BM Retrofit DEMO Saalfelden

In Saalfelden am Steinernen Meer in Salzburg, a multi-year modernization and optimization process of the district heating network is being carried out, which includes the demonstration and testing of a multi-stage and sustainable modernization concept.

The biomass heating plant in Saalfelden was built in 1997 and today comprises a district heating network with a length of about 6.5 km and a total of 70 heating customers who are supplied with heat from sustainable biomass.

The starting signal for how to lead the existing heating infrastructure into an even greener future for future generations was already given in 2018: the first step of a very comprehensive modernization process for the Saalfelden district heating network was taken as part of the ThermaFLEX flagship project for the comprehensive demonstration and evaluation of modernization concepts, and the first measures have already been implemented. The first innovative technological approaches such as flue gas recirculation, flue gas condensation and flue gas cleaning with electrostatic precipitators were demonstrated and further developed. A 150 m3 thermal storage tank has also been installed.

Based on the results and findings of the long-term monitoring, the next modernization and optimization steps will be developed and tested in the BM Retrofit project.

Objective of the project BM Retrofit Saalfelden

The aim of the demonstration project is to show how optimization potentials in the existing infrastructure can be exploited in a concrete way.

This includes the development of innovative approaches to increase boiler efficiency and the technical and economic evaluation of control strategies. The integration of a heat pump concept in combination with flue gas condensation to further increase efficiency will also be investigated and developed.

The overall objective is to increase and optimize generation capacities and to develop innovative control strategies for targeted grid expansion.

Approach and methodology of the project BM Retrofit Saalfelden

In order to optimize the operation of biomass boilers, the BM Retrofit Saalfelden demonstration project is now carrying out further detailed investigations to increase the boiler efficiency and to reduce the residual oxygen content in the flue gas in order to ensure complete burnout conditions in the gas phase and stable boiler operation. This means that the existing boilers will be retrofitted to achieve an even better yield.

To this end, available control strategies and sensors (e.g. CO lambda control) will be analyzed and technical and economic evaluations will be carried out to ensure long-term economic operation. Innovative approaches that allow optimized and precisely measurable control of the operation using sensor technology are key elements that are being investigated at the Saalfelden site.

For example, an integration concept for the integration of a compression heat pump into the existing flue gas condensation (heat source) has been further developed to further increase efficiency. In the winter of 2023, a heat pump cascade (three heat pumps with 250 kW each) was added to the heating plant. The district heating return is used as a heat sink. The energy is therefore coupled into the boiler circuit as preheated boiler RL (return flow boosting).

What are the benefits? Thanks to the many measures to increase efficiency, the capacity of the heating network can be increased accordingly, allowing the network to be expanded in a targeted manner. This means that more households can be supplied with green heat.

In the research project, network expansion and densification will be accompanied by thermohydraulic simulations and calculations in order to best explore the limits of sustainable network expansion.

The BM Retrofit demonstrator in Saalfelden am Steinernen Meer is an impressive example of how biomass heating plants can be made fit for an even greener energy future.

Read more about the BM Retrofit research project:

Flagship Project BM Retrofit