PM10 emissions from wood fuels

Woody biomass is a renewable and carbon neutral source of energy. It can be derived from forestry residues, clean material such as joinery and arboriculture wastes, and the sawmilling industry. The advantages of being both renewable and carbon neutral, as well as the increasing price of fossil fuels, are drivers for the conversion to woody biomass from other fuels for heating and energy.

The potential for the increased use of woody biomass to contribute to particulate matter emissions, in particular, those smaller than ten microns in diameter (PM10), is of concern to local authorities with responsibility for managing air quality and ensuring compliance with the National Environmental Standards for Air Quality.

This document sets out to provide a source of information to local authorities to assist them when considering both regulatory provisions in plans and individual applications for resource consent for discharge to air. The focus of this guidance is on small scale thermal plants for burning woody biomass that may be sited for example within of!ce buildings, schools, sports centres, hospitals, up to industrial scale thermal plant applications. Woody biomass combustion processes for domestic use within homes is outside the scope of this review and the sector is already covered under national regulations. The following approach was taken to gathering information for this review:

• An international literature review on the available technology and particulate matter emission limits for woody biomass combustion.
• Regional air plan provisions for woody biomass compiled and summarised for the thresholds and general conditions currently operative for this sector.
• PM10 emission measurement data obtained principally via contact with stack emission testing companies, equipment suppliers and local authorities.