District heating for China’s energy transition: Lessons from Sino-Danish collaboration

Cities are important role models for achieving sustainable green urban development. More than half the world’s population now lives in cities, which are responsible for over 70% of global energy use. Energy use in the urban areas of municipal corporations accounts for 40 to 50% of GHG emissions worldwide, compared to rural areas outside cities (Gielen 2019). In 2013, the United Nations Environment Program (UNEP) initiated research on and surveyed low-carbon cities worldwide to identify the key factors underlying their success in scaling up energy efficiency and renewable energy, as well as in attaining targets for low or zero greenhouse gas (GHG) emissions (UNEP 2015).

District energy provision, including centralized heating and/or cooling at the regional level, is a proven energy solution; indeed, in many locations with the appropriate circumstances, it has been deployed for many years in a growing number of cities worldwide (Dhar 2013) District energy systems have three main components: energy production as suppliers, distribution systems as thermal networks, and end-users as consumers(see Figure 1). They represent a diversity of technologies to develop synergies between the production and supply of heat, cooling, domestic hot water and electricity. However, there is no fixed term for 'district energy system' (DES) in use worldwide. For district heating (DH) or district cooling (DC), such systems are defined as distributing thermal energy in the form of steam, hot water or chilled liquids from a central production source through a thermal network to multiple buildings or sites for space or process heating or cooling (EU 2010).