2.1. Accounting Method of TMR
The indicator, TMR, was accounted following three guidelines: the Technical Report of European Environment Agency “Total material requirement of the European Union: Technical part” [8
], the EUROSTAT Methodological Guide “economy-wide material flow accounts and derived indicators” [7
], and the “Economy-wide material ﬂow accounts: Compilation guidelines for reporting to the 2009 EUROSTAT questionnaire” [29
]. According to the first two reports, TMR comprises two major components: domestic material flows and foreign material flows. As shown in Table 1
, they can be further subdivided into direct material input [DMI = Domestic Extraction Used (DEU) + Imports] and hidden flows (HF). Hidden flows were originally called “ecological rucksacks” in the MIPS-concept [9
], and the EUROSTAT (2001) guide [3
] addresses HF as indirect flows. Domestic hidden flows are usually called unused extraction, which will not enter the economy as raw materials (e.g., mining overburden, excavation in the construction of infrastructure). Foreign hidden flows comprise both used and unused extraction linked to imports and exports.
Components of total material requirement (TMR); HF: hidden flows; DEU: domestic extraction used.
Components of total material requirement (TMR); HF: hidden flows; DEU: domestic extraction used.
|Components ||Material categories|
|DEU||biomass, metallic minerals, non-metallic minerals and fossil fuels|
|Imports||biomass, metallic minerals, non-metallic minerals, fossil fuels and others|
|Domestic HF||biomass, metallic minerals, non-metallic minerals, fossil fuels and excavations|
|Foreign HF (from Imports)||HF from biomass, metallic minerals, non-metallic minerals, fossil fuels and others|
According to MFA conventions, the DEU of biomass is expected to include all biomass of vegetable origin harvested by humans and their livestock, as well as fish capture and hunted animals [29
]. In this study, the biomass extraction includes the amount of harvested primary crops (up to 190 items), used crop residues (10 items), harvest of fodder crops and grazed biomass (five items), wood extraction (seven items) and fish capture (two items). Hunted animals are not included, because no related data is available. The DEU of metallic minerals distinguishes data of iron ores and non-ferrous metal ores (eight items). The accounts for non-metallic minerals include stone and industrial use (17 items) and construction materials (three items: limestone, gravel and sand and clays and kaolin). The accounts of fossil fuels include solid energy resources and liquid and gaseous petroleum resources.
International trade material flows and monetary flows between China and its partners are well-recorded in the United Nations Commodity Trade Statistics Database
]. At the most differentiated product level, we collected China’s imported goods (about 42,000 items) during 1995–2008. As the physical data (i.e.
, weight in kilograms) of imported goods is incomplete in the UN Comtrade, we estimated the missing part of the physical ﬂows of imported goods (reported in monetary units) for China based on the calculation of the average global annual price per kilogram for each commodity group (see [31
] for details). More than 3000 items of imported goods for China were estimated, which accounts for around 5% of the total weight of China’s imported goods in the studied period.
To account for the hidden flows associated with DEU, we found only direct data of hidden flows for non-ferrous metal ores and country-specific coefficients for hard coal and brown coal. For the other materials, we used the coefficients provided by the Wuppertal Institute, which stand for Germany. The soil excavations in China’s domestic hidden flows include excavation of building construction, excavation of road construction, excavation of water infrastructure and excavation of irrigation. As for the soil excavation of building construction and road construction, we used the coefficients from [32
] (0.91 ton per finished square meter) and the coefficients for each class of road provided by the Wuppertal Institute. In terms of excavation of water infrastructure and irrigation, we can find direct data in China’s statistical yearbooks.
With regard to hidden flows of imports, the EUROSTAT (2001) guide [3
] suggests converting the imported materials and commodities into Raw Material Equivalents (RME), firstly, and, then, the hidden flows of unused extraction associated to this RME. In this study, the hidden flows from imports of China were directly calculated from the imported materials and commodities with the coefficients provided by Wuppertal Institute, which also stand for Germany, because insufficient data can support the calculation of RME of China’s Imports for each year of the studied period.
In the technical report provided by Bringezu and Schuetz [8
], domestic erosion was included in the accounting of TMR. However, only very roughly estimated data of domestic erosion can be found in China’s statistical books. As the conditions of domestic erosion differs significantly between countries [25
], we decided not to include domestic erosion into China’s TMR. For the comparison with other countries, the domestic erosion was also removed from their TMR. As for the erosion of imports, we also excluded it in China’s TMR for consistency.
As the hidden flows of China were mostly calculated with the coefficients from Germany and the other European countries, an underestimation might be caused considering the relatively lower level of technology of China.
2.2. Decomposition Equation and Method
Decomposition analysis has been used since the 1970s, and recently, it has been applied to material ﬂow analyses [34
]. In this study, we used this technique to examine the influence factors of China’s TMR. The decomposition equations we used are in the following.
represents the type of material (five types: TMR of biomass, metallic minerals, non-metallic minerals, fossil fuels and excavation). As the share of others (other products from imports) in TMR was negligible (see Figure 1
), we allocated the values of other products into the other four categories based on their proportions to the total amount. POP
represents population, GDP
is given in US dollars for the price of 2000 and TMRk
(ton) of material, k
Equation (1) was developed from the well-known IPAT (Impacts = Population × Affluence × Technology) identity [36
], which has been regarded as the “master equation” in industrial ecology [37
]. Based on Equation (1), we divided the influence factors of TMR into three: The first factor (P
) in Equation (2) represents population. We regard population as a main influential factor of China’s TMR. The second factor (A
) in Equation (2) represents affluence, which can be expressed as GDP per capita. With the increase of Chinese people’s income, more materials are required, and it will influence TMR domestically. Thus, the factor of affluence is regarded as a key driving force for increasing China’s TMR. The third factor (Tk
) represents the TMR of material k
) per unit of GDP. This factor is called material intensity for the purposes of this study. In Equation (2), factor T
is the residual, which represents everything that affects the TMR that is not population and affluence. Therefore, the indirectly influential factors associated with T
should also be considered (e.g., economic structure and consumption pattern).
If changes in these three factors described above can explain the variations of TMR, then these variations can be expressed by the following equation:
For this study, we use the additive form for this explanation (see [38
] for decomposition methodology). Peffect
are respective effects of factors P
on changes in TMR. The effects of each factor were calculated with a complete decomposition model [39
Based on the above equations, the respective effects of factors P, A and T on changes in TMR can be calculated.
2.3. Data Preparation
With regard to data collection of DEU, we used Chinese national data to account for fossil fuels, metallic minerals and non-metallic minerals. For the accounting of biomass and international trade flows, we used datasets of Food and Agriculture Organization (FAO) [40
] and UN Comtrade [30
]. The details are introduced in the following.
For all biomass extraction, we used data reported by FAO [40
], except for data of fish capture, because data of fish capture for China in this dataset is insufficient. Thus, we collected relevant data from the 1996–2009 China Statistical Yearbooks
]. Crop residues were estimated using harvest factors and recovery rates for the most common crop residues in Europe [42
]. In the dataset of FAO, no data of fodder crops is provided for China. Therefore, we estimated the extracted fodder crops and grazed biomass based on livestock numbers [40
] and daily roughage intake factors of different livestock species in Europe [29
]. It is noteworthy that according to the guide of EUROSTAT (2009) [29
], the amount of imported fodder crops was not subtracted. For China, this amount is only about two million tons in 2008, compared with 700 million tons of the total demand of fodder crops and grazed biomass. Thereby, little influence could be made by this double accounting. In addition, for this study, we adopted the daily biomass intake factors of livestock species in Europe, because no such factor was found for China, although the biomass intake factors might vary considerably within one species in different regions. This represents another data gap, which needs to be resolved in future work. Wood harvest is reported in terms of volume (solid cubic meters, scm). Then, we converted the volume data into weight data using factors provided by Penman and colleagues (2003) [43
]. According to the guidelines of EUROSTAT (2009) [29
], wood bark should be included; it accounts for approximately 10% of stem wood weight. All biomass ﬂows were reported in fresh weight at the time of harvest, except for the harvest of fodder crops and grazed biomass, which were assumed to contain 15% moisture.
The DEU of metallic minerals distinguishes data of iron ores and non-ferrous metal ores, which were obtained from the 1996–2009 China Steel Industry Yearbooks
] and China Nonferrous Metal Industry Yearbooks
Material flow accounts for non-metallic minerals comprise two categories: non-metallic minerals for stone and industrial use and bulk materials used primarily for construction (limestone, gravel and sand and clays and kaolin). For the first category, we used data from the 1996–2009 China Land and Resources Statistical Yearbook
]. A gap of missing physical data for a few years was estimated based on the relevant economic values. No sufficient data exists for extracted construction materials in China’s official statistical yearbooks. Therefore, we estimated their quantities according to the guidelines of EUROSTAT (2009) [29
]. The estimation of limestone was based on data of cement production, which was presented in the 1996–2009 China Statistical Yearbooks
]. The ratio of 1.19 tons of limestone for the production of one ton of cement was used [29
]. The estimation of gravel and sand was based on concrete production and road construction. With respect to concrete production, the necessary input of sand and gravel to produce one ton of concrete is 6.09-times the input of cement [47
]. Regarding road construction, we used the requirement factors of sand and gravel per kilometer of road construction [48
]. Data of road construction length for China was obtained from the official website of the Ministry of Transport of China [49
]. The estimate for clays and kaolin was based on the production of normal bricks and roof bricks. According to the guidelines of EUROSTAT (2009) [29
] and the Chinese production standard of bricks, we estimated that 3.2 kg of crude clay was necessary to produce one piece of normal brick and that 16.5 kg of crude clay and kaolin were necessary to produce one square metre of roof brick. The brick production data was collected from the 1996–2009 China Construction Materials Industry Yearbooks
The fossil fuel data was from the 1996–2009 China Energy Statistical Yearbooks
Regarding imports, we first distinguished imported materials of biomass, metallic minerals, non-metallic minerals, fossil fuels and other products according to the guidelines of EUROSTAT (2009) [29
], and then, we allocated the values of other products into the other four categories based on their proportions to the total amount.
To account for the hidden flows associated with DEU, we used direct data of hidden flows for non-ferrous metal ores from China Nonferrous Metal Industry Yearbooks
]. For the other materials, the coefficients used are provided by the Wuppertal Institute. For the accounting of soil excavation of building construction, we collected data of the completed floor space from the 1996–2009 China Statistical Yearbooks
]. For the accounting of soil excavation of road construction, we collected data of road construction length for China from the official website of the Ministry of Transport of China [48
]. For the accounting of excavation of water infrastructure and irrigation, we collected data from the 1996–2009 China Water Resources Yearbooks [52
As for the estimation of hidden flows from imports, we also used the coefficients provided by Wuppertal Institute.
For the decomposition analysis of China’s TMR, we collected data of GDP (at the constant price of 2000) and population from World Development Indicators 2010
] and the 1996–2009 China Statistical Yearbooks
Finishing the data collection and estimation, we compiled the accounts for China’s TMR for 1995–2008. In the next section, we will present the indicator of the TMR for Chinese economy, with a subsequent general comparison with results from previous studies and the TMR of foreign countries.