In the district heating system, energy recycling means the utilisation of a mix of electrical heat pumps, waste heat, ground heat and geothermal production instead of traditional combustion-based heat production. This kind of district heating system supports carbon neutral energy system which is based on the clean electricity.
Next generation district heating – great potential to reduce emissions
As combustion-based heat production decreases and heating becomes electrified, heat production will be scattered here and there. Instead of a few large primary production plants, there will be many smaller production units that will supply heat for the district heating network, each in its own way. This will lead to a complex district heating system.
The district heating network also provides an irreplaceable flexibility element for the new energy system. The increase of wind and solar power will also affect the future electricity market. However, because the wind is not always blowing and the sun is not always shining, the future electricity system will require flexibility, i.e. ways to store the energy. The district heating system will enable this.
Heat can be produced from electricity and heat can be stored. On a daily basis, heat can be stored in district heating networks, heat accumulators and in buildings. In the future, heat can be even stored in longer-term seasonal storages. District heating also significantly differs from other heating options by enabling energy recycling through the district heating network. For example, it can recycle the excess heat of buildings, industrial processes, data centres and sewage water and utilize it in cost-efficient way.
Smart and sustainable district heating holds great potential to reduce emissions. However, maximising this potential will require residential buildings, commercial buildings and other counterparties to actively connect to the district heating networks. The only way to recycle the energy is inside the network. Individual heat pumps and other similar stand-alone solutions cannot transfer heat between consumers. This needs to be kept in mind when considering the actions we in society want to take to resolve the climate challenge.
How can buildings provide flexibility for the system?
Heat demand varies by season, week day, time of day, temperature etc. Traditionally, demand peaks have been covered by increasing heat production. Usually this has meant producing extra heat at heat plants, often by using fossil fuels.
In the future, demand and supply in a smart district heating system can be optimised and controlled automatically in order to bring flexibility to the system. Buildings are used for different purposes and at different times. Everything does not have to be heated simultaneously. For example, when spaces are not being used, heating and ventilation could be reduced. Or, for example, to avoid peak loads, heating could be reduced while hot water is being used. Consumers wouldn’t notice these kinds of short interruptions.
Fortum cooperates with several different actors in different countries to provide energy savings at the real-estate level. However, just the real-estate level is not enough – a demand side response is needed at the entire district heating system level. Centralized demand side response is a kind of virtual battery, which enables real-estate level steering from the district heating system’s point of view. Fortum has started the development, and the first pilots will be done in the near future in cooperation with the City of Espoo in Finland.
Artificial intelligence (AI) to optimise the entire district heating system
Fortum has developed artificial intelligence to optimise the district heating system and its operations; this will enable the flexible district heating system of the future. AI predicts the heat demand of our customers, steers the usage of storages and guides the control room in the optimal utilisation of assets. In practice, already now, this often also means the prioritisation of carbon-neutral production. AI has already been implemented in Fortum’s district heating systems in Finland, the Baltic countries, Poland and Norway.
AI development work and integration into operations continues. Artificial intelligence will enable automation of district heating when electrification increases the amount of controllable units as the energy system becomes more complex. This way, the district heating system becomes an enabler of flexibility for the electricity system. It can provide mechanisms for the frequency market and cost efficiently decrease investment needs for the electricity distribution network.
The author leads the development of smart energy systems in Fortum’s Heating & Cooling business