## In a glance

This module generates a shapefile of potential district heating areas based on the following input data: a heat demand density map with 1 ha resolution, a heat demand threshold for the heat demand in each cell of the heat demand density map and a heat demand threshold for groups of connected cells with heat demand above the previous threshold (=coherent area).

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## Introduction

The heat demand plays an important role in determination of potential district heating (DH) areas. For example, implementation of district heating in areas with low heat demand is not economically viable. On the other hand, defining any area with high heat demand density as potential DH area can also be inaccurate. A high heat demand density in an area could be due to presence of a few consumers with a very high heat demand within that area. In contrary, a low average heat demand density could be a sign of zones with a very low heat demand within the selected area. The aim of DH potential module is to provide a reasonable balance between heat demand density in an area and its constituting zones.

The DH potential module determines the DH areas and their corresponding DH potential based on heat demand densities. The heat demand densities are obtained from the input GIS layer, namely European Heat Density Map (EHDM), which was developed in course of Hotmaps project. The EHDM is in raster format and has a resolution of one hectare and Coordinate Reference System (CRS) of "ETRS89 / LAEA Europe - EPSG 3035". The cells in EHDM show the heating densities in MWh/ha.

As output, one GIS layer, three indicators and two diagrams are presented. These outputs are explained in detail in Sample Run section. The output layer demonstrates the potential DH areas. By clicking on each area on the map, a window is popped up and the DH potential corresponding to that area is shown. Within the indicator/graph window, relevant indicators and charts regarding DH potential within the selected zone and potentials in sub-zones are illustrated.

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## Inputs and outputs

The input parameters and layers as well as output layers and parameters are as follows.

Input layers and parameters are:

• Minimum heat demand in each hectare [MWh/ha]: a value between 0 and 1000
• Minimum heat demand in a DH area [GWh/year]: a value between 0 and 500
• Heat density map (by default is provided by the toolbox)
• in raster format (*.tif)
• with 1 hectare resolution
• demand densities in MWh/ha

Output layers and parameters are:

• DH areas
• DH potential in each DH area

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## Method

The potential for DH in a specific region can be defined by the overall heat demand and its spatial allocation. In the Hotmaps toolbox, the heating demand is shown in EHDM in form of a raster map. Any selection or cut from EHDM is constitute from one or more one-hectare cells. In order to properly define potential DH areas, both the heat demand in each cell and also in an area should reach a certain level. For starting point, the Hotmaps toolbox suggests default values for these two parameters. However, depending on the distribution of heat demand and also the local consideration, the Hotmaps user can modify these values.

The determination of DH areas is done in two steps:

In the first step, all the cells with heating demand below the input parameter for the minimum heating demand in hectare are filtered. By eliminating these cells from the map, we obtain groups of cells that are attached to each other. Each set of these attached cells constitute small zones that here, are referred as “coherent areas”. In the second steps, the total heat demand in each coherent area is calculated. For each coherent area, if the total heat demand is higher than the input parameter for the "minimum heat demand in a DH area", then, it is considered as potential DH area.

Finally, for the DH areas, the potential is calculated and presented in form of GIS layer, which can be seen in the toolbox.

This code uses the concept of connected components from image processing library of Scipy in order to detect the potential district heating areas.

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## GitHub repository of this calculation module

Here you get the bleeding-edge development for this calculation module.

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## Sample run

Here, the calculation module is run for the case study of Aalborg in Denmark.

• First, use the "Go To Place" bar to navigate to Aalborg and select the city.

• Follow the steps as shown in the figure below:
• Click on the "Layers" button to open the "Layers" window:
• Click on the "CALCULATION MODULE" tab.
• Click on the "DISTRICT HEATING POTENTIAL" button.

• Now, the "DISTRICT HEATING POTENTIAL" opens and is ready to run.

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### Test Run 1: default input values

The default input values show the general conditions under which an area can be considered as a potential DH area. These values should be regarded as starting point only. You may need to set values bellow or above default values considering additional local considerations. Therefore, the user should adapt these values to find the best combination of thresholds for his or her case study.

To run the calculation module, follow the next steps:

• Assign a name to the run session (optional - here, we chose "Test Run 1") and set the input parameters (here, default values were used).

• Wait until the process is finished.
• As output, indicators and diagrams are shown in the "RESULTS" window. The indicators show:
• the total heat demand in GWh within the selected zone,
• total DH potential in GWh within the selected zone,
• the share of DH potential from totoal demand, which is obtained by division of DH potential by total heat demand in the region.

Additionally, also two diagrams are generated. The first one shows the DH potential in each DH area. The correponding labels can be found in the map, too. The second diagram illustrates the total DH potential in comparision with the total heat demand in the selected area.

• Also a new layer is added to the canvas showing DH areas. This layer is added to the list of layers under the "Calculation module" category. The run session name distinguishes the outputs of this run from other ones.

Following these steps, you will get an impression about the input values and potential DH areas.

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### Test Run 2: modified input values

Depending on your experience and local knowledge, you may increase or decrease the input values to obtain better results. In case of Aalborg, for instance, you may know that the heat demand in outer city areas is relatively close to the central part of the city and DH system is also feasible in those areas. Therefore, you may decide to reduce the minimum heat demand in cells that are part of a DH area; however, to guarantee enough heat demand, you may increase the minimum heat demand in a DH area. Here you re-run the calculation modules with new input parameters.

• Assign a name to the run session (optional - here, we chose "Test Run 2") and set the input parameters (250 MWh/ha for min. heat demand in hectare and 35 GWh/year for the minimum demand in DH area).

• Wait until the process is finished.
• As output, indicators and diagrams are shown in the "RESULTS" window. The indicators show:
• the total heat demand in GWh within the selected zone,
• total DH potential in GWh within the selected zone,
• the share of DH potential from totoal demand, which is obtained by division of DH potential by total heat demand in the region.

Additionally, also two diagrams are generated. The first one shows the DH potential in each DH area. The correponding labels can be found in the map, too. The second diagram illustrates the total DH potential in comparision with the total heat demand in the selected area.

• Also a new layer is added to the canvas showing DH areas. This layer is added to the list of layers under the "Calculation module" category. The run session name distiguishes the outputs of this run from other ones.

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## References

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## How to cite

Mostafa Fallahnejad, in Hotmaps-Wiki, CM-District-heating-potentials (April 2019)

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## Authors and reviewers

Institute of Energy Systems and Electrical Drives

Gusshausstrasse 27-29/370

1040 Wien

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