On District Heating and Cooling Research in China

The growth of the Chinese district heating sector has been very rapid during recent years. No other country in the world can show the same rapid growth of district heating systems during the last decades. Heated building area increased six times between 1995 and 2008 according to the Chinese district heating statistics. China has also enjoyed strong growth of scientific articles and papers published about district heating in recent years. During 2010-2012, one third of all international scientific journal articles and conference papers about district heating came from Chinese scientists, while Swedish researchers accounted for one quarter. It is important to identify the Chinese district heating and cooling research to judge the potential for future collaborative research on district heating systems between Sweden/Europe and China. Until 2013, Chinese district heating and cooling scientists have published 205 international publications on district heating and 36 publications on district cooling. In this paper, these articles are mapped and summarised with respect to topics, active research institutions, and their technology focuses. Another approach is to grasp the Chinese interest for more diversified heat supply, since many new systems are established and thereby have more degrees of freedom when choosing by various heat supply and technology options. INTRODUCTION/PURPOSE China is the second largest building energy user in the world, ranked the first in residential energy consumption, the third in commercial energy consumption [1], and the highest ranks in CO2 emission, about 27% of world’s CO2 emission in the world [2]. The average annual growth rate of CO2 emission from urban district heating has been 10.3%, it was responsible for 4.4% of China’s total CO2 emission in 2009 [3]. Coal is the primary fuel in Chinese heat supply. About 40% of the air pollution in China came from coal dust [4]. In order to improve energy efficiency and reduce CO2 emission, many scientists work within the field of district heating and cooling system. The growth of the Chinese district heating sector has been very rapid during recent years. No other country in the world can show the same rapid growth of the district heating during the last 10-15 years. Heated building area and total pipe length increased 8 and 17 times, respectively, between 1995 and 2012 according to the Chinese district heating statistics [5]. In many respects, the technology used in China is similar to the technology in Scandinavian, which is characterized by high quality and has been a prerequisite for district heating high market shares in Sweden, Denmark and Finland. In the 1950s, both China and Sweden started to build district heating systems. Denmark became the guiding example for Sweden, while the former Soviet Union became the guiding example for China. Both these guiding examples started their first district heating systems in the 1920s. One important feature of Danish district heating was customer heat demand control and flow control in each substation. This feature gave automatically a proper flow allocation. The Russian systems lacked this feature, and worked with balancing valves creating average constant flow in the system. This Russian principle is a major drawback in system functioning, giving severe flow allocation problems. The huge amount of district heating comes from both Combined Heat and Power (CHP) and boilers in China, about half of each. The heat supply from CHP and boiler continues increased by year to year. In Sweden, the CHP accounted for 45% of the supplied district heating in 2011 [6]. In recent years, the interest on biofuel based CHP has increased in Sweden, while China will transfer coal boilers to natural gas boilers with higher efficiency. More than half of the heat supply to district heating systems in Sweden came from biofuel and waste, while the fuel used in China is still dominant by coal. China has become the largest national air conditioning equipment market in the world, the annual growth rate of urban households have been very high during the last 10-15 years [7]. In Sweden, district cooling is used mainly in offices and business premises and for cooling some industrial processes. To our knowledge there is no organised research cooperation between China and Sweden for district heating system and district heating technologies. The purpose of this paper is to identify the Chinese district heating and cooling research to judge the potential for future collaborative research on district heating systems between Sweden/Europe and China.