It sounds obvious to set up sustainable local heating networks after the flood disaster in the Ahr valley. But it is not that easy. Above all, it’s not fast.
Before the flood disaster, most of the heating systems along the Ahr were not up to date. Many houses were heated with oil, some with wood and some with gas.
The many oil tanks that were swept away and destroyed by the water were also to blame for the fact that many flood ruins were not just water damage, but were so contaminated with heating oil that they had to be demolished. Experts very quickly recognized that the catastrophe gave rise to an opportunity to take a big step towards sustainability when it came to heating.
When the local heating ambassador rings
When Paul Ngahan, head of the district heating competence center of the Rhineland-Palatinate Energy Agency, came to the Ahr Valley shortly after the flood, he left everything else behind and became a district heating ambassador. “With 195 volunteers, we went through all the streets in the valley and spoke to the people who needed a new heating system. Not everyone was there because their houses were uninhabitable, but we came back with 2,500 completed forms from interested parties.”
Ngahan brought all the players to a round table, municipal umbrella organizations, energy suppliers, chambers of crafts, chimney sweeps and officials. That was the promising start to installing local heating networks. They only pay off if enough households can be connected.
Advantage construction site
At many information events in the Ahr Valley, the mayor and residents were convinced of the local heating. The Ahr Valley is still a huge construction site. This is even an advantage for the installation of local heating networks. In order to build such a network, major interventions in the existing infrastructure have to be made.
“In the flooded area, there is now an opportunity to carry out the expansion relatively quietly,” says Thomas Hoppenz, Managing Director of Ahrtalwerke, which was already offering local heating in Bad Neuenahr-Ahrweiler before the flood. “For the construction of a local heating network, the streets have to be torn up everywhere and a place for the heating center found.” Of course, the Ahr Valley in reconstruction offers the possibility to do it at the same time.
First of all, feasibility studies had to be carried out, because which type of local heating is most suitable depends on the size of the settlement and its topography. Most of the 14 communities affected were eligible for the technology, and in six of them there were enough interested parties. However, the status of the expansion is very different.
Reconstruction as an opportunity: But local heating networks need time.
Marienthal is the first
Marienthal, in the middle of the Ahr Valley, is the first community to operate its own local heating network since the end of 2022. 33 households have a connection in the basement. There is now a central thermal power station in the village in which wood pellets are burned – so it is a warm local heating network. In addition, solar thermal energy on the village community center provides energy that is fed into the grid.
Village caretaker Rolf Schmitt says: “In addition to the effect that we can heat relatively cheaply with the village heat, we have also been able to reduce CO2 emissions from 238 to 18 tons.”
Search for investors
But why can’t many more people benefit from the technology? Several communities are still fighting for it. In Dernau, a local heating project is estimated at around 17 million euros, in Mayschoß it will cost eleven million.
District heating ambassador Ngahan from the energy agency is still looking for investors. “Even if the big utilities should jump out, the municipalities can build it themselves. They operate it and earn money with it. You only have to explain that to the lenders. The investments would be recovered – a sure thing,” he says.
Also, doing it yourself would probably be cheaper for consumers. Municipalities do not have to make a profit like energy suppliers. They could deliver the heat to households at cost price.
The impatience grows
Nevertheless, some residents in Dernau are angry: they lack the political will for sustainable heating technology. At information events, where it was always said that local heating would come soon, people complained that they had been waiting for two years. They deliberately did not install gas heating, but instead waited for sustainable local heating. Now the boxes with the transitional oil heaters are still in front of their houses.
Elaborate and expensive
Local heating cannot be implemented quickly. The two years that it took in Marienthal were already an absolute record time, explains Thomas Hoppenz from Ahrtalwerke. “It’s a complex and expensive infrastructure.” After the feasibility studies, holes would have to be drilled and lines laid throughout the village. “It’s easier to hang a thermal bath in the house”, says the managing director, “nevertheless, the idea of supplying heat via pipes is currently experiencing a renaissance. It corresponds to the political will to reduce the CO2 emissions of heating systems to zero, because every type of heat generation can put in front of it.”
Coal, gas and wood could even be used as an interim solution, but the systems could later be converted to geothermal, solar, biogas or even hydrogen at some point.
Of course, local heating is particularly suitable where directly regenerative energy sources are available and can be used. This is the case almost everywhere in the Ahr Valley. “Municipalities must also support planning security. For the implementation, we need infrastructural spaces that the municipalities have to make available, i.e. land for the central heating system and for the generation of renewable energies,” says Hoppenz.
Flood aid for reconstruction only
Paul Ngahan points out another problem for local heating networks in the Ahr Valley: “The flood aid may only be used for infrastructure that was destroyed by the flood – which therefore existed before the flood. There were almost no local heating networks anywhere in the Ahr Valley, which is why we have to look for other help pots here.”
He blames politics for this: “Politics didn’t think far enough in the direction of decarbonisation, which makes it more complicated for those affected to break new ground. They have to apply for flood aid to rebuild their houses and to connect to a local heating network EU , federal and state funds.”
In the search for funding and because of the long waiting time, many in the Ahr Valley have given up and put up a gas boiler again – not sustainable, but eligible.
district heating
There are two types of district heating. The classic “warm local heating” (like district heating) brings heat generated at a central point in the form of water with a temperature of at least 70 degrees through well-insulated pipes into the connected houses. There, a heat transfer station (heat exchanger) transfers the heat to the water in the house’s internal heating circuit and heats the heating system and the water heater. Unused heat flows back into the grid. The heat for the network can come from a wide variety of energy sources. However, the heat is generated outside the buildings. A lot of heat is lost during transport, and the necessary cable insulation is a major cost factor.
With “cold local heating” the heat is only generated in the house. Here, thermal groundwater only comes through the pipe network at a temperature of five to 35 degrees Celsius. Every house must be equipped with a heat pump that uses electricity, refrigerant and pressure to evaporate the water. The resulting heat is passed on to a heat accumulator. Much cheaper non-insulated piping can be used with this system. However, every house needs a heat pump. That makes this technique more expensive.