Exergy-based systems account of national resource utilization: China 2012

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Exergy-based systems account of national resource utilization: China 2012 ⁎

Bo Zhanga,b, , Zheng Menga, Lixiao Zhangc, Xudong Suna, Tasawar Hayatd,e, Ahmed Alsaedid, Bashir Ahmadd a

School of Management, China University of Mining & Technology (Beijing), Beijing 100083, PR China Research Center for Energy Strategy, State Key Laboratory of Coal Resources and Safe Mining, China University of Mining & Technology (Beijing), Beijing 100083, PR China c State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Beijing Normal University, Beijing 100875, PR China d NAAM Group, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia e Department of Mathematics, Quaid-i-Azam University, 45320, Islamabad, Pakistan b

A R T I C L E I N F O

A B S T R A C T

Keywords: Exergy accounting Resource use Systems diagram Physical sustainability China

Resource input is the prerequisite to maintain the operation of socio-economic systems. Exergy analysis provides a wide and clear vision of the use and degradation of natural resources, with essential implications to sustainability. This paper aims to perform an exergy-based system account of the resource utilization in China, one of the most complex societies around the world. An overall systems diagram with seven independent and complimentary social departments is designed to illustrate the clear-cut processes of resource use and exergy destruction and loss. The national total input of resource exergy in 2012 reached 158.11 EJ, with the net input of 155.87 EJ. Its per capita resource consumption increased to 111.95 GJ, compared with 51.5 GJ in 2003. Industry accounted for 26.3% of the total resource exergy consumption, followed by Conversion 23.2%, Household 18.3%, Agriculture 10.2%, Tertiary 10.0%, Exaction 6.7% and Transportation 5.3%. The sectoral conversion coefficients of resource exergy were estimated as 91.92% for Extraction, 34.58% for Conversion, 29.75% for Agriculture, 32.18% for Industry, 18.46% for Transportation, 34.28% for Tertiary and only 1.28% for Household. The structure and efficiencies of resource exergy use of the Chinese society haven’t witnessed a prominent improvement in the recent decade, and its resource utilization performance was still inferior to those of some industrialized societies. Exergy-based unified accounting for a benchmark year provides solid foundation for resource policy formation and can serve as the tool for identifying resource footprint and sustainable development mode.

1. Introduction Natural resources are the material basis and basic driving force to sustain socio-economic development (Warr and Ayres, 2012). The use of resources is an irreversible course, while excessive consumption of non-renewable resources will have adverse effects on human society (Nguyen and Yamamoto, 2007). Using a unified accounting tool, such as thermodynamic concepts, to measure the availability of resources and evaluate resource use efficiency is a pre-requisite to evaluate natural resource utilization and related environmental impacts (Chen, 2006; Dewulf et al., 2008; Valero et al., 2015). As the outcome of the combination of the first and second laws of thermodynamics, exergy is defined as the maximum amount of work which can be produced by a system such as a flow of matter or energy carrier as it comes into equilibrium with a reference environment (Szargut, 2005; Sciubba and Wall, 2007). Distinguishing from the traditional economic analysis, exergy accounting with solid scientific basis provides a unified way for ⁎

the measurement of all kinds of natural and human-made resources (Wall, 1977; Tsatsaronis, 2007). The potential usefulness or ability to perform work for each type of natural resource is its exergy content. Exergy analysis can provide a wide and clear vision of the use and degradation of natural resources (Sciubba, 2005; Valero and Valero, 2010). Owing to the scarcities of diverse resources (Szargut, 1978; Chen, 2005, 2006; Hermann, 2006), minimizing resource exergy utilization at different scales is essential for promoting sustainable development (Gong and Wall, 2001; Dincer and Rosen, 2007; Gasparatos and Scolobig, 2012). Societal exergy account for the use and conversion of natural resources was firstly introduced by Wall (1977) covering both energy carriers and materials. Since then, exergy analysis has developed into a widely accepted approach for the unified account of resources extraction, conversion and consumption. The accounting of resources exergy can reflect the internal exergy change of irreversibility and provide a better understanding of the resource use and degradation in a society

Corresponding author at: School of Management, China University of Mining & Technology (Beijing), Ding No.11 Xueyuan Road, Haidian District, Beijing 100083, PR China. E-mail addresses: [email protected], [email protected] (B. Zhang).

http://dx.doi.org/10.1016/j.resconrec.2017.05.011 Received 24 December 2016; Received in revised form 23 April 2017; Accepted 24 May 2017 0921-3449/ © 2017 Elsevier B.V. All rights reserved.

Please cite this article as: Zhang, B., Resources, Conservation & Recycling (2017), http://dx.doi.org/10.1016/j.resconrec.2017.05.011

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systematic accounting and assessment for China’s resources utilization with a unitary and objective measure, adapting to the new circumstance. The aim of this paper is to systematically examine the resource procurement, allocation and consumption of the Chinese society in 2012 based on exergy unifying accounting method. For the Chinese society broken down into seven independent and supplementary sectors as the subsystems, a systems account of resource exergy utilization can illustrate the complex process and network relationship of resource exergy fluxes. A new system diagram is devised to display the integrity and hierarchy of resource exergy utilization across the social network. Furthermore, comparisons of resource utilization structures and efficiencies with other societies and the Chinese society in previous years will facilitate the understanding of the country’s resource use patterns on the international and development horizons. An overall exergy analysis of national resource utilization will be useful for identifying resource metabolism pattern of specific social system and providing solid foundation in establishing effective regulatory strategies of economic activities to accelerate a shift towards sustainability.

(Wall, 1990; Zhang and Chen, 2010). In recent two decades, a large number of studies have analyzed the resource exergy utilization of different countries (e.g., Ertesvåg and Mielnik, 2000; Ayres et al., 2003; Ertesvåg, 2005; Warr et al., 2008; Gasparatos et al., 2009a; Koroneos et al., 2011; Seckin et al., 2012; Al-Ghandoor, 2013; Gong and Wall, 2016), concrete regions (e.g., Liu et al., 2011; Bligh and Ugursal, 2012; Nielsen and Jørgensen, 2015), and specific industrial sectors or production systems (e.g., Dincer et al., 2004; Ji and Chen, 2006; Ignatenko et al., 2007; Koroneos and Nanaki, 2008; Chen et al., 2009; Gasparatos et al., 2009b; Yang et al., 2009; Ahamed et al., 2011; Chen et al., 2011; Zhang et al., 2011; Sanaei et al., 2012; Zhang et al., 2012b; Seckin et al., 2013; Liu et al., 2014; Yang and Chen, 2014; Shao and Chen, 2015; Wu et al., 2015; Bühler et al., 2016), which have provided strong evidence that exergy analysis is a valuable practical technology to quantify resource use. Moreover, systems account of exergy resource utilization for typical macroscopic systems can effectively reveal their functioning or metabolism structure and provide the basis for the ecological diagnosis of the large complex socio-economic systems, with essential implications to physical sustainability (Gong and Wall, 2001; Dewulf and Langenhove, 2005; Rosen et al., 2008). As one of the most complex social systems around the world, China’s social metabolisms are maintained by a large quantity of energy and material resources (Dai et al., 2012). An et al. (2014) reported that the natural resources input such as energy resources kept pace with the rapid growth of the country’s gross domestic product (GDP). Given the complexity of social systems, the extraction and procurement of natural resources in the Chinese society regularly encompass raw coal, crude oil, natural gas, hydropower, wind power, nuclear power, agricultural products, forest yields, bio-fuels (straw, firewood), metal ores, nonmetal minerals, recycling materials and others, while the outputs as products or services consist of nonferrous metals, steel, chemicals, electricity, paper, food, lighting, mechanical work, space heating, cooking, water and process heating, transportation, etc. (Zhang and Chen, 2010). Some scholars have performed exergy-based resource accounting for the Chinese society in a given year (e.g., Chen and Chen, 2006; Chen et al., 2006; Chen and Qi, 2007; Zhang and Chen, 2010; Shao et al., 2013) and in the time-series periods (Chen and Chen, 2007a,b,c; Chen et al., 2014; An et al., 2014). For instance, Chen et al. (2014) and An et al. (2014) investigated the variation of natural resource production in China within an exergy foundation. By considering the network structure of societal exergy fluxes, Chen and Qi (2007) and Zhang and Chen (2010) presented the system account of resource uses in China 2003 and 2006, respectively. In addition, Chen and his colleagues (e.g., Chen and Chen, 2009; Dai et al., 2012, 2014) focused on the extended exergy analyses for China society including socio-economic factors such as labor and capital. Nevertheless, the literature list of exergy analysis of the Chinese society, specifically focusing on the resource utilization, is still very short. It is worth noting that the current resource situation within China including the scale and structure of resources input/output become more complicated, when the country is speeding up the process of industrialization and urbanization. China recorded as the world’s largest primary energy producer and consumer, and this country alone consumed about half of global coal in 2012 (BP, 2016). The degree of dependence on commodity imports such as oil, natural gas, ores and some agricultural products continue to increase, and the influences of foreign trade on the economy are continually expanding. The main industrial products have also expanded rapidly in the recent decade. For instance, the outputs of crude steel, ten major nonferrous metals, motor vehicles, ethylene, cement, plate glass, electricity, chemical fiber and primary plastic in 2012 were 3.9, 3.3, 4.6, 2.6, 2.4, 2.8, 2.5, 4.4 and 3.8 times of those in 2000, respectively (NBSC, 2013). In view of the drastic socioeconomic transition, previous studies are insufficient to explain the current state of the Chinese society and may be no longer applicable to an efficient understanding of the country’s resource use (Brockway et al., 2015). Therefore, this context necessitates a

2. Methodology and data sources In the accounting of resource exergy in a society, it is important to understand the main factors that affect exergy conversion process, and to simplify the complex data processing to avoid repetitive and trivial calculation (Chen and Qi, 2007). Resource input into the Chinese society contains the imported, gathered and extracted commodities as exergy carriers. The entrance and boundary points are set at the same level to avoid repetitive and cross calculations of exergy fluxes. To keep consistency with previous studies, the Chinese society is classified into seven sectors, i.e., the extraction (Ex), conversion (Co), agriculture (Ag), industry (In), transportation (Tr), tertiary (Te) and households (Do). The extraction sector includes mining and quarrying, and oil and natural gas refining and processing. The conversion sector mainly refers to electricity and heat production from power and heat plants. The department of agriculture is the source of people's food and clothing, covering crop farming, forestry, animal husbandry, fishery, water conservancy and food processing. In this study, the industry sector mainly refers to the manufacturing industries except oil refineries. The transportation sector represents the commercial transportation services (passenger, goods) as well as services directly related to transportation (e.g., storage, dak). The tertiary sector includes wholesale, retail, hotels, entertainment, restaurant, finance, real estate, construction, and public services such as governments, hospitals, and schools, but excluding transportation services (Zhang and Chen, 2010). The domestic sector comprises urban households and rural households. All the resource data are processed according to the special characteristics of sectoral socioeconomic status as embodied in relevant statistics. In the updated energy statistical yearbook of China (CESY, 2014), the usual energy carriers include coal, coke, oil and petroleum products, natural gas, electricity and district heat. Most primary energy data are available from China Electric Power Yearbook 2013 (CEPY, 2013), China Energy Statistical Yearbook 2014 (CESY, 2014) and China Statistical Yearbook 2013 (NBSC, 2013). The lower heating values of traditional fossil fuels including coal, oil and natural gas are adopted from China Energy Statistical Yearbook 2014. The mineral resources can be divided into three parts in terms of ferrous metal minerals, non-ferrous metal minerals and non-metallic minerals. Corresponding statistical data can be obtained from Chinese Iron and Steel Yearbook 2013 (CISIY, 2013), China Mining Yearbook 2013 (CMY, 2013), China Nonferrous Metals Yearbook 2013 (CNMY, 2013) and China Statistical Yearbook 2013 (NBSC, 2013). The biomass resources are supplied by agricultural production in terms of cropping, forest, stockbreeding and fishery. The agricultural statistical data are mainly available from China Agriculture Yearbook 2013 (CAY, 2013) (e.g., rice, wheat, oil crops, other agricultural 2

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in 2006. The consumption of energy carriers is shown in Table 2. 9054.49 PJ coal was used in coal mining and washing (CMW), 109.89 PJ in oil and gas extraction (OGE), and 403.83 PJ in other mining (OMA). 9288.40 PJ coal was consumed in oil refining and coking (ORC). The use of oil and its products totaled 20641.55 PJ, of which 106.28 PJ, 517.02 PJ, 184.37 PJ and 19833.87 PJ were used in CMW, OGE, OMA and ORC, respectively. Unlike the former three items in terms of CMW, OGE and OMA, the energy uses in ORC as raw materials mainly were converted to other energy carriers such as coke and petroleum products. Table 3 lists the output of energy carriers covering the inland supply and exports. The total exergy output of this sector was 113859.59 PJ, of which 2114.46 PJ was exported. Coal contributed the largest output of 72753.18 PJ, followed by oil and PP of 22537 PJ. Only 5239.39 PJ was contributed by natural gas. Other than fossil fuels regarded as energy carriers, most of minerals are used as raw materials for metallurgical industry, chemical industry, other industries and other societal sectors. Mineral resources can be classified as ferrous metal, non-ferrous metal and non-metallic minerals. The ferrous metal minerals mainly include iron ore, manganese ore and chrome ore, which are the major raw materials for the iron and steel industry. The nonferrous metal minerals include copper, aluminum, lead, zinc, tin etc. Non-metallic minerals (e.g., graphite, limestone and pyrite) are important natural resource input in the construction and chemical industry. These raw materials are mainly from domestic extraction and partly imported from abroad. Recycled metals from the Te-sector and the Do-sector are also very important. The analyses of mineral materials will be presented in the subsequent sections.

products and aquatic products), China Forestry Statistical Yearbook 2013 (CFSY, 2013) (e.g., wood, bamboo), and China Rural Statistical Yearbook 2013 (CRSY, 2013) (firewood and biogas). In addition, the recycling waste is also an important part of resource inputs, such as waste paper, scrap metal and garbage (CRRY, 2013). A variety of industrial products need to be investigated as the output of specific sectors. The statistical data of manufacturing product consumption and related industrial production are adopted from China Energy Statistical Yearbook of 2014, China Industry Statistical Yearbook 2013 (CISY, 2013), China Circular Economy Yearbook 2013 (CCEY, 2013), China Paper Industry Yearbook 2013 (CPIY, 2013), China Statistical Yearbook of the Tertiary Industry (CSYTI, 2013), China Transportation Yearbook 2013 (CTY, 2013) and other statistical yearbooks. All the imports and exports of commodities are derived from some statistical yearbooks such as China Foreign Economic Statistical Yearbook 2013 (CFESY, 2013). According to the basic definition of exergy, the reference environment needs to be clarified. As to the systems account at a national scale in this study, it is reasonable to select a global standard environment model to resemble the atmosphere, the ocean and the earth’s upper crust with average geophysical chemical characteristics as the reference environment (Chen and Qi, 2007). The chemical exergy of various resources including energy and materials can be calculated according to the chemical potential and chemical concentration of substance in its present state and reference environment (Zhang and Chen, 2010). Szargut (2005) provided the standard chemical energy for various elements and compounds. Wall (1986) provided the chemical exergy of some traditional resources. For a large-scale national account, thermophysical exergy of the materials can be neglected, compared with chemical exergy (Wall, 1977). Detailed resource categories and exergy coefficients of the accounted resources are listed in Table S1 of Supplementary material. Extensive illustrations for the exergy account of various resources in China have been specifically provided by Chen and his colleagues in their series works on resources accounting (e.g., Chen and Qi, 2007; Zhang and Chen, 2010; Zhang et al., 2012b; Dai et al., 2014).

3.2. Conversion sector The total input of energy carriers into the Co-sector was 53543.37 PJ, of which 47352.93 PJ was from the Ex-sector. As listed in Table 4, coal consumption summed up to 46023.04 PJ by exergy, of which 40743.88 PJ was used for thermal power to produce electricity. In addition, 973.87 PJ natural gas and 356.02 PJ oil and petroleum products were used by this sector. The water potential energy input was 3422.40 PJ and contributed 3080.16 PJ electric power. About 1179.6 PJ nuclear power input resulted in 353.88 PJ electricity output. The input of wind energy was estimated at 1236.00 PJ and its wind power generation was 370.8 PJ. Moreover, exergy input from the Te-sector was the recycling waste with an amount of 327.96 PJ, though its conversion efficiency was only 10% (Ertesvåg, 2005). The main output of this sector was electricity and district heat. The total electricity production was 17951.4 PJ, of which thermal power accounted for 78.72% of the total, hydropower 17.16%, wind power 2.07%, nuclear power 1.97%, and the others only 0.08% (see Table 5). In addition, 63.55 PJ electricity was exported to the Association of Southeast Asian Nations (ASEAN), and 24.75 PJ was imported mostly

3. Exergy accounting 3.1. Extraction sector The input of energy carriers into the Ex-sector comprise fossil fuels extracted from the environment, including coal, crude oil and natural gas, and secondary energy sources such as coke and electricity, as shown in Table 1. Coal takes a large and stable proportion of China’s energy resource production (An et al., 2014). In 2012, coal maintained a dominance share of 73.93% in the total energy extraction. Oil and petroleum products as the second largest energy input accounted for 18.96%, against 23.0% in 2006. In particular, 58.76% of the oil and its products were from abroad, compared with 43.0% in 2003 and 51.9% Table 1 Input of energy carriers into the Ex-sector (Unit: PJ). Source: CESY (2014). Category

Coal Coke Oil and PP Natural gas Electricity Total input

Total

Inland supply

Storage contribution

Imported

Energy

Exergy

Energy

Exergy

Energy

Exergy

Energy

Exergy

87874.75 308.83 21418.66 5220.13 1100.07 115922.44

93147.24 324.29 23132.16 5428.94 1100.07 123132.70

82624.42

87581.89

8702.55 4360.51 1075.32 96762.80

9398.75 4534.93 1075.32 102590.89

−789.98 306.67 −875.65

−837.38 322.02 −945.7

−1358.96

−1461.06

6040.31 2.16 13591.76 859.62 24.75 20518.6

6402.73 2.27 14679.1 894.01 24.75 22002.86

Note: Storage contribution, i.e., stock change, equals to the difference of stock between the beginning and end of the year with the negative figure indicating increasing storage. PP: petroleum products.

3

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Table 2 Use of energy carriers within the Ex-sector (Unit: PJ). Source: CESY (2014). Energy carrier

Total use

Extraction

CMW

OGE

OMA

ORC

Coal Coke Oil and PP Natural gas Electricity Sum

18856.24 97.18 20641.55 1016.80 1075.32 41687.09

9568.2 75.05 807.68 610.90 861.12 11922.95

9054.49 19.44 106.28 45.10 316.44 9541.75

109.89

403.82 55.61 184.37 41.00 401.76 1086.56

9288.04 22.13 19833.87 405.90 214.20 29764.14

Table 3 Output of energy carriers from the Ex-sector (Unit: PJ). Source: CMY (2013); CESY (2014). Energy carrier

Coal Coke Oil and PP Natural gas Total output

Total

517.02 524.80 142.92 1294.63

Table 5 Electricity production of the Co-sector. Source: CESY (2014); NBSC (2013).

Inland supply

Exported

Energy

Exergy

Energy

Exergy

Energy

Exergy

68635.06 12695.26 21062.62 5037.87 107430.8

72753.18 13330.02 22537.00 5239.39 113859.6

68440.71 12666.21 19418.27 4923.94 105449.1

72547.16 13299.52 20777.55 5120.9 111745.1

194.35 29.05 1644.35 113.93 1981.68

206.02 30.50 1759.45 118.49 2114.46

from Russia. In addition, the total input of hydropower, nuclear power, wind power and other renewable power increased from 1768 PJ in 2003–5838.00 PJ in 2012. The gross output of energy carriers from this sector amounted to 18636.01 PJ by exergy, of which electricity was 17953.35 PJ and heating was 682.66 PJ. Table 6 shows the detailed output of energy carriers for inland supply and exports. The real outputs of energy carriers inputted into other sectors may be less than the data listed in Table 6, in view of the loss in the power grid and low conversion efficiency of space heating.

Source

Electricity (108 kWh)

Exergy (PJ)

Fraction

Total domestic production Thermal power Hydropower Nuclear power Wind power Other power Imports Exports

49865 39255 8556 983 1030 41 68.74 176.53

17951.4 14131.8 3080.16 353.88 370.8 14.76 24.75 63.55

100.00% 78.72% 17.16% 1.97% 2.07% 0.08%

Table 6 Output of energy carriers from the Co-sector (Unit: PJ). Source: CESY (2014); CEPY (2013). Item

Electricity Heating Total

Total

Inland supply

Exported

Energy

Exergy

Energy

Exergy

Energy

Exergy

17953.35 3413.3 21366.65

17953.35 682.66 18636.01

17889.8 3413.3 21303.1

17889.8 682.66 18572.46

63.55

63.55

63.55

63.55

of the total domestic input, of which timber contributed 468.16 PJ, vegetable oil 203.65 PJ, beans 227.68 PJ and grain 123.86 PJ. The gross inputs of energy carriers and industrial products amounted to 6026.35 PJ by exergy, of which 4066.13 PJ (67.47% of the total) was used for agricultural activities and 1960.22 PJ (35.53%) for food processing, as listed in Table 9. The consumption of industrial products from the In-sector totaled 2483.35 PJ by exergy, of which chemical fertilizer reached 2193.35 PJ and pesticide 290.00 PJ. As to the energy carriers, 2834.75 PJ was from the Ex-sector and 708.25 PJ from the Co-sector. Table 10 lists the exported exergy from the Ag-sector. The exported exergy of raw materials amounted to 60.73 PJ. It can be concluded that

3.3. Agriculture sector The main input into the Ag-sector can be divided into three parts, the indigenous and imported natural resources, the fertilizer and pesticide from the In-sector, and the energy carriers provided by the Exsector (e.g., coal, oil and PP) and the Co-sector (electricity and heat). The major natural resource inputs into the Ag-sector were the harvest production, as listed in Tables 7 and 8. The domestic yield exergy inputted into this sector was 13901.93 PJ, of which 10641.49 PJ was from farm products, 1063.12 PJ from forest products, 1854.66 PJ from livestock products and 342.66 PJ from aquatic products. In addition, the imported yield exergy was only 1176 PJ, being equivalent to 8.46% Table 4 Input of energy carriers into the Co-sector (Unit: PJ). Source: CESY (2014); NBSC (2013); CEPY (2013). Energy carrier

Coal Oil and PP Natural gas Input from Ex-sector Waterfall energy Nuclear energy Wind Power Waste (from Te-sector) Total domestic input Electricity (imported) Total input

Total

Thermal power and other power

Heating supply

Energy

Exergy

Energy

Exergy

Energy

Exergy

43417.96 332.73 936.42 44687.11 3422.40 1120.60 1236.00 327.96 50605.10 24.75 50818.55

46023.04 356.02 973.87 47352.93 3422.40 1179.60 1236.00 327.96 53329.92 24.75 53543.37

38437.62 123.79 805.85 39367.26 3422.40 1120.60 1236.00 327.96 45285.25 24.75 45498.7

40743.88 132.45 838.08 41714.41 3422.40 1179.60 1236.00 327.96 47691.40 24.75 47904.85

4980.34 208.94 130.57 5319.85

5279.16 223.56 135.79 5638.51

5319.85

5638.51

5319.85

5638.51

4

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Table 7 Input of the yield exergy into the Ag-sector. Source: CAY (2013); CFIN (2013).

Table 10 Exported exergy from the Ag-sector. Source: CAY (2013).

Item

Mass (Mt)

Exergy (PJ)

Item

Mass (Mt)

Exergy (PJ)

Rice Wheat Corn Other corn Beans Potatoes Peanut Rapeseed Sesame Other oil crops Cotton Hemp Sugarcane and beet Tea and tobacco Vegetable Fruit Total farm products Wood Bamboo Total forest products Pork Beef Mutton Milk Egg Silkworm cocoon Wool Total livestock products Total aquatic products Total

204.24 121.02 205.61 8.47 17.31 32.93 16.69 14.01 0.64 3.03 6.84 0.26 134.85 5.20 708.83 240.57 10641.49 81.75(M m3) 25.57 1063.12 53.43 6.62 4.01 38.75 28.61 0.91 0.40 1854.66 59.08

3226.93 1682.22 1768.28 72.87 67.49 138.30 410.61 518.27 18.54 87.85 112.11 4.28 674.27 55.60 1346.78 457.08

Grain Beans Peanut Vegetable oil Sugar Cotton yarn Tea and tobacco Fruit Vegetable Meat Egg Aquatic products Total

0.28 0.32 0.15 0.10 0.05 0.26 0.41 1.92 7.41 0.34 0.12 3.68

2.48 1.25 3.69 2.41 0.83 2.24 4.39 3.65 14.08 3.64 0.74 21.34 60.73

capita per year (Zhang and Chen, 2010). The total population of China was 1354.04 million in 2012, of which 711.82 million were in urban areas and 642.22 million in rural areas. The total exergy of food consumption in the Do-sector amounted to 4874.54 PJ. It is assumed that the exergy inflows of harvests from the Ag-sector directly enter into the Do-sector in rural areas, whereas the foods from the Te-sector flow into the Do-sector in urban areas. By considering a 5% loss in the Do-sector and a 10% loss for the Te-sector, referring to previous studies (e.g., Chen and Qi, 2007; Chen et al., 2009; Zhang and Chen, 2010), the food supply from the Ag-sector can be calculated to be 2847.27 PJ for the Tesector and 2433.68 PJ for the Do-sector.

654.00 409.12 1341.09 76.13 64.56 189.88 177.38 4.10 1.52 342.66 13901.93

3.4. Industry sector Table 8 Imported yield exergy to the Ag-sector. Source: CFESY (2013); NBSC (2013). Item

Mass(Mt)

Exergy(PJ)

Grain Beans Cotton Wool Hemp Vegetable oil Sugar Timber Total

13.98 58.38 5.13 0.32 0.33 8.45 3.75 58.52 (Mm3)

123.86 227.68 84.13 1.22 5.41 203.65 61.89 468.16 1176.00

As the stanchion of national economy, the In-sector always has the largest resource exergy consumption. According to the important, concrete process of resource exegy utilization, this sector can be divided into seven subsystems in term of iron and steel industry, nonferrous metal industry, nonmetal industry, chemical industry, textile industry, wood and paper industry, and other sub-sectors. Totally, the energy carriers used in the In-sector was 52617.69 PJ, of which coal contributed 25866.33 PJ, coke 13258.55 PJ, and electricity 8701.82 PJ. Detailed results are shown in Table 11. 3.4.1. Iron and steel industry The total input of energy carriers into the iron and steel industry amounted to 21139.05 PJ, as listed in Table S2. The total input of iron ore as the main raw material reached 2053.24 Mt, of which 1309.6 Mt was from domestic mining and 743.6 Mt was imported from abroad. It was worth noting that the iron content of domestic mine was about half of that of the imported concentrated iron ore, and 1.0 t imported ore is equal to about 2.0 t lean ore of inland (Zhang and Chen, 2010). The imported iron ore contributed 624.62 PJ by exergy and the domestic mine only provided 550.05 PJ to this sub-sector. Manganese ore and chromite ore contributed 4.08 PJ and 3.77 PJ, respectively. Compared with the output of 413.6 Mt pig iron, 421.0 Mt crude steel and 470.8 Mt steel products in 2006, their values in 2012 increased to 670.1 Mt, 731.04 Mt and 950.65 Mt, respectively. The exergy of the steel products was 6464.42 PJ, of which the exported steel and steel billet was 378.96 PJ, much larger than the imports of 92.82 PJ. In 2003, the exergy of iron and steel products was only 1639.5 PJ (241.1 Mt).

Table 9 Input of energy carriers and chemical products into the Ag-sector (Unit: PJ). Source: NBSC (2013); CESY (2014). Item

Coal Coke Oil and PP Natural gas Input from Ex-sector Electricity Heat Input from Co-sector Fertilizer Pesticide Total input

Total

Agriculture

Food processing

Energy

Exergy

Exergy

Exergy

1880.72 20.70 712.39 55.19 2669.00 707.97 1.41 709.38 2193.35 290.00 5861.73

1993.56 21.53 762.26 57.40 2834.75 707.97 0.28 708.25 2193.35 290.00 6026.35

503.05 17.04 693.78 4.10 1217.97 364.53 0.28 364.81 2193.35 290.00 4066.13

1490.51 4.49 68.48 53.30 1616.78 343.44 343.44

1960.22

3.4.2. Nonferrous metal industry The total input of energy carriers into the nonferrous metal industry was 3365.74 PJ, of which 1990.87 PJ was from the Ex-sector and 1374.87 PJ from the Co-sector (see Table 11). As shown in Table S3, 468.32 PJ mineral materials were invested, of which 95.19 PJ was

China was a net importer of agricultural products, though a majority of agricultural resources were supplied by the domestic harvests. The average food intake of Chinese people was about 3.6 GJ per 5

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Table 11 Use of energy carriers in the In-sector, exergy figure (Unit: PJ). Source: CESY (2014); NBSC (2013). Item

Coal

Coke

Petroleum products

Natural gas

Electricity

Textile Wood and paper Iron and steel Nonferrous metal Nonmetal Chemical Other Total

799.64 1348.21 7571.09 1635.70 7149.51 6224.21 1137.97 25866.33

2.09 1.50 11502.53 184.48 295.11 929.89 342.95 13258.55

48.92 33.07 50.74 58.89 243.26 1712.8 207.93 2355.61

12.30 24.60 135.30 111.80 282.90 1135.70 246.00 1948.60

647.33 358.56 1879.39 1374.87 1062.45 1904.49 1474.73 8701.82

Heat

Total

486.78

1510.28 1765.94 21139.05 3365.74 9033.23 11907.09 3409.58 52617.69

Note: Only the total amount of heat used by the In-sector was provided in CESY (2014).

utilized 1407.38 PJ exergy of energy carriers from the Ex-sector and 358.56 PJ from the Co-sector. As to the input of industrial raw materials into this sub-sector (see Table S9), 1626.08 PJ were from the Ag-sector (mainly wood, bamboo and straw), 760.24 PJ from the Te-sector and 1149.55 PJ from abroad. Since the total yield of crop harvest was 630.0 Mt, the straw output was estimated to be 756.0 Mt, about 50.0% of which could be recycled as industrial materials (Zhang and Chen, 2010), with the exergy value of 5564.00 PJ. Owing to the low recovery rate, about 556.40 PJ straw was utilized in the In-sector. Table S10 shows that the major products of this industry were paper, cardboard and wood products. The output of paper and cardboard was 1862.69 PJ and wood products 654.00 PJ. In addition, the exported paper and cardboard amounted to 79.90 PJ, accounting for 4.3% of the total paper and cardboard yield. The exported wood products were only 3.76 PJ.

provided by the Ex-sector, 192.81 PJ by imports and 180.32 PJ by the Te-sector.Copper ore extracted inland was 159.21 Mt or 4.78 PJ, and imported 7.83 Mt concentrated copper gave 8.61 PJ. The exergy of alumina ore was 177.34 PJ, within inland production of 88.1 PJ and imports of 89.24 PJ. The yield of total ten nonferrous metals (copper, aluminum, lead, zinc, tin, nickel, tungsten, molybdenum, magnesium and stibium) was 36.97 Mt, the largest output in the world. The total product exergy of all the ten nonferrous metals was estimated at 786.74 PJ, as listed in Table S4. In addition, the imports and exports of the nonferrous metal products were 52.27 PJ and 190.21 PJ, respectively (see Table S5). 3.4.3. Nonmetal industry The total consumption of energy carriers to produce nonmetal products in this sub-sector was 9033.23 PJ, as listed in Table 11. As to the raw materials, graphite had the largest exergy content with an amount of 102.8 PJ. Pyrite has been widely used in the chemical industry to produce sulfur and sulfuric acid. The production of pyrite amounted to 8.86 Mt or 79.74 PJ. 63.23 Mt phosphorite gave 6.32 PJ exergy. Crude salt as the raw materials of industrial salt and food-grade salt had the exergy amount of 14.96 PJ. 1035.45 Mt limestone contributed only 10.35 PJ by exergy, due to its low exergy content. Details are shown in Table S6.

3.4.7. Other subsectors The other industry refers to machinery industry, electronic industry, medical industry, etc. The exergy usage of energy carriers in other industry was 3409.58 PJ, which was only 6.50% of the total in the Insector. Based on the proportion assumption in Chen and Qi (2007), the output of this subsector was estimated as 23% of the input, i.e., 784.2 PJ, of which 235.26 PJ was for exports.

3.4.4. Chemical industry The total input of energy carriers into the chemical industry amounted to 11907.09 PJ, of which 10002.60 PJ was provided by the Ex-sector and 1904.49 PJ by the Co-sector (mainly electricity). In addition, 709.85 PJ chemical fibers were invested to the textile industry. The products of this sub-sector mainly comprised cement, fertilizer, chemical fiber, plastic and sulfuric acid. As shown in Table S7, 3314.76 PJ cement and 1732.58 PJ plastic were supplied to construction activities belonging to the Te-sector, whilst 2193.35 PJ fertilizer and 290.00 PJ pesticide were inputted into the Ag-sector. The exergy content of domestic fertilizer production was calculated to be 2534.67 PJ, larger than the demand of the Ag-sector

3.4.8. Overall outputs of industrial products Due to the limitation of data and information, the main outflows of industrial products by exergy were roughly investigated. Table 12 lists the domestic use and exports of industrial products. In fact, some industrial products were the interior uses within the In-sector. For instance, chemical fiber products of the chemical industry can be regarded as raw materials of the textile industry. On the whole, the total domestic use in other sectors can be calculated as 16990.70 PJ, of which 12912.71 PJ was inputted into the Te-sector (68.38% of the total), 3124.43 PJ into the Ag-sector (16.55%), 699.04 PJ into the Trsector (3.70%), 181.8 PJ into the Ex-sector (0.96%) and 72.72 PJ into the Co-sector (0.39%). For instance, according to the consumption statistics of steel products in CISIY (2013), the steel for real estate (belonging to the Te-sector) accounted for 45.4% of the total steel

3.4.5. Textile industry The exergy of energy carriers invested in textile industry was 1510.28 PJ. Texile materials from the Ag-sector, gave 122.00 PJ exergy, including cotton, hemp, wool, silkworm, cocoon, etc. The raw material provided by the chemical industry was chemical fiber, about 709.85 PJ. The product exergy of the textile industry was 1284.72 PJ (see in Table S8), of which 489.38 PJ was from yarn, 87.55 PJ from wool, 5.67 PJ from silk, and 701.52 PJ from chemical fiber fabric. Particularly, the yield of chemical fiber fabric increased from 145.5 PJ in 2003–701.52 PJ in 2012.

Table 12 Domestic use and exports of industry products (Unit: PJ).

3.4.6. Wood and paper industry The wood and paper industry is constituted by paper making, paper producing, wood producing and bamboo producing. This sub-sector 6

Industry subsector

Ex

Co

Iron and steel Nonferrous metal Chemical Textile Wood and paper Others (including nonmetal) Total Fraction (%)

161.61 20.19

64.64 8.08

Ag

Tr

Te

Exports

458.97 57.33

378.96 190.21 294.58 213.26 83.66 732.90 1893.57 10.03

299.76

182.74

2934.85 366.6 5462.61 488.26 2433.03 1227.36

3124.43 16.55

699.04 3.70

12912.71 68.38

2824.67

181.80 0.96

72.72 0.39

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Table 13 Input of energy carriers into the Tr-sector. Source: NBSC (2013); CESY (2014).

Table 15 Input of energy carriers into the Te-sector (Unit: PJ). Source: CESY (2014); NBSC (2013).

Item

Mass(Mt)

Exergy(PJ)

Item

Mass (Mt)

Exergy (PJ)

Coal Petroleum products Natural gas Total from the Ex-sector Electricity Total from the Co-sector Total

6.14 177.7 154.51 (108 m3)

136.31 8049.81 633.49 8819.61 329.53 329.53 9149.14

Coal Coke Petroleum products Natural gas Input from the Ex-sector Electricity Heat Input from the Co-sector Total

84.02 0.15 43.06 72.83 (108 m3)

1865.24 4.49 1950.62 298.6 4118.95 1938.07 28.62 1966.69 6085.64

915.37 (108kW h)

products (2935.85 PJ), steel for industrial activities 44.0%, steel for construction activities belonging to the Ex-sector 2.5% (161.61 PJ), steel for the Co-sector’s production 1.0% (64.64 PJ), and steel for transportation construction 7.1% (458.97 PJ). In addition, the exergetic value of industrial products used for exports was 1893.57 PJ.

sector was 6085.64 PJ, of which 4118.95 PJ from the Ex-sector and 1966.69 PJ from the Co-sector. With regard to the Ex-sector’s input, petroleum products contributed the largest amount of 1950.62 PJ, followed by coal of 1865.24 PJ, natural gas of 298.60 PJ and coke of 4.49 PJ. In addition, 1938.07 PJ electricity and 28.62 PJ heat from the Co-sector were supplied to this sector. Furthermore, stone and gravel from the Ex-sector contributed 42.69 PJ into the real estate and construction activities of this sector. The maximum exergy input into the Te-sector was industrial products, amounting to 12912.71 PJ (see in Table 12). The Tr-sector also contributed 722.06 PJ to this sector as shown in Table 14. The main output of the Te-sector was food, which was supplied to the Do-sector with 2847.27PJ. Other output such as resale of industry products to the Do-sector amounted to 3873.81 PJ. This sector also provided 327.96 PJ waste energy by exergy to the Co-sector. Particularly, about 361.36 PJ from the Do-sector was consumed in the Te-sector (Zhang and Chen, 2010; CCEY, 2013), which can be divided into two parts in terms of recycled materials (262.97 PJ) and the waste for energy (98.39 PJ).

3.5. Transportation sector As shown in Table 13, the energy carriers input into the Tr-sector totaled 9149.14 PJ, of which petroleum products (PP) were the primary energy carriers with 8049.81 PJ by exergy, accounting for 87.98% of the sectoral total and 34.48% of the national total PP consumption. Meanwhile, 136.31 PJ coal was consumed in this sector. It is worthy of noting that the rapid development of gas-fueled public transportation resulted in the increase of natural gas use, 633.49 PJ, compared with an amount of only 70.70 PJ by exergy in 2006. 329.53 PJ electricity was used in railways, urban public transportation and other transportation services. The industrial raw materials and transportation equipments were mainly provided from the In-sector, with 699.04 PJ industrial products consumed in the Tr-sector. The overall exergy conversion coefficient of utilizing energy carriers for the Tr-sector was estimated to be 20.0% (Ji and Chen, 2006), and the output in this sector was about 1829.83 PJ by exergy. The passenger turnover (PT) of each mode (railways, highways, waterways and civil aviation) was converted into corresponding freight turnover by multiplying a conversion coefficient (See Table S11). By adding up the equivalent freight turnover, a total quantity for passenger transport was obtained. The output of the Tr-sector could be assigned for each sector based on the proportion in the total freight turnover (Zhang and Chen, 2010). About 50% of PT was conducted for the Do-sector, and the remaining PT was divided for other sectors according to their shares in the total labor work-hours, referring to previous studies (Ertesvåg, 2005; Zhang and Chen, 2010). The total number of labor was taken as a substitute by assuming an equal work-hour for each labor. The results of freight transport can be listed in Table S12, which comprised railways, highways, waterways, civil aviation and pipelines (CTY, 2013; NBSC, 2013; CTDR, 2015). The input of exergy from the Tr-sector to other sectors was roughly proportional to the economic output. The calculation results are shown in Table 14.

3.7. Domestic sector Table 16 lists the input of energy carriers into the Do-sector. The total input of energy carriers from the Ex-sector and the Co-sector reached 7585.77 PJ, of which coal was 2054.17 PJ, coke 11.36 PJ, petroleum products 1944.28 PJ, natural gas 1181.92 PJ, heat 155.22 PJ, and electricity 2238.82 PJ. Petroleum products and natural gas consumption increased rapidly in recent years, while those in 2006 were only 906.00 PJ and 420.90 PJ, respectively. The energy consumption of rural households depended on a considerable amount of bio-fuels such as straw, firewood and biogas (see Table 17). Straw was estimated at 5564.00 PJ (about 50.0% of the total straw yield for energy purpose into domestic consumption), firewood 3091.27 PJ and biogas 401.05 PJ. Owing to the low thermal efficiency associated with direct biomass burning, only 15% of biomass resource exergy was used for cooking and water heating in rural households (Zhang and Chen, 2010).

3.6. Tertiary sector

Table 16 Input of energy carriers into the Do-sector (Unit: PJ). Source: NBSC (2013); CESY (2014); CRSY (2013).

As shown in Table 15, the total input of energy carriers into the TeTable 14 Exergy output from the Tr-sector to other sectors (Unit: PJ). Item

Ex

Co

Ag

In

Te

Do

Passenger

2.46 (2.1%) 85.54 (5%) 88.00

1.34 (1.1%) 85.54 (5%) 86.88

1.32 (1.1%) 222.42 (13%) 223.74

16.64 (14%) 633.03 (37%) 649.67

37.7 (31.7%) 684.36 (40%) 722.06

59.47 (50%)

Freight Total

59.47

7

Item

Total energy

Total exergy

Urban

Rural

Coal Coke Petroleum products Natural gas Input from the Ex-sector Electricity Heat Input from the Co-sector Total

1937.89 10.82 1834.23 1136.46 4919.4 2238.82 776.1 3014.92 7934.32

2054.17 11.36 1944.28 1181.92 5191.73 2238.82 155.22 2394.04 7585.77

340.1 5.38 1387.54 1178.72 2911.74 1281.36 155.22 1436.58 4348.32

1714.06 5.98 556.28 3.2 2279.52 957.46 957.46 3236.98

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structure of resource exergy inputs and outputs of all the seven social sectors. The results of resource exergy accounting are further integrated in Table S13 to present the detailed input-output relationship of resource exergy. Totally, the resource exergy consumption of the Chinese society was estimated at 151.58 PJ, and its per capita consumption was 111.95 GJ, compared with 72.2 GJ in 2006 and 51.5 GJ in 2003. The In-sector accounted for 26.3% of the national total consumption, followed by the Co-sector 23.2%, the Do-sector 18.3%, the Ag-sector 10.2%, the Te-sector 10.0%, the Ex-sector 6.7%, and the Tr-sector 5.3%. In the process of industrialization, the two sectors of industry and conversion contributed about half the exergy consumption, due to large amounts of nonrenewable resource use. Correspondingly, the conversion coefficient of resource exergy in each sector is calculated by the product exergy as output divided by the resource input (Zhang and Chen, 2010). This indicator can reflect how effective and efficient the exergetic resources have been used. The Ex-sector had the largest value of 91.92%, due to its low resource exergy loss, followed by the Cosector of 34.58%, the Te-sector of 34.28%, the In-sector of 32.18%, the Ag-sector of 29.75%, the Tr-sector of 18.46% and the Do-sector of only 1.28%. The Do-sector, as the main consumer of exergy, had the lowest exergy conversion coefficient. Abundant resource exergy inputs were consumed in this sector, but its outputs were only the waste which can be partly recycled into the Te-sector. The low conversion coefficients of societal exergy utilization represent serious exergy destruction and loss within the society. It is worth noting that coal is the largest natural resource produced in China. Coal supply plays an important role in sectoral resource uses, as shown in Fig. 2. The exergy input into the Co-sector was dominated by coal, which accounted for 85.99% of the total, indicating that coalfired power dominated China’s generation mix. As a major energy carrier input, coal accounted for 44.14% of the total exergy input into the In-sector, due to the direct fuel uses of coal in this sector. Coal was also an important resource input in the Ag-sector and the Te-sector, representing 9.1% and 8.1% of the sectoral total, respectively. In the Do-sector, coal also occupied 7.28% of the exergy input of this sector, which was mainly consumed by rural residents. It is worthy of noting that China has become a net importer of coal since 2009. In 2012, the imported coal amounted to 6402.73 PJ, while the exported coal was only 206.02 PJ. Therefore, the coal input could significantly affect resource size, structure and efficiency of the whole social system. A network analysis can quantify and evaluate the systems structure of resource exergy utilization in a society (Milia and Sciubba, 2006). Referring to the system model proposed by Chen and Qi (2007) and Zhang and Chen (2010), a new overall systems diagram is designed to illustrate the integrity and hierarchy of resource exergy utilization across the social network, as presented in Fig. 3. All the major exergy fluxes are integrated into and depicted on the system diagram to display the complex network linkages. The whole social system is surrounded by a ring (annulus) in terms of imported resources, natural resources supplied by the earth, and exported resources. This implies that the motive forces of the Chinese society are the large amount of resource exergy input by natural ecosystem and the imported resources exergy from other social systems (Dai et al., 2012). For the Chinese society broken down into seven sectors, inter-sectoral and cross-sectoral exergy fluxes associated with raw materials and products are clearly demonstrated by the sectoral resource inflows and outflows. As to the destruction and loss of exergy within the social system, the size gap between the upward (output) and downward (input) semicircles presents an intuitive feeling to sectoral exergy consumption. In particular, the pyramid-shaped system diagram reflects the hierarchical relationship of various sectors in the society. Like the producer in the food chain, the Ex-sector is the top providers of natural resources in to the social systems, followed by the Ag-sector. The Do-sector locates at the top of the pyramid-shaped system, just like the top predator in the food chain. Therefore, this enclosing system diagram as a systems model can make the processes of resource exergy utilization clear and intuitive, and

Table 17 Exergy of bio-fuel resources in the rural households. Source: CRSY (2013). Item

Mass (Mt)

Exergy (PJ)

Firewood Biogas Straw Total

105.14 157.61 (108 m3) 378.5

3091.27 401.05 5564 9056.32

The exergy of the People's food intake mainly came from the Agsector (2433.68 PJ) and the Te-sector (2847.27 PJ). As 52.57% of the population lived in the urban area, per capita exergy utilization of urban households was estimated to be 1.6 times that of rural households. In addition, the exergy of industrial products supplied by the retail business of the Te-sector into this sector was estimated at 3873.81 PJ. Meanwhile, the exergy outflows from this sector were recycling materials and waste for energy. 4. Results and discussion The input of natural resources is the prerequisite to maintain the operation of human society. The Chinese society has no exception, the development of which depends largely on the exergy flux procurement from natural ecosystems and other countries/regions. In 2012, the total input of resources exergy into the Chinese society was 157.55 EJ, compared with 97.62 EJ in 2006 and 69.95 EJ in 2003. As shown in Table 18, the largest input was fossil fuels as energy carriers. The net input of resources exergy amounted to 153.41 EJ. In addition, the total import of resources by exergy was 25925.91 PJ, while the total export was only 4132.31 PJ. Particularly, the imported exergy input of China’s Ex-sector in 2012 amounted to 22757.45 PJ and was 2.35 times of that in 2006, but its exported exergy was only 2114.46 PJ. The net import by exergy of the Ag-sector was also very high, amounting to 1115.26 PJ. The structure of international trade can partly reflect China’s industrial development patterns. The resource allocation of a social system can be directly determined according to the exergy flux process. Fig. 1 displays the Table 18 Summary of resources input into the society (Unit: PJ). Fluxes

Energy

1. Non-biological resources (NBR) NBR-Ex 95687.48 NBR-Ex 689.64 NBR-Co 5838 NBR-Ex (import) 20493.86 NBR-Co (import) 24.75 NBR-In (import) 818.18 2. Biological resources (BR) BR-Ag 13901.93 BR-Do 9056.32 BR-In 556.4 BR-Tr 61.89 BR-Ag (import) 1175.99 BR-In (import) 1149.55 Total extracted resources 125791.66 Total imported resources 23662.32 Total input of resources 149453.98 Total exported resources 3999.53 Ex-NBR (export) 1981.68 Co-NBR (export) 63.55 In-NBR (export) 1893.57 Ag-BR (export) 60.73 Net input of resources 145454.45

Exergy 131643.59 101515.57 689.64 5838 22757.45 24.75 818.18 25902.07 13901.93 9056.32 556.4 61.89 1175.99 1149.55 131619.75 25925.91 157545.66 4132.31 2114.46 63.55 1893.57 60.73 153413.35

Energy carriers Ores, minerals Energy carriers Energy carriers Energy carriers Ores, minerals Harvest, wood Bio-fuels Straw, etc Bio-fuel Harvest, wood Pulp, etc.

Energy carriers Energy carriers Industrial products Harvest

Note: NBR: non-biological resources, including primary energy, secondary energy, ores and minerals, and other mineral products; and BR: biological resources (e.g., farming, forestry, husbandry and fishing products).

8

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Fig. 1. Exergy input and output of seven social sectors in 2012.

2005 (Cai, 2009), China 2006 (Zhang and Chen, 2010) and China 2012 (this study). There were substantial differences in the resource use structure between China and other countries, though similar structure can be found for the same society in different years. In Siena, Italy and UK, the Tr-sector had important contributions to the social exergy consumption. The energy extraction industry played the large role within Norway and Nova Scotia societies, due to the massive exergy input to oil and gas production. The In-sector and the Do-sector in different societies always had large resource exergy uses. As the world’s largest developing country, China has relied on a large amount of resources to maintain the economic growth in the past decade. The In-

present the locations, types and magnitudes of exergy destruction and loss within the Chinese society in a straightforward way. Comparisons with other societies and with Chinese society in previous years can further illustrate the structure and efficiency of resource exergy utilization per se but also the difference among different macrolevel socio-economic systems on the international and development horizons (Zhang and Chen, 2010). Fig. 4 present the structures of resource exergy consumption in eight social systems in terms of Siena, Italy 2000 (Sciubba and Bastianoni, 2008), Norway 2000 (Ertesvåg, 2005), UK 2004 (Gasparatos et al., 2009a), Nova Scotia, Canada 2006 (Bligh and Ugursal, 2012), China 2003 (Chen and Qi, 2007), China 9

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Fig. 1. (continued)

past decade, along with the huge input of natural resources. The conversion coefficients in China’s Ex-sector and Tr-sector were similar to the ratios calculated for other developed countries except for Siena, Italy. The Co-sector of China dominated by thermal power generation had much lower exergy conversion coefficients than those of Norway, Siena, Italy and Nova Scotia, Canada, though the slight efficiency improvement in its Co-sector can be found. Along with increasing resources input into the Ag-sector in China, its exergy conversion coefficient had declined in the past decade, far below the developed societies’ figures. The exergy conversion coefficient of the In-sector of China was always less than those of other countries, particularly 88%

sector and the Co-sector were the top resource users in China rather than other sectors, largely driven by the enormous demands for certain resource and energy-intensive products in manufacturing, infrastructure and real estate related industries. In addition, China’s per capita resource uses have increased by 117.4% in recent decade, but its value in 2012 (111.95 GJ) was still much less than those of some developed societies such as 318.8 GJ in Norway and 406.4 GJ in Nova Scotia, Canada. Fig. 5 further displays the performance of resource exergy conversion coefficients in different societies. Social exergy conversion efficiencies in China haven’t witnessed a prominent improvement in the 10

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Fig. 2. Coal inflows and outflows in term of exergy in the Chinese society.

resource exergy utilization patterns of socio-economic systems at different scales. An exergy-based systems account of national resource utilization is carried out for China 2012, one of the most complicated cases in the world. The exchange and utilization of resources are quantified by exergy fluxes between the sectors of the society and between the sectors and the natural environment or other countries/regions. Correspondingly, the Chinese society with seven independent and complimentary departments, sustained by domestic natural resources and imports from abroad, is depicted on a system diagram to present the locations, types and magnitudes of exergy destruction and loss in a straightforward way. After examining the resource exergy procurement, allocation and consumption in 2012, this study identified that the development mode of the Chinese society was still dependent on the heavy input of natural resources and serious exergy destruction and loss, mainly driven by the expansion of production sectors, infrastructure construction activities, and household consumption and trade demands. The total resource exergy input into the Chinese society was estimated at 157.55 EJ, with the net input of 153.41 EJ. Its per capita resource consumption was 111.95 GJ, compared with 72.2 GJ in 2006 and 51.5 GJ in 2003. Industry accounted for 26.3% of the national total resource exergy consumption, followed by Conversion 23.2%, Household 18.3%, Agriculture 10.2%, Tertiary 10.0%, Exaction 6.7% and Transportation 5.3%. The conversion coefficients of the seven sectors were estimated as 91.92% for Extraction, 34.58% for Conversion, 29.75% for Agriculture, 32.18% for Industry, 18.46% for Transportation, 34.28% for Tertiary and only 1.28% for Household. By comparing with different social systems, the evolution pace of the Chinese society and the gap between China and some developed countries was clarified. The resource utilization performance in China was inferior to those of industrialized societies. Anthropogenic excessive exploitation and utilization of terrestrial exergy resources has been regarded as the basic physical cause of

for the Norwegian society 2000. In fact, the resource use efficiencies in China’s resource-intensive or energy-intensive sectors have large gaps in production technology and management, compared with the international advanced level (Zhang et al., 2012b; CESY, 2014). Since irreversibility is intrinsic to any resource conversion process, natural resources from the natural ecosystem required for producing and supplying goods and service in social systems should not run out to ensure sustainable development. All environmental effects are strongly related to the amount of exergy in the utilization of resources and disposal of waste products (Zhang et al., 2012a). Previous studies have indicated that exergy-based assessment can be used to illustrate the sustainability of production sectors (e.g, Dewulf and Langenhove, 2005; Yang and Chen, 2014; Wu et al., 2015). The utilization patterns of exergy resources in the macro-level accounting system could also serve as the basis for sustainability analysis of a socio-economic system (Dincer and Rosen, 2007; Rosen et al., 2008; Gasparatos et al., 2009a; Zhang and Chen, 2010). The challenges confronted with the Chinese society are the ever-increasing pressures on natural ecosystems due to large amounts of nonrenewable resource consumption and low exergy conversion coefficients in production sectors. Resource-driven developing mode with no regard for environmental consequences is not sustainable. Effective resource uses with a minimum impact on the environment should be given special attention in policy design to assess all possible paths to promoting resource utilization level. Exergy-based analyses reveal the potentials for possible efficiency improvement and contribute to identifying resource conservation opportunities and paths as well as establishing sound resource and environmental policies of an industrial sector or a social system at different scales.

5. Concluding remarks Exergy method has received a wide acceptance for investigating 11

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Fig. 3. Systems diagram of China’s resource exergy utilization in 2012. Note: The seven sectors are as follows: Ex, extraction; Co, conversion; Ag, agriculture; In, industry; Tr, transportation; Te, tertiary; and Do, domestic household. The surroundings of the social system are: NR, natural resources from the environment or natural ecosystems; IR, imported resources from other countries or regions; and ER, exported resources to other countries or regions. In this diagram, the resource input and output of each sector are indicated by the upward and downward semicircle, respectively. The diameter of the semicircle in each sector is approximately proportional to the magnitude of exergy amount. The line thickness roughly indicates the size of exergy inflow and outflow. The red line represents the exergy fluxes from the higher-order sector to the lower-order sector in the pyramid-shaped system (Top-down); for the black line, the inverse is true (bottom-up).

socioeconomic sectors by combing with a systems diagram, which provide a sound physical basis for resource and environmental policy formulation. The structural and functional patterns of national resource utilization could be used to review the development process of different countries and contribute to finding a better social development mode for a sustainable future.

resources shortage and ecological degradation (Chen, 2005, 2006; Hermann, 2006). A well-functioning social system should pay equal attention to the quality and the speed of development. Increasing resources exergy use can maintain rapid economic development in the developing countries, but the massive “resource footprints” will accelerate the resource depletion, especially for non-renewable material resources, and generate adverse environmental impacts and effects such as air pollution and prominent greenhouse gas emissions (Dewulf et al., 2008). Exergy as a tool for the scientific unitary measurement of resource utilization can contribute to capturing the complex network linkage of societal exergy fluxes and understanding the behavior of

Acknowledgements This study has been supported by the National Natural Science Foundation of China (Grant nos. 71403270, 71373262 and L1624054), 12

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Fig. 4. Resource exergy utilization patterns in different societies.

Fig. 5. Conversion coefficients of resource exergy utilization in different societies.

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