District energy systems
To decarbonize districts, district energy systems are a proven approach to exploit synergies between different energy sectors (electricity, heating, cooling and mobility) and achieve a sustainable, zero-emission energy supply.
What are the benefits of district energy systems?
Unlike decentralized energy systems for buildings, in district energy solutions buildings are networked with each other in terms of energy and can thus exchange energy with each other. This can include the electricity sector as well as the heating and cooling sector. By connecting buildings, synergies can be exploited in terms of energy storage, load shifting, and balancing of heating and cooling loads. Furthermore, setting up a centralized heating and cooling supply instead of many decentralized producers can be more economical.
The networked district
The interesting thing about district projects is that no two districts are the same. On the one hand, the supply of local energy sources varies, and on the other hand, the customer structure and the energy demands to be met differ from district to district. A energy network of buildings and producers can be realized for electricity, heating and cooling.
A common element in districts are microgrids. These are electricity grids that are not part of the public electricity grid and that the district operator can use to exchange electricity between buildings and energy hubs. The advantage of microgrids is that their operation is subject to fewer regulations than the public power grid. For example, there are fewer or no grid fees if a building with a photovoltaic system supplies electricity to another building. A microgrid thus enables the interconnection of regenerative generators such as photovoltaics or wind energy, with electrical storage (district battery) and consumers.
District heating and cooling
District heating or district cooling networks can be constructed to thermally connect buildings for a central heating and cooling supply. A third network type are 5GDHC networks, which can provide both heat and cold to buildings and additionally shift surplus waste heat from one building with high cooling demands to another building with high heating demands. 5GDHC networks are therefore particularly suitable for districts with a heterogeneous consumer structure (districts with different types of buildings).
Hydrogen technologies can also be an interesting addition for districts. The use of hydrogen enables the long-term storage of surplus electricity (for example from photovoltaic or wind power plants). Here, an electrolyzer converts electricity into hydrogen, which can then either be stored or fed into the natural gas grid. Stored hydrogen can be converted back into heat and electricity in a fuel cell or in a suitable combined heat and power (CHP) unit. The waste heat from the conversion of hydrogen into electricity in a fuel cell or a CHP unit can then be distributed to buildings with district heating networks.