German cities towards 100 % renewable energy - Heat Hub Hennigsdorf

The Heat Hub Hennigsdorf is a lighthouse example how cities can contribute to the German energy transition to renewable energies ("Energiewende") by setting binding targets themselves and decarbonizing their heat supply together with local stakeholders. The municipal utilities of Hennigsdorf aims at a district heating with 100 % renewable and CO2-neutral heat in 2025 for its yearly heat demand of 120 GWh/a. Until the year 2022, the share of CO2-neutral heat in the district heating will be increased from 50 to 84 %. To reach this target, different decentralized and renewable heat sources are on the way to be integrated into the district heating net. Biomass driven combined heat and power plants are already used to about 50 % of the annual heat load. To be able to operate the district heating with fluctuating industrial waste and solar thermal heat, the entire network has to be developed to a Heat Hub by integrating two heat storages of 1 000 and 22 000 m(3). This is one of the largest funded research and demonstration projects of the German Federal Ministry for Economic Affairs and Energy (BMWi) in the field of heating networks and a model for the decarbonization of existing district heating supplies (Gintars, 2018).