Heat Recovery in Sustainable Cities
1, Core Value: Efficient Utilization of Urban 'Invisible Energy Storage'
Energy substitution: The total amount of waste heat in global cities can cover the heating needs of buildings; The waste heat from the 22 EU countries can meet over 50% of energy demand.
Significant carbon reduction: Recycling 1 ton of waste heat ≈ reducing 0.2-0.3 tons of CO ₂ emissions, is a key lever for urban carbon neutrality.
Economy and Security: Reduce dependence on fossil fuels, stabilize energy price fluctuations, and enhance urban energy autonomy.
2, Mainstream sources and recovery technologies of waste heat
1. Urban sewage/recycled water (the most stable and largest scale)
Heat source: domestic sewage, recycled water, stable temperature throughout the year (10-25 ℃).
Technology: Sewage source heat pump (direct extraction/indirect heat exchange), COP can reach 3-5.
Application: District heating/cooling, hot water supply.
Case: Beijing Qinghe Reclaimed Water Plant provides cooling and heating for 1.6 million square meters, reducing CO ₂ emissions by approximately 50000 tons annually; The Qingdao Regenerated Water Heat Source Project has an annual heating capacity of 5.444 million GJ and saves 28000 tons of coal.
2. Waste heat from data centers (high-grade, continuously stable)
Heat source: Server heat dissipation (30-45 ℃), continuous emission throughout the year.
Technology: Liquid cooled/air-cooled recycling+heat pump heating, combined heat, electricity, and cooling.
Application: Heating for surrounding buildings, greenhouses, and driving absorption refrigeration.
Case: Alibaba Zhangbei Data Center provides waste heat for a 100000 square meter greenhouse, reducing PUE to 1.08.
3. Industrial waste heat (large amount, wide range of grades)
Heat sources: circulating water from power plants, waste heat from chemical/steel/petrochemical industries, flue gas, and steam condensation heat (20-300 ℃).
Technology: Cascade heat exchange, lithium bromide absorption heat pump, steam injection, long-distance pipeline transportation.
Application: Urban centralized heating, industrial reuse.
Case: Jinan's "Talking Heat into Jinan" 100 kilometer pipeline network replaces 1.3 million tons of standard coal annually, supplying 100 million square meters; Qingdao Petrochemical waste heat+natural gas cascade heating.
4. Waste heat from urban public facilities (dispersed and easily overlooked)
Heat source: subway/tunnel heat dissipation, mall/supermarket exhaust, underground garage, waste incineration plant flue gas.
Technology: Air/Water Water Heat Exchange, Small Heat Pump Clusters, Regional Energy Network Integration.
Case: Singapore's Marina Bay 15km thermal energy network integrates waste incineration, data centers, and subway waste heat to supply 2 million square meters, reducing air conditioning energy consumption by 40%.
5. Building and HVAC system waste heat (end cycle)
Heat sources: condensation heat from air conditioning, exhaust waste heat, and waste heat from domestic hot water.
Technology: Total heat exchanger, condensation heat recovery, heat pump water heater.
Value: Reduce the building's own energy consumption by 20-40%.
