Chemistry Reference
In-Depth Information
consequence, wood burning can in the Alpine region be the dominating source of
PM, OC and BC [
12
-
15
]. This chapter gives an overview about the results of
studies on ambient particulate pollutants from residential wood burning in the
Alpine region.
1.1 Fine Particulate Matter From Wood Burning
The chemical composition of fine particulate matter from wood burning depends on
many factors such as the type of wood burning appliance, fuel type and the
combustion conditions [
16
]. Incomplete combustion conditions as often prevailing
in small residential wood stoves lead to emissions of refractory carbonaceous
particles denoted as black carbon, elemental carbon (EC) or soot and also particu-
late organic carbon including constituents of high toxicity [
17
,
18
]. Under incom-
plete combustion conditions, VOCs present in wood smoke can act as precursors for
secondary organic aerosol (SOA) formation. The contribution of SOA to total wood
burning-related PM may even be larger than that of primary particles [
19
].
Depending on the burning processes wood burning emissions can also be
dominated by incombustible inorganic compounds such as potassium and calcium
salts and oxides. This is, for example, the case during constant and ideal burning
conditions occurring in larger wood-firing appliances (e.g. boilers). Inorganic PM
from wood burning is typically considered to be less harmful than the carbonaceous
fraction. Particle diameters of both primary and secondary PM from wood burning
are predominantly in the lower range of the accumulation mode and therefore have
atmospheric lifetimes of several days.
1.2 Volumes of Wood Fuel and Used Appliances
In central Europe the use of wood fuel varies widely between the countries. For
some of the Alpine countries statistics about the amount of wood used as fuel is
available [
20
]. According to this publication the use of wood for energy production
is currently about 41 Mm
3
in France, 30 Mm
3
in Germany, 14 Mm
3
in Austria,
4.5 Mm
3
in Switzerland and 2 Mm
3
in Slovenia. From this total consumption,
private households account for 90% of the wood in France, 44% in Germany, 59%
in Austria, 34% in Switzerland and 75% in Slovenia. The remainder is used in
power plants, for heat production and other industrial appliances.
The use of wood for heating purposes in the Alpine region has a long tradition
and is still very popular because wood is a renewable and locally available source of
energy. However, detailed numbers about the temporal development of installed
and used wood burning appliances in Alpine countries are difficult to obtain. For
Switzerland, detailed wood energy statistics has been published on an annual
basis since 1993 by the Swiss Federal Office of Energy. These reports provide an
inventory of the wood burning appliances used in the country as retrieved from
