100 % Renewable District Heating Leibnitz


Efficient heat supply with biomass and waste heat


The district heating supply of the city of Leibnitz and the surrounding communities will be massively expanded over the next few years – with 100% renewable energy from the biomass heating plants in Tillmitsch and Kaindorf (Nahwärme Tillmitsch , NWT) as well as from waste heat from the rendering plant (TKV) in Gabersdorf (Bioenergie Leibnitzerfeld, BEL). At the same time, the efficiency of the district heating network and the energy producers is to be increased. In order to achieve these two goals, various measures are required to increase the flexibility of the district heating system.
The central approach is to merge the two heating networks in order to enable the mutual exchange of heat. This ensures an efficient and resource-saving supply. Particularly in winter, the NWT supplies heat from biomass to the BEL on weekends when the TKV is out of operation. This means that the BEL gas boiler remains out of operation at these times and is only available as a backup. In summer, the heat requirement in the BEL network is lower than the available waste heat of the TKV. The excess heat is sold to the NWT during the summer time, which saves valuable wood chips.
In addition to cooperation, the differences between generation and consumption must be balanced by flexible storage capacities and intelligent control strategies in order to efficiently supply district heating customers with 100% renewable heat throughout the year. In addition, the implementation of low-temperature district heating for smaller urban districts will increase the efficiency (and thus the heat yield) of the biomass heating plants and the TKV’s waste heat extraction. Lowering the network temperatures also reduces network losses and the energy requirements of the network pumps.
The most important key facts are:

Investment volume
Classic district heating expansionEUR 2.1 million
Flexibility measures ThermaFLEXEUR 8.6 million
Environmental effects (reference: gas)
CO2 savings in district heating expansion (from 2019)8,100 t/year
CO2 savings ThermaFLEX2,000 t/year
CO2 emissions Leibnitz city total107,000 t/year
Technical data
Tillmitsch heating plant (2 boilers + heat recovery)1.1 MW
Kaindorf heating plant (2 boilers + heat recovery)6.8 MW
Waste heat extraction TKV4.5 MW
Gas boiler TKV (backup)6.0 MW
District heating customers (connected load 2019)19.6 MW
Total heat sold (2019)34,000 MWh
Heat network length (2019)30.8 km
Total planned storage volume1,185 m³