Municipal heat planning Hamburg – Potential analysis
The Behörde für Umwelt, Klima, Energie und Agrarwirtschaft (BUKEA) Hamburg commissioned Averdung Ingenieure & Berater and FfE to analyze the potential of various centralized and decentralized heat generation technologies for the city of Hamburg. We investigated the potential for environmental heat from outside air, watercourses, subway tunnels and near-surface geothermal energy from borehole heat exchangers.
Motivation
Germany faces the challenge of developing a climate-neutral heat supply by 2045. The Wärmeplanungsgesetz, which came into force in January 2024, obliges municipalities with more than 100,000 inhabitants to submit a municipal heat plan by June 30, 2026. Kommunale Wärmeplanung is basically divided into the steps of inventory analysis, potential analysis, target scenario and implementation strategy.
Project Objectives
As part of the potential analysis for municipal heating planning, the potential for various decentralized and centralized technologies is quantified spatially. Decentralized potentials provide information on a building-by-building basis as to whether a climate-neutral heat supply is possible or not. This is particularly important in areas where there are no plans to connect buildings to a district heating network. From the potential for central heat sources, it should be possible to derive statements about the share of renewable technologies in district heating generation that will be possible in the future. The data and findings obtained in the course of the potential analysis, together with the analysis of the existing situation, form the basis for the development of the target scenario for municipal heating planning. As part of the project, we investigated the potential for the following technologies / heat sources:
- Decentralized air source heat pumps
- Geothermal borehole heat exchangers (for decentralized and centralized heat supply)
- River water heat pumps
- Waste heat from subway tunnels
In addition, Averdung Ingenieure & Berater identified potential for biomass, waste water and solar thermal energy and Consulaqua identified potential for medium and deep geothermal energy.
Methodology
Air source heat pumps
Air source heat pumps currently account for the largest share of decentralized heat pumps in Germany and are expected to continue to do so in the future. Whether an air source heat pump can be installed and operated depends not only on the existing heating system (radiators, pipe system), but also on whether legal sound insulation limits can be complied with. The methodology developed as part of the Wärmepumpen-Ampel project to determine decentralized potential for air source heat pumps, taking sound insulation into account, was further developed and applied to the individual building data in Hamburg. In order to quantify the potential, it is necessary to answer the following three questions:
- How loud are air source heat pumps (sound emissions)?
- How loud can the noise of air source heat pumps be at the place of immission (neighboring residential building)?
- Where are air source heat pumps located and how far away are they from the place of immission?
The sound emissions of air source heat pumps were taken from an analysis of manufacturer data on around 100 systems from the Wärmepumpen-Ampel project. Geodata on development plans in Hamburg were used to assign specific immission limit values to the buildings depending on the area category (see TA Lärm, BImSchG [1]). For each individual building, potential installation locations and their distance from neighboring residential buildings were determined using a GIS analysis. The resulting heat supply potential for each building was compared with the heat requirements from the Hamburger Wärmekataster in order to determine which buildings could potentially be supplied with air source heat pumps.
Borehole heat exchangers
The potential for borehole heat exchangers depends not only on the space available on the respective property, but also on the possible drilling depth and local restrictions on geothermal use (e.g. water protection areas and well sites). With regard to the latter, the requirements according to the Hamburg guidelines for geothermal energy use [2] were taken into account in the potential analysis. Furthermore, specific geodata on drilling depths and thermal conductivities were provided by the Geologisches Landesamt of the BUKEA. A GIS analysis was used to determine the maximum possible number of boreholes per property, taking distance regulations into account. By intersecting all the data, a heat supply potential can be determined for each property based on VDI standard 4640 (2) [3], which was compared with the heat demand of the buildings from the Hamburger Wärmekataster on the property. The heat supply potential of undeveloped properties was also determined and compared with potential district heating network areas.
Waste heat from subway tunnels
Trains and subway electrical systems generate waste heat that is otherwise released unused into the environment. A GIS analysis was carried out to determine the theoretical potential of waste heat from subway railroad tunnels for Hamburg. The first step was to determine the length and location of the rail network under consideration. In a further step, a theoretical potential was identified for each district based on literature values in combination with the previously determined route lengths.
Environmental heat from watercourses
The analysis of potential for watercourses was limited to the Elbe in consultation with the BUKEA. Furthermore, only locations on hard bank edges were considered. These were identified using a GIS analysis. In addition to aquatic ecological aspects, which must be investigated as part of a detailed assessment but cannot be covered in a potential analysis, the main question to be answered is whether the use of river water heat pumps would cool the Elbe by more than 3 Kelvin. According to the FfE study “Heat pumps along watercourses”, cooling is generally to be welcomed. The Elbe in Hamburg has the particularity that due to the tides of the North Sea there is an undercurrent and an upper current, whereby the fresh water inflow is largely limited to the upper current, so that the temperature exchange is generally slower than in other rivers. With the support of the Hamburg Port Authority (HPA), the effect of multiple large river water heat pumps on the water temperatures was calculated for various measuring points.
Project Partners
FfE carried out the work as a subcontractor of Averdung Ingenieure & Berater. Another partner in the project was Consulaqua.
Literatur
[1] Sechste Allgemeine Verwaltungsvorschrift zum Bundes-Immissionsschutzgesetz (Technische Anleitung zum Schutz gegen Lärm – TA Lärm). Ausgefertigt am 26.8.1998, Version vom 1.6.2017; Bonn: Bundesministerium für Umwelt, Naturschutz, Bau und Reaktorsicherheit, 2017.
[2] Leitfaden Erdwärmenutzung. 5. Auflage; Hamburg: Freie und Hansestadt Hamburg – Behörde für Umwelt, Klima, Energie und Agrarwirtschaft (BUKEA), 2021.
[3] Thermische Nutzung des Untergrunds – Erdgekoppelte Wärmepumpenanlagen (VDI 4640, Blatt 2). Ausgefertigt 2019-6; Düsseldorf: VDI-Gesellschaft Energie und Umwelt, 2019.