### EP

A’ s Methodology for Estimating Emissions from Residential Wo od Combustion

Briefing for OMB August 21, 2013

# Purpose of Briefing

► 

### Explain how EP

A estimates emissions from residential wood combustion (RWC) for the National Emission Inventory (NEI)

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# National Emission Inventory (NEI) ► 

### Published on a triennial cycle (e.g., 2005, 2008, 201 1) ► 

### Criteria pollutants and their precursors, and hazardous air pollutants ► 

### NEI is a mix of State/Local/Tribal (SL T) data, and EP

A data ► The EP

A data are used for SL

Tsthat do not submit ► For 201 1, agencies that submitted their own RWC estimates are: CA, DE, IL, MD, ME, MN, OR, W A, WV, Clark county (NV), & 8 tribes ► 

### EP A & SL Tsestimate emissions using the Residential Wood Combustion T

ool

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# Residential Wood Combustion To ol ► 

### To ol first created for 2005 NEI ► Updated for 2008 and 201 1 ► 

### Includes previously ignored appliance types, like outdoor hydronic heaters (aka outdoor wood boilers (OWB)), wax logs, indoor wood furnaces, and other outdoor burning (firepits, chimeneas) ► As well as fireplaces, fireplace inserts, and woodstoves ► Other outdoor burning added in 201 1 ► 

### Includes criteria pollutants and HAPs ► Key pollutants include PM 2.5 ► 

### Microsoft Access - based tool ► Transparent and flexible ► Allows SL

Tsto view and update parameters at the county level to provide local specific emissions estimates ► Includes queries to recalculate emissions ► 

### Determines EP

A- certified woodstoves and inserts separately 4

# How Does the To ol Estimate Emissions?

Emissions = n × b × d × EF n = number of appliances b = burn rate of appliance Cords of wood burned/yr d = wood density (lbs/ft3 

### ) Converts cords of wood burned to tons of wood burned Must be oven dried basis EF = emission factor lbs pollutant / ton of oven dry wood burned
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# Appliance Counts ► 

### Fireplaces, Inserts, and Woodstoves ► Uses the American Housing Survey (AHS) from the US Census ► Derives county- specific number of households that use these for heating by using percentages from AHS and number of occupied households from Dept of Census ► Separately counted for primary heating or supplemental heating ► Other data sources are state surveys ► 

### Outdoor Hydronic Heaters ► Wehave population numbers by state • Sales data by state from NESCAUM for hydronic heaters from 1990 to 2005 • Population grown to 2008 and 201 1 using data from MN, VT and a Frost and Sullivan market research report • Allocated to county in various ways (too much detail for this briefing) 6

# Appliance Counts (con’t) ► 

### Pellet Stoves ► Population determined by sales data • Sales data from Pellet Fuel Institute by state thru 2008 • Population in tool held constant from 2008 to 201 1 due to limited resources

– PM emissions are 1/10 tha t of a con ve ntional w oodstove on a per ton burned basis ► 

### Indoor Wood - Fired Furnaces ► MANE -VU states: • Have estimated number of centralized cordwood heating systems 1 • Determine indoor wood -fired furnaces by subtracting the outdoor hydronic heater count • Data are based on 2002 • We assume no growth since no reliable growth rate data are available 2

7 1 “ Control Analysis and Documentation for Residential Wood Combustion in the MANE- VU Region, ” Prepared for: Mid -Atlantic Regional Air Management Association, Inc., James E. Houck and Brian N. Eagle. OMNI Environmental Services, Inc. December 19, 2006. 2 Personal communication from John Crouch of Hearth, Patio, and Barbeque Assoc. saying that sales have been very slow since the N SPS in 1988.

# Appliance Counts (con’t) ► 

### Indoor Wood -fired Furnaces (con’t) ► LADCO states: • Use Minnesota data to estimate population “ Residential Fuelwood Assessment, State of Minnesota, 2002-2003 heating season, ” Minnesota Department of Natural Resources • Report has number of units in state

– Allocate to county level same technique as OWBs ► For all other states: • Populate states with furnaces proportionately to 0.7% of occupied units

– This percent is from 2001 survey in WA, OR, and ID • Allocate to county level same technique as OWBs • Zero out counties in climate zones 4 and 5 (southern US)

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# Burn Rates ► 

### Forest Service Reports from 8 states ► MN, IN, WI, KS, ND, SD, NE, MI ► Ye ars varying from 1992 to 2002 ► Surveys of residential fuel wood consumption ► 

### Problem : How to adjust burn rates in states with warmer climates? ► Use ratio of the average BTU consumption to heat a house in climate zone 5 to the average BTU consumption in climate zone 1 to adjust burn rates in warmer climates • Based on US Energy Information Administration (EIA) 2005 data ► (Climate zones map on next slide)

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# Climate Zones for Burn Rate Adjustment

10 CCD = Cooling degree days = days above 75 ° F HHD = Heating degree days = days below 65 ° F

# Wo od Density ► 

### Burn rate data in cords (volume unit) and emission factors in tons of oven - dried wood (mass unit) ► Wo od density is needed to make equations work ► 

### Use the Ti mber Products Output database, US Forest Service ► County level database ► Survey results of sawmill operators that provides volume of wood by species for several dif

ferent categories of use, one of the uses being fuel wood ► Used averages where no county sawmill data available ► Assumed 80 ft3/cord to account for airspaces

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# Wo od Density Result

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# Emission Factors ► 

### Fireplaces ► AP42, section 1.9 ► 

### Wo odstoves, Inserts, & Pellet Stoves ► AP42, section 1.10 ► 

### Indoor Furnaces ► 2006 MARAMA

report referenced on Slide 7 ► 

### Wax Firelogs ► Content and emission characteristics of Artificial Wax Firelogs, Environment Canada

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# Emission Factors (con’t) 

### ► 

## Outdoor Wood Boilers: ► 

### EP A tested OWBs in 2009 ► 

### Te st covered a conventional unit, a unit with cleaner burning design, and a unit that burns wood pellets ► 

### Results released in 2012 show: • Conventional units are very dirty (emissions ~ twice that of a conventional woodstove on a per ton wood burned basis); 

### • New design emits significantly less (~10% of conventional units); and 

### • Pellet unit emits lowest emissions (~1% of conventional units).

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# QUE **ST IONS?** 

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