In August, Jinan, Shandong is sweltering. At 8:30 a.m., Ms. Zhao walks into the Qilu Tech-Finance Tower in the city's central business district; the lobby reads 26 degrees C. 'Our office building has no air conditioning we use centralized cooling,' she says. The cool comes from an energy station underground.
Centralized cooling means building a central refrigeration plant to make chilled water, sending it through underground pipes into buildings, then blowing cool air indoors via terminal fan-coil units. In recent years more cities have rolled out such zones. Twenty-one meters below Jinan's CBD sits a centralized-cooling energy center. Xue Lei, who heads big-data at the city's cooling-heating utility, walked reporters into the machine room of the southern energy center, where four large variable-frequency centrifugal chillers were running.
'We supply heat in winter and cooling in summer through the same pipe network,' Xue said. Chilled water from the plant goes through municipal pipes to office towers; after heat exchange it returns about 7 degrees C water, then the room fan-coils blow cool air. Meanwhile the heat the chillers produce is sent hundreds of meters to a water-air heat-exchange unit that releases it outdoors. The southern station was built and commissioned in June 2021 and currently cools about 1 million square meters. Compared with AC, the outlet temperature is a bit higher, giving a gentle, mild coolness.
Zhang Xiaosong, a professor at Southeast University's School of Energy and Environment, said centralized cooling is not a brand-new concept in China but has mostly targeted offices, malls and industrial users and requires replanning and laying underground utility tunnels. Promotion to residential communities is still at an early stage and public understanding and acceptance need time to develop.
Through centralized-cooling technology, idle resources are effectively activated. Ling Yunzhi, an associate professor at China University of Mining and Technology, said abandoned mines are seen as a 'burden' for resource-exhausted cities impossible to mine and carrying long-term safety-monitoring and ecological-restoration costs, but cooling with underground mine water turns this waste into a 'green cold source.'
High renovation cost is a key factor restricting promotion. In Xuzhou's centralized-cooling pilot community, the heating company invested in R&D of technical solutions and dedicated equipment; each household got corrosion-proof pipes and dehumidifiers installed, costing nearly 7,000 yuan including installation, currently provided free of charge on a rental basis by the heating company. Industry experts note this model also needs stable groundwater, a mature pipe network and proximity to users, making it hard to replicate at other abandoned-mine sites.
Zhang Xiaosong and other experts suggest encouraging innovative development and comprehensive use of idle resources such as abandoned mine water, and promoting low-cost residential centralized cooling. Wu Feng, head of assets at the Xuzhou Mining Group, said policy incentives and technological support should be improved to bridge the 'last kilometer' of recycling stock resources such as abandoned mines and idle pipe networks.
This July the State Council issued the '15th Five-Year Plan' carbon-peak action plan, calling for accelerating the green and low-carbon transformation of heating and cooling systems. Many places are actively exploring paths to bring centralized cooling to residential areas. At the Minghu Yin residential project in Jinan's Tianqiao district, a show flat is already equipped with centralized-cooling devices. In the early design, some buildings were fitted with centralized-cooling equipment and terminal fan-coil units, so residents need no separate AC.
'Residents only need to switch on the temperature-control panel to enjoy the gentle cool air of centralized cooling,' said Xu Mingyong, operations manager of the Minghu Yin project. Buildings 3 and 4 are the centralized-cooling pilots; building 3 is already sold out, showing home buyers' relatively high acceptance of this new cooling method.
