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Comparison of Clean Diesel and Comparison of Clean Diesel and Natural Gas HD VehiclesNatural Gas HD Vehicles

Tim Johnson

Corning Incorporated

May 24, 1999

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AgendaAgenda

Objectives

To inform ARB of the potential benefits of Clean Diesel technologies as they compare to CNG vehicles.

Approach

1) Show progress in diesel engine and aftertreatment technologies.

2) Look at recent results on CNG vs. diesel

3) Compare emission levels of clean diesel to CNG

4) Relate actual real-life vehicle results from the UK.

5) Compare economics.

Some key dieseltechnologies

Johnson 25 minutes

Comparisons to CNG Johnson 20 minutes

Overview ofcontinuousregenerating traps

Smith 30 minutes

Discussion/wrap-up all 45 minutes

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Emerging Regulations Emerging Regulations and Health Concernsand Health Concerns

Market Drivers for Clean Diesel

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Tighter regulations are driving diesel to Tighter regulations are driving diesel to become very cleanbecome very clean

g/ b

hp

-hr

0

1

2

3

4

5

6

En

g.-

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t, 2

005+

US

2007

Eu

roIV

/V

US

2004

Eu

ro I

II

US

No

w

Eu

rop

e N

ow

NOx

PMX10

4.0/0.05

1/0.051.58/0.026

2.0/0.1

3.8/0.044.0/0.1

5.56/0.177

•Adjusted for test differences

•Tightest tests are assumed (steady state or transient)

•Euro IV/V is the Council proposal

HDD: 65% NOx and 50% PM efficiencies will be needed to hit the Euro IV/V standards; 75% NOx will be needed to hit the US2007 assumed standards

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Diesel engines are coming under much scrutiny Diesel engines are coming under much scrutiny regarding toxinsregarding toxins

•PM2.5, and particularly particles less than 100 nm, deposit in the respiratory tract

•Carcinogens and other toxins from Diesel, or general motor vehicle, exhaust are becoming a concern

Pollutant Cancer Risk(X 10-6 / lifetime)

Benzene 19.6

Formaldehyde 12.6

1, 3 – Butadiene 85.4

Acetaldehyde 1.4

Diesel PM 30.8

Allowable maximum threshold: 1 X 10-6 per lifetime Source: 1993 EPA Study

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Engine technologies and emissionsEngine technologies and emissions

Diesel is getting very clean

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Fuel injection is getting increasingly sophisticatedFuel injection is getting increasingly sophisticated

•There is much work on using injection shape control to reduce PM and NOx and improve fuel economy.

•30% reductions in NOx and PM and 5% reductions in fuel consumption due to pilot injections and rate shaping.

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Fine particle number distributions from a common rail Fine particle number distributions from a common rail HDD engine vary with increasing injection pressureHDD engine vary with increasing injection pressure

EPA SAE 1999-01-1141 7.9 liter, 144 kW engine Scanning mobility particle sizes (SMPS) showed minimal effects of

dilution ratio from 50:1 to 560:1.

At low load, increased injection pressure creates more fine particulates.

At high load greater injection pressure keeps distribution the same, but decreases the numbers at low RPM and increase them at high RPM.

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Variable Geometry Turbocharging (VGT) and EGR Cut NOx 10-Variable Geometry Turbocharging (VGT) and EGR Cut NOx 10-40% under low load conditions in a 1.8 l Euro III engine40% under low load conditions in a 1.8 l Euro III engine

Low Load: VGT drops NOx 45% at baseline fuel consumption.

High Load: VGT/EGR could not be optimized, no NOx reductions

Ford SAE 1999-01-0835

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0.000.501.001.502.002.503.003.504.00

g/b

hp

-hr

Effect of EGR on NOx

EGR drops NOx about 40%, regardless EGR drops NOx about 40%, regardless of what else is addedof what else is added

12.7 L Heavy Duty EngineDetroit Diesel Series 60

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Cooled EGR or SCR, and Cooled EGR or SCR, and Traps will be NeededTraps will be Needed

Euro IV

•Euro 3 HDD engines will have “common rail”, high-pressure fuel injection with rate shaping VGT, and electronic engine controls

•60% NOx and PM reductions will be necessary to hit the corner of Euro 4

•Cooled EGR with Traps hits corner, but has 3% fuel penalty vs. Euro 3

•SCR hits NOx, but may require 40%PM reduction

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Advancements in Diesel Particulate TrapsAdvancements in Diesel Particulate Traps

2+ orders of magnitude reductions in particulate numbers

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Retrofitting Off-Road Diesel Equipment with Catalysts Retrofitting Off-Road Diesel Equipment with Catalysts & Filters Significantly Reduced Emissions& Filters Significantly Reduced Emissions

25% of Big Dig off-road (Boston tunnel) will be equipped with DOCs and passive DPFs.

Nescaum SAE 1999-01-0110

Catalysts Filters

PM -3 to 50% 80-95%

20% typ.

NOx 0-17% 2-15%

12% typ.

Emissions reductions from DPF and oxidation catalysts depend on the equipment

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The VERT Study on LDD & Off Road HDD Showed Filters The VERT Study on LDD & Off Road HDD Showed Filters Significantly Reduce PM and Gaseous EmissionsSignificantly Reduce PM and Gaseous Emissions

Sponsors: Swiss & Austrian Accident Insurance Agencies, German Association of Construction Professionals, Swiss EPA

VERT SAE 1999-01-0116

Filters reduced PM by 99%+ by number, but only 70% by mass

EC: elemental COC: organic C

Filters reduced PM by more than 99% by number at all load points

Filters reduced CO by 40%, HCs by 85%, and NOx by 25%. No secondary emissions were formed

Considering reform fuel and fuel additives, filters had the greatest impact on reducing PAHs. New lubricants, catalysts, and engine controls are also effective in curtailing PM

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Diesel particulate filters are very effective in Diesel particulate filters are very effective in reducing particulatesreducing particulates

These two studies and several more have shown that DPFs remove 95+% of ultrafine particulates, bringing emissions down to gasoline levels

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One of the new technologies that reduces toxins and One of the new technologies that reduces toxins and particulates is the CRT systemparticulates is the CRT system

Continuous Regenerating Trap

– NO is first oxidized to NO2: NO + 1/2 O2 = NO2

– The NO2 then oxidizes the soot: 2NO2 + 2C = 2CO2 + N2

– Net: one pollutant eliminates the other

NOx/soot ratios are important

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JMI CRT System is very effective, but JMI CRT System is very effective, but requires low-S fuel and min. NOx/C requires low-S fuel and min. NOx/C

A minimum NOx/PM ratio of 8:1 was determined to be needed for CRT operation. It is generally available over most of the operating range.

AVL SAE 980190

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Advanced diesel aftertreatment systems are Advanced diesel aftertreatment systems are very effective in reducing pollutantsvery effective in reducing pollutants

•The CRT reduces hydrocarbons and CO by >90% under the conditions of the study

•The soluble organic fraction (SOF) of the PM was reduced by >70%

•The two aldehyde toxins were significantly reduced

•NOx was not affected

NOx,g/kWh

PMg/kWh

HC,g/kWh

CO,g/kWh

w/o CRT 2.42 0.18 0.125 1.083

w/ CRT 2.37 0.015 0.010 0.072

Source: AVL SAE 980190

10 ppm sulfur in fuel, 9 liter Euro IV engine w/ EGR,tuned to low NOx, ACEA/OICA 13-mode cycle

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NOx and HC TreatmentNOx and HC Treatment

70+% reductions in NOx and toxins

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0.000.501.001.502.002.503.003.504.004.50

g/b

hp

-hr

NOx

SCR drops NOx levels 70 to 75%SCR drops NOx levels 70 to 75%

12.7 L Heavy Duty EngineDetroit Diesel Series 60

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Diesel engines can be run rich enough to desorb NOx traps, with only 2% penalties in smoke & fuel efficiency

NOx Traps are Evolving for DieselNOx Traps are Evolving for Diesel

FEV SAE 1999-01-0108

91% NOx eff. at 2000 rpm/2 bar

Very low sulfur levels are needed (<10 ppm)

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Catalysts Performance on Toxic EmissionsCatalysts Performance on Toxic Emissions

Toxic Hydrocarbon Compounds Reduced by 58% with 368 ppm S Fuel

0

2

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6

8

10

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Before After

mg/bhp-hr

MECA: API Diesel Issues Forum 4/99

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Increased catalyst loading will reduce toxins by 80%, Increased catalyst loading will reduce toxins by 80%, but 50ppm sulfur fuel is needed to keep SObut 50ppm sulfur fuel is needed to keep SO44 down down

Pt loadings:

A 0 g/l

B 0.02

C 0.2

D 2.0

Hino SAE 1999-01-0471

Low - S fuel (50ppm) is needed to control PM emissions, especially at the high Pt loading that is most beneficial for toxin reductions

Higher catalyst loadings are effective for reducing all non-PM emissions.

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Clean diesel technologies are effective Clean diesel technologies are effective for both new and retrofitsfor both new and retrofits PM

– Traps will take out 99+% of particles

– Traps will take out 70 to 95% of PM mass

• soluble organic fraction gives lower percentages

• engines can be tuned to minimize SOF

NOx

– EGR gets 40% reductions

– SCR gets 70%+

– NOx Traps are emerging at 70 to 90%

HC and Toxins

– 60 to 95% reductions with catalysts or traps

– depends on sulfur

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Compressed Natural Gas EmissionsCompressed Natural Gas Emissions

CNG emissions are low

Page 26Colorado School of Mines SAE 1999-01-1507

CNG vehicles emit 60 to 95% less PM and 0 to 30% CNG vehicles emit 60 to 95% less PM and 0 to 30% less NOx than equivalent diesel vehiclesless NOx than equivalent diesel vehicles

Buses and airport vehicles

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Choice of CNG Engine management technique is Choice of CNG Engine management technique is critical to controlling emissionscritical to controlling emissions

High CNG NOx due to insufficient lean operation at high load. Early mixer type engines

High CNG NOx due to insufficient lean operation or ignition retard.

Closed-loop stoichiometric TWC reduces CNG emissions. Fuel economy suffers

• Depending on CNG engine management strategies, CNG may have higher NOx levels or fuel consumption then diesel.

WVU SAE 982456

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Relative emissions depend on driving behaviorRelative emissions depend on driving behavior

With non-aggressive driving in CBD cycle, CNG NMHC emissions are double, NOx is 50% less, and PM is 97% less than diesel

With aggressive driving in CBD cycle, CNG NMHC emissions are 10X, NOx is 30% less, and PM is 97% less than diesel

WVU, Colorado School of Mines, NRELSAE 1999-01-1469

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CNG with catalysts have reduced emissions vs. diesel, CNG with catalysts have reduced emissions vs. diesel, but advanced aftertreatment can make them similarbut advanced aftertreatment can make them similar

CNG vs. diesel Diesel aftertreatment

NMHC +2X to +10X+2X typ.

-60 to -95%catalysts and filters

NOx -10 to –75%-10 to –40% typ.

-20% catalysts-40% cooled EGR-70% SCR

PM -60 to –97%-85 to –97% typ.

-70 to –95% filters

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In the critical sub-100 nm range, CNG particulate In the critical sub-100 nm range, CNG particulate numbers may not be much different from dieselnumbers may not be much different from diesel

Millbrook Proving Ground SAE 1999-01-0470ELPI used for measurements

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The U. K. City Diesel ExperienceThe U. K. City Diesel Experience

City buses and refuse trucks are going to clean diesel instead of CNG

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““Diesel buses are becoming very clean indeed”Diesel buses are becoming very clean indeed” Simon Brown, Principle Engineer, London Transport Buses Simon Brown, Principle Engineer, London Transport Buses

•Two years ago, only one supplier of “City Diesel”. Now, the UK is going low-sulfur across the country. Price differential is 1.4p/liter.

•On old engines, City Diesel and Oxidation catalysts go a long way.

•On newer engines, City Diesel and the CRT were very clean.

Emission City Diesel Effect Catalyst Effect

HC -1 to –40% -83 to –92%

CO -8 to +2% -92 to –95%

NOx -5 to –6% -9 to –10%

PM10 -32 to –44% -45 to –50%

Millbrook Proving Grounds Seminar 12/97

Pre-Euro 1 EngineEmission City

DieselCity Dieselwith CAT

City Dieselwith CRT

HC -0.7% -46.5% -77.8%

CO +2.8% -78.6% -84.2%

NOx -5.3% -6.02% -16.41%

PM10 -32.2% -54.5% -87.9%

Source: Millbrook Proving Grounds Seminar of 12/97

Euro 2 Engine

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London Diesel buses are cleaner and more London Diesel buses are cleaner and more fuel efficient than CNG or LPG busesfuel efficient than CNG or LPG buses

“it is beginning to look as if the most beneficial and cost effective solution is high quality, fully reformulated Diesel combined with exhaust aftertreatment. We will have 50% of our bus miles on City Diesel by December 1997.” Simon Brown

Emissiong/km

Stoich. LPGwith TWC CAT

Euro 2 withCity Diesel

& CRTHC 0.36 0.143

CO 0.91 0.212

NOx 3.53 12.5

PM10 0.090 0.028

Source: Millbrook Proving Grounds 12/97

Emissiong/km

CNG withOxy CAT

Euro 2 withCity Diesel

&CRT

HC 3.01 0.136

CO 0.66 0.202

NOx 9.92 11.9

PM10 0.050 0.022

CO2 1344 1281

Source: Millbrook Proving Grounds 12/97

No deNOx technologies

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““For refuse collection vehicles, the lowest cost and cleanest For refuse collection vehicles, the lowest cost and cleanest alternatives were City Diesel and a CRT” alternatives were City Diesel and a CRT” Alison Simmons, Principle Pollution Control Officer, Walsall Metro. Borough CouncilAlison Simmons, Principle Pollution Control Officer, Walsall Metro. Borough Council

•Emissions are roughly equivalent to a catalyzed CNG truck

•CNG truck lost 7% of payload

•Annual operating cost of CRT was -11% vs. CNG and +18% vs. std. Diesel

•Capital cost of CNG buses was 7 to 20% higher than CRT (BP127,000 base)

RelativeEmission

BaselineSeddonDieselEuro 2

SeddonCity

Diesel& CRT

ScaniaCity

Diesel &CRT

ScaniaCNG

THC 0 -98% -89% +706%

CO 0 -90% -96% -91%

NOx 0 -13% -22% -2%

PM10 0 -81% -77% -83%

Source: Millbrook Proving Grounds 12/97

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Economics - Diesel is $20,000/yr/bus cheaperEconomics - Diesel is $20,000/yr/bus cheaper

No CNG retrofits are feasible

– need to replace significant numbers of vehicles to see impact

– two fuel services will be needed

Infrastructure costs are high

– $40,000 to $60,000 per CNG bus incremental difference; clean diesel may be $2000 to $5000

– $500,000 (10 buses, 2-3/hr refueled) to $5,000,000 (200 buses, 30/hr refueled); clean diesel requires low-sulfur fuel - marginal infrastructure

Operating costs are higher

– -10% vs. +50% more equivalent energy; +35% typical

– +15% more maintenance

$50,000/yr/bus for CNG vs. $30,000/yr/bus for diesel; amortization and overhead

Source NYC MTA private communication

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SummarySummary

Diesel engine technologies have come a long way, and have significant potential

Diesel after-treatment technologies can make diesels as clean or cleaner than CNG

Clean diesel technologies are much cheaper than CNG and can be retrofit or purchased new

California is well-positioned to take advantage of clean diesel technologies, with emerging supply of low-sulfur fuel