WAS HI NGTON STATE D E P ARTM E NT OF 

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Assessment ofPotential Strategies to Reduce Emissions from Diesel Engines in Washington State

December31,2003

Prepared for: 

### Washington StateDepartmentofEcology

Prepared by: 

### Kim Lyons Washington StateUniversity CooperativeExtension

- EnergyProgram 

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Publication Number 05-02-005

### Table ofContents
Introduction
- Diesel Particulate Matter Emission Reduction Measures


### 1 Fuels 1.1 Ultra-Low Sulfur Diesel 1.2 Biodiesel 1.3 Fuel/WaterEmulsions (PuriNox)


### 2 Engines and ExhaustAfter-treatment (Retrofit) Technologies 2.1 New Engine Technologies 2.2 Diesel Oxidation Catalysts 2.3 Diesel Particulate Filters


### 3 Programs 3.1 SmokeTesting orEmission Inspection Programs 3.2 Idling Restrictions 3.3 Diesel Emission Reduction Programs (Other States)


### 4 Source Categories 4.1 School Buses 4.2 Marine Engines 4.3 Locomotives 4.4 Construction Equipment 4.5 Agricultural Equipment 4.6 Logging Equipment 4

.7 Commercial/Industrial Equipment 4 

### 8 13

15 

### 20 24

29 33 

### 38

41 46 

### 50 53 56 59 61

### Diesel Particulate MatterEmission Reduction Measures

Introduction
Diesel is the dominant fuel used by the commercial transportation sector. Because diesel engines offer important fuel economy, powerand durability advantages, they are often the engine ofchoice for heavy-duty applications. In the United States, approximately 94 percent ofall freight is moved by diesel power. Dieselengines also power most non-road equipment including construction and agricultural equipment, marine vessels and locomotives.
While the operational advantages ofdiesel engines are clear, diesel fuel is a major contributorto particulate matter (PM) emissions. Diesel particulate emissions are of increasing concern as they are small (often less than 2.5 microns in size), and consist ofa complex mix ofengines oils, sulfates and inorganic materials. These particles have been identified by health experts as contributing to a variety oflung related illnesses including asthma, emphysema and bronchitis. There is also growing evidence that exposure to diesel particulates may increase the risk ofcancer in humans. In 1998, the California Air Resources Board declared diesel particulate emissions a toxic air contaminant and a potential cancer risk

. In 2000, the U.S. Environmental Protection Agency (EPA) identified diesel PM as a "likely human carcinogen," and followed this with new stringent standards aimed at reducing emissions from on-road vehicles by as much as 90 percent. Although the new EPA standards will go a long way to improve dieselemissions in the future, these standards remain a few years offand will primarily impact new engines. However, because oftheir durability and long life, older uncontrolled diesel engines will continue to make up a significant portion ofthe heavy duty vehicle fleet for years to come. As a result, efforts are underway to improve emissions from diesel engines already in operation and include a variety ofstrategies from fuel reformulations to engine retrofits.
The purpose ofthis report is to identify technologies and actions which can reduce PM emissions in existing diesel engines. Information was gathered through an extensive web-based search, followed up, in some cases, by direct contact with industry representatives and project managers involved in specific diesel reduction programs.
To date, most ofthe diesel PM reduction efforts have focused on either new engine replacements orretrofitting existing engines with post-combustion emission control equipment. Ofprimary interest are diesel oxidation catalysts and diesel particulate filters. Diesel oxidation catalysts (DOCs) have been in use for over 20 years in more than 270,000 retrofit applications. They are relatively inexpensive and are robust enough to be used in many non-road applications such as construction and mining equipment. They
are not overly sensitive to fuel sulfur content and can achieve PM reductions of25 percent or more.Diesel particulate filters (DPFs) also offer retrofit opportunities

. However, because these devices require specific engine conditions to operate effectively, they cannotbe used in
some applications

. DPFs work best with newer enginesthat achieve higher, sustained engine exhaust temperatures. DPFs also require the use ofultra-low sulfur diesel. Although DPFs cost two to three times more than oxidation catalysts, they can achieve PM removal efficiencies in excess of90 percent.
Low sulfur diesel fuels or alternative fuels can also provide PM control. Reducing the sulfur content ofdiesel fuels provides a direct fuel-related reduction in particulate matter emissions. More importantly, low sulfur fuel allows the use ofemission control technologies which have been proven effective in providing significant PM control. As a result, most diesel PM control programs also include a low sulfur diesel component. Currently, ultra-low sulfur diesel is available in western Washington at a cost premium of 1 0 to 11 cents per gallon.
Other fuels and fuel technologies that can provide PM benefits include biodiesel, natural gas, diesel/water emulsions and diesel/electric hybrids

. Natural gas, biodiesel and diesel/electric hybrid technology are all currently being used in heavy-duty engine applications in Washington. However, natural gas and diesel/electric hybrid applications would typically fall under a new vehicle purchase, although natural gas retrofits or repowering opportunities do exist. While significant emission benefits can be achieved through the use ofthese technologies when compared to baseline diesel equipment; a more meaningful comparison should include advanced diesel technology engines fueled with ultra-low sulfur diesel. Here, emission benefits may still favor the diesel alternatives, but the degree ofbenefits is smaller.

In contrast, biodiesel and water /diesel emulsions are direct fuel substitutes that can be used with little or no modifications to an existing diesel engine. For most biodiesel applications, a 820 blend is used, which consists of80 percent diesel and 20 percent biodiesel. The fuel is available in Washington at a price premium ofaround $0.20-$0.30 per gallon. PM emission reductions are estimated at about I0 percent or more for 820. Water/diesel emulsion fuels blend about 20 percent water with diesel. A surfactant and additives make up about one percent ofthe mix and maintain the emulsion. For the most part, this is a proprietary fuel marketed underthe name PuriNOx. While there are no current users ofPuriNOx in Washington, it is being used successfully in other parts ofthe country where PM reductions of40 percentor more have been reported.
Smoke testing and idling restrictions may also provide PM control. A smoke test program uses opacity measurements to identify trucks which emit high levels ofsmoke. Failing trucks are then targeted for improvements, typically at the owners' expense. Idling restrictions are intended to reduce the idle time ofa diesel engine, which in turn reduces diesel engine emissions. This control measurement is being applied in a couple ofways
. One is to establish operational guidelines which direct a vehicle driver, such as a school bus or construction equipment operator, to turn their engine offduring queuing
or other idle periods. This approach is being used extensively in NewEngland states.

2Another approach is to employ auxiliary powertechnologies which allow drivers to turn offtheir main engines during extended idle periods. In some cases, the powertechnology is provided independent ofthe truck through a plug system, often referred to as truck stop electrification. Some ofthese technologies can reduce engine idle emissions by 90 percent.
While otherPMcontrol strategies are available, those discussed appearto be the primary control measures currently being employed around the U.S. Because PM control measures may differ for different applications, this report also looked at some end use applications, including marine engines, buses, agricultural equipment and construction equipment. Forthe most part, PM control actions are being investigated and applied
across sectors. However, small market sectors, such as agricultural equipment, are only justbeginning to receive attention, with little to no demonstrated use ofspecific PM control measures.



### 3

### 3.1 Smoke Testing or Emission Inspection Programs
The 1990 Clean Air Act required EPA to develop light duty vehicle inspection and maintenance standards (liM) to help control vehicle emissions. Program implementation ofthese standards was relegated to the states. A growing concern over health related PM effects motivated some states to extend l/M programs to include heavy duty diesel vehicles (HDDV). Currently, 

### 17 states, including Washington, have some type ofdiesel I /M program (Colorado 2002)

. HDDV 1 /M programs may employ a roadside measurement ofthe amount ofvisible smoke being emitted from a vehicle's exhaust system under some specified test conditions. In addition, somejurisdictions require annual or semi-annual inspections of HDDVs which are performed at fleet maintenance facilities orcentralized inspection sites.
The roadside smoke opacity test is often carried outat weigh stations, custom inspection facilities or any other suitable site which allows easy access to and from the highway. Tests are random in that they are unannounced and are held at varying inspection sites. Vehicles are selected for opacity testing based on visual observation ofthe vehicles as they approach the test site. High smoke emitters are flagged for inspection, with selection based on inspector experience. The roadside test usually applies to all HDDVs, regardless oforigin, and is free ofcharge

. Failing the test may result in a fine, which is often waived or reduced ifthe ownerfurnishes proofthat the reason for failure has been corrected.
Annual or periodic programs operate similar to the light duty liM test. Here, HDDV operators are required to complete a smoke test within ajurisdiction, are charged for the testing, and can be fined or denied registration renewals until the reason for failure is fixed orat least attempted to be fixed

. Unlike roadside testing, periodic testing does not single out high emitters for testing. Instead, all vehicles (with the possible exception of
newer vehicles up to the latest three or four model years) need to show that they can pass inspection. Proponents ofperiodic inspections argue that this approach captures all registered vehicles within a givenjurisdiction and encourages vehicle owners to consistently maintain their vehicles with respect to smoke emissions. Proponents ofroadside inspections argue that roadside testing targets only the gross emitters and can be moved around to areas where dirty vehicles are observed to operate. Further, roadside testing treats all smoking vehicles the same and does not discriminate between vehicles registered in and out ofstate.
Because HDDVs often move betweenjurisdictions and states, a push was made to develop a standardized protocol for smoke testing. In 1997, the EPA Office ofMobile Sources issued a "Guidance to States on In-Use SmokeTest Procedure for Highway Heavy-Duty Diesel Vehicles." This document provides guidance on how to conduct smoke tests using the SAE Recommended Practice J1667, Snap-Acceleration SmokeTest

29Procedure. 11667 was developed in 1996 with the help ofthe engine manufacturers, trucking industry, smoke testing equipment manufacturers and state and federal regulators (http://www.arb.ca.gov/msprog/hdvip/saej 1667.pdf).
Thetest is performed on a vehicle when it is standing still and in neutral. The engine is accelerated without any external load to the maximum governed speed. A smoke meter is placed at the end ofthe exhaust pipe and the opacity ofthe smoke is measured. The opacity is expressed in percent oflight reduction, and is the degree to which the exhaust obscures a beam oflight shining through it.
EPA recommends that states employ 11667opacity failure points (the point at which the vehicle fails a smoke test) of55 percent for pre-1991 vehicles and 40 percent for 1991 and later model year vehicles.
Emissions
Actual emission benefits resulting from smoke testing programs have not been well documented

.The goal ofsmoke testing is to reduce visible, black exhaust smoke. While it is commonly accepted that less smoke means lower particulates, a reduction in the opacity ofthe particulate matter does not necessarily result in a reduction in its total mass (CanadaEPS 2000). The Colorado Diesel StakeholderGroup noted that the continued use ofopacity as a surrogate measurement tool to identify high-emitting vehicles should be reevaluated. At best, opacity levels identify some but not all high-emitting engines (Colorado 2002). Recently, Energy and Environment Analysis, Inc (EEA) was contracted by the state of Colorado to quantify the emissions benefits ofsmoketesting ofheavy duty vehicles (EEA, 2001). Although their research sample was small (only 26 vehicles total), EEA did come up with some interesting observations. Their primary conclusion was that the standard opacity cut-points of55 percent for pre-1991 vehicles and 40 percent for later vehicle models may not be appropriate, at least for the state ofColorado

. EEA argued that the cut-points, initially developed by the state ofCalifornia, are too high, and were originally set conservatively because ofCalifornia's requirement ofzero errors ofa vehicle being failed incorrectly.
EEA found that, for pre-1991 vehicles failing at a 45 percent opacity cutpoint (instead of the standard 55 percent), repair reduced PM emissions by 45 to 50 percent. For 1991 and
newer vehicles (all ofwhich failed the 40 percent opacity cutpoint), repairs produced a greaterthan 40 percent reduction in opacity and a 25 to 30 percent reduction in emissions ofPM (EEA.) EEA also found that NOx levels went up but still remained within the established standards, and that aldehyde and PAH emissions were reduced dramatically following repair. The average cost ofrepair was $1,088. Early work by various researchers suggests that there is some correlation between smoke opacity and PM emissions. Based on their study results, however, EEA indicated that smoke opacity is at best a poor predictor ofPM emissions. They suggested that driving

30cycle CO and THC emissions are correlated much more strongly with PM and that an improved 

### liM test procedure based on tailpipe measurement ofCO and THC be developed (EEA).

Smoke testing costs are difficult to assess as it depends on what is counted as cost. Costs could include:
• program administration costs; • administrative costs to fleets, including annual labor costs to complete the inspections; and
• costs to fleet orvehicle owners which could include vehicle down time, vehicle repair costs, testing fees, testing fines, and annual increased maintenance costs due to voluntary repairs done in order to avoid failing the test.
California's Heavy Duty Vehicle Roadside Inspection Program has an estimated total program cost ofabout $5

.6 million peryear, or $280 per vehicle inspected (Colorado 2002). Ofthis amount, vehicle owners pay about $1.9 million for increased maintenance and lost opportunity costs, and the state pays about $3.7 million to annually inspect the vehicles (notcounting Highway Patrol costs). Between June 1998 and September2001 , 64,648 visual inspections were performed

. During this time frame, the fail rate was 4,538 vehicles, or about seven percent. Program managers indicate that they inspect about 20,000 vehicles annually, which equates to about 1,400 vehicle failures per year at a seven percent fail rate (Colorado 2002)

. California also conducts a periodic inspection program. Here, all fleets oftwo or more California-registered HDDYs (about 291 ,600) are subject to an annual self-inspection using the snap acceleration test. A four model year exemption is allowed, which is estimated at 26 percent ofthe fleet. The state audits the fleets for compliance, with less than one percent ofthe fleets requiring formal action (Colorado 2002)

. State costs for auditing are $0.5 million annually. The cost ofselftesting is estimated at $18.1 million per year. The annual program cost is estimated at $84 per vehicle inspected. In addition, vehicle repairs resulting from inspection programs are estimated to improve fuel economy and effectively offset the costs ofrepair to the operator.
In 1997, CARB estimated that the cost-effectiveness ofthe HDDV smoketest program in reducing criteria pollutants was superior to other emission control programs. In fact, the HDDV smoke test program was estimated to be between 2.4 and 4.7 times more costeffective than other control method (Canada 2000). Currentestimates by CARB suggest that the programs cost about $1.05 per pound ofemission reduction (tri-national HDDV smoke test workshop-3/2002).
Other issues
In a recent workshop sponsored by the Northeast States for Coordinated Air Use Management and CARB, participants raised some common themes concerning heavy

31duty vehicle emission testing (tri-nat workshop). These issues included a need to better correlate opacity and PM (and NOx); a need to revisit current opacity cut-points; and a need to develop new, advanced emission testing methods ( loaded test, chassis test, onboard diagnostics) for use with new engine technologies. Representatives from a number oforganizations had concerns with the current opacity cut-points

. Some felt thatthe current levels may be allowing too many potentially polluting vehicles to pass the smoke test. The state ofColorado has lowered their cutpoints to belowthe accepted EPA standard and California is investigating the need for
more restrictive cut-points as well. While the current snap-idle test appeared to be acceptable to the majority ofparticipants, a need for advanced testing methods was raised in response to newer engines. Some participants argued that with newer engines, visible smoke was not necessarily a good indicator ofparticulate emissions, and as a result, spot orroad-side inspections were going to lose their effectiveness.
Smoke testing is primarily a tool to reduce visible smoke emissions from heavy duty diesel vehicles

.The relationship between opacity and PM is not fully understood; however, it appears that lowering opacity should provide PM emission reductions. The Colorado Diesel Stakeholder Work Group observed that, although high opacity readings indicate high PM emissions, low opacity does not necessarily indicate low PM emissions

. They further acknowledged that the lack ofquantitative emissions data makes it difficult tojudgethe effectiveness oftheir HDDV Inspection and Maintenance program in reducing diesel emissions. However, they concluded thatthe program provides undeniable benefits as an incentive for good maintenance and as a deterrentto vehicle tampering (Colorado 2002)

.

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