Rules of Thumbs for Designing

8/11/2019 Rules of Thumbs for Designing

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S C S E N E R G Y

DESIGNING A LANDFILL GAS TO ENERGYDESIGNING A LANDFILL GAS TO ENERGY

PROJECTPROJECTRULES OF THUMB AND QUESTIONS TO ASKRULES OF THUMB AND QUESTIONS TO ASK

Intermountain CHP Application Center WorkshopIntermountain CHP Application Center WorkshopCHP andCHP and BioenergyBioenergy for Landfills and for Landfills and

Wastewater Treatment PlantsWastewater Treatment Plants

August 11, 2005August 11, 2005

Salt Lake City, UtahSalt Lake City, Utah

Jeffrey L. Pierce, P.E.Jeffrey L. Pierce, P.E.

Vice PresidentVice PresidentSCS EnergySCS EnergyLong Beach, CaliforniaLong Beach, California


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S C S E N E R G Y

Three Principal Factors Affect Project FeasibilityThree Principal Factors Affect Project Feasibility

Energy sales ratesEnergy sales rates

Landfill gas qualityLandfill gas quality

Landfill gas quantityLandfill gas quantity


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S C S E N E R G Y

Factor No. 1: Energy Sales RatesFactor No. 1: Energy Sales Rates

Affected by project typeAffected by project type

Sale to grid (wholesale)Sale to grid (wholesale)

OnOn--site utilization (retail deferral)site utilization (retail deferral)

Off Off --site utilization (retail deferral)site utilization (retail deferral)

Electricity valueElectricity valueVaries by region and utility andVaries by region and utility and greenpower greenpower policy policy

Stable pricesStable prices

Natural gas value Natural gas valueLess variable by regionLess variable by region

Prices fairly unstable if indexed Prices fairly unstable if indexed


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S C S E N E R G Y

Sale to Grid Sale to Grid

Bid into utility solicitations for brown or green power Bid into utility solicitations for brown or green power

LongLong --term market rateterm market rateMinimum size plant (usually 1 MW+)Minimum size plant (usually 1 MW+)

Complicated to respond to and very competitiveComplicated to respond to and very competitive

Utility standard offersUtility standard offers

PURPA ratesPURPA rates

Short run avoided cost (SRAC)Short run avoided cost (SRAC)

Bilateral contracts sometimes possible inBilateral contracts sometimes possible in deregulated deregulated statesstates


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S C S E N E R G Y

Candidates for OnCandidates for On --Site Retail Deferral at LandfillsSite Retail Deferral at Landfills

Landfill gas flare station itself Landfill gas flare station itself

Leachate or groundwater treatment plantLeachate or groundwater treatment plant

MRF or transfer stationMRF or transfer stationOffice complexOffice complex

Maintenance garageMaintenance garage


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S C S E N E R G Y

Candidates for Off Candidates for Off --Site Retail DeferralSite Retail Deferral

Over Over --thethe --fence power salefence power sale

Use of gas transmission line with remote generationUse of gas transmission line with remote generation

Typical end users are hotels, WWTP plants and officeTypical end users are hotels, WWTP plants and office buildings buildings


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S C S E N E R G Y


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S C S E N E R G Y


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S C S E N E R G Y


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S C S E N E R G Y


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S C S E N E R G Y

Revenue Considerations for Retail Deferral ProjectsRevenue Considerations for Retail Deferral Projects

Discount to retailDiscount to retail

Standby chargesStandby charges

Exit feesExit fees


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S C S E N E R G Y

Incentives for Landfill Gas UtilizationIncentives for Landfill Gas Utilization

Section 45 tax creditSection 45 tax credit

10 years10 yearsPlace in service prior to December 2008Place in service prior to December 2008

0.90.9 /kWh (will escalate)/kWh (will escalate)

Sale to other partySale to other party

Section 29 tax creditSection 29 tax credit

Renewable energy creditsRenewable energy creditsGreenpower Greenpower premiums and subsidies premiums and subsidies

Capital cost grantsCapital cost grants


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S C S E N E R G Y

How to Incorporate Heat RecoveryHow to Incorporate Heat Recovery

Into a Landfill Gas ProjectInto a Landfill Gas Project

A landfills onA landfills on --site heat uses are generally minor andsite heat uses are generally minor andlargely limited to space heatinglargely limited to space heating

Can send hot water or steam off Can send hot water or steam off --site by pipesite by pipeLocate generation at end user Locate generation at end user


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S C S E N E R G Y

Factor No. 2: Landfill Gas QualityFactor No. 2: Landfill Gas Quality

35% to 55% methane35% to 55% methane65% to 45% Carbon dioxide plus air 65% to 45% Carbon dioxide plus air

Saturated with moistureSaturated with moisture

Hydrogen sulfideHydrogen sulfide

NMOCs NMOCs

SiloxanesSiloxanes


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S C S E N E R G Y

Factor No. 3: Landfill Gas QuantityFactor No. 3: Landfill Gas QuantityLandfill Gas Generation is Affected byLandfill Gas Generation is Affected by

Waste compositionWaste composition

Waste ageWaste age

MoistureMoisture

TemperatureTemperature

pH pHOther environmental factorsOther environmental factors


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S C S E N E R G Y

Quantification of Landfill GasQuantification of Landfill Gas

If a wellfield does not exist, a landfill gas model must beIf a wellfield does not exist, a landfill gas model must beutilized utilized

If a wellfield exists, direct measurement of flow andIf a wellfield exists, direct measurement of flow and

methane is possiblemethane is possibleFuture landfill gas flow is an unknown in latter case; thus,Future landfill gas flow is an unknown in latter case; thus,a model is still needed a model is still needed


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S C S E N E R G Y

Alternative Types of Landfill Gas ModelsAlternative Types of Landfill Gas Models

Zero order Zero order

First order First order

Compound modelsCompound models


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S C S E N E R G Y

EPAs Landfill Gas Emissions Model:EPAs Landfill Gas Emissions Model:

LandGEMLandGEM

Can be downloaded from EPAs website at:Can be downloaded from EPAs website at:http://http:// www.epa.gov/oar/oaqps/landfill.htmlwww.epa.gov/oar/oaqps/landfill.html

Most widely used and accepted modelMost widely used and accepted model

First order exponential modelFirst order exponential model

Metric unitsMetric units


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S C S E N E R G Y

LandGEM Model Inputs (continued):LandGEM Model Inputs (continued):

Setting k and LSetting k and L oo values:values:

NSPS rule: k = 0.02 for dry sites (


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S C S E N E R G Y

Estimating Landfill Gas Collection EfficiencyEstimating Landfill Gas Collection Efficiency

EPAs APEPAs AP --42: range of 6042: range of 60 --85%, with 75% as typical for85%, with 75% as typical forsites with comprehensive wellfield sites with comprehensive wellfield

Can compare actual recovery to modeled generation atCan compare actual recovery to modeled generation atsites with wellfield sites with wellfield


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S C S E N E R G Y

Independent Estimates of Collection EfficiencyIndependent Estimates of Collection EfficiencyUse collection system asUse collection system as -- built plan to estimate wellfield built plan to estimate wellfieldcoverage of refuse masscoverage of refuse mass

Wellfield monitoring data to evaluate methane, oxygen,Wellfield monitoring data to evaluate methane, oxygen, pressure readings in wells pressure readings in wells

Rates of disposal vs. timing of wellfield expansionsRates of disposal vs. timing of wellfield expansions

Landfill configuration: deeper landfill versus shallowerLandfill configuration: deeper landfill versus shallower

landfilllandfillTypes of landfill liners, coversTypes of landfill liners, covers closed with final coverclosed with final coveryields highest collection efficiencyyields highest collection efficiency


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S C S E N E R G Y

Typical Landfill Gas Recovery ProjectionTypical Landfill Gas Recovery Projection

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 2025 2030

L F G F l o w a t

5 0 %

M e t

h a n e

( m 3 / h r )

LFG Generation LFG Recovery - High Estimate LFG Recovery - Low Estimate


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S C S E N E R G Y

Electric Power Generation TechnologiesElectric Power Generation Technologies

Reciprocating enginesReciprocating engines

Combustion turbinesCombustion turbines

Steam cycle power plantsSteam cycle power plants

Emerging technologiesEmerging technologiesMicroturbinesMicroturbines

Fuel cellsFuel cells

StirlingStirling Cycle enginesCycle engines


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S C S E N E R G Y

Reciprocating EnginesReciprocating Engines

Engines range from 0.8 MW to 3.0 MWEngines range from 0.8 MW to 3.0 MWCaterpillar,Caterpillar, Jenbacher Jenbacher ,, DeutzDeutz and Waukeshaand Waukesha

Net heat rate = 10,600 Btu/kWh (LHV) Net heat rate = 10,600 Btu/kWh (LHV)

Inlet pressures of 3 psig to 60 psigInlet pressures of 3 psig to 60 psig

NO NO xx = 0.17 lbs/mmBtu CO = 0.57 lbs/mmBtu= 0.17 lbs/mmBtu CO = 0.57 lbs/mmBtu

$1,100 to $1,400/kW installed $1,100 to $1,400/kW installed


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S C S E N E R G Y

Reciprocating EnginesReciprocating Engines

AdvantagesAdvantages

Better heat rateBetter heat rate

Moderate capital costModerate capital cost

DisadvantagesDisadvantagesHigher air emissionsHigher air emissions

Maintenance intensiveMaintenance intensive

Require 40% to 45% methane LFGRequire 40% to 45% methane LFG


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S C S E N E R G Y


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S C S E N E R G Y


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S C S E N E R G Y

Combustion TurbinesCombustion Turbines

1.2 MW to 5.5 MW1.2 MW to 5.5 MWSolar Turbines dominates the marketSolar Turbines dominates the market

Net heat rate = 13,300 to 16,500 Btu/kWh (LHV) Net heat rate = 13,300 to 16,500 Btu/kWh (LHV)

Inlet pressure 150 psig to 250 psigInlet pressure 150 psig to 250 psig




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S C S E N E R G Y

Combustion TurbinesCombustion Turbines

AdvantagesAdvantagesLower air emissionsLower air emissions

Moderate capital costModerate capital cost

More tolerant to low methane contentMore tolerant to low methane content

DisadvantagesDisadvantages

Worse heat rateWorse heat rateRequires high fuel pressureRequires high fuel pressure


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S C S E N E R G Y


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S C S E N E R G Y

Steam Cycle Power PlantSteam Cycle Power Plant

6 MW to 50 MW plants are currently in operation6 MW to 50 MW plants are currently in operation

Custom designed plantCustom designed plant ---- not modular not modular

Net heat rate = 11,000 Btu/kWh to 16,500 Btu/kWh (HHV) Net heat rate = 11,000 Btu/kWh to 16,500 Btu/kWh (HHV)

Inlet pressure of 2 psig to 4 psigInlet pressure of 2 psig to 4 psig

NO NO xx = 0.03 lb/mmBtu CO = 0.01 lb/mmBtu= 0.03 lb/mmBtu CO = 0.01 lb/mmBtu

$1,500/kW to $2,500/kW installed $1,500/kW to $2,500/kW installed


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S C S E N E R G Y


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S C S E N E R G Y

MicroturbinesMicroturbines

30 kW to 250 kW units available30 kW to 250 kW units availableCapstone and IngersollCapstone and Ingersoll --Rand Rand

Net heat rate = 13,100 to 15,300 Btu/kWh (LHV) Net heat rate = 13,100 to 15,300 Btu/kWh (LHV)

Inlet pressure of 80 psigInlet pressure of 80 psig




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S C S E N E R G Y

MicroturbinesMicroturbines

AdvantagesAdvantagesSmall increment capacities are well suited to retail deferralSmall increment capacities are well suited to retail deferral

Tolerant of low methane content landfill gasTolerant of low methane content landfill gas

Very low air emissionsVery low air emissions

DisadvantagesDisadvantages

Very high capital costVery high capital costCapacity factor less than other technologiesCapacity factor less than other technologies


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S C S E N E R G Y

Other Emerging TechnologiesOther Emerging Technologies

Fuel CellsFuel Cells200 kW and 250 kW units200 kW and 250 kW units

Inlet pressure = 20 psigInlet pressure = 20 psig

Heat rate = 7,550 Btu/kWhHeat rate = 7,550 Btu/kWh

NO NO xx = zero= zero

$7,000/kW installed $7,000/kW installed


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S C S E N E R G Y

Other Emerging TechnologiesOther Emerging Technologies

StirlingStirling Cycle enginesCycle engines55 kW available from STM Power 55 kW available from STM Power

Inlet pressure = 2 psigInlet pressure = 2 psig

Heat Rate = 10,400 Btu/kWh (LHV)Heat Rate = 10,400 Btu/kWh (LHV)

NO NO xx = 0.04 lbs/mmBtu= 0.04 lbs/mmBtu

$2,000/kW installed $2,000/kW installed


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S C S E N E R G Y

Landfill Gas Pretreatment IssuesLandfill Gas Pretreatment Issues

Historically only an air cooler and coalescing filter, butHistorically only an air cooler and coalescing filter, butrefrigeration and reheat was not uncommonrefrigeration and reheat was not uncommon

Hydrogen sulfide removal byHydrogen sulfide removal by SulfaTreatSulfaTreat (or other media)(or other media)

or liquid scrubber at a level beginning at 100or liquid scrubber at a level beginning at 100 ppmv ppmvSiloxane removal is seeing increased interestSiloxane removal is seeing increased interest

Some technologies it is mandatorySome technologies it is mandatory

Some technologies it is optionalSome technologies it is optional


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S C S E N E R G Y

Landfill Gas to Energy Project DevelopmentLandfill Gas to Energy Project DevelopmentSoft IssuesSoft Issues

OwnershipOwnership

FinancingFinancing

Air and environmental permittingAir and environmental permitting


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S C S E N E R G Y

Primary Institutional Question for Landfill OwnersPrimary Institutional Question for Landfill Owners

Self Development of ProjectSelf Development of Project

VersusVersus

Second Party Development of ProjectSecond Party Development of Project


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S C S E N E R G Y

Project Self DevelopmentProject Self Development

Landfill owner covers 100 percent of capital costLandfill owner covers 100 percent of capital costLandfill owner bears 100 percent of project risk Landfill owner bears 100 percent of project risk

Landfill owner receives 100 percent of project rewardsLandfill owner receives 100 percent of project rewards

Diverts some management attention away from his primaryDiverts some management attention away from his primary business business

Requires his involvement in an unfamiliar businessRequires his involvement in an unfamiliar business


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S C S E N E R G Y

Project Second Party DevelopmentProject Second Party Development

Landfill owner covers zero percent of capital costLandfill owner covers zero percent of capital cost

Landfill owner bears zero percent of project risk Landfill owner bears zero percent of project risk

Developer receives most of project rewardsDeveloper receives most of project rewards

Landfill owner shares in reward:Landfill owner shares in reward:

On a percentage of gross or net revenue basisOn a percentage of gross or net revenue basis

Through energy purchase on a $/Through energy purchase on a $/ MMBtuMMBtu basis basisWell field operation/maintenance and/or capital cost reductionsWell field operation/maintenance and/or capital cost reductions


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S C S E N E R G Y

Third Party Project ParticipationThird Party Project Participation

Monetization of tax credits is necessary when developerMonetization of tax credits is necessary when developerhas no appetite for tax creditshas no appetite for tax credits

Public ownersPublic owners

Small second party developersSmall second party developers

Necessary when an arms length gas sale is required Necessary when an arms length gas sale is required between two parties to satisfy Section 29 requirements for between two parties to satisfy Section 29 requirements for

tax credittax credit

LFGTE Facilities Financing OptionsLFGTE Facilities Financing Options


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S C S E N E R G Y

LFGTE Facilities Financing OptionsLFGTE Facilities Financing Options

Municipal sector projectsMunicipal sector projects

TaxTax --free borrowingfree borrowing

Landfill closure and postLandfill closure and post --closure fundsclosure funds

Private sector projectsPrivate sector projects

Balance sheet financingBalance sheet financing

Project (nonProject (non --recourse) financerecourse) finance

Private sector prefers project financePrivate sector prefers project finance

DebtDebt --toto--equity ratio (less than 80/20)equity ratio (less than 80/20)

Debt coverage (1.2+)Debt coverage (1.2+)

Internal rate of return on equity (20 percent +)Internal rate of return on equity (20 percent +)


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S C S E N E R G Y

Air PermittingAir Permitting

Normally straightforward Normally straightforward

BACT determinationsBACT determinations

NO NO xx is primary concernis primary concern

CO is secondary concernCO is secondary concern

VOCsVOCs are critical at NSPS landfills (98% DRE)are critical at NSPS landfills (98% DRE)

Health risk assessments (sometimes)Health risk assessments (sometimes)


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S C S E N E R G Y

Interconnection In ParallelInterconnection In Parallel


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S C S E N E R G Y

Interconnection In ParallelInterconnection In Parallel

Always allows backflow of power Always allows backflow of power

Types of interconnections vary by intent of projectTypes of interconnections vary by intent of project

No export No export

Inadvertent/uncompensated exportInadvertent/uncompensated export

Net metering Net metering

Full export (sale to grid)Full export (sale to grid)

Interconnection requirementsInterconnection requirements

Protective relaysProtective relaysGround banksGround banks

Upgraded transformers and/or tie linesUpgraded transformers and/or tie lines


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S C S E N E R G Y

ConclusionsConclusions

Development of a landfill gas to energy project isDevelopment of a landfill gas to energy project is

difficult and time consuming, and requires patience anddifficult and time consuming, and requires patience andinnovative thinkinginnovative thinking

Technology and air permitting are not issues. TheTechnology and air permitting are not issues. The problems are contractual and institutional problems are contractual and institutional

Rewards are greatRewards are great

SCS has successfully completed almost twenty biogasSCS has successfully completed almost twenty biogas projects over the last four years projects over the last four years

Rules of Thumbs for Designing

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