Local and district heating solutions in regional spatial heat planning

 

The transformation of the heating sector towards sustainable energy sources requires the consideration of local and district heating solutions in the spatial heat planning. Green Energy Lab and AEE INTEC addressed this topic in the Insight Talk on 25 February 2025. After looking at strategic district heating planning in Kapfenberg, the BM Retrofit project was discussed. This focuses on the modernisation of biomass-based heating networks. This was then illustrated using the best practice example of local heating in Kreuzstetten. 

 

Strategic district heating planning: Municipality of Kapfenberg 

Franz Mauthner from AEE INTEC discussed spatial energy and heat planning. In this context, he mentioned the “Green Energy Lab – Spatial Energy Planning” (GEL SEP) project. The aim of this project was to create the necessary data basis to enable spatial energy planning. As a result, spatial structures can subsequently be made more sustainable in order to minimise energy consumption and CO₂ emissions. 

 

As a result, an Energy Atlas was developed for spatial energy planning, which is available to the three participating federal states of Styria, Vienna and Salzburg. The Energy Atlas is designed as a bottom-up model and brings together different types of information. The data basis can be used in a variety of ways, from strategic planning to implementation planning. AEE INTEC has developed a WebGIS tool that enables flexible handling of the spatial data bases. This tool is used in various planning cases. 

The strategic district heating planning of Kapfenberg, in which the Stadtgemeinde Kapfenberg (municipality of Kapfenberg) worked together with the Stadtwerke Kapfenberg (municipal utilities), was mentioned as a practical example. They received support from AEE INTEC and Pink GmbH. Following a status analysis, a step-by-step plan was developed for the expansion and defossilisation of district heating by 2030. A waste heat potential survey and analysis was then carried out, followed by a thermo-hydraulic network simulation. Finally, the results were visualised in maps. These include a district heating plan, a heat density map and a heating network zoning. According to the plan, the district heating route is to be expanded by 200 percent and the connected load increased by 150 percent. At the same time, greenhouse gas emissions per kilowatt hour are to be reduced by 83 percent and the use of renewable energy sources expanded. 

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Modernisation of biomass-based heating grids 

In Austria, heat production is responsible for around 50 percent of energy demand. The BM Retrofit project is developing efficiency enhancement and modernisation concepts for biomass-based heating systems, from which around 2,500 district heating systems in Austria could benefit. Joachim Kelz from AEE INTEC addressed this topic in the Insight Talk and began by discussing the challenges and objectives in the heating sector. Challenges arise, for example, in connection with system temperatures or summer operation. Important goals include minimising the proportion of fossil fuels and using available regional resources. Flexibility and system efficiency should also be increased and supply capacity expanded. The aim should be to meet future heating requirements sustainably and efficiently. 

In order to further develop the existing heating networks, systemic and organisational measures are required in addition to technical measures. In this regard, the integration of stakeholders, stakeholder management and innovation processes were emphasised. A holistic system evaluation will also become increasingly important in the future. The solutions developed were therefore implemented in real biomass-based district heating networks, which are referred to as demonstrators. 

 

Demonstrators: 

• Wald im Pinzgau: The special feature of this system is that the boiler house is located in the immediate vicinity of a hydroelectric power plant. The waste heat generated during the cooling of the hydroelectric power plant is utilised by a heat pump system to supply households with heat. This means that the biomass heating plant’s boiler no longer needs to be operated in the summer months, saving biomass and CO₂ emissions. –> More information about the demo project Wald im Pinzgau 

• Kreuzstetten: The optimisation of grid technology, buffer management and biomass boiler operation enables a reduction in CO₂ emissions and grid losses. –> More information about the demo project Kreuzstetten 

• Saalfelden: The first phase involved the technical modernisation of the biomass boiler system, the integration of a buffer storage tank with a volume of 150 m³ and the installation of a flue gas condensation system for heat recovery. A cascading heat pump concept consisting of three heat pumps, each with an output of 250 kilowatts, serves to increase the efficiency of heat recovery from the flue gas. By reinforcing the main line of the heating network and integrating an innovative control strategy using CO lambda sensors, the operation of the biomass boiler was ultimately further optimised and the use of biomass and fossil fuels significantly reduced.–> More information about the demo project Saalfelden 

 

The results of the BM Retrofit project show the potential for reducing fossil fuels and improving sustainable heat supply. The optimisation conserves biomass as a valuable resource. The increases in efficiency also have a positive impact on economic aspects. In addition, waste heat potential can be utilised synergistically and local emissions reduced. The three demonstrators mentioned are intended to serve as a blueprint for similar plants. Finally, it was emphasised that the reduction of system temperatures is an important measure and that the modernisation of heating networks is a long-term process. 

 

BM Retrofit – Best practice example Kreuzstetten 

Christoph Walla from EQUANS Energie GmbH then explained the best-practice example of Kreuzstetten in more detail. A biomass heating plant was built there in 2011 to supply local heating. The local heating network is 8.7 kilometres long and supplies around 140 consumers. In the course of the BM Retrofit project, challenges and potential for improvement were identified and sustainable modernisation concepts developed. The aim is to optimise the control and operation of the entire heating network and a large consumer (drying plant for agricultural products). In the course of improving the local heating network, a network expansion and densification is also to be implemented. The analysis of the firing operation of the biomass heating plant showed that an adjustment of the output and buffer management is necessary in order to increase the combustion quality. 

As a result, 25 tonnes of CO₂ emissions were saved per year. By lowering the return temperature by 20 degrees, it was possible to reduce network losses by 15 percent. In addition, the pumped electricity was reduced and the buffer storage optimised. Boiler starts were reduced by two thirds, which extended the service life of the boiler. In addition to technical measures, the project also realised economic measures such as a reduction in internal administration costs. 

 

Here you can find more information about the project BM Retrofit.

 

All presentations for download

• Strategic district heating planning Kapfenberg – Franz Mauthner (AEE INTEC) – German only
• BM Retrofit – Joachim Kelz (AEE INTEC) – German only
• BM Retrofit Kreuzstetten – Christoph Walla (EQUANS Energie GmbH) – German only