

before the newsletter is mailed.

To speak to a human

being, call the

National Alternative

Fuels Hotline at 

800-423-1DOE.