For Immediate Release
9 October, 2007

Study shows wood pellet burners improve air quality in Rotorua

With nightly winter fires nearly over for 2007, Rotorua home owners are being urged to consider switching to clean burning wood pellet burners before next winter.

A study carried out by Crown Research Institute Scion has shown that using pellets, rather than wood, could significantly cut emissions of PM10 and help improve air quality in the city.

PM10 emissions are fine dust particles that can be breathed in causing heart and respiratory problems, particularly in asthmatics, elderly people and children. Burning firewood is estimated by Environment Bay of Plenty to contribute around 60 per cent of all winter time PM10 emissions in Rotorua.

Dr Per Nielsen, from Scion's Bioenergy Group, says a range of scenarios were studied and showed that if all dwellings in Rotorua used pellet stoves for heating, the total amount of PM10 emitted each year would be just 28 tonnes, a reduction of 92 per cent from current emission levels.

"The difference is significant, even though both fire wood and pellets are renewable energy sources. The findings show that using the best technology, as well as appropriate raw materials, is crucial when promoting renewable energy," says Dr Nielsen.

Wood pellets are typically made of sawdust or shavings and are between six and ten millimetres in diameter and 15 millimetres long. They are easily available in Rotorua, where Solid Energy has a plant producing pellets from recycled wood waste.

Calculations made in the Scion study were based on census statistics and emission factors, with Geographical Information Systems (GIS) used to model and visualise the results.

The findings also showed that central and western parts of Rotorua are the biggest users of energy for heating, while the largest amounts of firewood are burned in the residential parts of the city.

Dr Nielsen says as well as being cleaner, wood pellets are about 10 per cent more efficient than firewood in giving out heat.

He says converting to wood pellet burners is not the silver bullet that will solve Rotorua's air emission problem, but it is a simple, straightforward and immediate step that home owners can take to make a difference.

Other emission saving options are combining pellet heating with heat pumps, geothermal and solar heating says Dr Nielsen and, if firewood is being used, making sure it is fully dried.

"Wet firewood is much more of a problem than dry. Using modern log burners with dry wood can also make a difference, but it's often difficult for people to judge whether the wood they are burning is really dry."

The findings from Scion's research have contributed to a research programme undertaken into cleaner heating by Environment Bay of Plenty.

Environment Bay of Plenty (EBOP) environmental scientist, Shane Iremonger, says EBOP has supported pilot studies carried out over the recent winter months in houses where wood burners have been replaced by modern wood pellet fires to determine a range of economic and social impacts. The findings are yet to be assessed.

"Wood pellets are definitely part of the mix of actions needed to improve air quality in Rotorua. They are not the sole answer, but we are supportive of moves to encourage people to consider newer heating technologies and the warmer summer months are a good time to take stock and think about doing that," says Mr Iremonger.

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