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Heat sources for 5GDHC networks (anergy networks)

One of the most important decisions when planning 5GDHC networks (anergy networks) is the heat source. On this page, you find an overview of commonly used sources.

What are heat sources for 5GDHC networks?

A major advantage of 5GDHC networks is that a large number of different heat sources can be used. Furthermore, it is not uncommon to exploit several heat sources for a single 5GDHC network. Table 1 lists a number of heat sources that are commonly used for 5GDHC networks. Some heat sources can be used directly with the help of a heat exchanger (e.g. geothermal energy). Other heat sources are usually used together with a heat pump (e.g. ambient air). The grid temperature should always be chosen to be close to the temperature level of the (most productive) heat source. Solar thermal energy therefore makes only limited sense as the main heat source for 5GDHC networks, because they usually achieve supply temperatures of more than 40 °C. If solar thermal represents a high share of the heat supply, it should be examined whether a normal heat network (low-ex network or hot heat network) is a better alternative. The following list provides a brief overview of heat sources in 5GDHC networks:

  • Ambient air
  • Horizontally installed geothermal collectors
  • Geothermal probes
  • River water, lake water or seawater
  • Waste heat from sewage water
  • Ground and well water
  • Mine and tunnel water
  • Photovoltaic thermal (PVT) collectors
  • Solar thermal energy
  • Waste heat
  • District heating return pipe
  • Boiler / CHP unit (also with biomass)
A variety of heat sources for 5GDHC networks can be simulated in the nPro tool.

List of 5GDHC networks

Our list of 5GDHC networks also includes the used heat sources for each network. If you are planning a 5GDHC network yourself, you can submit our survey form, and we will add your 5GDHC network to our list.

Table 1: Heat sources with temperature level and advantages and disadvantages.
Heat source Temperature level Advantages Disadvantages
Ambient air -15 - 35 °C Can be used everywhere,
Efficiency seasonally opposite to demand (for heating and cooling)
Horizontally laid ground collectors (near-surface geothermal energy) -5 - 20 °C Largely independent of location Yield depends on ground type,
unbuilt collector area required
Geothermal probes 2 - 14 °C Largely independent of location Thermal yield dependent on ground type and is generally unknown
River water 0 - 20 °C Constant supply throughout the year,
no regeneration required
Supply varies locally,
biological use restrictions may apply
Lake water 0 - 20 °C Cost-effective,
natural regeneration
Yield depends on lake size,
biological use restrictions may apply
Sea water 5 - 15 °C Inexhaustible source of heat Only available in a few locations
Waste heat from sewage water 10 - 20 °C Largely constant temperature level all year round Yield should be monitored during one year before district planning
Ground and well water 5 - 15 °C Largely constant temperature level all year round Only available in a few locations
Mine and tunnel water 5 - 35 °C Often high temperature level,
available all year
Only available in a few locations
Photovoltaic thermal (PVT) collectors > 10 °C High temperature level Yield depends on weather and season
Solar thermal energy < 120 °C Usable everywhere,
high efficiencies at low flow temperature,
Weather-related fluctuation in supply,
supply seasonally opposite to demand,
installation space necessary
District heating return pipe 30 - 70 °C Reduction of return temperatures in the district heating network Extracted heat must be added at (partly fossil) heating center of the district heating network
Boiler / CHP unit (also with biomass) > 60 °C Freely scalable capacity Too high temperature level for 5GDHC,
local emissions
Waste heat > 20 °C Cost-effective heat Backup necessary,
tie to heat suppliers,
availability locally different

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