Using LandGEM to Model Methane Emissions from Landfills:

Application at a Multi-phase Site

Brookhaven Landfill, NY

Federation of New York Strive for Sustainability Conference 2017

LORI CLARK AND DR. DAVID TONJES DEPARTMENT OF TECHNOLOGY AND SOCIETY

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Landfill Gas at a typical Municipal Solid Waste (MSW) Landfill

>55% of U.S. waste landfilled, >60% degradable MSW digestion under anaerobic conditions Gas Composition: A nearly equal composition of

CO2 and CH4 flows for decades with other trace gases

Fugitive Emission Problems: Odor, H2S, SOx, GHG, Flammability

Landfill Gas Benefits: CNG, Electricity, Pipeline Gas

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3 Landfill Gas Composition Evolves with Time

Months Decades

“All models are wrong…But some are useful”- George Box Why Model? A major Anthropogenic contributor to GHG – Difficult to

measure directly 2009 US-EPA mandated the reporting of GHG emissions

from landfills starting in 2010 (GHGRP – Greenhouse Gas Reporting Program)

2009 U.N. Economic Commission for Europe’s Kiev Protocol requires GHG reporting with PRTRs (pollutant release and transfer registers)-34 Countries + E.U.

Increasing reliance on Methane as a primary energy source - LFGTE plants increasing

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Landfill Gas to Energy Plants in the U.S.

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Problems with LFG Models Balancing simplicity with specifications Models often assume homogeneity or national average

composition of waste Uniqueness of landfill conditions, components, design –

need for customization Seasonal temperature and precipitation patterns Leachate or moisture contact time with waste Cover soil or material choices Rate of burial Waste composition Phase changes – based on environmental regulations

and consumer trends Gas collection efficiency and oxidation

Validation tests show that model over-estimates are common (Denmark, Canada, U.S.)

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Choosing a Model Model Developed by Brief Description First order model (TNO) Oonk and Boom, 1995 Exponential decay of

waste Multi-phase model Afvalzorg, 1996 8 categories of waste

component and 3 fractions with different LFG production

LandGEM US-EPA, 2001 FOD, Homogenous MSW GasSim Env. Ag. UK and Golder

Assoc., 2003 Multiphase, and relates to LandGEM

EPER model France (ADEME)

Budka, 2003 Considers lfg recovery system influence

EPER model Germany Hermann, 2005 Zero order, “unconditioned residential or similar waste”

SWANA zero order Zero order waste age and type do not influence gas production, it remains steady over time.

LandGEM Mexico/China/Colombia/Central America, etc.

SCS Engineering 2003-2010 Assumes 1 year lag in decay, includes decay values specific to regional climate factors

CLEEN Karanjekar R, Bhatt A, Chen V, et al, 2015

Considers mass, rainfall and temperature

IPCC Bogner and Mathews , 2003

Mass balance for national estimates

CALMIM Spokas, 2014 Considers cover, soil, climate impacts

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Accepted Models for U.S. EPA: GHGRP

LandGEM IPCC

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Site Description – climate

Climate: The average annual nearby (Islip, NY) temperature is 11.36 deg. C and the average annual rainfall is 118cm (NWS, 2017) . Using the potential evapotranspiration value of 22 inches or 55.88cm (Peterson, 1987), the mean annual precipitation to potential evapotranspiration ratio is 2.1. This places our location in a non-tropical climate region with a MAP/PET>1, a category IPCC uses to designate K values for specific organic materials (IPCC, 2006)

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MAT: 53 deg F, MAP :46”, PET: 22”, MAP/PET=2.1

Site Description - Decisions

Closure Year/s Phase shift Collection

Efficiency

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Component Specifics – Data Breakdown for multi-component analysis 11

Research Approach 12

Simple approach: • K=0.04, L0 = 100 • C&D tonnage

halved • Single Phase • Dual Phase

Complex approach: • MSW split into

components by % • IPCC informed K • Research

informed L0

LandGEM Basic 13

*Mass of C&D halved

LandGEM output 1

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• One Closure Year • Cells 1-4 likely over

contributing • Model output is 10-20

times the measured values

• Demonstrates the weakness of a simple approach to using the model

LandGEM output 2

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• Two closure years • Cells 5&6 biggest

contributor • Model output is 125-500%

above measured • Cells 5&6 more closely

align with measured (5-200% over)

Digestion experiments informing K and L0 component values

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Multi-Component Analysis Component K L0

Wood 0.03 62.6*

Paper and Textile 0.06 140

Other -non food 0.10 128.1 **

Yard, garden and park 0.10 72**

Food 0.185 300.7**

Bulk 0.09 100-170

C&D 0.04 51.14***

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Custom decay values used for models 3 and 4 *Wang et al. 1997, **Staley and Barlaz, 2009, ***Assuming C&D is 70% wood, 10% gypsum, 5% paper, 15% non degradable

Component % of MSW at Brookhaven

Paper

33% (Newspaper 4, corrugated cardboard 10, office paper and mail 12, other compostable 7)

Food Scraps 18%

Yard Trimmings (<3->10% urban to rural)

Plastic 14%

Wood >3%

Textile 5% Metals 7%

Glass 4%

Other/C&D, durables, diapers, electronics HHW, tires

11%

Customizing the model by components

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Custom Values

LandGEM output 3

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• Single Closure Year • % Components • Customized decay values

• Methane off by up to an order of magnitude (10x or 1000%)

LandGEM output 4

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• Dual closure years • Customized decay

values • % components • Food, Bulk, and Paper

dominate • Phase 1 output much

higher • Phase 2 less dominant

• Cell 5&6 modeled gas

varies by 50-200% from measured

Comparing Outputs Brookhaven composition is somewhat different from

the national average with higher proportions of food waste, lower wood and yard waste and much higher C&D waste.

This deviation from the average gave justification for doing a customized model.

The models that included cell closure gave better output.

Simple and Complex dual phase models errors were nearly identical when phase 2 gas is considered relative to the measured gas. If we include the trailing gas stream from phase 1, the error increases with a closing gap.

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Next Steps

Further customize K values according to NCSU study

Validate with separate gas stream data from Brookhaven

Find additional data for ‘non traditional’ or traditional sites Multi-phase

Unique component % breakdown

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Thank you

Lori Clark Department of Technology and Society

Stony Brook University Lori.Clark@stonybrook.edu

Dr. David Tonjes David.tonjes@stonybrook.edu

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