Mahlatie 6 & Pihkatie 14, Oulu

Northern Energy Leap – Powerful Mid-Cooling Connection helps the transition towards sustainable energy

HögforsGST implemented the first district heating substations utilizing the new Mid-Cooling connection for two terraced house properties in Oulu, Finland. The mid-cooling connection, a revolutionizing innovation for the district heating industry, has improved the energy efficiency and lowered the return temperatures of district heating already during the first heating season.

Mid-cooling connection (MCC) is a connection model for district heating substations developed by HögforsGST. The MCC utilizes the district heating input energy more efficiently than regular connections. Juha Virkki, Business Director of HögforsGST’s Engineering Services, describes MCC as a groundbreaking invention connected to the fast development the industry is currently going through.

– The district heating sector is moving from a traditional third generation system towards the fourth generation of district heating (4GDH). 4GDH is smarter, more energy efficient and more environmentally friendly way of heating. Energy-efficient mid-cooling connection is an invention that revolutionizes district heating, as it improves the energy efficiency of the entire system through lower return temperatures, Virkki says.

The first pilot was commissioned in collaboration with Oulun Energia. According to Markku Sutinen, Oulun Energia’s Product Manager, Oulun Energia was happy to collaborate with HögforsGST in the first pilot projects.

– The MCC seems to be a simple, yet efficient innovation. In addition, it is as easy to install as a traditional substation. We definitely support this kind of development, Sutinen says.

The first pilot was a great success – research-proven benefits

The ball is now rolling in Oulu, and new steps have been taken to move towards the fourth generation of district heating. As a part of this development, smart FiksuGST substations with mid-cooling connection were installed to two terraced house properties in the autumn of 2020. The properties were built in the late 1990s and in the renovation, their original oil heating system gave way to a state-of-the-art smart district heating system. The performance results of the system after the first heating season makes Juha Virkki smile.

– The three-step MCC has worked exactly as we expected: district heating’s Delta T has improved by several degrees and there were no technical issues, so the first pilot was a great success, Virkki says.

In addition to HögforsGST’s own calculations, a more detailed study of the operation and efficiency of the MCC was carried out by the consulting firm AFRY before this heating season. AFRY’s theoretical calculations were supported during the first heating season, when Olli Krankka from Oulu University of Applied Sciences studied the efficiency of the MCC in his bachelor’s thesis. A practical study showed that AFRY’s calculations were spot on, and that the MCC does indeed improve district heating’s Delta T even in mid-winter, although the most efficient operating time of the MCC is during the milder temperatures of the heating season. Markku Sutinen had high expectations for MCC technology, and those expectations were met already during the first heating season.

– According to the preliminary calculations, the MCC seemed to be a functioning solution, so the expectations were high. The results then proved that the MCC improved the district heating’s Delta T by several degrees. This gave us the final confirmation that this technology works. We plan to continue researching the effects of the MCC in the coming heating season, Sutinen says.

Virkki also brings up the contribution of HögforsGST’s R&D team to the success of the project.

– Our research and development team did a great job: the first prototype worked perfectly. The process itself was also really smooth, as the MCC was developed from an idea into a functional solution in less than a year.

Mid-cooling connection contributes to the development of 4GDH

Juha Virkki believes that the mid-cooling connection is an important piece in the 4GDH puzzle and will accelerate the green transition towards a low-carbon society.

– The MCC is one factor in the development of district heating, but the importance of digitalisation should not be overlooked either. FiksuGST substation equipped with the MCC has more to offer than just an energy-efficient connection: it is a modern, intelligent data sharing substation. FiksuGST’s smart features benefit both district heating consumers and producers. Innovations like FiksuGST and MCC are friendly to the environment and to the wallet as well, Virkki laughs.

Markku Sutinen also points out that the benefits of MCC are visible to both consumers and energy companies.

– The MCC reduces the flow rate of district heating, which can benefit Oulun Energia’s customers in the form of lower water flow fees. At the same time, the pumping costs of the power plant are reduced and the efficiency of production is improved. Of course, in order to achieve large-scale benefits, there must be a lot of substations equipped with MCCs, but this is a good start, Sutinen ponders.

The MCC technology has aroused well-deserved interest around Finland: we have already supplied MCC-equipped heating systems to Pori, Vaasa, Helsinki, Turku and Kotka. According to Virkki, this speaks to the fact that the MCC technology has been received very positively among stakeholders in the Finnish energy industry. The Swedes have also noted the MCC’s potential, as the first Swedish MCC equipped properties will be connected to the district heating network later this year.

The competitiveness of the future is built today

In recent years, Oulun Energia has been involved in several development projects, in which various 4GHD solutions are piloted, e.g. in the neighbourhoods of Kaukovainio and Karjasilta. According to Markku Sutinen, this is an indication of Oulun Energia’s desire to invest in the development of energy efficiency.

– Pushing towards better energy efficiency, be it from the energy company’s or the customer’s side, is our common task. At Oulun Energia, we strive to do our best and show that we are actively involved in energy efficiency efforts, Sutinen says.

Juha Virkki is pleased with Oulun Energia’s desire to develop district heating and renew its business models to match the requirements of the modern operating environment.

– Oulun Energia has realized that the change must start today in order to ensure the competitiveness and efficiency of district heating in the future. In Oulu, 4GDH is being built in a determined and long-term way. That’s a great thing for the whole industry, Virkki says.

Especially the renewal of the district heating equipment is critical in order to properly unleash the benefits of fourth generation district heating.

– Third generation equipment simply cannot produce fourth generation district heating. 4GDH requires different, smarter and better cooling equipment, Virkki emphasizes.

4GDH system supports the best forms of heating production: alternative heat sources that don’t require combustion and surplus heat. The best thing about 4GDH is that the current district heating network can also be utilized for 4GDH’s needs. As a result, none of the investments made in the past will be wasted and can continue to be utilized until the end of their technical life. 4GDH guarantees the competitiveness of district heating compared to stand-alone production, while being just as reliable and much more environmentally friendly than the traditional district heating system.