## 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 Ram** **anathan Chandrasekaran, Clarkson University** 2



## 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 issues3



## 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)4



## 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 pellets5



## 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 analysis6



## Analysis • What is “normal” for ions and metals pellet analysis? – No accepted standards (ash or wood) at this time – No SRM or similar reference materialfor 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)7



## “Normal” Pellets • Typically, the pellets identified as normal looked like wood8



## Pellet Analysis • This pellet exhibited high levels of: – Chromium – Copper – Arsenic – Lead – Mercury9



## 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.1011 

## PFI Standards**Analysis –**  **Normal Samples**12 

## PFI Standards**Analysis –** **All Samples**13141617



## Potential **Sources of Elevated**

**Elements** • Harvesting/processing practices • Uptake from soluble sources • Wood species • Inclusion of bark • Use of waste wood18



## 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