BACKGROUND AND AIMS
Fireplaces and wood log stoves that burn wood in a suboptimal manner are an important source of particle emissions in Europe. By phasing out polluting woodstoves and introducing better stoves, improving stove installations and educating stove users, large emission reductions can be achieved.
Experts from IEA Bioenergy task 32
(Biomass Combustion and Cofiring), in collaboration with various
national and European branche organisations have jointly organized an
expert workshop on ways to introduce efficient and clean wood log
stoves. This workshop was held on Thu 29 Oct in Berlin. All
presentations can be downloaded below.
RESULTS OF THE WORKSHOP
The workshop provided insight into the effectiveness of various technical measures that can help to further improve efficiency and emissions of typical woodstoves sold in Europe today. Wood stoves continue to be sold on the European market and provide significantly to renewable energy use, however, in case obsolete technologies are applied or the stove is not properly operated, there may be significant adverse effects on public health.
Good combustion starts with a properly designed combustion chamber. CFD aided design tools are being developed to translate the improved fundamental understanding of the combustion process into better practical designs. The application of such tools however is relatively costly and it is doubtful whether smaller stove producers can afford this at the moment. For new stoves it is advised to start with a proper furnace design, and then design an attractive casing around it (currently the design process often takes place the other way around).
Very positive results have been achieved with stoves equipped with automatic combustion control, to optimise the combustion parameters through the various phases of the combustion process. For the validation of such improvements also new test procedures are required, which better reflect real life operational behavior, such methods are currently being developed.
Positive results have also been achieved for the application of catalysts in stoves, in Germany, stove catalysts are now commercialised. The effect of foam ceramic elements without catalyst, aimed at extending the reaction time and thereby reducing the emission of particles, seems only marginal.
Other major influencing factors on emissions are
the use of wood with suitable moisture content, proper user behaviour
and an adequate installation and integration of the stove into the
building. These factors can be addressed by user trainings organized by
stove suppliers and by quality certification schemes for installers.