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Heat pumps for district heating: Fossil-free alternative and flexibility potential for Sweden's electrification

EKA strives to always stay updated on innovations and market products. We were on-site last week to see Advansor's turnkey product - an R744 air-to-water heat pump with large capacity (200–600 kW per module) that is well-suited for district heating production.

Picture: Advansor Heat Quantum showcase vid Arlanda XPO, april 2024.

The topic is very relevant. The same week, another supplier, Fenagy, held a webinar about the hot market in Denmark and presented a number of references that have been installed there. Here are two of their references:

Sdr. Felding Fjärrvärme, Danmark,

MODEL: 2 x H-1800-AW

APPLICATION: Air-to-water heat pump


3.5 MW (0° C Ambient, 35/70° C hot water)

Haderup Fjärrvärme, Danmark

MODEL: H1200-AW-4+4B

APPLICATION: Air-to-water heat pump

CAPACITY (HEAT): 1.2 MW (5 °C Ambient)

Using large heat pumps/electric boilers in district heating networks alongside storage has significant potential to utilize surplus energy and serve as an 'upregulating' resource.

It's no coincidence that various actors are focusing on the same segment. Heat pumps for district heating providers will play a crucial role in Sweden's electrification. The Swedish Energy Agency itself mentions the flexibility potential of district heating for the electricity grid in its report "Framtidens elektrifierade samhälle - Analys för en hållbar elektrifiering - ER 2021:28" (The Future Electrified Society - Analysis for Sustainable Electrification).

 The flexibility potential of district heating

In addition to the potential to store energy in buildings, there is also significant potential to store energy in the distribution systems for district heating and cooling, as well as in energy storage systems connected to them. District heating and cooling systems integrate many different technical components and sectors. It is an important infrastructure that also enables combined heat and power (a flexible production source that can also help manage power and capacity challenges) and carbon dioxide capture through bio-CCS. Therefore, it becomes a complex optimization problem to try to utilize as much of the flexibility potential as possible. Currently, the systems are mainly controlled to optimize the instantaneous district heating demand. However, there are several initiatives where, through research and demonstrations, efforts are made to optimize the flexibility potential and investigate how significant this potential is.

Digitalization is an enabler for this development as it requires both monitoring and collection of a large amount of data and control algorithms that can automate and control the system efficiently.

In the scenarios in this study, investments are made in both large heat pumps and electric boilers in district heating systems. Utilizing large heat pumps/electric boilers in district heating networks alongside storage has significant potential to utilize surplus energy and serve as an 'upregulating' resource. We have assumed that the entire capacity of large-scale district heating pumps can be flexible, amounting to approximately 800 MW by 2050.

Heat storage connected to the district heating and cooling infrastructure can be a cost-effective storage option to create flexibility in the electricity system, not least to contribute to utilizing situations with large surpluses in electricity production. Storage options include various solutions with storage in mediums that do not undergo phase change (sensible storage) such as accumulator tanks, aquifers, boreholes, rock caverns, and pit storages. These all represent proven solutions, but there are also more innovative alternatives being developed and tested in pilot plants. This includes storage utilizing phase change (latent storage) and storage utilizing chemical reactions (thermochemical storage).

EKA assists district heating providers who want to replace old installations (such as pellet, oil, and gas boilers) with high-capacity heat pumps that use electricity as the energy source. This decision is usually made for both economic and environmental reasons – since Swedish electricity production is fossil-free up to 98 percent (source: Energiföretagen). Naturally, we recommend the use of natural refrigerants in these heat pumps.

Explore our relevant service and technology pages:

Naturally sustainable engineering solutions


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