Wood as a regenerative commodity is a perfect raw material and renewable energy source. The use of forest biomass by people is carbon-neutral, if in the long run the amount of biomass that is removed from the forest is the same as the amount that grows, and where the fossil energy used for harvest, haulage, transport and production (grey energy) is omitted from a first approximation. In regionally produced wood fuel, this grey energy accounts for only one to two percent of the energy contained in the fuel and is also considerably less than in fossil fuels such as oil and gas.
All carbon dioxide (CO2), which is stored in wood is extracted from the atmosphere and is rereleased along differing timeframes according to use. It is therefore a classic cycle, which takes place both naturally – without human intervention – and also through the use of biomass.
In regard to climate protection, wood products should be used where they can store CO2 as long as possible and/or replace products which cause high CO2 emissions such as plastic, steel, coal or oil. This is known as the “substitution effect”. Depending on the product life, the CO2 can remain in the wood products for a few weeks or in the case of construction timber for many years. By-products from harvesting (firewood, woodchip goods), from processing (sawdust, off-cuts) or industry (cutting waste, wood shavings, black liquor) can be used to produce energy. Through the use of bioenergy less fossil fuels need to be burned.
Wood as a carbon sinkThe total aboveground biomass of the Austrian forest comes to 628 megatonnes (dry mass) or 1124 megatonnes CO2 in 2010. This contains an energy value of 12,624 Petajoules (PJ). The total energy use in Austria comes to around eleven percent of this figure, at 1,100 PJ per year. As a numerical projection this translates to an annual gross domestic use of 180 petajoules of woody biomass, which is around 1.4 percent of the energy content present in forests and is therefore easily sustainable for the forest. The Austrian oil and gas reserves are in contrast non-regenerative and will dwindle within 20 years.
Important raw materials for the production of renewable energyWoody biomass is by far the most important raw material for the production of renewable energy globally, both in Europe and in Austria. Whereas wind power presently amounts to only two percent of renewable energy in Austria, the share of woody biomass is, at 45 percent, considerably higher than hydropower (34%). Firewood, wood chips, sawmill by-products and bark come to about 60 percent, black liquor from the paper industry comes to 12 percent and pellets 5.3 percent of the biomass used for energy.
Federal Research and Training Centre for Forests, Natural Hazards and Landscape (BFW)
Austria, 1131 Vienna, Seckendorff-Gudent-Weg 8 | Tel.: +43 1 878 38-0
Autor: Schadauer K.