BM Retrofit DEMO Wald im Pinzgau
At the Wald im Pinzgau site, the focus was on utilizing low-temperature waste heat from a nearby hydroelectric power plant using a 250-kW heat pump. A power-to-heat system was added to ensure operational redundancy, along with a 30,000-liter thermal storage tank to increase system flexibility and balance out load fluctuations.
This demo is part of the BM Retrofit project that has been completed. Download the BM Retrofit Publishable Final Report here.
The district heating plant in Wald im Pinzgau supplies approximately 60 customers with a thermal load of about 1.8 MW via a local district heating network. The annual heat demand amounts to more than 3 GWh. Prior to the upgrades, heat was generated by a biomass boiler with a thermal output of 0.9 MW and an oil-fired boiler with a thermal output of 1.5 MW. However, this system faced several operational challenges. In particular, the low heat demand during the summer months led to comparatively high network losses. At the same time, the biomass boiler did not operate efficiently under all load conditions, which resulted in increased maintenance requirements and higher costs. Another weakness of the existing system was its limited flexibility, as there are currently no measures in place — such as thermal storage — to better align heat generation with demand.
Objective of the BM Retrofit Wald in Pinzgau project
The aim of the demonstration project was to optimize the biomass heating plant Wald with an innovative heat pump concept and to make it climate-friendly. The planned measures were intended to ensure that the heat supply can be provided with 100% renewable energy. In the future, customers of the Wald heating plant would be supplied exclusively with green heat.
Display board for the BM Retrofit Wald im Pinzgau demo project. Click on the image to download the PDF! (available in German only)
Approach and methodology of the BM Retrofit Wald im Pinzgau project
Based on the results of the baseline analysis, a multi-stage methodology was developed. In the first phase (Phase 1), an innovative combination of technologies involving sector coupling was developed for waste heat utilization using a compression heat pump. In general, heat pump technologies offer great potential for integration into biomass-based district heating systems. One of their key features is their ability to utilize low-temperature heat to provide heat at a higher temperature level through the use of electricity (compression heat pumps). Waste heat from the cooling circuit of a nearby hydroelectric power plant is utilized through an innovative heat pump concept (250 kWth) powered by renewable electricity generated directly on-site at the hydroelectric power plant. The heat pump is combined with a 180 kWth power-to-heat system, which serves as a backup in case no waste heat from the hydroelectric power plant is available. Furthermore, this increases the system’s flexibility, as it serves to raise the temperature downstream of the heat pump during peak load periods. Accordingly, a suitable redesign of the (process) control and measurement systems was developed.
To increase flexibility and ensure the efficient operation of the heat pump and the biomass boiler, a concept for a thermal storage tank (30 m³) and a suitable storage management system, including the necessary adjustments to the existing process control system and visualization, was developed and implemented.
A detailed monitoring plan was developed to collect data on each heat generation unit, the heat storage system, the system’s load management, and the district heating network. On the one hand, this data-driven approach ensured that necessary adjustments could be made to optimize performance. On the other hand, this data enables a detailed assessment of the impact of the implemented modernization measures.
The primary goal of integrating the heat pump was to enable fossil-fuel-free operation during the summer. The system was commissioned in July 2024. During the 2024–2025 heating season, the biomass boiler was the primary source of heat, while the newly installed buffer tank significantly reduced the need to run the oil boiler. Starting in May 2025, the biomass boiler was shut down for summer operation, and the heat supply was switched to the heat pump and the P2H system.
The future heat supply in Wald im Pinzgau will thus be provided entirely by renewable and local heat sources (biomass, waste heat, electricity), and the fossil fuel oil boiler will be used exclusively for emergencies. This direct substitution results in annual savings of approximately 10,000 liters of oil (about 100,000 kWh) and a CO₂ reduction of roughly 30 tons. In addition, the total consumption of biomass was significantly reduced (by approximately 1,000 cubic meters) through the optimized operation of the biomass boiler in combination with waste heat recovery, contributing to the conservation of biomass.
Profile of the BM Retrofit DEMO Wald im Pinzgau project. Click on the image to download the PDF (german only)!
Links:
- Flagship Project BM Retrofit
- Report Insight Talk Innovative Heating Solutions
- BM Retrofit solutions for heating network operators >> information sheet (german only)
- BM Retrofit solutions >> optimised display for mobile phones (german only)
The following model solutions were being developed in the BM Retrofit DEMO Wald im Pinzgau project:
Holistic modernization concept for biomass-based District Heating systems
Media reports on the project
Increased efficiency and decarbonization of heating networks
Around 50 percent of Austria's energy requirements are needed in the heating sector, whereby the current level of supply with fossil fuels is around 60 percent. Half of Austria's district heating supply alone is currently still based on fossil fuels. The BM Retrofit project is concerned with the development of highly efficient, biomass-based district heating systems as the basis for a climate-friendly heat supply.
To the articleIncreased efficiency and decarbonization of heating networks
As part of the practical BM Retrofit research project, holistic modernization and expansion concepts for existing biomass-based heating networks are being developed. The developed elements and solutions are implemented in various biomass-based district heating networks, so-called demonstrators, and analyzed with accompanying data evaluation and holistic system validations including life cycle and value chain analysis.
To the article
