S C S E N G I N E E R S

CNG, LNG, and Other Fuels from Landfill GasCNG, LNG, and Other Fuels from Landfill Gas------Prospects for Future DevelopmentProspects for Future Development--------

California Biomass Collaborative California Biomass Collaborative 44thth Annual ForumAnnual ForumMarch 28, 2007March 28, 2007

Sacramento, CaliforniaSacramento, California

Patrick SullivanPatrick SullivanSCS EngineersSCS Engineers

Sacramento, CaliforniaSacramento, California

S C S E N G I N E E R S

Landfill Gas UtilizationLandfill Gas Utilization

Electric power generationElectric power generation

MediumMedium--Btu gas utilizationBtu gas utilization

HighHigh--Btu gas productionBtu gas production

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Operating Landfill Gas to Energy FacilitiesOperating Landfill Gas to Energy Facilitiesin the United Statesin the United States

Electric Power Electric Power ---- 290 projects290 projects

MediumMedium--Btu (direct use) Btu (direct use) ---- 80 projects80 projects

Pipeline Quality Gas Pipeline Quality Gas ---- 8 projects8 projects

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Electric Power GenerationElectric Power Generation

Reciprocating enginesReciprocating engines

Combustion turbinesCombustion turbines

Steam cycle power plantsSteam cycle power plants

Emerging technologiesEmerging technologiesMicroturbinesMicroturbines

Fuel cellsFuel cells

Stirling Cycle enginesStirling Cycle engines

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Why are Medium & HighWhy are Medium & High--Btu Gas ProjectsBtu Gas ProjectsPositioned for Growth?Positioned for Growth?

Dramatic increase in natural gas and vehicle fuel pricesDramatic increase in natural gas and vehicle fuel prices

Well proven technologies are availableWell proven technologies are available

Conflicts with wellfield operation are resolvableConflicts with wellfield operation are resolvable

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MediumMedium--Btu Gas UtilizationBtu Gas Utilization

Direct pipeline to end userDirect pipeline to end user

Blend with natural gas or install new burners at end userBlend with natural gas or install new burners at end user

Light cleanLight clean--up (refrigeration and filtration)up (refrigeration and filtration)

50 psig to 100 psig50 psig to 100 psig

$600,000 to $900,000/mmscfd for plant$600,000 to $900,000/mmscfd for plant

Pipeline = $30 to $50/footPipeline = $30 to $50/foot

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HighHigh--Btu Gas ProductionBtu Gas Production

Pipeline quality gas or vehicle fuelPipeline quality gas or vehicle fuel

Technologies now in use include:Technologies now in use include:Membrane processMembrane process

Molecular sieveMolecular sieve

Absorption processesAbsorption processes

Require Require ““zerozero”” air infiltration wellfield operationair infiltration wellfield operation

Plant sizes are generally 5 to 10 mmscfd (inlet)Plant sizes are generally 5 to 10 mmscfd (inlet)

$1.25 to $1.5 million per mmscfd installed$1.25 to $1.5 million per mmscfd installed

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CNG and LNG are Viable AlternativesCNG and LNG are Viable Alternativesto Diesel/Gasolineto Diesel/Gasoline

Compressed natural gas (CNG)Compressed natural gas (CNG)

Liquefied natural gas (LNG)Liquefied natural gas (LNG)

Now produced from pipeline gasNow produced from pipeline gas

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Natural Gas Prices Have RisenNatural Gas Prices Have Risen

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CNG/LNG Versus Diesel/GasolineCNG/LNG Versus Diesel/Gasoline

CNG/LNG BenefitsCNG/LNG BenefitsReduces air emissionsReduces air emissions

Lower cost than liquid fuelLower cost than liquid fuel

Safer than liquid fuelSafer than liquid fuel

Lower engine maintenance costsLower engine maintenance costs

CNG/LNG DisadvantagesCNG/LNG DisadvantagesEngines are more expensiveEngines are more expensive

Fewer available fueling stationsFewer available fueling stations

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CNG Versus LNGCNG Versus LNG

LNG has a higher energy densityLNG has a higher energy densityLess expensive to storeLess expensive to store

Less expensive to transportLess expensive to transport

Less onboard storage volume requiredLess onboard storage volume required

LNG vehicles are more complex and expensiveLNG vehicles are more complex and expensive

LNG costs more to produceLNG costs more to produce

LNG is convertible to CNG at a fueling stationLNG is convertible to CNG at a fueling station

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Landfill Gas Conversion to Vehicle FuelLandfill Gas Conversion to Vehicle Fuel

Landfill gas can be used to produce:Landfill gas can be used to produce:Compressed natural gas (CNG)Compressed natural gas (CNG)

Liquefied natural gas (LNG)Liquefied natural gas (LNG)

CNG or LNG can be used to:CNG or LNG can be used to:Fuel landfill vehiclesFuel landfill vehicles

Refuse trucks (short or long haul)Refuse trucks (short or long haul)

Supply the general clean fuels marketSupply the general clean fuels market

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Typical Landfill Gas CharacteristicsTypical Landfill Gas Characteristics

0.2 to 10 ppmv0.2 to 10 ppmvSiloxaneSiloxane

200 to 2000 ppmv200 to 2000 ppmvNMOCsNMOCs

20 to 500 ppmv20 to 500 ppmvHydrogen SulfideHydrogen Sulfide

<10 ppmv<10 ppmvCarbon MonoxideCarbon Monoxide

2% to 45%2% to 45%NitrogenNitrogen

0.5% to 5%0.5% to 5%OxygenOxygen

20% to 45%20% to 45%Carbon DioxideCarbon Dioxide

35% to 55%35% to 55%MethaneMethane

RangeRangeComponentComponent

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Typical CNG Vehicle Fuel SpecificationTypical CNG Vehicle Fuel Specification

≤≤ 16 ppmv16 ppmvSulfurSulfur

≤≤ 4.5%4.5%Inert Gas (COInert Gas (CO22 + N+ N22))

≤≤ 0.1%0.1%Carbon MonoxideCarbon Monoxide

≤≤ 1%1%OxygenOxygen

≤≤ 0.1%0.1%HydrogenHydrogen

≤≤ 0.2%0.2%C6 and higherC6 and higher

≤≤ 3%3%C3 and higherC3 and higher

≤≤ 6%6%Ethane (C2)Ethane (C2)

≥≥ 88%88%MethaneMethane

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Conversion of Landfill Gas to CNGConversion of Landfill Gas to CNG

Remove carbon dioxide through either:Remove carbon dioxide through either:Membrane separationMembrane separation

Molecular sieve (pressure swing adsorption)Molecular sieve (pressure swing adsorption)

Both have been used to produce pipeline quality gas on a large Both have been used to produce pipeline quality gas on a large scalescale

To date only membrane separation has been used for vehicle To date only membrane separation has been used for vehicle fuel on a production scalefuel on a production scale

Fuel specification for oxygen and nitrogen limits these Fuel specification for oxygen and nitrogen limits these parameters in the raw landfill gas to about 0.6 percent and 2.5 parameters in the raw landfill gas to about 0.6 percent and 2.5 percent, respectivelypercent, respectively

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Residual Gas

Feed Gas

Permeate Gas

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Puente Hills Landfill CNG ProjectPuente Hills Landfill CNG Project

Los Angeles County Sanitation DistrictsLos Angeles County Sanitation Districts

250 scfm of 55 percent methane landfill gas converted 250 scfm of 55 percent methane landfill gas converted to 100 scfm of 96 percent methane CNGto 100 scfm of 96 percent methane CNG

1,000 gallons of gasoline equivalent per day1,000 gallons of gasoline equivalent per day

70 percent of raw methane to final product and 30 70 percent of raw methane to final product and 30 percent of raw methane to wastepercent of raw methane to waste

Construction cost in 2006 dollars Construction cost in 2006 dollars ≈≈ $1.6 million$1.6 million

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Puente Hills Landfill CNG ProjectPuente Hills Landfill CNG Project

Landfill gas compression and moisture removal;Landfill gas compression and moisture removal;

Activated carbon;Activated carbon;

Gas heating to 140Gas heating to 140ºº F;F;

Membranes for carbon dioxide removal;Membranes for carbon dioxide removal;

Compression of the product gas to 3,600 psig;Compression of the product gas to 3,600 psig;

Compressed gas storage facilities; andCompressed gas storage facilities; and

A fuel dispenser to dispense 3,000 psig CNG.A fuel dispenser to dispense 3,000 psig CNG.

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Sonoma County CNG ProjectSonoma County CNG Project

Sonoma County Transit currently fuels its bus fleet with Sonoma County Transit currently fuels its bus fleet with CNGCNG

A 100 scfm (inlet) pilot scale project is currently being A 100 scfm (inlet) pilot scale project is currently being implementedimplemented

The full scale project is expected to be 860 scfm (inlet)The full scale project is expected to be 860 scfm (inlet)

Project is to be located at the CountyProject is to be located at the County’’s Central Landfills Central Landfill

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Sonoma County Pilot Scale ProjectSonoma County Pilot Scale Project

100 scfm (inlet) and 40 scfm (outlet)100 scfm (inlet) and 40 scfm (outlet)

Compression to 125 psig, chilling, and activated carbon Compression to 125 psig, chilling, and activated carbon treatmenttreatment

Membranes for carbon dioxide removalMembranes for carbon dioxide removal

Compression to 3,900 psigCompression to 3,900 psig

Waste gas to engines or flareWaste gas to engines or flare

CNG production cost = $9.30/mmBtuCNG production cost = $9.30/mmBtu

S C S E N G I N E E R S

Sonoma Full Scale ProjectSonoma Full Scale Project

860 scfm (inlet) and 360 scfm (outlet)860 scfm (inlet) and 360 scfm (outlet)

Hydrogen sulfide removal, compression to 145 psig, Hydrogen sulfide removal, compression to 145 psig, chilling, and activated carbon treatment (TSA)chilling, and activated carbon treatment (TSA)

Membranes for carbon dioxide removalMembranes for carbon dioxide removal

Compression to 3,900 psigCompression to 3,900 psig

Waste gas burned in a flareWaste gas burned in a flare

Production cost = $6.60/mmBtuProduction cost = $6.60/mmBtu

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Conversion of Landfill Gas to LNGConversion of Landfill Gas to LNG

Purify landfill gas and remove carbon dioxide, and then Purify landfill gas and remove carbon dioxide, and then follow with liquefaction of methanefollow with liquefaction of methane

Cryogenic process generally used for this purposeCryogenic process generally used for this purpose

Montauk has recently commenced operation of a project at Montauk has recently commenced operation of a project at the Frank R. Bowerman Landfill in Orange Countythe Frank R. Bowerman Landfill in Orange County

Prometheus Energy is in development of project at Kiefer Prometheus Energy is in development of project at Kiefer Landfill for Sacramento CountyLandfill for Sacramento County

Several stops and starts at Bay and Los Angeles area Several stops and starts at Bay and Los Angeles area landfills have occurred landfills have occurred

S C S E N G I N E E R S

Typical LFG/LNG ModuleTypical LFG/LNG Module

5,000 gal/day of LNG from 900 scfm of landfill gas5,000 gal/day of LNG from 900 scfm of landfill gas

LNG is 97% methane / 20 psig / LNG is 97% methane / 20 psig / --250250ºº FF

750 kW of power is required750 kW of power is required

Production cost = $1.00/gallon (?)Production cost = $1.00/gallon (?)

S C S E N G I N E E R S

LFG/LNG IssuesLFG/LNG Issues

Fuel specification for methane percentage at 97 percent Fuel specification for methane percentage at 97 percent limits nitrogen and oxygen in the raw landfill gas to about limits nitrogen and oxygen in the raw landfill gas to about 1.5 percent combined (unless process employed can also 1.5 percent combined (unless process employed can also strip nitrogen and oxygen)strip nitrogen and oxygen)

High oxygen in feed stock may represent an explosion riskHigh oxygen in feed stock may represent an explosion risk

Requires ultraRequires ultra--low carbon dioxide prior to liquefactionlow carbon dioxide prior to liquefaction

Loss of economy of scale at LFG facility sizingLoss of economy of scale at LFG facility sizing

S C S E N G I N E E R S

ConclusionConclusion

Experience with landfill gas to vehicle fuel is limitedExperience with landfill gas to vehicle fuel is limited

One longOne long--term, successful, small LFGterm, successful, small LFG--toto--CNG project exists. CNG project exists. Another pilot scale project is being implementedAnother pilot scale project is being implemented

One commercial LFGOne commercial LFG--toto--LNG demonstration project has been LNG demonstration project has been completed. completed.

Conversion of landfill gas to CNG and LNG is technically Conversion of landfill gas to CNG and LNG is technically feasible, and is economically feasible if natural gas cost feasible, and is economically feasible if natural gas cost exceeds $6.00/mmBtuexceeds $6.00/mmBtu