As part of its low-carbon energy network, Solihull, a town of 126,000 in the West Midlands, U.K., has installed six Refra hydrocarbon heat pumps to provide 1.6MW (455TR) of district heating and hot water to local government owned buildings, community centers and educational institutions.
The project, backed by a £9.6 million ($12.9 million/€11.1 million) loan from the U.K. government’s National Wealth Fund, is a collaborative effort between the Solihull Metropolitan Borough Council and Vital Energi, a British provider of sustainable heat infrastructure. As part of the project, Vital Energi has already laid 5km (3.1mi) of underground piping.
“Heating is the biggest contributor to the UK’s carbon footprint,” said Solihull Councillor Andy Mackiewicz, Cabinet Member for Climate Change and Planning. “The air source heat pumps at the heart of our energy center will play a major role in delivering cleaner energy where it’s needed most.”
The installation supports the Council’s decarbonization goals to achieve net zero by 2041, including its specific target for public buildings by 2030.
Besides hydrocarbon chillers and heat pumps, Lithuanian HVAC&R manufacturer Refra also produces CO2 (R744) refrigeration systems. The company was reapproved for the ATMO Approved Natural Refrigerants Label in February. ATMOsphere, which awards the label, is the publisher of NaturalRefrigerants.com.
The heat pumps: Absolutely Chilled, Refra’s U.K. distributor, supplied five air-to-water propane (R290) units and one water-to-water isobutane (R600a) unit to the Solihull Energy Center.
- The hybrid system delivers up to 80°C (176°F) hot water to the existing high-temperature heating network, Absolutely Chilled told NaturalRefrigerants.com.
- Each of the R290 heat pumps provides a heating capacity of 171.6kW (48.8TR) and a cooling capacity of 169.8kW (48.3TR), with a COP of 4.64, according to Refra.
- The R600a unit provides a heating capacity of 1.7MW (483TR) and cooling capacity of 1,3MW (370TR), with a COP of 4.48.
Commissioning: With the first phase nearly complete, customers will soon benefit from being connected to the network, according to the Council. However, the district energy network is not expected to be fully operational until spring 2026.
- The system allows the energy center to increase the network in future phases.
- Absolutely Chilled estimates that upon completion of the third and final phase, the new energy center, with hydrocarbon heat pumps, has the potential to avoid over 6,000 metric tons of CO2e emissions annually.
New application: Generally, district heating networks with natural refrigerant heat pumps use CO2 or ammonia (R717) refrigerant. However, hydrocarbon heat pumps are also starting to be used in such applications.
- Danish manufacturer Fenagy has developed a water-to-water 1MW (284TR) isobutane heat pump to support the subcooling of CO2 heat pumps in district heating networks with high return temperatures.
- Six Fenagy isobutane /propane heat pumps will supply more than 30MW (8,530TR) of heat to a district heating network in a Finnish city using waste heat from a local data center.
Quotable: “This project is a clear demonstration of our commitment to investing in a sustainable future,” said Karen Grinsell, Leader of the Solihull Council. “It’s extremely encouraging to see the rapid progress on the ground. We are well on our way to realizing this bold vision.”
“The air source heat pumps at the heart of our energy center will play a major role in delivering cleaner energy.”
Andy Mackiewicz, Solihull Councillor
