District heating systems can be a good lever for climate protection and for becoming independent of oil and gas. On 25 February, around 60 participants, including mayors, architects and energy consultants, learned what to consider when planning district heating systems at an online event organised by Energiewende Oberland in the EU-funded heating transition project REPLACE.
Almost half of the energy in the Bavarian Oberland is used for heating, 44% of it in private households. As Stefan Drexlmeier from Energiewende Oberland (EWO) reported at the event on 25 February, district heating systems are an ideal way to supply entire streets with climate-friendly heat in addition to replacing individual heating systems, and at the same time to make oneself independent of fluctuating energy prices and oil and gas supplies from abroad. District Administrator Anton Speer (Garmisch-Partenkirchen district) also emphasised in his welcoming address that regional supply from own products is becoming increasingly important and pointed out, among other things, the supply of three Murnau schools by forest residues.
How to plan a district heating system
Andreas Scharli from EWO explained how to plan a district heating system. As a heating engineer and energy consultant, Scharli has already accompanied numerous projects in the Oberland, including community-supported systems in Valley and Warngau in the district of Miesbach back in 2013, where existing properties and a newly planned kindergarten were connected to a common heating system. Or Scharli’s most recent project in Schwabsoien, where there is no gas pipeline and heating is needed for a new development area.
For Scharli, the planning of a district heating system always starts with a meeting of residents, at which he determines the interest in a joint system, the amount of oil needed so far and the age of the heating systems. The next step is to plan the shortest pipe route between the buildings in order to lose as little heat as possible and to operate the system profitably. The design of the heat price, considerations on the operator model and advice on subsidies for heating houses, heat paths or the disposal of the oil tanks finally lead to a preliminary contract, which, according to Scharli, creates commitment in the planning.
Commitment is also important for Felix Uhlschmied, who represented the perspective of a bank at the event. As an employee of the Raiffeisenbank, Uhlschmied was involved in the founding of the Steingaden cooperative in order to make the project also financially sustainable. Since there are hardly any collateral values for heating networks and if a project fails, e.g. pipelines cannot be dug up and sold again, other safeguards are necessary for banks, e.g. through the liability of an individual entrepreneur or, in the case of a cooperative, through the participation of a municipality in the project. As another important point, Uhlschmied emphasised the calculation of profitability, which enables a reliable repayment of loan instalments.
Operators of agricultural district heating systems who supply themselves and their neighbours with heat reported from practice. Among them was Josef Schweyer from Antdorf, who supplies heat for his own family’s buildings and those of his neighbours and creates added value for the farm by using his own wood. Theresa Singer from Hofheim, whose family has been supplying four houses and a company since the end of 2020. And Georg Miller, second mayor of the municipality of Riegsee, who has not let go of the idea of district heating since his time at the Bavarian Forest Farmers’ School in Scheyern. With the Bäuerliche Hackschnitzelliefergesellschaft, he supplies forest residues to schools in Murnau and has meanwhile replaced 25,000 litres of heating oil with his own village heating system.
Experience from the long-term operation of a heating network was shared by Walter Huber, Managing Director of Stadtwerke Bad Tölz. Huber emphasised the important interplay between emotion and technology. The commitment to climate protection is also important for customer loyalty and satisfaction, because “the more satisfaction there is, the more customers connect, the more favourable the offer can be for everyone,” said Huber. At the same time, the supply must function reliably, for which the Bad Tölz municipal utility provides, for example, a 24/7 service that repairs heating systems immediately in the event of breakdowns.
The future of heating networks What does the future of heating networks look like? According to the energy wood study, there is sufficient forest residue in the Oberland, says Andreas Scharli and emphasises “No tree falls because we need wood chips. The tree is felled for forest maintenance, harvesting and sawmilling, but not to produce wood chips.” To conserve resources, energy saving plays a central role with insulation of roofs, replacement of windows and full thermal insulation, he said. And if buildings that are already connected to a village heating system were to be better insulated during operation, buildings that are also on the route could be additionally connected. Georg Miller from Riegsee can use wood for the schools in Murnau even more efficiently with a drying hall powered by solar energy. And Walter Huber from the Bad Tölz public utility company sees the future in the coupling between the heat, electricity and transport sectors, so that when there is an energy surplus in one sector, the other sectors can be served. In this way, surplus electricity produced on summer Sundays, for example, would not be given away, but would be fed into boilers connected to the local heating network. At the end of the event, Andreas Scharli also emphasised that heating grids are not fixed on biomass: “In the future, we can gradually integrate other energy sources, e.g. fuel cells, hydrogen or solar thermal energy. Because district heating systems in the Oberland are currently still operated with biomass, he answers the question about particulate matter “Differentiation is important here. Every modern wood heating system, no matter how small, has CO2 sensors, filter technology and measures residual air volumes in real time, for example”.