District heating and cooling networks: Technology advances
Seawater heat pumps, data-centre heat and cold from LNG terminals
What this tab covers The newest technologies in service or close to adoption, what each improves, and how the main options compare.The main direction is cooler networks fed by large heat pumps, waste heat and thermal storage, with plastic pipes where pressures allow. Steam systems mostly improve through maintenance rather than new technology.
Latest advances
4th-generation low-temperature networks being deployed · 2020 to 2050Supply at 50 to 60 C with low returns, integrated with the wider energy system1
Improves: Lower pipe losses and access to low-grade heat
Large seawater heat pumps in service · 202470 MW CO2 heat pump at Esbjerg, with compressors from MAN Energy Solutions (renamed Everllence in 2025)525
Improves: About 280 GWh of heat a year from seawater
Flexible plastic service pipes in service · 2010sPEX or polybutylene carrier pipes in polyurethane foam2
Improves: Cheaper laying for networks below about 80 C
Asymmetric twin pipes demonstration · 2010sSupply pipe given more insulation than the return in one casing2
Improves: About 3% lower total loss than a symmetric twin (DN 65)
LNG cold for district cooling in service · 2024Barcelona network using cold recovered from regasification at the Enagás LNG terminal (Veolia, Enagás and the city)34
Improves: About 131 GWh a year of cooling energy from otherwise wasted cold
Data centre waste heat with large heat pumps being deployed · 2026Fortum heat pump plants in Espoo and Kirkkonummi to use waste heat from Microsoft data centres31
Improves: Planned to supply 40% of district heat in the network area
Comparing the options
| Option | Efficiency | Cost | Capacity or distance | Maturity |
|---|---|---|---|---|
| Steam mains (1st generation and industry)17 | high losses if bare; insulation cuts losses about 90% | US DOE example: about USD 45,620 a year saved by insulating a plant's bare lines (2012) | high temperatures for industry; city scale in Manhattan | mature, legacy |
| Pressurised hot water above 100 C (2nd generation)12 | 15 to 25% losses typical of older eastern networks | not stated | city scale | legacy |
| Pre-insulated pipes below 100 C (3rd generation)26 | 8 to 15% losses | 2.16 euro cents per kWh distributed (Swiss model) | city scale | mature |
| Low-temperature 4th generation12 | about 43% lower losses at 55/25 C | flexible pipes 36 to 48 EUR/m installed (32 to 50 mm, excluding soil works, Sweden 2013) | districts to cities | early commercial |
| District cooling910 | 0.8 to 1.05 kW/RT; about 40% less energy than air-cooled chillers | not stated | Empower 1.7 million RT | mature in the Gulf |
Lower temperature and heat pumps reinforce each other: a heat pump works better the less it has to lift temperature, and cooler water loses less heat on the way. The catch is that old buildings need hot radiators, so cities move gradually. Steam remains where industry needs temperatures well above 100 C. District cooling is mature where cooling demand is dense and constant.
Sources
- Progression of District Heating: 1st to 4th generation Aalborg University (Thorsen, Lund, Mathiesen), 2018
- Distribution technologies for low-temperature district heating (LTDH) European Commission, Smart Cities Marketplace, 2019
- World's largest CO2-based seawater heat pump goes online pv magazine, 2024
- Sensitivity of System Design on Heat Distribution Cost in District Heating (Nussbaumer and Thalmann) IEA Bioenergy Task 32 / Verenum, 2014
- Steam Tip Sheet 2: Insulate Steam Distribution and Condensate Return Lines US Department of Energy, 2012
- Decarbonising the Grid: District Cooling (Tabreed presentation) UNEP Copenhagen Climate Centre (C2E2), 2022
- Empower's connected capacity has increased by 315 times since its establishment International District Energy Association, 2026
- MAN Energy Solutions is now Everllence Turbomachinery International, 2025
- Fortum to invest approximately EUR 225 million in waste heat projects in Espoo and Kirkkonummi Fortum, 2023
- World first: Veolia, Enagás and Barcelona City Council inaugurate first urban cold recovery network from an LNG terminal Veolia, 2024