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The competitive relationship between food and energy production for water in China
Journal Pre-proof The Competitive Relationship between Food and Energy Production for Water in China
En Hua, Xinyu Wang, Bernard A. Engel, Shikun Sun, Yubao Wang PII:
S0959-6526(19)33973-3
DOI:
https://doi.org/10.1016/j.jclepro.2019.119103
Reference:
JCLP 119103
To appear in:
Journal of Cleaner Production
Received Date:
18 June 2019
Accepted Date:
29 October 2019
Please cite this article as: En Hua, Xinyu Wang, Bernard A. Engel, Shikun Sun, Yubao Wang, The Competitive Relationship between Food and Energy Production for Water in China, Journal of Cleaner Production (2019), https://doi.org/10.1016/j.jclepro.2019.119103
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The Competitive Relationship between Food and Energy Production for Water in China En Hua1,2, Xinyu Wang1,2, Bernard A Engel3, Shikun Sun1,2, Yubao Wang1,2,3* 1
Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid
Areas, Ministry of Education, Northwest A&F University, Yangling 712100, Shaanxi, China 2
Institute of Water Saving Agriculture in Arid regions of China, Northwest A&F
University, Yangling 712100, Shaanxi, China 3
Department of Agricultural and Biological Engineering, Purdue University, West
Lafayette, Indiana 47907, USA Corresponding author at: Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A&F University, Yangling, Shaanxi 712100, PR China Email: [email protected] (Yubao Wang)
Abstract:
Water, Energy and Food（ WEF） are key elements of
economic and social sustainable development, and present a complex nexus. Existed WEF nexus research is mainly confined to qualitative analyses, and it needs constant improvement and increases quantitative analyses. In China, water security is the most prominent problem in the WEF-nexus, which is manifested in the competitive relationship between food and energy production for water. Therefore, the matter of alleviating water stress has become a difficult and hot issue. After improving the 1
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existed water footprint accounting method for food and energy production, this study calculated the food water footprints (blue water footprint and green water footprint) in the 31 provinces of mainland China in 2015, as well as the blue water footprints of major energy systems (coal, oil, gas and thermal power generation). This study proposed water resources pressure index ( IWS ), water resources pressure contribution rate of food and energy (WCR), water consumption rate of food and energy (n) and competition composite index (CCI) of WEF, which were used to evaluate the consumption of water resources in food and energy production in different regions, and assess the intensity of competition for water resources in food and energy production. The results showed that the national food water footprint in 2015 was 690.8 Gm³, and the blue food water footprint was 287.8 Gm³. The main water-consuming blue energy water footprint was 18.5 Gm³, and coal production accounted for 9.9% and thermal power generation accounted for 87.6%. According to the competition
indicators,
the
competition
relationship
among
the
administrative regions of the 31 provinces in mainland China was obtained. For example, 5 provinces had serious competition and 19 provinces had weak competition. The water consumption of the energy industry continues to grow rapidly by economic development. Corresponding measures should be taken according to the different competition levels for water resources. 2
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Keywords: water; energy; food; water footprint; China
1. Introduction Global water resources are increasingly scarce, and high water consumption of food and energy production will significantly increase water consumption in the future. Population growth, climate change and commodity trade (Li et al., 2019) will further increase the consumption of water resources in food and energy production. Water demand is expected to increase 40% (McKinsey & Company, 2009) by 2030, while the water demand for both energy and food will increase 50% (International Energy Agency, 2012; Food and Agriculture Organization of the United Nations, 2012). With the rapid development of new bioenergy sources, the water demand for some important biofuel feedstocks such as soybean, grape seed and sugar cane will continue to increase (Hoogeveen et al., 2009), resulting in water scarcity. The WEF relationship is complicated. The Water, Energy and Food Security Nexus Conference, held in Bonn, Germany, in 2011, identified the relationship as a ‘nexus’ (The United Nations Economic and Social Commission for Asia and the Pacific, 2013) for the first time. However, existed research efforts are often based on the relationship between two of the three. In water–food relationship research, water demand, irrigation efficiency, and irrigation method are the main fields of focus. For example, Grafton et al. (2017) used a bottom-up model to predict the 3
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amount of irrigation water and food production in 19 countries in 2010-2050 under different scenarios. In the research related to the water–energy relationship, sustainable development paths that promote energy and water conservation are often explored. For example, some researches focused on the supply and demand of energy and water in India's end-user sector, and the distribution of resources among agriculture, industry and domestic sectors in California, USA (Malik, 2002; Lofman et al., 2002). These studies on the relationship between water and food or energy are mainly aimed at the occupation and consumption of water in food or energy production, and how to improve water use efficiency. In the WEF-Nexus relationship, water resources allocation is a multi-factor system. There is complex synergistic competition between systems. Therefore, the study of pairwise relationships has limitations. In the research progress of WEF-Nexus, many concepts and connotations of WEF-Nexus are introduced from the perspective of scientific intersection (Chang et.al, 2016; Albrecht et.al, 2018). Hoff (2011) believed that the water-energy-food relationship was a governance path to deal with resource scarcity, ensure the safety of the three and improve the efficiency of the three. FAO (2014) incorporated ecosystems into its definitions, emphasizing the inclusion of stakeholders in resource management related to resource use. Conway et al. (2015) viewed 4
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WEF-Nexus as a paradox between resources to reflect trade-offs and potential conflicts among water, energy and food. White et al. (2018) discovered the intrinsic link between resources and economic activity through surveys. Based on the above research, it can be seen that the research on WEF-Nexus is relatively wide, but there are still many research fields to be explored. In the complex WEF-Nexus, water security is the most prominent problem, especially in China. In 2015, China's total water consumption reached 610.3 Gm3, but the per capita water consumption was lower (444.0 m3) (Ministry of Water Resources of the People's Republic of China, 2016). Among them, agricultural water consumption accounted for more than 60% of the country's total, and energy water consumption exceeded 10% of the country's total. At present, the production of food crops and bioenergy has increased year by year, forcing water resources use to increase (Liu et al., 2013). Water consumption such as primary energy extraction has increased year by year (Zhan et al., 2015; Yang et al., 20017). The water pollution of energy production has made a profound impact (Bao et al., 2015), which also makes food and energy highly dependent on water resources. In terms of resources distribution, China's water resources are mainly concentrated in the south, while agricultural production and coal reserves are mostly distributed in the north. These will increase the intensity of competition between food and 5
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energy production for water. At the same time, the World Resources Institute's report has pointed out that China's thermal power generation faces huge risks (2016), which are due to the spatial mismatch of coal reserves and water resources. Water footprint provides a good way to examine the competitive relationship between food and energy for water. Water footprint, proposed by Hoekstra, refers to the amount of water needed for all products and services consumed by a country, region or individual for a certain period of time (Hoekstra and Chapagain, 2007). The water footprint can represent the development of the socio-economic system for the possession of water resources and pressure on the water resources environment (Hoekstra and Hung, 2005). Since the water footprint was proposed, it has been rapidly applied to different scales such as global and region (national, provincial, etc.). It can identify scale change, structural change, and influencing factors of water footprints at these scales, which provide decision support for issues such as water security, food security and ecological pressure (Zhang et al., 2013). At the same time, due to the virtual water trade caused by international trade, water footprint research extends to the industrial product field by agricultural products such as rice, corn and wheat (Herath et al., 2013). In recent years, water footprint studies on typical industrial processes and energy production have begun (Pacetti et al., 2015), such as printing, dyeing, steel and textiles (Wei and 6
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Shi, 2015). At present, the theoretical systems and research methods for WEF-Nexus have not been fully constructed, and significant work still needs to be done in terms of research perspective, dimensionality, scale and tool. The research on WEF-Nexus is mainly qualitative and lacks quantitative evaluation in many cases. The three resources of water, energy and food are essential resources for human survival and development. By quantitatively analysing the nexus and proposing solutions to improve safety and sustainable utilization of WEF-Nexus, it is helpful to enhance the synergy of the three, improve the overall utilization efficiency, and promote regional sustainable development. Existed research results of the pairwise relationship in the WEF-Nexus are not enough to support the formulation and implementation of decision-making programs, and even mislead decision-making. However, the WEF-Nexus relationship is complex. Therefore, this study uses the important link in WEF-Nexus—the competition between food and energy production for water as a breakthrough to carry out research, and proposes indicators to quantitatively evaluate the degree of competition. This study is aimed at the insufficient quantitative research on the core relationship between water resources competition in food and energy production in WEF-Nexus. On the basis of calculating the water footprint of food and main water-consuming energy, this study assesses the degree 7
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of competition between food and energy for water by using indicators such as Competition Composite Index (CCI) of WEF. This paper analyses the water resources competition in food and energy production in different provincial administrative regions of China. It proposes corresponding countermeasures for different competition levels, which alleviate regional water resources pressure and ecological pressure, and promote sustainable economic and social development.
2. Case study background The research objects are 31 provinces in mainland China. According to the food output, the 31 provinces are divided into 13 main food production areas, 11 food balance areas and 7 main food sale areas (Figure 1). In 2015, food production in the main food production areas, the food balance areas and the main food sale areas, respectively, accounted for 76.2%, 18.5% and 5.3% of the national total. There are 14 coal production bases in the country. In 2015, the production scale of coal bases accounted for 66.0% of the country's total. China's water resources are primarily in the south, accounting for 81.0% of water in the country. The cultivated land is small in the south, accounting for 35.9% of the country total.
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Fig. 1. Distribution of the study area, main food production areas and coal bases in China.
3. Methods 3.1. Calculation of food production water footprint The food crops in this study included cereal, bean and potato. The food water footprint of this study does not consider the grey water footprint. The grey water footprint is calculated based on the chemical material which is the most pollutants in food or energy production, while the pollutants of them are different. Therefore, this study only considers the blue water footprint and the green water footprint. The blue water footprint is the amount of surface and groundwater consumed to produce a product or service. Consumption means that fresh water is used to evaporate or enter the product and to take water from one watershed and then return to another watershed or ocean, i.e. water extracted from 9
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surface water or groundwater in the watershed does not return to the watershed. The green water footprint is the amount of rainwater consumed during the production process and is closely related to agricultural and forestry products. The green water footprint of these products refers to the amount of rainwater evaporation (from field or vegetation), plus the water stored in crops or trees. The food water footprint calculation formula is: WFi G
Wi g Wi b Gi
(1)
where WFi G is food production water footprint in the i provincial administrative districts, m3/kg; Wi g 、 Wi b is the green water footprint or blue water footprint during food production in the i provincial administrative districts, m3; Gi is total food production in the i provincial administrative districts, kg. Wi g is the product of the effective precipitation of the food growth
period and the corresponding cultivated land area: Wi g
105 Pi e SiG
iG
(2)
where iG is food multiple cropping index in the i provincial administrative districts; SiG is sown area of food in the i provincial administrative districts, kha;
Pi e is effective precipitation in the i
provincial administrative districts, mm. Wi b is the product of irrigation water consumption per unit area of food 10
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districts. Wi b IRiG SiG,IR
SiG,IR
Si , IR SiG Si
(3) (4)
where Si , IR is irrigation area (effective irrigated area) in the i provincial administrative districts, kha; SiG 、 Si is sown area of food and total sown area of crops in the i provincial administrative districts, kha. The formula of IRiG is: IRiG
IRi Si S i SiE
(5)
G i
where IRi is average irrigation water per unit area in the i provincial administrative districts, mm; SiE is sown area of other crops, kha; i is integrated crop irrigation ratio for cash crops and food crops in the i provincial administrative districts.
3.2. The calculation of energy production water footprint The main water-consuming energy sources include coal, oil, natural gas and thermal power generation. According to the energy production process flow, we determine the energy water footprint by distinguishing the water consumption categories at different stages of production. Water resources consumption can be divided into three categories: evaporation water, recycling water and pollution water. The calculation steps of the main water-consuming energy water footprint are as follows (Figure. 2). 11
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Fig. 2. Main water-consuming energy production water footprint calculation process.
The main water-consuming blue energy water footprint calculation formula is: Wi E Wi C Wi O Wi G Wi T
（6）
where Wi E is the main water-consuming blue energy water footprint in the i provincial administrative districts, m³; Wi C is the blue coal production water footprint in the i provincial administrative districts, m³; Wi O is the blue oil production water footprint in the i provincial
administrative districts, m³; Wi G is the blue natural gas production water footprint in the i provincial administrative districts, m³; WiT is the blue water footprint for thermal power generation in the i provincial administrative districts, m³.
3.2.1. The blue coal production water footprint The coal process is divided into two categories. One is underground mining and washing, and the other is open pit mining and washing. According to the process flow, the blue coal production water footprint is 12
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calculated based on the WFN method (Ding et al., 2016). The blue coal production water footprint calculation formula is: Wi C Wi m Wi w
(7)
The blue coal mining water footprint is: Wi m Qic Qiu
(8)
where Wi m is water consumption during coal mining in the i provincial administrative districts, m³; Qic is water consumption in the i provincial administrative districts, m³. The underground mining mainly divides into the processes of coal crushing, coal loading, coal transportation, mine hollowed out area support and treatment. There are 12 water consumption links, including dustproof water, hydraulic drilling machine water, flushing roadway water, road spray water and rescue tank water. Open pit mining mainly divides into processes such as coal rock pre-crushing, loading, transportation and dumping. There are 5 water consumption links, including road sprinkling, dust sprinkling, blasting rig water, land reclamation water and coal storage yard sprinkling. Qiu is recycling water in the i provincial administrative districts, m³. The mining process mainly includes air return and transport groove flushing deposition coal dust water consumption. The blue coal washing water footprint is： Wi w Qic Qiu
(9)
where Wi w is water consumption during coal washing process in the i 13
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3.2.2. The blue oil and natural gas production water footprint The technological process of oil mainly includes the auxiliary process of seismic exploration, logging production, downhole operation, oil production and oil and gas gathering and transportation. The natural gas production process mainly includes three parts, the wellhead, the gas collecting station and the gas distribution station. The water use of oil and natural gas is roughly similar. The blue water footprint is calculated as: Wi O Qib Qiind Qic Qiu
(10)
where Qib is the amount of water produced or imported into the product in the i provincial administrative districts, m³; Qiind is the production guarantee water volume in the i provincial administrative districts, m³. In addition, Qic includes the amount of water that cleans and transports the substance; Qiu includes the amount of cooling water and the amount of water that converts energy and transfers heat.
3.2.3. The blue water footprint for thermal power generation The thermal power generation process of secondary energy is composed of five parts, such as pulverized coal into furnace combustion, 14
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hot air drying and conveying pulverized coal, and fully burning and ash to grey field. It also includes the blue coal production water footprint link. The blue water footprint for thermal power generation is calculated as： Wi T Qic Qiu
(11)
where Qic includes boiler part, steam turbine unit, various water tank losses, piping system and heat consumption of heating; Qiu includes water consumption for cooling water and condensate.
3.3. Water resources competition intensity index 3.3.1. Water resources pressure index（ IWS ） There are many water scarcity indicators can reflect the water resources pressure and sustainability (Tommaso Pacetti et al., 2015). Such as, water-related risks and water pressure index. Among them, the water resources stress index can identify whether the relationships between water resources in a certain region and regional population, economy, and environment are coordinated. It can also determine whether water resources become a bottleneck for economic development in the region (Jia et al., 2002). This study use IWS to evaluate water resources pressure of provincial administrative region in China according to Wang et al. (2015). IWSi
(Wtvi Wtrvi Witvi ) (WAi 20%)
(12)
where IWSi is the water resources pressure index in the i provincial 15
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3.3.2. Water resources pressure contribution rate (WCR) of food and energy In the production process of food and energy, on the one hand, they consume a lot of water resources, which account for more than 70% of the country's water consumption (IEA, 2012; UNESCO-IHE, 2013). On the other hand, they exert strong pressure on water resources and contribute to the use of water resources. Therefore, this study analyses WCR in 31 provinces in China by the blue food water footprint and the main water-consuming blue energy water footprint. WCRi 2 I Fi I Ei
(13)
where WCRi is the water resources pressure contribution rate of food and energy in the i provincial administrative districts, dimensionless; I Fi is the water resources pressure contribution rate of food in the i provincial administrative districts, dimensionless;
I Ei is the water resources
pressure contribution rate of energy in the i provincial administrative districts, dimensionless. 16
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water-consuming blue energy water footprint and the total water consumption. I Fi
wif wDi
(14)
I Ei
wie wDi
(15)
where wif is the blue food production water footprint in the i provincial administrative districts, m3; wie is the main water-consuming blue energy water footprint in the i provincial administrative districts, m3; wDi is the total water consumption in the i provincial administrative districts, m3. The range of I E、F is [0,1]. The greater the value, the greater the competition between the province's food and energy for water.
3.3.3. Water consumption rate (n) of food and energy The WEF-nexus is affected by economic, social and environmental factors. Therefore, water for food and energy production in different regions accounts for different proportions of total water consumption. This has resulted in different levels of competition between food and energy production for water resources. Meanwhile, water for food and energy production have an impact on water resources pressure, which could use n to correct IWS . ni
wif wie wDi 17
(16)
Journal Pre-proof where ni is water consumption rate of food and energy in the i provincial administrative districts, dimensionless.
3.3.4. Competition composite index (CCI) of WEF In the calculation of CCI, it can be mainly divided into two parts. The first part is the impact of water resources pressure on competitive relationship. The water resources shortage limits the water consumption of food and energy production. Different places have different geographical and meteorological factors, using n to correct water resources pressure. The second part is the pressure and contribution to water resources in the production of food and energy. It can be represented by WCR. (17)
CCI i ni IWSi WCRi
where CCI i is the competition composite index of WEF in the i provincial administrative districts, dimensionless. The intensity of water resources competition is shown in Table 1. Table 1. Water resources competition intensity standard Level CCI
Weak
Moderate
Strong
Serious
competition
competition
competition
competition
<1
[1，1.5]
[1.5，2]
>2
3.4. Data sources Grain sowing area, total production, and other related data were obtained from the China Statistical Yearbook 2016. Precipitation and 18
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other data were obtained from the China Meteorological Data Network (http://data.cma.cn/site/index.html). Data on raw coal production, raw coal washing, oil production, natural gas production, firepower generation and raw coal used for thermal power generation were obtained from the China Energy Statistics Yearbook 2016.
4. Results and discussion 4.1. Spatial distribution characteristics of food production water footprint In 2015, China's food water footprint was 690.8 Gm3, of which the blue water footprint was 287.8 Gm3 and the green water footprint was 403.0 Gm3. The distribution of the food water footprint in each province is shown in Figure 3.
Fig. 3. Food water footprint in China (Blue water footprint 19
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and green water footprint).
In the figure, the high value areas of China's blue food water footprint distribute in the northeastern region and the central region of China. The water footprint of the 13 main food production areas accounted for 70.7% of the country's total, reaching 488.0 Gm3. Among the provinces, Heilongjiang had the largest food water footprint value of 82.4 Gm3. The water footprint is related to its planting area, crop type and meteorological condition. For the blue-green water ratios of each province, the blue water footprint of the main food production areas and the food balance areas was smaller than the green water footprint, while the blue water footprint of the main food sale area was larger than the green water footprint. It indicated that the main food production areas and the food balance areas had a high proportion of green water with lower marginal cost. The proportion of green water footprint mainly relates to factors such as crop type, meteorological condition and irrigated area ratio. The blue water footprint of Heilongjiang and Jiangsu was larger than 20 Gm3. The green water footprint of Heilongjiang, Henan and Anhui was larger than 30 Gm3.
4.2. Spatial distribution characteristics of energy production water footprint The main water-consuming blue energy water footprint is large in the northwest and the coastal areas of China (Fig. 4(a)). The reason is that 20
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coal production scale and thermal power generation in these provinces are large (Fig. 4(b) and (e)). Among them, the blue coal water footprint was higher than oil and natural gas. The calculation results were consistent with Ding N et. al (2018), which also proved the blue coal water footprint and the blue water footprint for thermal power generation accounted for more than 90% of the country's total blue energy water footprint. Therefore, coal and thermal power generation are the important parts of the main water-consuming energy. The energy water footprint is related to coal reserves and the increase in the proportion of thermal power generation due to lack of electricity. Therefore, there are significant differences in the blue water footprint of each province.
Fig. 4. The blue water footprint of coal, oil, natural gas and thermal power generation in China. 21
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For coal, the blue water footprint high value areas distribute in northern China, including Shanxi, Inner Mongolia, Heilongjiang and Shaanxi. Qinghai, Beijing and Guangxi are low value blue water footprint areas in China. The blue water footprint in the south is generally lower than that in the north, which is related to the distribution of China's coal reserves. China's coal reserves mainly distribute in the area north of Kunlun Mountain-Qinling-Dabie Mountain. Among them, Shanxi, Shaanxi and Inner Mongolia have the most abundant reserves, which total coal resources storage exceeds 75% of the country (Li, 2014). However, the technologies and environment of mining are poor in these provinces, which would limit the exploitation of coal resources. In addition, the five northwestern provinces are rich in coal resources (coal reserves could reach 800 Gt) (Qiu and Zhou, 2007), but the ecological in the northwestern region is relatively fragile. These lead to restrictions on mining and other processes, so the blue energy water footprint is relatively small in the northwestern region. For oil, the high value areas of the blue water footprint distribute in Shaanxi, Heilongjiang and Tianjin. The blue water footprint of them reached 0.112 Gm³ , 0.107 Gm³ and 0.060 Gm³ , respectively. The low value blue water footprint areas distribute in Inner Mongolia, Ningxia and Shanghai (Fig. 4(c)). The size of blue oil water footprint is in good agreement with the distribution of the oil and gas fields. China's oil 22
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resources mainly distribute in the eight major basins including Bohai Bay, Songliao, Tarim, Erdos and Junggar, which lead to significant differences in oil production and the blue water footprint in each province. For natural gas, the blue water footprint high value areas distribute in western China, including Shaanxi, Xinjiang and Sichuan. The blue water footprint of them reached 0.009 Gm³, 0.007 Gm³ and 0.005 Gm³, respectively. In addition, Guangdong's blue water footprint is also large. The low blue water footprint value areas distribute in Jiangsu, Henan, Guangxi and Gansu (Fig. 4(d)). China's natural gas resources mainly distribute in nine basins such as Tarim, Sichuan, and Erdos. The size of the blue natural gas water footprint is related to factors such as reserves and mining process. For thermal power generation, the blue water footprint high value areas mainly distribute in the central and eastern provinces of China, including Hubei, Zhejiang and Shandong. The blue water footprint of them reached 1.85 Gm³, 1.70 Gm³ and 1.68 Gm³, respectively. This is mainly related to the large energy consumption in production and strong thermal power plant construction investment capacity. The low value areas mainly distribute in the west. Among them, the blue water footprint in Qinghai was 0.51 Gm³, which was the lowest. The reason is that the western region is rich in hydraulic resources, and a large amount of hydropower development and utilization have also reduced the demand for thermal 23
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power generation. In addition, the spatial distribution of the blue water footprint for thermal power generation is also related to coal production. As a primary energy source, coal would have a direct impact on the production layout of secondary energy such as thermal power generation. It is worth noting that the thermal power generation of Zhejiang, Guangdong and Hubei were relatively large, while coal production consumes less water. The several provinces imported coal from outside, which caused a mismatch between the blue water footprint for thermal power generation and coal production.
4.3. Spatial distribution characteristics of water resources pressure According to the weighted average of the land area of each provincial administrative region, China's IWS was 1.46. The IWS of the food output area (1.71) was larger than that of the food input area (1.04). The IWS of coal bases was 2.26, which shows a serious water shortage in coal bases. These above could reflect the main food production areas and coal bases have strong ecological pressure and water resources pressure (Fig. 5(a)). The main food production areas and coal bases are mainly located in the north, and the calculation results also show that the IWS of south (0.48) was smaller than that of north (2.19). Therefore, the water consumption in the south is less than that in the north, which is exactly the opposite of the available water resources. For the I F , the high value areas mainly distribute in the main food 24
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production areas. Jilin, Heilongjiang and Jiangxi had relatively large value, and the values of I F were 0.75, 0.68 and 0.61, respectively. The high value areas of I E mainly distribute in the coal bases and coastal cities. Shanxi, Beijing and Tianjin had relatively large value, and the values of I E were 0.16, 0.14 and 0.10, respectively. This is mainly related to the production of food and primary energy.
Fig. 5. Indicators of competition between food and energy production for water.
In Figure. 5(b), WRC in Shanxi and Shandong are larger, mainly due to large blue coal water footprint in Shanxi, while the blue food water footprint and the blue water footprint for thermal power generation of Shandong were large. WRC in non-coal bases and food balance areas or main sale areas is small, which have low energy storage and low food production. Therefore, food and energy competition for water is weak. The larger n value mainly concentrates in agricultural provinces such as Heilongjiang and Anhui. The smaller n value mainly distributes in the provinces with abundant water resources such as Guangdong and the 25
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provinces with less energy and food production, such as Beijing and Tianjin. According to indicators such as CCI, 31 provinces were classified. For the first level composed of Shanxi, Liaoning, Heilongjiang, Hebei, and Shandong, there was a serious competitive relationship. The second level, Ningxia, had a strong competitive relationship. The third level, Beijing, Tianjin, Henan, Gansu, Xinjiang, Jilin, had a moderate competitive relationship. The fourth level, Inner Mongolia, Anhui, Shaanxi, Qinghai, Shanghai, Zhejiang, Fujian, Hunan, Hubei, Jiangxi, Guangdong, Guangxi, Hainan, Chongqing, Sichuan, Guizhou, Yunnan, Tibet, Jiangsu, had a weak competitive relationship.
4.4 Food and energy compete for water In 2015, the blue food water footprint accounted for 47.2% of the national water consumption. Compared with food production, the energy water footprint was small in China. While in developed countries, the energy water footprint is large. Among them, American electricity production consumed 39% of total water consumption (Fernando, 2016), almost just as much as the agricultural irrigation use. With economic development, China's energy water footprint will also increase rapidly. This could force food and energy to intensify competition for water resources. In order to better analyse the causes of competition and propose solutions, 31 provinces were classified. 26
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First, there was a big difference in the spatial distribution of water resources pressure in China. In areas with high water resources pressure, water conflicts among different industries are prominent, which increased the competition between water and energy. This type of province was collectively referred to as the water-dominant areas (Figure 6). The second type was the dominant area for food production. When the pressure on water resources was small, it was divided according to the relative size of the blue water footprint of food and energy production. The provinces with the blue food water footprint accounting for above 90% of the total water consumption, which belonged to the food-dominated areas. These provinces mainly distribute in the north, and most of them are also main food production areas. The third type was the energy-dominated areas, which mainly distribute in central and coastal areas of China. In these areas, the blue energy water footprint was more than 10% of the total water consumption. In the last type, food and energy production were weak competition for water resources, and the water resources pressure index was lower. It indicated that other water use sections except water for food and energy production dominated in this type, and such cases are classified as other water-dominated areas.
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Fig. 6. Zoning map of food and energy competition for water resources (The radar chart shows the proportion of the blue water footprint of food and energy in each province). Table 2 Summary of provincial competition level and regional division Province
CCI Grade
Province
CCI Grade
Province
CCI Grade
Beijing water
Ⅲ
Anhui food
Ⅳ
Chongqing other
Ⅳ
Tianjing water
Ⅲ
Fujianother
Ⅳ
Sichuan food
Ⅳ
Hebeiwater
Ⅰ
Jiangxi food
Ⅳ
Guizhouother
Ⅳ
Shanxiwater
Ⅰ
Shandong water
Ⅰ
Yunnanother
Ⅳ
NM food
Ⅳ
Henanwater
Shannxienergy
Ⅳ
Liaoning water
Ⅰ
Hebeienergy
Ⅰ
Gansuwater
Ⅲ
Hunan food
Ⅳ
Qinghaiother
Ⅳ
Guangdong other
Ⅳ
Ningxiawater
Ⅱ
Guangxi food
Ⅳ
Xinjiang water
Ⅲ
Jilin food Heilongjiang food Shanghaiwater
Ⅲ
IIIⅠ Ⅳ
Ⅲ
28
IV
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Jiangsu food Zhejiang energy
Ⅳ
IV Ⅳ
Hainanother
Ⅳ
Tibetother
Ⅳ
4.5. Four major areas analysis This section analyses the specific causes of water-dominated areas, food-dominated
areas,
energy-dominated
areas
and
other
water-dominated areas (Table 2). It also proposes corresponding measures to reduce water resources pressure, improve water efficiency and promote sustainable development of agriculture and industry.
4.5.1. Water-dominated areas Whether a province can be classified as water-dominated areas depends on two aspects. One is that food or energy should be the dominant industry of the province, which needs to consume a lot of water resources. Shandong, Henan and Hebei are the main food production areas, with large output and high water consumption. The contribution rate of the blue energy water footprint in Beijing, Tianjin and Shanxi were among the large in the country. The other aspect is that the province has a prominent shortage of water resources. For example, Ningxia is located in northwestern China with little precipitation. The Ningdong coal base requires a large amount of water for energy production, making its water resources even more scarce. In the water dominant areas provinces, in order to alleviate the pressure on water resources, industrial structure adjustment should be carried out 29
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to minimize the production of food or energy with high water consumption. For example, Ningxia should reduce certain water for food production and improve water use efficiency to alleviate water resources pressure. Beijing and Tianjin should reduce energy production and import food and energy from neighboring provinces as much as possible.
4.5.2. Food-dominated areas The food-dominated areas are the districts in which water resources pressure is not too high. Compared with energy consumption water, food production is the main water consumption industry. Generally, the blue energy water footprint of these areas is low. However, the situation of Jiangxi was complicated, as its natural gas processing industry resulted in a large blue energy water footprint. In terms of food production, many provinces produced more than 30 Mt. The food-dominated areas are mainly located in water-rich areas, and are dominated by rice with high water consumption, which leads to a large blue food water footprint. This type of province needs to vigorously develop and apply agricultural water-saving technology to improve the water use efficiency of food cultivation. In addition, water-deficient areas such as Jilin and Heilongjiang should encourage the cultivation of drought-tolerant crops. Meanwhile, education and training for agricultural water users should be strengthened to raise their water-saving awareness helping them to make good use of water. 30
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4.5.3. Energy-dominated areas The water resources of the energy-dominated areas are not too rich, and energy is also a main water-consumption industry relative to food production. The blue water footprint of coal and thermal power generation in these provinces is generally high. Among them, Zhejiang mainly focused on secondary energy production of thermal power generation, and its blue water footprint was much higher than that for primary energy. Under normal circumstances, the food yield and the blue water footprint of these areas are generally small. However, the blue water footprint of Hubei and Shaanxi were large, which is mainly related to factors such as planting area. This type of province needs to improve water use efficiency in energy production. It is wise for the government to encourage the development of renewable energy and new energy sources that consume less water. In addition, developing the specific technology which can reuse wastewater for energy production is necessary. Provinces with abundant water resources like Zhejiang are likely to increase their production of thermal power generation. Meanwhile, they can increase export trade, trying to alleviate energy reserves in neighboring provinces.
4.5.4. Other water-dominated areas Other water-dominated areas are generally rich in water resources, and the blue water footprint of food and energy is also small, making their 31
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competition for water weak. Among them, the main water-consuming blue energy water footprint in Fujian and Yunnan was relatively small, which is mainly related to the reserve of energy resources such as coal. The food output in Qinghai and Tibet was relatively small, mainly because the plateau terrain is not suitable for growing food. Other water-dominated areas could increase the number of high-water-consuming industries and take more measures to ease pressure on food and energy production in other provinces. The southern provinces should use the advantages of abundant water resources to increase food production and water use efficiency, such as Guangdong and Fujian. The province in this region could transport their food and energy to other provinces which have strong competition between food and energy for water.
5. Conclusions This study calculates the water footprint of food and main water-consumption energy production in 31 provinces of China, and analyses the competition relationship between food and energy production for water. In terms of water footprint calculation, the national food water footprint was 690.8 Gm3 in 2015, of which the blue water footprint was 287.8 Gm3. The main water-consuming blue energy water footprint was 18.5 Gm3. Among them, the provinces with large food water footprint 32
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included all main food production areas in China, and their distribution were mainly related to terrain and meteorological conditions. The provinces with large energy water footprint mainly distributed in China's coal bases and coastal cities. Through analysis of the water resources competition intensity index, the situation of the competition between food and energy for water in 31 provinces across the country was obtained. Among them, there were 19 provinces with weak competition, 6 provinces with medium competition, 1 province with strong competition, and 5 provinces with serious competition. According to the water resources pressure and industrial distribution, the country was divided into water-dominated areas (11 provinces), food-dominated areas (9 provinces), energy-dominated areas (3 provinces), and other water-dominated areas (4 provinces). In order to alleviate the competition between food and energy production for water, measures have been proposed for different types of areas to alleviate water resources pressure. Regarding the corresponding solution, in the water dominant area provinces, industrial structure adjustment should be carried out to minimize the production of food or energy with high water consumption. The food-dominated areas need to vigorously develop and apply agricultural water-saving technology to improve the water use efficiency of food cultivation. The energy-dominated areas need to improve water 33
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use efficiency in energy production. It is wise for the government to encourage the development of renewable energy and new energy sources that consume less water. Other water-dominated areas could increase the number of high-water-consuming industries and take more measures to ease pressure on food and energy production in other provinces. The WEF-Nexus is extremely complex, and this study is an important part of it – research on the competition between food and energy production for water. In fact, the relationship between food and energy has also shown some synergy, and we will conduct further research in follow-up work.
Acknowledgments This work was jointly supported by the National Key Research and Development Program of China (2016YFC0400205), the National Natural Science Foundation of China (41871207), Science and Technology Integrated Innovation Project, Shaanxi Province of China (2016TZC-N-14-1) and the 111 Project (No.B12007).
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Declaration of interests ☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ☐The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:
En Hua, Xinyu Wang, Bernard A. Engel, Shikun Sun, Yubao Wang PII:
S0959-6526(19)33973-3
DOI:
https://doi.org/10.1016/j.jclepro.2019.119103
Reference:
JCLP 119103
To appear in:
Journal of Cleaner Production
Received Date:
18 June 2019
Accepted Date:
29 October 2019
Please cite this article as: En Hua, Xinyu Wang, Bernard A. Engel, Shikun Sun, Yubao Wang, The Competitive Relationship between Food and Energy Production for Water in China, Journal of Cleaner Production (2019), https://doi.org/10.1016/j.jclepro.2019.119103
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The Competitive Relationship between Food and Energy Production for Water in China En Hua1,2, Xinyu Wang1,2, Bernard A Engel3, Shikun Sun1,2, Yubao Wang1,2,3* 1
Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid
Areas, Ministry of Education, Northwest A&F University, Yangling 712100, Shaanxi, China 2
Institute of Water Saving Agriculture in Arid regions of China, Northwest A&F
University, Yangling 712100, Shaanxi, China 3
Department of Agricultural and Biological Engineering, Purdue University, West
Lafayette, Indiana 47907, USA Corresponding author at: Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A&F University, Yangling, Shaanxi 712100, PR China Email: [email protected] (Yubao Wang)
Abstract:
Water, Energy and Food（ WEF） are key elements of
economic and social sustainable development, and present a complex nexus. Existed WEF nexus research is mainly confined to qualitative analyses, and it needs constant improvement and increases quantitative analyses. In China, water security is the most prominent problem in the WEF-nexus, which is manifested in the competitive relationship between food and energy production for water. Therefore, the matter of alleviating water stress has become a difficult and hot issue. After improving the 1
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existed water footprint accounting method for food and energy production, this study calculated the food water footprints (blue water footprint and green water footprint) in the 31 provinces of mainland China in 2015, as well as the blue water footprints of major energy systems (coal, oil, gas and thermal power generation). This study proposed water resources pressure index ( IWS ), water resources pressure contribution rate of food and energy (WCR), water consumption rate of food and energy (n) and competition composite index (CCI) of WEF, which were used to evaluate the consumption of water resources in food and energy production in different regions, and assess the intensity of competition for water resources in food and energy production. The results showed that the national food water footprint in 2015 was 690.8 Gm³, and the blue food water footprint was 287.8 Gm³. The main water-consuming blue energy water footprint was 18.5 Gm³, and coal production accounted for 9.9% and thermal power generation accounted for 87.6%. According to the competition
indicators,
the
competition
relationship
among
the
administrative regions of the 31 provinces in mainland China was obtained. For example, 5 provinces had serious competition and 19 provinces had weak competition. The water consumption of the energy industry continues to grow rapidly by economic development. Corresponding measures should be taken according to the different competition levels for water resources. 2
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Keywords: water; energy; food; water footprint; China
1. Introduction Global water resources are increasingly scarce, and high water consumption of food and energy production will significantly increase water consumption in the future. Population growth, climate change and commodity trade (Li et al., 2019) will further increase the consumption of water resources in food and energy production. Water demand is expected to increase 40% (McKinsey & Company, 2009) by 2030, while the water demand for both energy and food will increase 50% (International Energy Agency, 2012; Food and Agriculture Organization of the United Nations, 2012). With the rapid development of new bioenergy sources, the water demand for some important biofuel feedstocks such as soybean, grape seed and sugar cane will continue to increase (Hoogeveen et al., 2009), resulting in water scarcity. The WEF relationship is complicated. The Water, Energy and Food Security Nexus Conference, held in Bonn, Germany, in 2011, identified the relationship as a ‘nexus’ (The United Nations Economic and Social Commission for Asia and the Pacific, 2013) for the first time. However, existed research efforts are often based on the relationship between two of the three. In water–food relationship research, water demand, irrigation efficiency, and irrigation method are the main fields of focus. For example, Grafton et al. (2017) used a bottom-up model to predict the 3
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amount of irrigation water and food production in 19 countries in 2010-2050 under different scenarios. In the research related to the water–energy relationship, sustainable development paths that promote energy and water conservation are often explored. For example, some researches focused on the supply and demand of energy and water in India's end-user sector, and the distribution of resources among agriculture, industry and domestic sectors in California, USA (Malik, 2002; Lofman et al., 2002). These studies on the relationship between water and food or energy are mainly aimed at the occupation and consumption of water in food or energy production, and how to improve water use efficiency. In the WEF-Nexus relationship, water resources allocation is a multi-factor system. There is complex synergistic competition between systems. Therefore, the study of pairwise relationships has limitations. In the research progress of WEF-Nexus, many concepts and connotations of WEF-Nexus are introduced from the perspective of scientific intersection (Chang et.al, 2016; Albrecht et.al, 2018). Hoff (2011) believed that the water-energy-food relationship was a governance path to deal with resource scarcity, ensure the safety of the three and improve the efficiency of the three. FAO (2014) incorporated ecosystems into its definitions, emphasizing the inclusion of stakeholders in resource management related to resource use. Conway et al. (2015) viewed 4
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WEF-Nexus as a paradox between resources to reflect trade-offs and potential conflicts among water, energy and food. White et al. (2018) discovered the intrinsic link between resources and economic activity through surveys. Based on the above research, it can be seen that the research on WEF-Nexus is relatively wide, but there are still many research fields to be explored. In the complex WEF-Nexus, water security is the most prominent problem, especially in China. In 2015, China's total water consumption reached 610.3 Gm3, but the per capita water consumption was lower (444.0 m3) (Ministry of Water Resources of the People's Republic of China, 2016). Among them, agricultural water consumption accounted for more than 60% of the country's total, and energy water consumption exceeded 10% of the country's total. At present, the production of food crops and bioenergy has increased year by year, forcing water resources use to increase (Liu et al., 2013). Water consumption such as primary energy extraction has increased year by year (Zhan et al., 2015; Yang et al., 20017). The water pollution of energy production has made a profound impact (Bao et al., 2015), which also makes food and energy highly dependent on water resources. In terms of resources distribution, China's water resources are mainly concentrated in the south, while agricultural production and coal reserves are mostly distributed in the north. These will increase the intensity of competition between food and 5
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energy production for water. At the same time, the World Resources Institute's report has pointed out that China's thermal power generation faces huge risks (2016), which are due to the spatial mismatch of coal reserves and water resources. Water footprint provides a good way to examine the competitive relationship between food and energy for water. Water footprint, proposed by Hoekstra, refers to the amount of water needed for all products and services consumed by a country, region or individual for a certain period of time (Hoekstra and Chapagain, 2007). The water footprint can represent the development of the socio-economic system for the possession of water resources and pressure on the water resources environment (Hoekstra and Hung, 2005). Since the water footprint was proposed, it has been rapidly applied to different scales such as global and region (national, provincial, etc.). It can identify scale change, structural change, and influencing factors of water footprints at these scales, which provide decision support for issues such as water security, food security and ecological pressure (Zhang et al., 2013). At the same time, due to the virtual water trade caused by international trade, water footprint research extends to the industrial product field by agricultural products such as rice, corn and wheat (Herath et al., 2013). In recent years, water footprint studies on typical industrial processes and energy production have begun (Pacetti et al., 2015), such as printing, dyeing, steel and textiles (Wei and 6
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Shi, 2015). At present, the theoretical systems and research methods for WEF-Nexus have not been fully constructed, and significant work still needs to be done in terms of research perspective, dimensionality, scale and tool. The research on WEF-Nexus is mainly qualitative and lacks quantitative evaluation in many cases. The three resources of water, energy and food are essential resources for human survival and development. By quantitatively analysing the nexus and proposing solutions to improve safety and sustainable utilization of WEF-Nexus, it is helpful to enhance the synergy of the three, improve the overall utilization efficiency, and promote regional sustainable development. Existed research results of the pairwise relationship in the WEF-Nexus are not enough to support the formulation and implementation of decision-making programs, and even mislead decision-making. However, the WEF-Nexus relationship is complex. Therefore, this study uses the important link in WEF-Nexus—the competition between food and energy production for water as a breakthrough to carry out research, and proposes indicators to quantitatively evaluate the degree of competition. This study is aimed at the insufficient quantitative research on the core relationship between water resources competition in food and energy production in WEF-Nexus. On the basis of calculating the water footprint of food and main water-consuming energy, this study assesses the degree 7
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of competition between food and energy for water by using indicators such as Competition Composite Index (CCI) of WEF. This paper analyses the water resources competition in food and energy production in different provincial administrative regions of China. It proposes corresponding countermeasures for different competition levels, which alleviate regional water resources pressure and ecological pressure, and promote sustainable economic and social development.
2. Case study background The research objects are 31 provinces in mainland China. According to the food output, the 31 provinces are divided into 13 main food production areas, 11 food balance areas and 7 main food sale areas (Figure 1). In 2015, food production in the main food production areas, the food balance areas and the main food sale areas, respectively, accounted for 76.2%, 18.5% and 5.3% of the national total. There are 14 coal production bases in the country. In 2015, the production scale of coal bases accounted for 66.0% of the country's total. China's water resources are primarily in the south, accounting for 81.0% of water in the country. The cultivated land is small in the south, accounting for 35.9% of the country total.
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Fig. 1. Distribution of the study area, main food production areas and coal bases in China.
3. Methods 3.1. Calculation of food production water footprint The food crops in this study included cereal, bean and potato. The food water footprint of this study does not consider the grey water footprint. The grey water footprint is calculated based on the chemical material which is the most pollutants in food or energy production, while the pollutants of them are different. Therefore, this study only considers the blue water footprint and the green water footprint. The blue water footprint is the amount of surface and groundwater consumed to produce a product or service. Consumption means that fresh water is used to evaporate or enter the product and to take water from one watershed and then return to another watershed or ocean, i.e. water extracted from 9
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surface water or groundwater in the watershed does not return to the watershed. The green water footprint is the amount of rainwater consumed during the production process and is closely related to agricultural and forestry products. The green water footprint of these products refers to the amount of rainwater evaporation (from field or vegetation), plus the water stored in crops or trees. The food water footprint calculation formula is: WFi G
Wi g Wi b Gi
(1)
where WFi G is food production water footprint in the i provincial administrative districts, m3/kg; Wi g 、 Wi b is the green water footprint or blue water footprint during food production in the i provincial administrative districts, m3; Gi is total food production in the i provincial administrative districts, kg. Wi g is the product of the effective precipitation of the food growth
period and the corresponding cultivated land area: Wi g
105 Pi e SiG
iG
(2)
where iG is food multiple cropping index in the i provincial administrative districts; SiG is sown area of food in the i provincial administrative districts, kha;
Pi e is effective precipitation in the i
provincial administrative districts, mm. Wi b is the product of irrigation water consumption per unit area of food 10
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districts. Wi b IRiG SiG,IR
SiG,IR
Si , IR SiG Si
(3) (4)
where Si , IR is irrigation area (effective irrigated area) in the i provincial administrative districts, kha; SiG 、 Si is sown area of food and total sown area of crops in the i provincial administrative districts, kha. The formula of IRiG is: IRiG
IRi Si S i SiE
(5)
G i
where IRi is average irrigation water per unit area in the i provincial administrative districts, mm; SiE is sown area of other crops, kha; i is integrated crop irrigation ratio for cash crops and food crops in the i provincial administrative districts.
3.2. The calculation of energy production water footprint The main water-consuming energy sources include coal, oil, natural gas and thermal power generation. According to the energy production process flow, we determine the energy water footprint by distinguishing the water consumption categories at different stages of production. Water resources consumption can be divided into three categories: evaporation water, recycling water and pollution water. The calculation steps of the main water-consuming energy water footprint are as follows (Figure. 2). 11
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Fig. 2. Main water-consuming energy production water footprint calculation process.
The main water-consuming blue energy water footprint calculation formula is: Wi E Wi C Wi O Wi G Wi T
（6）
where Wi E is the main water-consuming blue energy water footprint in the i provincial administrative districts, m³; Wi C is the blue coal production water footprint in the i provincial administrative districts, m³; Wi O is the blue oil production water footprint in the i provincial
administrative districts, m³; Wi G is the blue natural gas production water footprint in the i provincial administrative districts, m³; WiT is the blue water footprint for thermal power generation in the i provincial administrative districts, m³.
3.2.1. The blue coal production water footprint The coal process is divided into two categories. One is underground mining and washing, and the other is open pit mining and washing. According to the process flow, the blue coal production water footprint is 12
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calculated based on the WFN method (Ding et al., 2016). The blue coal production water footprint calculation formula is: Wi C Wi m Wi w
(7)
The blue coal mining water footprint is: Wi m Qic Qiu
(8)
where Wi m is water consumption during coal mining in the i provincial administrative districts, m³; Qic is water consumption in the i provincial administrative districts, m³. The underground mining mainly divides into the processes of coal crushing, coal loading, coal transportation, mine hollowed out area support and treatment. There are 12 water consumption links, including dustproof water, hydraulic drilling machine water, flushing roadway water, road spray water and rescue tank water. Open pit mining mainly divides into processes such as coal rock pre-crushing, loading, transportation and dumping. There are 5 water consumption links, including road sprinkling, dust sprinkling, blasting rig water, land reclamation water and coal storage yard sprinkling. Qiu is recycling water in the i provincial administrative districts, m³. The mining process mainly includes air return and transport groove flushing deposition coal dust water consumption. The blue coal washing water footprint is： Wi w Qic Qiu
(9)
where Wi w is water consumption during coal washing process in the i 13
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3.2.2. The blue oil and natural gas production water footprint The technological process of oil mainly includes the auxiliary process of seismic exploration, logging production, downhole operation, oil production and oil and gas gathering and transportation. The natural gas production process mainly includes three parts, the wellhead, the gas collecting station and the gas distribution station. The water use of oil and natural gas is roughly similar. The blue water footprint is calculated as: Wi O Qib Qiind Qic Qiu
(10)
where Qib is the amount of water produced or imported into the product in the i provincial administrative districts, m³; Qiind is the production guarantee water volume in the i provincial administrative districts, m³. In addition, Qic includes the amount of water that cleans and transports the substance; Qiu includes the amount of cooling water and the amount of water that converts energy and transfers heat.
3.2.3. The blue water footprint for thermal power generation The thermal power generation process of secondary energy is composed of five parts, such as pulverized coal into furnace combustion, 14
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hot air drying and conveying pulverized coal, and fully burning and ash to grey field. It also includes the blue coal production water footprint link. The blue water footprint for thermal power generation is calculated as： Wi T Qic Qiu
(11)
where Qic includes boiler part, steam turbine unit, various water tank losses, piping system and heat consumption of heating; Qiu includes water consumption for cooling water and condensate.
3.3. Water resources competition intensity index 3.3.1. Water resources pressure index（ IWS ） There are many water scarcity indicators can reflect the water resources pressure and sustainability (Tommaso Pacetti et al., 2015). Such as, water-related risks and water pressure index. Among them, the water resources stress index can identify whether the relationships between water resources in a certain region and regional population, economy, and environment are coordinated. It can also determine whether water resources become a bottleneck for economic development in the region (Jia et al., 2002). This study use IWS to evaluate water resources pressure of provincial administrative region in China according to Wang et al. (2015). IWSi
(Wtvi Wtrvi Witvi ) (WAi 20%)
(12)
where IWSi is the water resources pressure index in the i provincial 15
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3.3.2. Water resources pressure contribution rate (WCR) of food and energy In the production process of food and energy, on the one hand, they consume a lot of water resources, which account for more than 70% of the country's water consumption (IEA, 2012; UNESCO-IHE, 2013). On the other hand, they exert strong pressure on water resources and contribute to the use of water resources. Therefore, this study analyses WCR in 31 provinces in China by the blue food water footprint and the main water-consuming blue energy water footprint. WCRi 2 I Fi I Ei
(13)
where WCRi is the water resources pressure contribution rate of food and energy in the i provincial administrative districts, dimensionless; I Fi is the water resources pressure contribution rate of food in the i provincial administrative districts, dimensionless;
I Ei is the water resources
pressure contribution rate of energy in the i provincial administrative districts, dimensionless. 16
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water-consuming blue energy water footprint and the total water consumption. I Fi
wif wDi
(14)
I Ei
wie wDi
(15)
where wif is the blue food production water footprint in the i provincial administrative districts, m3; wie is the main water-consuming blue energy water footprint in the i provincial administrative districts, m3; wDi is the total water consumption in the i provincial administrative districts, m3. The range of I E、F is [0,1]. The greater the value, the greater the competition between the province's food and energy for water.
3.3.3. Water consumption rate (n) of food and energy The WEF-nexus is affected by economic, social and environmental factors. Therefore, water for food and energy production in different regions accounts for different proportions of total water consumption. This has resulted in different levels of competition between food and energy production for water resources. Meanwhile, water for food and energy production have an impact on water resources pressure, which could use n to correct IWS . ni
wif wie wDi 17
(16)
Journal Pre-proof where ni is water consumption rate of food and energy in the i provincial administrative districts, dimensionless.
3.3.4. Competition composite index (CCI) of WEF In the calculation of CCI, it can be mainly divided into two parts. The first part is the impact of water resources pressure on competitive relationship. The water resources shortage limits the water consumption of food and energy production. Different places have different geographical and meteorological factors, using n to correct water resources pressure. The second part is the pressure and contribution to water resources in the production of food and energy. It can be represented by WCR. (17)
CCI i ni IWSi WCRi
where CCI i is the competition composite index of WEF in the i provincial administrative districts, dimensionless. The intensity of water resources competition is shown in Table 1. Table 1. Water resources competition intensity standard Level CCI
Weak
Moderate
Strong
Serious
competition
competition
competition
competition
<1
[1，1.5]
[1.5，2]
>2
3.4. Data sources Grain sowing area, total production, and other related data were obtained from the China Statistical Yearbook 2016. Precipitation and 18
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other data were obtained from the China Meteorological Data Network (http://data.cma.cn/site/index.html). Data on raw coal production, raw coal washing, oil production, natural gas production, firepower generation and raw coal used for thermal power generation were obtained from the China Energy Statistics Yearbook 2016.
4. Results and discussion 4.1. Spatial distribution characteristics of food production water footprint In 2015, China's food water footprint was 690.8 Gm3, of which the blue water footprint was 287.8 Gm3 and the green water footprint was 403.0 Gm3. The distribution of the food water footprint in each province is shown in Figure 3.
Fig. 3. Food water footprint in China (Blue water footprint 19
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and green water footprint).
In the figure, the high value areas of China's blue food water footprint distribute in the northeastern region and the central region of China. The water footprint of the 13 main food production areas accounted for 70.7% of the country's total, reaching 488.0 Gm3. Among the provinces, Heilongjiang had the largest food water footprint value of 82.4 Gm3. The water footprint is related to its planting area, crop type and meteorological condition. For the blue-green water ratios of each province, the blue water footprint of the main food production areas and the food balance areas was smaller than the green water footprint, while the blue water footprint of the main food sale area was larger than the green water footprint. It indicated that the main food production areas and the food balance areas had a high proportion of green water with lower marginal cost. The proportion of green water footprint mainly relates to factors such as crop type, meteorological condition and irrigated area ratio. The blue water footprint of Heilongjiang and Jiangsu was larger than 20 Gm3. The green water footprint of Heilongjiang, Henan and Anhui was larger than 30 Gm3.
4.2. Spatial distribution characteristics of energy production water footprint The main water-consuming blue energy water footprint is large in the northwest and the coastal areas of China (Fig. 4(a)). The reason is that 20
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coal production scale and thermal power generation in these provinces are large (Fig. 4(b) and (e)). Among them, the blue coal water footprint was higher than oil and natural gas. The calculation results were consistent with Ding N et. al (2018), which also proved the blue coal water footprint and the blue water footprint for thermal power generation accounted for more than 90% of the country's total blue energy water footprint. Therefore, coal and thermal power generation are the important parts of the main water-consuming energy. The energy water footprint is related to coal reserves and the increase in the proportion of thermal power generation due to lack of electricity. Therefore, there are significant differences in the blue water footprint of each province.
Fig. 4. The blue water footprint of coal, oil, natural gas and thermal power generation in China. 21
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For coal, the blue water footprint high value areas distribute in northern China, including Shanxi, Inner Mongolia, Heilongjiang and Shaanxi. Qinghai, Beijing and Guangxi are low value blue water footprint areas in China. The blue water footprint in the south is generally lower than that in the north, which is related to the distribution of China's coal reserves. China's coal reserves mainly distribute in the area north of Kunlun Mountain-Qinling-Dabie Mountain. Among them, Shanxi, Shaanxi and Inner Mongolia have the most abundant reserves, which total coal resources storage exceeds 75% of the country (Li, 2014). However, the technologies and environment of mining are poor in these provinces, which would limit the exploitation of coal resources. In addition, the five northwestern provinces are rich in coal resources (coal reserves could reach 800 Gt) (Qiu and Zhou, 2007), but the ecological in the northwestern region is relatively fragile. These lead to restrictions on mining and other processes, so the blue energy water footprint is relatively small in the northwestern region. For oil, the high value areas of the blue water footprint distribute in Shaanxi, Heilongjiang and Tianjin. The blue water footprint of them reached 0.112 Gm³ , 0.107 Gm³ and 0.060 Gm³ , respectively. The low value blue water footprint areas distribute in Inner Mongolia, Ningxia and Shanghai (Fig. 4(c)). The size of blue oil water footprint is in good agreement with the distribution of the oil and gas fields. China's oil 22
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resources mainly distribute in the eight major basins including Bohai Bay, Songliao, Tarim, Erdos and Junggar, which lead to significant differences in oil production and the blue water footprint in each province. For natural gas, the blue water footprint high value areas distribute in western China, including Shaanxi, Xinjiang and Sichuan. The blue water footprint of them reached 0.009 Gm³, 0.007 Gm³ and 0.005 Gm³, respectively. In addition, Guangdong's blue water footprint is also large. The low blue water footprint value areas distribute in Jiangsu, Henan, Guangxi and Gansu (Fig. 4(d)). China's natural gas resources mainly distribute in nine basins such as Tarim, Sichuan, and Erdos. The size of the blue natural gas water footprint is related to factors such as reserves and mining process. For thermal power generation, the blue water footprint high value areas mainly distribute in the central and eastern provinces of China, including Hubei, Zhejiang and Shandong. The blue water footprint of them reached 1.85 Gm³, 1.70 Gm³ and 1.68 Gm³, respectively. This is mainly related to the large energy consumption in production and strong thermal power plant construction investment capacity. The low value areas mainly distribute in the west. Among them, the blue water footprint in Qinghai was 0.51 Gm³, which was the lowest. The reason is that the western region is rich in hydraulic resources, and a large amount of hydropower development and utilization have also reduced the demand for thermal 23
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power generation. In addition, the spatial distribution of the blue water footprint for thermal power generation is also related to coal production. As a primary energy source, coal would have a direct impact on the production layout of secondary energy such as thermal power generation. It is worth noting that the thermal power generation of Zhejiang, Guangdong and Hubei were relatively large, while coal production consumes less water. The several provinces imported coal from outside, which caused a mismatch between the blue water footprint for thermal power generation and coal production.
4.3. Spatial distribution characteristics of water resources pressure According to the weighted average of the land area of each provincial administrative region, China's IWS was 1.46. The IWS of the food output area (1.71) was larger than that of the food input area (1.04). The IWS of coal bases was 2.26, which shows a serious water shortage in coal bases. These above could reflect the main food production areas and coal bases have strong ecological pressure and water resources pressure (Fig. 5(a)). The main food production areas and coal bases are mainly located in the north, and the calculation results also show that the IWS of south (0.48) was smaller than that of north (2.19). Therefore, the water consumption in the south is less than that in the north, which is exactly the opposite of the available water resources. For the I F , the high value areas mainly distribute in the main food 24
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production areas. Jilin, Heilongjiang and Jiangxi had relatively large value, and the values of I F were 0.75, 0.68 and 0.61, respectively. The high value areas of I E mainly distribute in the coal bases and coastal cities. Shanxi, Beijing and Tianjin had relatively large value, and the values of I E were 0.16, 0.14 and 0.10, respectively. This is mainly related to the production of food and primary energy.
Fig. 5. Indicators of competition between food and energy production for water.
In Figure. 5(b), WRC in Shanxi and Shandong are larger, mainly due to large blue coal water footprint in Shanxi, while the blue food water footprint and the blue water footprint for thermal power generation of Shandong were large. WRC in non-coal bases and food balance areas or main sale areas is small, which have low energy storage and low food production. Therefore, food and energy competition for water is weak. The larger n value mainly concentrates in agricultural provinces such as Heilongjiang and Anhui. The smaller n value mainly distributes in the provinces with abundant water resources such as Guangdong and the 25
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provinces with less energy and food production, such as Beijing and Tianjin. According to indicators such as CCI, 31 provinces were classified. For the first level composed of Shanxi, Liaoning, Heilongjiang, Hebei, and Shandong, there was a serious competitive relationship. The second level, Ningxia, had a strong competitive relationship. The third level, Beijing, Tianjin, Henan, Gansu, Xinjiang, Jilin, had a moderate competitive relationship. The fourth level, Inner Mongolia, Anhui, Shaanxi, Qinghai, Shanghai, Zhejiang, Fujian, Hunan, Hubei, Jiangxi, Guangdong, Guangxi, Hainan, Chongqing, Sichuan, Guizhou, Yunnan, Tibet, Jiangsu, had a weak competitive relationship.
4.4 Food and energy compete for water In 2015, the blue food water footprint accounted for 47.2% of the national water consumption. Compared with food production, the energy water footprint was small in China. While in developed countries, the energy water footprint is large. Among them, American electricity production consumed 39% of total water consumption (Fernando, 2016), almost just as much as the agricultural irrigation use. With economic development, China's energy water footprint will also increase rapidly. This could force food and energy to intensify competition for water resources. In order to better analyse the causes of competition and propose solutions, 31 provinces were classified. 26
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First, there was a big difference in the spatial distribution of water resources pressure in China. In areas with high water resources pressure, water conflicts among different industries are prominent, which increased the competition between water and energy. This type of province was collectively referred to as the water-dominant areas (Figure 6). The second type was the dominant area for food production. When the pressure on water resources was small, it was divided according to the relative size of the blue water footprint of food and energy production. The provinces with the blue food water footprint accounting for above 90% of the total water consumption, which belonged to the food-dominated areas. These provinces mainly distribute in the north, and most of them are also main food production areas. The third type was the energy-dominated areas, which mainly distribute in central and coastal areas of China. In these areas, the blue energy water footprint was more than 10% of the total water consumption. In the last type, food and energy production were weak competition for water resources, and the water resources pressure index was lower. It indicated that other water use sections except water for food and energy production dominated in this type, and such cases are classified as other water-dominated areas.
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Fig. 6. Zoning map of food and energy competition for water resources (The radar chart shows the proportion of the blue water footprint of food and energy in each province). Table 2 Summary of provincial competition level and regional division Province
CCI Grade
Province
CCI Grade
Province
CCI Grade
Beijing water
Ⅲ
Anhui food
Ⅳ
Chongqing other
Ⅳ
Tianjing water
Ⅲ
Fujianother
Ⅳ
Sichuan food
Ⅳ
Hebeiwater
Ⅰ
Jiangxi food
Ⅳ
Guizhouother
Ⅳ
Shanxiwater
Ⅰ
Shandong water
Ⅰ
Yunnanother
Ⅳ
NM food
Ⅳ
Henanwater
Shannxienergy
Ⅳ
Liaoning water
Ⅰ
Hebeienergy
Ⅰ
Gansuwater
Ⅲ
Hunan food
Ⅳ
Qinghaiother
Ⅳ
Guangdong other
Ⅳ
Ningxiawater
Ⅱ
Guangxi food
Ⅳ
Xinjiang water
Ⅲ
Jilin food Heilongjiang food Shanghaiwater
Ⅲ
IIIⅠ Ⅳ
Ⅲ
28
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Jiangsu food Zhejiang energy
Ⅳ
IV Ⅳ
Hainanother
Ⅳ
Tibetother
Ⅳ
4.5. Four major areas analysis This section analyses the specific causes of water-dominated areas, food-dominated
areas,
energy-dominated
areas
and
other
water-dominated areas (Table 2). It also proposes corresponding measures to reduce water resources pressure, improve water efficiency and promote sustainable development of agriculture and industry.
4.5.1. Water-dominated areas Whether a province can be classified as water-dominated areas depends on two aspects. One is that food or energy should be the dominant industry of the province, which needs to consume a lot of water resources. Shandong, Henan and Hebei are the main food production areas, with large output and high water consumption. The contribution rate of the blue energy water footprint in Beijing, Tianjin and Shanxi were among the large in the country. The other aspect is that the province has a prominent shortage of water resources. For example, Ningxia is located in northwestern China with little precipitation. The Ningdong coal base requires a large amount of water for energy production, making its water resources even more scarce. In the water dominant areas provinces, in order to alleviate the pressure on water resources, industrial structure adjustment should be carried out 29
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to minimize the production of food or energy with high water consumption. For example, Ningxia should reduce certain water for food production and improve water use efficiency to alleviate water resources pressure. Beijing and Tianjin should reduce energy production and import food and energy from neighboring provinces as much as possible.
4.5.2. Food-dominated areas The food-dominated areas are the districts in which water resources pressure is not too high. Compared with energy consumption water, food production is the main water consumption industry. Generally, the blue energy water footprint of these areas is low. However, the situation of Jiangxi was complicated, as its natural gas processing industry resulted in a large blue energy water footprint. In terms of food production, many provinces produced more than 30 Mt. The food-dominated areas are mainly located in water-rich areas, and are dominated by rice with high water consumption, which leads to a large blue food water footprint. This type of province needs to vigorously develop and apply agricultural water-saving technology to improve the water use efficiency of food cultivation. In addition, water-deficient areas such as Jilin and Heilongjiang should encourage the cultivation of drought-tolerant crops. Meanwhile, education and training for agricultural water users should be strengthened to raise their water-saving awareness helping them to make good use of water. 30
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4.5.3. Energy-dominated areas The water resources of the energy-dominated areas are not too rich, and energy is also a main water-consumption industry relative to food production. The blue water footprint of coal and thermal power generation in these provinces is generally high. Among them, Zhejiang mainly focused on secondary energy production of thermal power generation, and its blue water footprint was much higher than that for primary energy. Under normal circumstances, the food yield and the blue water footprint of these areas are generally small. However, the blue water footprint of Hubei and Shaanxi were large, which is mainly related to factors such as planting area. This type of province needs to improve water use efficiency in energy production. It is wise for the government to encourage the development of renewable energy and new energy sources that consume less water. In addition, developing the specific technology which can reuse wastewater for energy production is necessary. Provinces with abundant water resources like Zhejiang are likely to increase their production of thermal power generation. Meanwhile, they can increase export trade, trying to alleviate energy reserves in neighboring provinces.
4.5.4. Other water-dominated areas Other water-dominated areas are generally rich in water resources, and the blue water footprint of food and energy is also small, making their 31
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competition for water weak. Among them, the main water-consuming blue energy water footprint in Fujian and Yunnan was relatively small, which is mainly related to the reserve of energy resources such as coal. The food output in Qinghai and Tibet was relatively small, mainly because the plateau terrain is not suitable for growing food. Other water-dominated areas could increase the number of high-water-consuming industries and take more measures to ease pressure on food and energy production in other provinces. The southern provinces should use the advantages of abundant water resources to increase food production and water use efficiency, such as Guangdong and Fujian. The province in this region could transport their food and energy to other provinces which have strong competition between food and energy for water.
5. Conclusions This study calculates the water footprint of food and main water-consumption energy production in 31 provinces of China, and analyses the competition relationship between food and energy production for water. In terms of water footprint calculation, the national food water footprint was 690.8 Gm3 in 2015, of which the blue water footprint was 287.8 Gm3. The main water-consuming blue energy water footprint was 18.5 Gm3. Among them, the provinces with large food water footprint 32
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included all main food production areas in China, and their distribution were mainly related to terrain and meteorological conditions. The provinces with large energy water footprint mainly distributed in China's coal bases and coastal cities. Through analysis of the water resources competition intensity index, the situation of the competition between food and energy for water in 31 provinces across the country was obtained. Among them, there were 19 provinces with weak competition, 6 provinces with medium competition, 1 province with strong competition, and 5 provinces with serious competition. According to the water resources pressure and industrial distribution, the country was divided into water-dominated areas (11 provinces), food-dominated areas (9 provinces), energy-dominated areas (3 provinces), and other water-dominated areas (4 provinces). In order to alleviate the competition between food and energy production for water, measures have been proposed for different types of areas to alleviate water resources pressure. Regarding the corresponding solution, in the water dominant area provinces, industrial structure adjustment should be carried out to minimize the production of food or energy with high water consumption. The food-dominated areas need to vigorously develop and apply agricultural water-saving technology to improve the water use efficiency of food cultivation. The energy-dominated areas need to improve water 33
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use efficiency in energy production. It is wise for the government to encourage the development of renewable energy and new energy sources that consume less water. Other water-dominated areas could increase the number of high-water-consuming industries and take more measures to ease pressure on food and energy production in other provinces. The WEF-Nexus is extremely complex, and this study is an important part of it – research on the competition between food and energy production for water. In fact, the relationship between food and energy has also shown some synergy, and we will conduct further research in follow-up work.
Acknowledgments This work was jointly supported by the National Key Research and Development Program of China (2016YFC0400205), the National Natural Science Foundation of China (41871207), Science and Technology Integrated Innovation Project, Shaanxi Province of China (2016TZC-N-14-1) and the 111 Project (No.B12007).
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Declaration of interests ☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ☐The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: