Benninghoven: First virtually carbon-neutral asphalt production in Germany

The asphalt mixing plant in Aichach was using around 600,000 l of heating oil to produce approx. 60,000 t of asphalt per year.

At the request of the operating company, an asphalt mixing plant in Aichach, Bavaria was to be powered exclusively by renewable energy and to be largely carbon-neutral. Asphalt mixing plant manufacturer Benninghoven was called in to implement the plan for green asphalt. Asphalt production now uses wood dust instead of heating oil.

The asphalt mixing plant in Aichach was using around 600,000 l of heating oil to produce approx. 60,000 t of asphalt per year. That meant emissions of 1,800 t of CO₂. As an expert in multi-fuel burners, Benninghoven recognised the great future potential of wood dust as a fuel early on. The processing technology required for producing high quality wood dust was provided by a specialist company.

The endeavour was designed to be a research and development project from the outset. First of all, grant applications and the expert’s reports for fire safety, noise and emissions had to be obtained from the operator of the plant. This was followed by a lengthy approval process, as the authorities had no experience figures to fall back on. Various requirements specified by the district administration had to be complied with, including continuous emissions measuring and the burner capacity. Taking into account the plant output, Benninghoven restricted the burner output to 12 MW/h. In the event of a future expansion of the plant, the burner has enough reserves to support the growth.

All requirements centred around complying with the German TA-Luft regulation which came into force in 2021. Only four weeks after installation of the burner, the Benninghoven design engineers were able to achieve levels 50% below the requirements of TA-Luft in continuous emissions measurements. Measurements carried out by the TÜV inspection association confirmed these values. Benninghoven is the only manufacturer who meets and can therefore guarantee the limits for the plant with a wood dust burner. 

For Christian Schweiger, contractor and operator of the mixing plant in Aichach, the investment has been worthwhile – also financially, as the carbon tax on fossil fuels has increased significantly. “At the start of the project, we assumed that sustainability will be an important topic for the future. The fact that we are already saving around 20% of costs due to the switch to wood dust was a pleasant surprise.”