Finnish energy company Seinäjoen Voima will employ ammonia (R717) heat pumps to supply 4.9MW of district heating to roughly 2,000 single-family homes in the city of Seinäjoki, Finland, using heat from the local wastewater treatment plant.
The system – designed by Caverion Teollisuuskylmä, a business unit part of the Finnish Assemblyn Caverion group – will use three Johnson Controls Sabroe DualPAC heat pumps, each supplying an approximate heating capacity of 1.6MW (455TR), Sami Hatakka, Head of Sales and Energy solutions at Caverion Teollisuuskylmä, told NaturalRefrigerants.com. The heat pumps are connected in parallel and operate with an evaporation temperature of 2/9°C (35.6/48.2°F) and a condensing temperature of 50/90°C (122/194°F).
“In our discussions with Seinäjoen Voima, we highlighted the benefits of ammonia heat pumps, including the heat rejection capacity, COP, the long equipment lifespan and the low-charge nature of the modern units,” Hatakka said. “They had the courage to change the project’s scope to ammonia.”
With the system expected to come online fall 2025, the installation will account for approximately 8% of the total district heating distributed by Seinäjoki Energia, which owns Seinäjoen Voima. Funding from the EU will cover 25% of the €4 million ($4.5 million) investment, according to Seinäjoki Energia.
System design: The new system will be located at Seinäjoki’s wastewater treatment plant and the adjacent heating center, with the heat pumps in a modular 12 × 15m (39 × 49ft) container.
- “Our delivery includes the complete [heat pump] plant: equipment rooms, electrical systems, piping, automation, commissioning and maintenance,” Hatakka said.
- Additional construction includes a 1,000m3 (35,315ft3) treated wastewater basin supplying a 14°C (57.2°F) intake to the heat pumps. The facility operates an internal circuit between the wastewater and the cooling brine.
Looking ahead: Hatakka told NaturalRefrigerants.com that Caverion Teollisuuskylmä has a connection built into the design to deliver cooling to the Seinäjoki district in the future.
- Mikko Mursula, Director of Heat Business at Seinäjoki Energia, estimates that the cooling investment will cost another few million euros. However, he called it an “affordable and environmentally good solution,” with the waste heat from the process integrated into other city systems like the wastewater treatment plant.
Similar projects: Caverion Teollisuuskylmä reports this is one of Finland’s first wastewater heat recovery solutions using ammonia. However, it is a proven technology in other parts of Europe.
- Four ammonia-based HicaHP units, with a total capacity of 27MW (7,677TR), from Johnson Controls’ Sabroe brand, recover heat from 65 million liters (17 million gallons) of treated wastewater in Utrecht, the Netherlands, to supply district heating to 20,000 households.
- Using heat from a local wastewater treatment plant and a waste incinerator, four GEA ammonia heat pumps, with a total capacity of 40MW (11,374TR), supply district heating to 10,000 homes in Malmö, Sweden.
Quotable: “Conditions are favorable for [this project], with incineration becoming expensive due to legislation and emissions trading,” Mursula said. “It fits well with our carbon neutrality goals, and this is a good location with everything needed nearby: a water treatment plant, a large district heating pipe and plant, and electricity.”
