Impacts of potential revisions to CNG fuel standards

1

Impacts of Potential Impacts of Potential Revisions to CNG Fuel Revisions to CNG Fuel

StandardStandard

California Air Resources BoardCalifornia Air Resources Board

May 19, 2010May 19, 2010Steven Moore, SDAPCDSteven Moore, SDAPCD

IntroductionIntroduction

2

San Diego ConcernsSan Diego Concerns

�� Potential emission impacts from LNGPotential emission impacts from LNG�� All emission impacts must be addressedAll emission impacts must be addressed

�� Gas distribution emissions, stationary source Gas distribution emissions, stationary source emissions, vehicle emissionsemissions, vehicle emissions

�� Emission impacts must be accurately Emission impacts must be accurately estimated estimated

�� Impacts are adequately mitigatedImpacts are adequately mitigated�� Possible safety issues, if any, from LNG Possible safety issues, if any, from LNG

use are considereduse are considered

OutlineOutline

�� BackgroundBackground

�� District concernsDistrict concerns

�� Characterizing & Quantifying Emission Characterizing & Quantifying Emission ImpactsImpacts

�� Possible Safety ConcernsPossible Safety Concerns

�� Emission Estimates & MitigationEmission Estimates & Mitigation

�� ConclusionConclusion

3

BackgroundBackground

District GoalsDistrict Goals

�� Protect air qualityProtect air quality

�� Attain & maintain (no backsliding) the state Attain & maintain (no backsliding) the state and federal ambient air quality standardsand federal ambient air quality standards

�� Mitigate any emission increases resulting Mitigate any emission increases resulting from changes in source of gas supplyfrom changes in source of gas supply

�� Compliance of permitted sourcesCompliance of permitted sources

4

San Diego Attainment StatusSan Diego Attainment Status

NonNon--AttainmentAttainmentNonNon--AttainmentAttainmentOzoneOzone

NonNon--AttainmentAttainmentAttainmentAttainmentParticulate MatterParticulate Matter

AttainmentAttainmentAttainmentAttainmentLeadLead

AttainmentAttainmentAttainmentAttainmentSulfur DioxideSulfur Dioxide

AttainmentAttainmentAttainmentAttainmentNitrogen DioxideNitrogen Dioxide

AttainmentAttainmentAttainmentAttainmentCarbon MonoxideCarbon Monoxide

StateStateFederalFederalPollutantPollutant

Days Exceeding Air Quality Days Exceeding Air Quality Standards for OzoneStandards for Ozone

0

20

40

60

80

100

120

140

160

180

200

220

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

State 8-Hour State 1-Hour Federal 8-Hour Federal 1-Hour

5

Significance of EmissionsSignificance of EmissionsEmission Increase

Stationary Source Requirements and Distr ict Mandates

10 lbs/day BACT

0.07 tons per day (25 tons per year)

LAER and Offsets at a major source

0.1 tons per day New rule to address source category

0.01–0.1 tons per day Potential new rule to address source category

6

District ConcernsDistrict Concerns

Potential Implications of Potential Implications of Revision to CNG StandardsRevision to CNG Standards

�� LNGsLNGs do not comply with current do not comply with current standardsstandards�� Less than 1.5% Less than 1.5% inertsinerts

�� More ethane (C2) and/or propane and butane More ethane (C2) and/or propane and butane (C3+) than standard(C3+) than standard

�� LNG has higher C2 and C3+ than LNG has higher C2 and C3+ than historical San Diego supply and most of historical San Diego supply and most of the supply in the rest of CAthe supply in the rest of CA

7

Potential Implications of Revision to Potential Implications of Revision to CNG StandardsCNG Standards

�� Revising gas quality standards removes Revising gas quality standards removes barrier to LNGbarrier to LNG--derived natural gas being derived natural gas being supplied to San Diego, Imperial County supplied to San Diego, Imperial County and SCAQMDand SCAQMD

�� Operational LNG terminal in Baja Operational LNG terminal in Baja California with 1000+ California with 1000+ MMscfMMscf/day capacity/day capacity

�� EnergiaEnergia Costa Costa AzulAzul or ECA terminalor ECA terminal——owned by owned by Sempra, parent company of Sempra, parent company of SDG&E and SDG&E and SoCalSoCal GasGas

Potential Implications of Revision to Potential Implications of Revision to CNG StandardsCNG Standards

�� Revision to gas quality standard could Revision to gas quality standard could immediately allow large amounts of LNG immediately allow large amounts of LNG useuse——up to 400 up to 400 MMscfMMscf/day in San Diego /day in San Diego and 400 and 400 MMscfMMscf/day elsewhere in S. CA/day elsewhere in S. CA

�� San Diego current maximum gas San Diego current maximum gas consumption about 400 consumption about 400 MMscfMMscf/day/day

9

Liquefied Natural Gas (LNG) Liquefied Natural Gas (LNG) vsvsHistorical Natural GasHistorical Natural Gas

�� San Diego natural gas composition has San Diego natural gas composition has been very stable over many yearsbeen very stable over many years

�� Natural gas derived by Natural gas derived by revaporizingrevaporizing LNG LNG has a significantly different gas has a significantly different gas composition from historic pipeline (base) composition from historic pipeline (base) natural gasnatural gas

LNG vs. CA Historic Natural GasLNG vs. CA Historic Natural Gas

13291341

1424

80%

85%

90%

95%

100%

Cool Avg Hot Cool Median Hot Cool Avg Hot

N. Cal S. Cal LNGs

Fu

el G

as C

om

po

sitio

n

1270

1312

1354

1395

1437

10

Emission ConcernsEmission Concerns

�� Combustion equipment can be tuned to Combustion equipment can be tuned to operate well over a wide range of gas operate well over a wide range of gas compositionscompositions

�� However, evidence shows that some However, evidence shows that some combustion devices tuned and/or combustion devices tuned and/or expected to operate on historic gas have expected to operate on historic gas have significantly increased NOx emissions on significantly increased NOx emissions on LNGLNG

Emissions ConcernsEmissions Concerns

�� All combustion equipment in the county All combustion equipment in the county could be affectedcould be affected

�� Device operation may otherwise be Device operation may otherwise be relatively unaffectedrelatively unaffected

�� Little incentive to retune to new gasLittle incentive to retune to new gas

�� Market forces can cause rapid and Market forces can cause rapid and unanticipated changes in gas qualityunanticipated changes in gas quality

11

Emission ConcernsEmission Concerns

�� LNG has higher VOC content than historic LNG has higher VOC content than historic natural gasnatural gas

�� Potential significant increase in emissions Potential significant increase in emissions from fugitive VOC leaks from gas from fugitive VOC leaks from gas transmission and distribution system transmission and distribution system expectedexpected

�� Potential increased VOC emissions from Potential increased VOC emissions from combustion devicescombustion devices

Impact from CA Producer GasImpact from CA Producer Gas

�� Limited amounts of gas and areas affected Limited amounts of gas and areas affected (San Diego(San Diego--little, if any)little, if any)

�� Historical gas in area gas system already Historical gas in area gas system already same qualitysame quality

�� Combustion devices tuned to existing Combustion devices tuned to existing supplysupply

�� Typically donTypically don’’t have rapid, unanticipated t have rapid, unanticipated changes in gas qualitychanges in gas quality

12

Quantifying and Characterizing Quantifying and Characterizing Emission ImpactsEmission Impacts

Characterizing Emission Characterizing Emission IncreasesIncreases

�� EEbaselinebaseline = E.F. x Activity= E.F. x Activity

�� ΔΔE = E = EEbaselinebaseline x [x [EI(x)/EI(xEI(x)/EI(xbaselinebaseline) ) –– 1]1]

�� EI is an emission index based on testing EI is an emission index based on testing (e.g., NOx (e.g., NOx ppmvppmv))

�� x is a parameter that characterizes the x is a parameter that characterizes the change in EI with gas qualitychange in EI with gas quality

13

Characterizing Emission Characterizing Emission IncreasesIncreases

�� Some assumptionsSome assumptions�� Activity (e.g., total annual heat input) is Activity (e.g., total annual heat input) is

approximately constant (i.e., small changes in approximately constant (i.e., small changes in efficiency)efficiency)

�� EI(x)/EI(xEI(x)/EI(xbaselinebaseline) is constant with changing ) is constant with changing baseline emissions (e.g., decreasing control baseline emissions (e.g., decreasing control efficiency)efficiency)

�� Representative x (or Representative x (or xx’’ss) to quantify increase) to quantify increase

�� Test population is applicable to population of Test population is applicable to population of devicesdevices

Stationary Source Emission Stationary Source Emission TestingTesting

�� Residential appliancesResidential appliances�� SoCalSoCal GasGas——NOx, CO, safety NOx, CO, safety

�� LBNL (CEC sponsored) LBNL (CEC sponsored) ——NOx, CO, PMNOx, CO, PM

�� AHRIAHRI——NOx and CO not publishedNOx and CO not published

�� PG&E and East Coast utilitiesPG&E and East Coast utilities——results not results not publicly availablepublicly available

�� Industrial/commercial equipmentIndustrial/commercial equipment�� SoCalSoCal Gas, GTI (CEC sponsored) Gas, GTI (CEC sponsored)

�� LNG event LNG event SoCalSoCal Gas, SDG&E, SDAPCDGas, SDG&E, SDAPCD

14

Vehicle Emission TestingVehicle Emission Testing

� SWRI Fuel Composition Testing Using DDC Series 50G Natural Gas Engines, 2006

� SwRI Heavy-Duty Natural Gas Engine Study, 2009

� SwRI Light-Duty Natural Gas Vehicle Study, 2010

� CE-CERT HD & LD Natural Gas Engine and Vehicle Study, 2010 DRAFT

Characterizing Combustion Characterizing Combustion EquipmentEquipment

15

Combustion CategoriesCombustion Categories

�� PremixedPremixed——turbulent or laminarturbulent or laminar�� Ideally same fuel/air ratio everywhere in flameIdeally same fuel/air ratio everywhere in flame

�� LowLow--NOx burners often leanNOx burners often lean--premixed premixed

�� ConventionalConventional——turbulent turbulent nonpremixednonpremixed(diffusion flame)(diffusion flame)�� Fuel/air ratio varies through out flameFuel/air ratio varies through out flame

�� Typical of Typical of nonregulatednonregulated devicesdevices

�� Partial premix (double flame)Partial premix (double flame)——appliancesappliances

Important Nonresidential Important Nonresidential Combustion EquipmentCombustion Equipment

�� Conventional burners (San Diego Conventional burners (San Diego unpermitted commercial/industrial)unpermitted commercial/industrial)

�� Premixed leanPremixed lean--burn (SCAQMD burn (SCAQMD unpermitted commercial/industrial)unpermitted commercial/industrial)

�� Permitted equipment usually OPermitted equipment usually O22 or load or load following (permitted equipment)following (permitted equipment)

�� AddAdd--on SCR with CEMS feedbackon SCR with CEMS feedback——no no significant NOx increases observed so farsignificant NOx increases observed so far

16

WobbeWobbe IndexIndex

WobbeWobbe IndexIndex

�� Common measure of effect of natural gas Common measure of effect of natural gas composition on combustion equipmentcomposition on combustion equipment

�� WI = HHV/(specific gravity)WI = HHV/(specific gravity)0.5 0.5

�� HHV and specific gravity at STPHHV and specific gravity at STP

�� Measure of fuel heat input to a combustor Measure of fuel heat input to a combustor through an opening with a fixed size through an opening with a fixed size (constant fuel T & P)(constant fuel T & P)

17

WobbeWobbe Index and EmissionsIndex and Emissions

�� For natural gas fuels metered through a For natural gas fuels metered through a fixed openingfixed opening and with a and with a fixed air supplyfixed air supply, , fuel to air ratio is directly proportional to fuel to air ratio is directly proportional to the the WobbeWobbe IndexIndex

�� Once tuned, changes in fuel/air ratio can Once tuned, changes in fuel/air ratio can strongly effect emissionsstrongly effect emissions

�� WobbeWobbe Index for most LNG is higher Index for most LNG is higher (1385 is PUC limit) than for historic San (1385 is PUC limit) than for historic San Diego pipeline gas (about 1335)Diego pipeline gas (about 1335)

Equivalence RatioEquivalence Ratio

�� Equivalence ratio, Equivalence ratio, φφ,, is (fuel/air)/(is (fuel/air)/(stoichiometricstoichiometricfuel/air)fuel/air)

�� φφ < 1 is lean (more air than needed for complete < 1 is lean (more air than needed for complete combustion)combustion)

�� φφ > 1 is rich (less air than needed for complete > 1 is rich (less air than needed for complete combustion)combustion)

�� Peak combustion temperature at or near Peak combustion temperature at or near φφ = 1= 1

�� NOx emissions are very sensitive to temperatureNOx emissions are very sensitive to temperature

18

Source: Gas Technology Institute

Increasing Wobbe

NOx FormationNOx Formation

�� Thermal NOxThermal NOx�� Categorized as NOx occurring outside of Categorized as NOx occurring outside of

flame zone where combustion primarily flame zone where combustion primarily occurs (usually a very narrow flame zone)occurs (usually a very narrow flame zone)

�� Increases very rapidly with temperatureIncreases very rapidly with temperature

�� Prompt NOxPrompt NOx�� Occurs within the flame zoneOccurs within the flame zone

�� Different NOx creation mechanisms may Different NOx creation mechanisms may dominatedominate

19

WobbeWobbe Index and EmissionsIndex and Emissions

�� Most commercial and residential Most commercial and residential equipment can not easily or routinely equipment can not easily or routinely adjust fuel or air flowadjust fuel or air flow

�� LeanLean--premix devices are especially premix devices are especially sensitivesensitive

�� Devices with diffusion flames may be less Devices with diffusion flames may be less sensitivesensitive

Large Industrial EquipmentLarge Industrial Equipment

�� Operational controls that may compensate Operational controls that may compensate for changes in for changes in WobbeWobbe Index are common Index are common but not universalbut not universal�� Fuel adjustment for load followingFuel adjustment for load following

�� Air adjustment with OAir adjustment with O22 trim systemstrim systems

�� Mitigates emission increases from Mitigates emission increases from WobbeWobbeIndex increasesIndex increases

20

Beyond the Beyond the WobbeWobbe IndexIndex

�� Ethane and propane have higher adiabatic Ethane and propane have higher adiabatic flame temperatures than methane at the flame temperatures than methane at the same fuel to air ratiosame fuel to air ratio

�� Ethane and propane have higher flame Ethane and propane have higher flame speeds than methane at the same fuel to speeds than methane at the same fuel to air ratioair ratio

�� Combustion chemistry detailsCombustion chemistry details

Characterizing NOx Emission Characterizing NOx Emission ImpactsImpacts

21

WobbeWobbe and Nonand Non--WobbeWobbe ImpactsImpacts

�� WobbeWobbe Index expected to be important for Index expected to be important for devices without fuel/air controlsdevices without fuel/air controls

�� NonNon--WobbeWobbe effects expected to dominate effects expected to dominate in devices with fuel/air controls or in devices with fuel/air controls or operating at very low NOx levels (i.e., at operating at very low NOx levels (i.e., at low temperatures)low temperatures)

WobbeWobbe Effects on NOxEffects on NOx

22

Source: Southern California Gas Company, Gas Quality and Research Study, Appendix G

NonNon--WobbeWobbe Effects on NOxEffects on NOx

23

Prompt NOx, Lean Premixed Combustion

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

0.7 0.8 0.9 1 1.1 1.2 1.3

Equivalence Ratio

NO

x, p

pmv

CH4C2H6C3H8C4H10Linear (C3H8)

Replotted from Bachmaier F. et al., Combust. Sci. Tech., 7, 77 (1973)

Source: Clark Atlanta University Dept. Of Engineering

(pp

mv)

24

Fuel Effect Lean Premix--Low Swirl

1.00

10.00

100.00

0.5500 0.6000 0.6500 0.7000 0.7500 0.8000 0.8500 0.9000 0.9500

Equiavalence Ratio

NO

x, p

pmv

@ 1

5% O

2

NOx(100% Propane)NOx (100% Methane)

Replotted from: Littlejohn, D. & Cheng, R.K. Proceed ings of the Combustion Institute, 31, 3155-3162, 2007.

Fuel Effect Lean Premix Burner--Low Swirl

0

0.5

1

1.5

2

2.5

0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95

Equivalence Ratio

NO

x(10

0% P

ropa

ne)/

NO

x(10

0% M

etha

ne)

Based on linear fit of log(NOx) vs phi, phi > 0.65

Based on data from: Littlejohn, D. & Cheng, R.K. Proceedings of the Combustion Institute, 31, 3155-3162, 2007.

25

Fuel Effect Conventional Burner@ 15% Excess Air

1

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2

0 10 20 30 40 50 60 70 80 90 100

Propane, %

NO

x/N

Ox

(Nat

ural

Gas

)Tip 1Tip 2Tip 3Tip 4Tip 5Tip 6

Replotted from Baukal, Jr, C. E.. and Colannino, J. “Pollutant Emissions,” Chapter 6, in Baukal, Jr, C .E. and Schw artz, R. E., eds., John Zink Combustion Handbook, CRC Press, 20 01.

Other Data with NonOther Data with Non--WobbeWobbe NOx NOx Emission IncreasesEmission Increases

�� Micro Turbine, Hack, R. L., and Micro Turbine, Hack, R. L., and McDonnelMcDonnel, , V. G., 2008V. G., 2008

�� SWRI leanSWRI lean--burn engine testing, 2006 and burn engine testing, 2006 and 20092009

� Dual fueled lean-burn engine, McTaggert-Cowan, et al., 2010� Nonpremixed

26

Tests with No Significant Emission Tests with No Significant Emission Increase Increase

�� LowLow--pressure (33 pressure (33 TorrTorr) laminar flame, ) laminar flame, PillierPillier, L., et al., 2005, L., et al., 2005

�� Turbine test combustor, Straub, D. et al., Turbine test combustor, Straub, D. et al., 2007.2007.

ConclusionsConclusions——Characterizing NOx Characterizing NOx Emissions Emissions

�� CanCan’’t rely on t rely on WobbeWobbe Index aloneIndex alone

�� Especially if fuel/air ratio is controlledEspecially if fuel/air ratio is controlled

�� Testing must cover wide range of gas Testing must cover wide range of gas compositionscompositions

27

Characterizing VOC Emission Characterizing VOC Emission ImpactsImpacts

Characterizing VOC Characterizing VOC Combustion EmissionsCombustion Emissions

�� Very limited testing (SWRI on engines)Very limited testing (SWRI on engines)

�� Increase in emissions expected to be Increase in emissions expected to be related NMHC in fuelrelated NMHC in fuel

�� Ethane Ethane ═►═► etheneethene and acetyleneand acetylene

�� Propane & Butane Propane & Butane ═►═► propane, butane, propane, butane, propenepropene, , etheneethene, acetylene, acetylene

�� Large relative increases possible because Large relative increases possible because of large relative change in of large relative change in NMHCsNMHCs

28

DD TK Total Organic Compounds & VOCs--SWRI Test Res ults

0.0

500.0

1000.0

1500.0

2000.0

2500.0

3000.0

3500.0

4000.0

4500.0

5000.0

70.0 75.0 80.0 85.0 90.0 95.0 100.0Methane No.

TO

G, m

g/bh

p/hr

0.0

200.0

400.0

600.0

800.0

1000.0

1200.0

1400.0

VO

Cs,

mg/

bhp-

hr

TOGVOCsLinear (VOCs)Linear (TOG)

Plot of data from SwRI Heavy-Duty Natural Gas Engine Study, 2009.

ISL G Total Organic Compounds & VOCs--SWRI Test Res ults

1000.0

1500.0

2000.0

70.0 75.0 80.0 85.0 90.0 95.0 100.0

Methane No.

TO

G,

mg/

bhp/

hr

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

160.0

180.0

200.0

VO

Cs,

mg/

bhp-

hr

TOGVOCsLinear (VOCs)Linear (TOG)


29

Relative VOC Increase DD TK Engine--Based on Linear Fit to SWRI Test Results

0

0.5

1

1.5

2

2.5

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

Volume % Propane or Ethane

VO

C/V

OC

(Met

hane

)

Propane

EThane

Based on fit of data from SwRI Heavy-Duty Natural Ga s Engine Study, 2009.

Relative VOC Increase ISLG--Based on Linear Fit to SWRI Test Results

0

10

20

30

40

50

60

70

80

90

100

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

Volume % Propane or Ethane

VO

C/V

OC

(Met

hane

) PropaneEThane


30

Gas Supply System VOC Gas Supply System VOC Emissions from LNGEmissions from LNG

�� Leaks of natural gas from supply systemLeaks of natural gas from supply system�� Supply piping, residential meters, industrial Supply piping, residential meters, industrial

meters, system regulating/metering system, meters, system regulating/metering system, compressors, etccompressors, etc

�� Assuming same mass leak rate of natural Assuming same mass leak rate of natural gas, VOC emissions proportional to wt% gas, VOC emissions proportional to wt% VOC in the natural gasVOC in the natural gas

�� May be very significantMay be very significant

VOC Content of LNGs Compared to Existing San Diego Natural Gas

0.0%

2.0%

4.0%

6.0%

8.0%

10.0%

12.0%

SD Baseline Tangguh, Indonesia Sakhalin Island Malaysi a

VO

C C

ont

ent,

wt%

31

Transmission and Distribution Transmission and Distribution Emission EstimatesEmission Estimates

�� Current estimate relies on AGA and Current estimate relies on AGA and INGAA emission factors ultimately based INGAA emission factors ultimately based on data collected in the 1990son data collected in the 1990s

�� Updated emission factors may be useful in Updated emission factors may be useful in refining emission estimatesrefining emission estimates

ConclusionsConclusions——Characterizing VOC Characterizing VOC EmissionsEmissions

�� Weight fractions of ethane, propane, and Weight fractions of ethane, propane, and butane are the important parametersbutane are the important parameters

32

PM10 (Soot) EmissionsPM10 (Soot) Emissions

�� SootingSooting tendencytendency�� Butane > Propane > Ethane > MethaneButane > Propane > Ethane > Methane

�� No observed trend with composition in No observed trend with composition in SWRI engine testing or LBNL appliance SWRI engine testing or LBNL appliance testingtesting

�� Probably because all test were done on Probably because all test were done on leanlean--burn and/or premixed devicesburn and/or premixed devices

PM Emissions from a Dual Fueled Engine

0.5

1

1.5

2

2.5

3

0 2 4 6 8 10 12 14 16

Time of 50% Charge Burn, Degrees ATDC

PM

/PM

(Bas

elin

e N

G)

Low EthaneHigh EthaneLow PropaneHigh PropaneMethane

Replotted from data in McTaggert-Cowan, et al., Fue l, 89, 752-759, 2010.

33

ToxicsToxics

�� Limited known testsLimited known tests�� SWRI engine testsSWRI engine tests——(full spectrum)(full spectrum)

�� LBNL appliance testsLBNL appliance tests——formaldehydesformaldehydes

�� Limited testing or so far as shown little Limited testing or so far as shown little correlation with fuel compositioncorrelation with fuel composition

�� Devices tested all or partially premixedDevices tested all or partially premixed

�� DualDual--fueled engine test indicates that fueled engine test indicates that nonpremixednonpremixed (i.e., diffusion flames) may (i.e., diffusion flames) may show increases in show increases in PAHsPAHs and BTEXand BTEX

Testing CommentsTesting Comments

34

LNG Event TestingLNG Event Testing

�� ““LNG EventLNG Event”” commissioning of Sempracommissioning of Sempra’’s s EnergiaEnergia Costa Costa AzulAzul (ECA) liquefied natural (ECA) liquefied natural gas (LNG) terminal in Baja, Californiagas (LNG) terminal in Baja, California

�� Large influx of LNGLarge influx of LNG--derived natural gas on derived natural gas on May 9, 2008, into San DiegoMay 9, 2008, into San Diego

Testing During LNG EventTesting During LNG Event

�� District source tests of permitted District source tests of permitted equipment using reference methodsequipment using reference methods

�� SoCalSoCal Gas and SDG&E testing of Gas and SDG&E testing of permitted and a few permitted and a few nonpermittednonpermitted devicesdevices�� Separate from, but coordinated with, District Separate from, but coordinated with, District

testingtesting

�� Used portable analyzerUsed portable analyzer

�� Collection of CEMS dataCollection of CEMS data

35

LNG Event Natural Gas Composition

0.000

1.000

2.000

3.000

4.000

5.000

6.000

Ethan

e

Propa

ne

Butan

es

Penta

nes

C6+CO2 N2

Base Natural Gas—WI = 1342

LNG—WI = 1382

LimitationsLimitations

�� Gas Composition tested did not fully Gas Composition tested did not fully capture the potential emission increasescapture the potential emission increases

�� Low C3+Low C3+

�� NonNon--WobbeWobbe effects not captured for effects not captured for NoxNox

�� VOC increase not representative of other VOC increase not representative of other LNG compositionsLNG compositions

36

Other IssuesOther Issues

�� Equipment tested selfEquipment tested self--selectedselected

�� Some equipment may not be Some equipment may not be representative of inventoryrepresentative of inventory

�� Equipment specific issuesEquipment specific issues

LNG Event TestingLNG Event Testing——Assessing Assessing Potential Compliance IssuesPotential Compliance Issues

�� District source tests and CEMS data District source tests and CEMS data showed no compliance problems for showed no compliance problems for equipment testedequipment tested�� However, even small increases may be an However, even small increases may be an

issue for some sitesissue for some sites

�� SoCalSoCal Gas/SDG&E testing showed two Gas/SDG&E testing showed two potential exceedances of NOx limitspotential exceedances of NOx limits�� Lean burn engineLean burn engine ——tuning resolved tuning resolved �� BoilerBoiler ——2 2 ppmvppmv , but exceeded by 1 , but exceeded by 1 ppmvppmv on base gason base gas

37

SWRI Engine TestingSWRI Engine TestingEngine Engine

Type Controls Status When

Procurred

Cummins ISL G

Rich-Burn 3-Way Catalyst New

Cummins C Gas Plus

Lean-burn Oxidation Catalyst

New

Cummins C Gas


New

Detroit Diesel TK

Lean-burn None Used

John Deere 6081H


Used—about 15% Life

Natural Gas Vehicle Engines InNatural Gas Vehicle Engines In--Use Emission IncreaseUse Emission Increase

�� In use emission increases need to be In use emission increases need to be considered when using test results on new considered when using test results on new engines to estimate actual emission increasesengines to estimate actual emission increases

Engine Emissions Relative to New Emissions @

435,000 miles

NOx NMHCs

HHD Lean-Burn 1.07 1.20

LHD Rich-Burn 5.58 5.43

Relative Increase based on Table 2 from EPA 420-R-0 1-033, MOBILE 6 Emission Factors for Natural Gas Vehicles, April 2001.

38

SafetySafety

Safety Concerns?Safety Concerns?

�� Large WI change from tuning level known Large WI change from tuning level known to increase CO from some appliancesto increase CO from some appliances

�� Previous (available) US testing has not Previous (available) US testing has not shown a problem (shown a problem (SoCalSoCal Gas and LBNL)Gas and LBNL)

�� Draft results of recently concluded AHRI Draft results of recently concluded AHRI tests may indicate a possible issuetests may indicate a possible issue

39

AHRI TestingAHRI Testing

�� AHRIAHRI—— an industry organization for an industry organization for appliance manufacturersappliance manufacturers——tested a large tested a large number (about 80) currently manufactured number (about 80) currently manufactured appliancesappliances

�� Measured CO levels for WI increase Measured CO levels for WI increase slightly higher than generally expected slightly higher than generally expected increase from LNG in CA (4.5% vs. 4%)increase from LNG in CA (4.5% vs. 4%)

�� Used industry standard safety test Used industry standard safety test proceduresprocedures

AHRI TestingAHRI Testing

�� Standard appliance test procedures Standard appliance test procedures challenges appliance with challenges appliance with overfiringoverfiring

�� OverfiringOverfiring test provides a margin of safety test provides a margin of safety to account for:to account for:�� Gas quality variation, ambient condition Gas quality variation, ambient condition

changes, manufacturing variations, poor changes, manufacturing variations, poor maintenance, etc.maintenance, etc.

40

AHRI Draft ResultsAHRI Draft Results

�� Observed CO increases exceed safety Observed CO increases exceed safety standards when devices standards when devices overfiredoverfired (mostly)(mostly)

�� One interpretation is that most devices One interpretation is that most devices may perform satisfactorily with change to may perform satisfactorily with change to high high WobbeWobbe gas, but safety margin may gas, but safety margin may be reducedbe reduced

�� Once again issue is change in gas quality Once again issue is change in gas quality from the expected gas quality used to tune from the expected gas quality used to tune the appliancethe appliance

Devices Failing Safety Standard--Normal Operation

0

10

20

30

40

50

60

70

80

90

100

Domestic andCommercialBoilers (13

Tested)

DomesticFurnaces (15

Tested)

Domestic ClothesDryers (9 Tested)

Domestic VentedFireplaces (4

Tested)

DomesticUnvented Space

Heaters (3Tested)

Domestic VentedSpace Heaters (3

Tested)

Domestic andCommercial

Water Heaters(19 Tested)

Commercial UnitHeaters (4

Tested)

Per

cent

Baseline Gas (1345 Wobbe) - NormalHigh Wobbe (1405 Wobbe) - Normal

Data taken from Williams, T.A., “MANUFACTURER TESTI NG OF U. S. APPLIANCES ON LNG COMPOSITIONS AND Other Gases, AGA , October, 2009. Based on unpublished data unpublished AHRI Program “GasInterchangeability Testing Report, prepared by Gas Consultants, Inc., May 2009.

41

Devices Failing Safety Standard--Overfire Test

0

10

20

30

40

50

60

70

80

90

100


Tested)


Tested)



Tested)


Heaters (3Tested)


Tested)




Tested)

Per

cent

Baseline Gas (1345 Wobbe) - OverfireHigh Wobbe (1405 Wobbe) - Overfire


Maximum CO Increase Among All Devices Tested--Overf ire Test

0

100

200

300

400

500

600

700


Tested)


Tested)



Tested)


Heaters (3Tested)


Tested)




Tested)

Per

cent

of S

tand

ard

Baseline Gas (1345 Wobbe) - OverfireHigh Wobbe (1405 Wobbe) - Overfire


42

UncertaintitiesUncertaintities

�� Draft resultsDraft results—— no conclusions from AHRI, no conclusions from AHRI, no details of devices tested publicly no details of devices tested publicly availableavailable

�� Not clear how appliances tested (and Not clear how appliances tested (and those failing) relate to installed appliance those failing) relate to installed appliance base in CAbase in CA

PreliminaryPreliminary Emission EstimatesEmission Estimates

�� San Diego emissionsSan Diego emissions

�� Based on expected worst case LNGBased on expected worst case LNG--derived natural gas (Malaysian)derived natural gas (Malaysian)

�� Emission increase relative to historical Emission increase relative to historical natural gasnatural gas

�� Still undergoing review by stakeholdersStill undergoing review by stakeholders

43

Annual Average Emission IncreaseAnnual Average Emission Increase

Category NOx, tpd VOC, tpd

Gas Transmission & Distribution 0 >5

District Inventoried Combustion Sources

0.12 0.27

Residential Appliances 0.07 0.05

Unpermitted Commercial & Industrial Equipment

0.35 0.03

Transit & School Busses, 2010 0.13 0.06

Transit & School Busses, Future ≈ 0 0.14

TOTAL, 2010 0.67 5.41

Peak Summer Day Emission Peak Summer Day Emission IncreaseIncrease

Category NOx, tpd VOC, tpd

Gas Transmission & Distribution 0 >5

District Inventoried Combustion Sources

0.17 0.50

Residential Appliances 0.03 0.03

Unpermitted Commercial & Industrial Equipment

0.33 0.02

Transit & School Busses, 2010 0.15 0.07

Transit & School Busses, Future ≈ 0 0.16

TOTAL 0.68 5.62

44

District Position on MitigationDistrict Position on Mitigation

�� Mitigation required for all emission Mitigation required for all emission increases not just vehicle emissionsincreases not just vehicle emissions

�� Mitigation based on emission increases Mitigation based on emission increases relative to historical gas compositionrelative to historical gas composition

�� Ideally, control gas quality to significantly Ideally, control gas quality to significantly reduce or eliminate emission increases reduce or eliminate emission increases and compliance issuesand compliance issues�� Remove excess C2 and C3+Remove excess C2 and C3+�� N2 injection (only addresses N2 injection (only addresses WobbeWobbe Index)Index)

ConclusionsConclusions

45

Some ConclusionsSome Conclusions

�� Potentially significant emission impacts Potentially significant emission impacts from LNG based on preliminary analysisfrom LNG based on preliminary analysis

�� Emission impacts not Emission impacts not soleleysoleley related to related to WobbeWobbe IndexIndex�� Methane No., C3+ wt%, C2 and C3+ Methane No., C3+ wt%, C2 and C3+ volvol %%

�� More research required to quantify More research required to quantify impactsimpacts

Critical Gas Quality Emission Critical Gas Quality Emission Research NeedsResearch Needs

�� Updated emission factors for gas transmission Updated emission factors for gas transmission and distributionand distribution

�� Emissions from Emissions from nonpremixednonpremixed (diffusion flame) (diffusion flame) commercial industrial/equipment with and w/o commercial industrial/equipment with and w/o fuel/air controlsfuel/air controls—— NOxNOx, CO, , CO, VOCsVOCs, PM, toxics, PM, toxics

�� Potential nonPotential non--WobbeWobbe effectseffects on on NOxNOx from from industrial equipmentindustrial equipment

�� NOxNOx and VOC emissions from industrial leanand VOC emissions from industrial lean--burn enginesburn engines

46

Overall ConclusionOverall Conclusion

�� Emission increases from LNGEmission increases from LNG--derived derived natural gas are counterproductive for natural gas are counterproductive for attainment of ambient air quality standardsattainment of ambient air quality standards

�� More research and information needed to More research and information needed to fully assess potential impacts basinfully assess potential impacts basin--widewide

�� Revision of CNG Fuel Standards would Revision of CNG Fuel Standards would facilitate LNG importationfacilitate LNG importation

Steven MooreSteven Moore

858858--586586--27502750

steve.mooresteve.moore @ @ sdcounty.ca.govsdcounty.ca.gov

Impacts of potential revisions to CNG fuel standards

Documents

Transcript of Impacts of potential revisions to CNG fuel standards