Biomass Combustion and Co-firing

Advanced Test Methods for Firewood Stoves


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This report by Gabriel Reichert and Christoph Schmidl compares a number of different test methods that are used around the world for determining the emission factors from woodstoves, and discusses how well these different methods are able to mimic the emission during typical use of the wood stoves in practise.

In different scientific studies test protocols which should better reflect real-life operation were applied, for example to investigate emission factors for different stove technologies. In this study those test procedures (e.g. the beReal test protocol) are presented and the emission and efficiency results are compared with official type testing (oTT) results, results of field tests and proposed emission factors.

The comparison of field test results showed by tendency a technological improvement of firewood stoves over the last decades. But in comparison with oTT results improvements are significantly higher. Furthermore, retests of serial-production stoves according to the EN 13240 standard showed much higher emissions and lower efficiency results compared to oTT results of the respective stove models. The beReal test concept showed a good conformity of test results in the lab compared to test results in the field. However, the thermal efficiency is still overestimated by the test stand results compared to field test results.

Comparing the field test results of advanced stoves with the proposed emission factors a good conformity for CO and PM emissions is evident. However, for OGC emissions it seems that the EEA (European Environment Agency) emission factor for advanced stoves is too high (by a factor of 2).

Concluding, an implementation of a real-life reflecting test protocol (e.g. beReal) as a quality label or standard should be considered as an instrument to push technological development further towards optimized real-life operation. Additionally, this would also enable a better differentiation of good and poor products for the end customer regarding typical real-life use.

The use of a real-life oriented test protocol (as in beReal) for determination of emission factors seems possible, but needs further investigations. The standardized measurement of emission factors according to a suitable test concept could be used for a regular update of emission inventories.

Download the report here: Advanced Test Methods for Firewood Stoves, Gabriel Reichert and Christoph Schmidl, Bioenergy2020+, 2018