Residential Wood Pellets: Elemental 

Composition, Market Analysis and 

Policy Implications 

NSPS Educational Forum

Minneapolis, MN

November 8, 2012

Lisa Rector, NESCAUM

George Allen, NESCAUM

Dr. Phillip Hopke, Clarkson University

Sriraam Ramanathan Chandrasekaran, 

Clarkson University
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Background

• Greater push to use biomass fuels as an 

alternative to fossil fuels

• Limited information on components of wood 

pellet fuels

• Examine the efficacy of existing standards?

• Understanding composition is important

– enhance knowledge of potential air pollution

– public health impact

– efficiency benefits and trade-offs

– potential solid waste issues
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Background

• Quantify wood pellet fuel chemical composition for 

fuels manufactured or available in New York State

• Assess variability of composition across/within 

brands

• Identify policy relevant strategies to reduce or control 

impacts from air emissions and/or solid waste

• Provide input into pending EPA NSPS regulation 

Residential Wood Heater Source Performance 

Standard (NSPS)
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Pellet Market

• U.S. has no regulatory pellet fuel standard 

• Pellet Fuel Institute (PFI) has voluntary 

standards

• All pellets found in retail outlets labeled as 

“Premium” wood pellets
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Sample Collection/Prep

• 132 40# bags obtained during winter 2010-11 in 5 NE 

States

• ~ 100 different brands (rest: duplicates purchased 

independently)

• 4 categories of analysis:

– Basic characterization (ASTM “proximate analysis”) calorific 

value, moisture content, ash content

– Ions: sulfate and chlorine by IC

– Trace metals by ICP-MS

– Mercury - gold trap followed by CVAA analysis
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Analysis

• What is “normal” for ions and metals pellet analysis?

– No accepted standards (ash or wood) at this time

– No SRM or similar reference material for wood/ash analysis

• Sample screening for “normal” values to estimate 

working “benchmark” concentration for ash analysis

– Use 95th percentile of normals as preliminary “benchmark” 

limit

– 85 out of 132 samples considered “normal” (64%) based on 

screening of all analytes

– Remainder, 47 samples, had outlier results

– 20 samples (15%) elements of concern (metals, mercury)
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“Normal” Pellets

• Typically, the pellets 

identified as normal 

looked like wood
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Pellet Analysis

• This pellet exhibited 

high levels of:

– Chromium

– Copper

– Arsenic

– Lead

– Mercury
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Pellet Analysis

• This pellet almost black

– Color could be a result of 

processing or of addition 

of black liquor

• 8% ash - PFI ash limit: 

1% for “premium grade” 

pellets.
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PFI Standards Analysis – Normal Samples
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PFI Standards Analysis – All Samples
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Potential Sources of Elevated 

Elements

• Harvesting/processing practices

• Uptake from soluble sources

• Wood species

• Inclusion of bark

• Use of waste wood
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Initial Conclusions

• PFI standards are not likely to identify contamination 

in pellets since primary focus is on physical 

properties

• Appropriate methods for analysis are critical in 

identifying elemental constituents

• Need to gain a better understanding what contributes 

to variability in pellets and minimize sources of 

contamination

• Impact of elevated elements for local exposures

• Significant policy issues remain