BioFfit project – Making biomass combustion fit for the future

Pelletofen
© Fraunhofer IPM
Older and high-emission single-room wood-burning stoves are among the main sources of harmful particulate emissions. Without retrofitting, many of them will have to be replaced in the foreseeable future.
Pelletofen
© Fraunhofer IPM
Fraunhofer IPM is working on the development of a highly efficient particle separator for the typical performance range of single wood combustion plants.

Separation of the smallest particles – even in the critical range

In times of climate change, wood or biomass as a local CO2-neutral raw material makes an important contribution on the way towards the energy transition. On the other hand, wood-burning systems – especially older and high-emission single-room wood-burning stoves – are among the main sources of harmful particulate emissions. Without retrofitting, many of them will have to be replaced in the foreseeable future (BImSchV, German Federal Emissions Control Act).

To reduce particulate emissions from such systems, they are often retrofitted with electrostatic particle separators, which use electrostatic charging to filter out or separate a large proportion of the particulate matter contained in the exhaust gas stream. However, such separators exhibit reduced separation efficiency for particle sizes in the 0.2 to 2 µm range - and thus precisely in the range that is considered particularly critical in terms of the harmful effects of such emissions on health. Under real operating conditions, the separation performance or the functional operation is also negatively influenced by the contamination of the electrodes.

Against this background, the BioFfit project aims at the research, development and demonstration of a highly efficient particle separator for the typical performance range of single wood combustion plants, which decisively improves the separation performance even for the smallest particles in the previously mentioned critical range.

Focus on maintenance, efficiency, economy

As an added feature, the particle separator is equipped with passive automatic cleaning, which prevents excessive particle accumulation in the exhaust pipe and thus significantly reduces the need for maintenance, but also ensures proper operation.

The project also aims at reducing harmful emissions during the combustion process. This will be achieved by using an additional combustion control system that increases the combustion efficiency of the plant and at the same time reduces pollutant emissions of carbon monoxide (CO), volatile organic components (VOC), NOX and polycyclic aromatic hydrocarbons (PAH).

The improvements (emission reduction) achieved from the interaction of the particulate separator and combustion control are analyzed and quantitatively demonstrated.

As an additional benefit, it is planned to operate the particle separator and combustion control developed as part of the BioFfit project with thermoelectrically generated electrical energy wherever possible. The upgrades would consequently be usable independently of the power grid. This would make a subsequent installation of a power supply superfluous and make the retrofit thus more economical.  

The development is primarily aimed at retrofitting existing systems, but is also attractive for the initial equipment of wood or pellet stoves.

 

Project coordination

Fraunhofer IPM

Project partners

Supplier to the automotive industry

Fiunding

Badenova Innovation Fonds

Project term

11/2019 – 08/2022