What is the role of district heating in the future energy system?

Introduction

In the future energy systems, with a high share of intermittent renewable energy sources, district heating will have a crucial role by using demand response through implementation of power-to-heat technologies.

According to Lund et al. (2018), district heating will have to satisfy several criteria in to face future challenges of energy systems:

Ability to supply low-temperature DH for space heating and domestic hot water
Ability to distribute heat in thermal networks with low thermal losses
Ability to recycle heat from low-temperature and integrate renewable energy sources
Ability to be integrated part of smart energy system
Ability to ensure suitable planning, cost, and motivation structures in relation to the operation and investment

The role of district heating in the future energy system

Efficiency

The efficiency of district heating in future energy systems can be assessed in terms of how they contribute to the overall efficiency of the energy system. There are different parameters that express energy system efficiency, including primary energy consumption, total greenhouse gas emissions, economic efficiency (operational costs, fuel costs, investment costs or combined as total annual costs of the system). Also, environmental efficiency in terms of e.g. airborne emissions (NOx, SOx, particulate matter etc.) and waterborne emissions is an important efficiency parameter.

Note that while DH technologies and DH systems share some of the same efficiency parameters as the future energy systems they are a part of, the efficiency of the the DH sector in an energy system can be different (relatively higher or lower) than the total efficiency of that total energy system. This depends, amongst others on how well the different energy sectors perform as such and coupled together (sector coupling).

While the energy and fuel efficiency of energy systems can be improved through more efficient technologies and operation resulting in a lower fuel consumption, reduction of energy demand also improves efficiency by reducing the need to produce energy in the first place. Particularly, in DH systems heat savings and improvements in the building envelope facilitate temperature reduction which in turn improve the efficiency of low-temperature heat sources and technologies, including heat pumps.

Advanced page: Efficiency

Sector coupling

Sector coupling refers to the coupling of energy sectors and energy grids with the objective of facilitating greater energy efficiency, higher renewable energy penetration and smart energy systems. On the district heating level it can mean combined heat and power production (CHP), integration of (industrial) excess heat, and Power-to-Heat solutions by means of which electricity is converted into heating through e.g. heat pumps. On a broader energy system level, it can generally involve solutions that utilize Power-to-X, including the conversion of (excess, renewable) electricity to hydrogen and other green fuels.

Advanced page: Sector coupling

Smart Energy Systems

According to Lund et al. (2017) a smart energy system "is defined as an approach in which smart electricity, thermal and gas grids are combined with storage technologies and coordinated to identify synergies between them in order to achieve an optimal solution for each individual sector as well as for the overall energy system."

District Heating can support the implementation of smart energy systems by, amongst others, facilitating the coupling between electricity and heat through power-to-heat technologies, such as heat pumps and electric boilers. In DH networks with lower temperatures, these technologies will operate more efficiently.

Advanced page: Smart Energy Systems

100% Renewable Energy Systems

District Heating and Cooling can support the transition to 100% renewable energy systems by facilitating the integration of renewable heat sources, such as solar thermal, geothermal, ambient heat (groundwater, air) as well as excess heat from a variety of sources (industrial excess heat, datacenters, supermarkets, transformer stations etc.). As temperatures in district heating networks are decreased, even more renewable heat sources and excess heat can be integrated.

Advanced page: 100% Renewable Energy Systems