Upgrading measures on the heat generation are related to the integration of renewable energies. For the assessment of the existing heat generation infrastructure, it is very important to have maps with all heat generation facilities and the network available. In addition, it is important to know the heat losses of the DH system. In order to determine the heat losses precisely, the measured generated heat (cold), as well as the measured heat (cold) sold to the customers are necessary.
Solar thermal collectors are widely applied for domestic hot water preparation and for supporting the heating systems, e.g. for individual heating systems in German households. There are also solar district heating (SDH) plants that consist of large fields of solar thermal collectors feeding their produced solar heat into DH networks. The solar collector fields are either installed ground-mountedor on roof-tops. Today, the plant capacities range up to 100 MWth for the presently largest systems installed. Competitive heat prices below 50 €/MWh are achieved due to scaling effects and optimized systems. The integration of solar thermal energy can be more efficient at rather low DH temperature systems, although the integration at higher temperatures is generally also possible.
Photo by Alexander Schimmeck on Unsplash
The integration of biomass in DH systems is flexible depending on the needs of the system. For larger DH systems, the following biomass can be used: bulkywaste wood (furniture, from the construction, painted wood, etc.), saw dust, wood chips from forests (residues, energy wood), wood chips from short rotation coppice (SRC), industrial pellets (wood pellets, mixed biomass pellets), torrefied biomass, biomethane (from anaerobic digestion of bio-waste), and pyrolysis oil. A key challenge for the use of biomass, especially for larger and centralized plants are the logistics of biomass. Therefore, new approaches, such as the use of intermediate bioenergy carriers (torrefied biomass, biomethane, pellets, biomethane) is of high interest, as they reduce logistical problems. Two very different approaches for upgrading DH systems with biomass apply, namely the installation of new biomass-fired boilers and CHP units, or the replacement of fossil fuel installations with biomass installations.
There is a number of different heat generation technologies in addition to solar and biomass DH systems, for example integration of geothermal heat, excess heat (industrial excess heat, low tempreture excess heat), power-to-heat (electric boilers, heat-pumps), as well as integration of heat storage technologies. More details on each technology are available in the Upgrade DH Handbook „Upgrading the performance of district heating networks: technical and non-technical approaches“. Experiences from different European countries were used to describe the technical and non-technical approaches in DH upgrading processes. The handbook is available in English and 6 other languages: Bosnian, Croatian, Danish, Italian, Lithuanian, and Polish. The aim is to inform stakeholders such as decision makers, politicians, utilities, operators, end consumers, or potential developers of DH systems, about upgrading opportunities. Thereby, the ambition of the handbook is not to provide a detailed technical guideline for technicians, but rather to give an overview on upgrading options.
Article written by Rita Mergner, Senior Project Manager at WIP Renewable Energies
More information on the UpgradeDH handbook also available in the Celsius Toolbox article “Improving energy efficiency – A handbook on DH upgrading paves the way”.