Ohrdruf is a city with 10.000 inhabitants in the district of Gotha located in the federal state of Thuringia. The district heating (DH) in Ohrdruf is currently under municipal operation. It currently supplies eight apartment blocks and three other public buildings such as schools and kindergarden via a district heating network. Natural gas is used as a fuel at around 3,5 GWh/a, and approx. 3GWh/a of heat is generated from it, with 2,3 GWh/a being supplied. The current heating grid has a heat loss of 1,2 GWh/a. The annual district heating consumption of the properties amounts to 2.296 MWh. The district heating is currently generated in three boilers using natural gas as the energy source. The district heating supplies 1.664 MWh/a to the residential buildings which is the significantly largest share.
In a first step the district heating network is being extended and the heat generation system remodelled. The aim is to generate heat mainly from waste heat from combined heat and power facility (949 kW(th)/ 907 kW(el)) based on natural gas (total share of 64 %) environmental heat (total share of 35 %; 2-stage heat pump: 1st stage air-water-heat pump, 2nd stage water-water-heat pump; approx. 550kWth). A power-to-heat-facility with 300 kW(th) and a large heat storage (100m³) are also planned. In addition, PV electricity, which is generated directly on site by the contractor using a PV system on a carport (260 kWp), will be used to operate the heat pumps.
In a second step a comprehensive transformation plan for the district heating system will be developed to reach the climate neutral heat generation by 2045. This is content of the pilot project.
The pilot action will improve the system by establishing a long-term strategy for the district heating system based on 100% renewable energy sources (RES).