Energy's Thirst for Water in China - Environmental Science

Publication Date (Web): September 22, 2014 ... Moreover, China's 12th Five-Year Plan of Energy Development does not change the existing energy strateg...
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Energy’s Thirst for Water in China Beiming Cai,† Bing Zhang,*,† Jun Bi,† and Wenjing Zhang‡ †

State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, China Chinese Academy for Environmental Planning, Beijing 100012, China

‡

S Supporting Information *

ABSTRACT: Water scarcity and uneven water distribution pose significant challenges to sustainable development and energy production in China. Based on the International Energy Agency (IEA)’s energy strategy scenarios for China, we evaluated the water withdrawal for energy production from 2011 to 2030. The results show that the amount of water withdrawal will be increased by 77% in 2030, which will aggravate China’s water scarcity risk under current energy strategy. We also observed that 67% of the energy production in China occurs in areas that are facing water scarcity. Moreover, China’s 12th Five-Year Plan of Energy Development does not change the existing energy strategies, and the planned total energy production is much higher than the IEA’s projection, which will result in an increased demand for water resources. However, if China were to apply broad policies to reduce CO2 emissions, the amount of water withdrawal would also decline compared with current energy strategy. Thus, reforming China’s energy structure and reducing energy usage are not only urgent because of climate challenges and air pollution but also essential to reducing the pressure of water scarcity.

1. INTRODUCTION According to the Fifth Assessment Report (AR5) of the International Panel on Climate Change (IPCC), global surface temperatures warmed by 0.85 [0.65 to 1.06] °C over the period 1901−2012, and at the end of this century, the temperature will have increased by 1.0−3.7 °C.1 Such climate change will have significant impacts on our planet’s ecosystem, food production, society, and human health.1 The scientific community has reached a broad agreement that the effects of increased atmospheric concentrations of greenhouse gases, including CO2 caused by human activities, are the main drivers of climatic change.2 In addition, the burning of fossil fuels such as oil, gasoline, and coal is the main source of air pollution. In the United States, fossil fuel-based power plants are responsible for 67% of the nation’s sulfur dioxide emissions, 23% of the nitrogen oxide emissions, and 40% of the man-made carbon dioxide emissions.3 Reducing the use of fossil fuels is essential for both developed countries and developing countries. Since 2006, China’s CO2 emissions have been greater than those of the U.S., with China topping the list of CO2-emitting countries.4 At the end of 2010, China’s CO2 emissions increased to 8.33 billion tons, which accounted for 25.1% of the global amount.4 During the Copenhagen Climate Change Conference in 2009, China committed to reducing its CO2 emission intensity by 40−45% by 2020 relative to 2005 levels based on the principle of “common but different responsibilities.” To reduce carbon emissions and air pollution, the Chinese government has adopted several proactive policies, including adjusting the energy structure, increasing the © 2014 American Chemical Society

proportion of renewable energy in energy sectors, and increasing the efficiency of energy use. Moreover, new technologies for CO2 emissions reduction, such as carbon capture and storage (CCS), will also be used in the near future. In addition, to improve the air quality, the Chinese government has adopted a series of policies for coal production that include increasing the ratio of raw coal for washing to 65% in 20155 and reducing the use of coal by replacing it with synthetic natural gas (SNG). Recently, an increasing amount of attention has been paid to water constraints for energy strategies.6−8 Water is used at various stages of the energy production cycle, including resource extraction (coal, oil, and natural gas), energy conversion (refining and processing), and power generation (coal, gas, and nuclear and biomass power plants).9,10 Energy accounts for an estimated 27% of all water consumption in the United States outside of the agricultural sector.11 Specifically, for traditional energy production, water used for thermoelectric cooling accounts for approximately 40% of the total water withdrawn in the United States.12 In China, recent research has also indicted that energy production was responsible for 12.3%, 4.1%, and 8.3% of the national water withdrawal, consumption, and wastewater discharge in 2007, respectively.13 In addition, unconventional energy is also facing water constraints. Received: Revised: Accepted: Published: 11760

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target CO2 emissions reduction, the following scenarios were used: the current policies scenario (CPS), new policies scenario (NPS), and 450 scenario (450S). The CPS is based on the perpetuation, without change, of the government policies and measures that had been enacted by mid-2012. The NPS considers the broad policy commitments and plans that have already been implemented to meet energy-related challenges, including those commitments with no identified or announced measures for implementation that are targeted at a 40% reduction of CO2 emissions intensity by 2020 relative to 2005 levels. The 450S is an ideal scenario in which a 450 ppm of CO2 equivalent (ppm of CO2-eq) target is achieved through the implementation of stricter policies and includes the CCS technology used for coal plants.16 The amount of energy production in three scenarios can be found in Supporting Information (SI) (Table S1). The predictions of the amount of coal, oil, and shale gas extraction were only available for the NPS, and the import shares in the NPS were used to calculate the amounts of coal and oil extraction in the other scenarios.26 For shale gas extraction, we assumed that the extraction ratio for China relative to global production in the other two scenarios was the same as in the NPS to make predictions for the CPS and the 450S. We also assumed that the amount of shale gas production per well is 4 million cubic meters per year according to the average production of shale gas well in Texas which is the main places for shale gas production in U.S.,14 for China has not begun shale gas extraction yet. We calculated the amount of wells through dividing the target of shale gas production in the report by the average production per wells per year as mentioned above. The SNG has not been included in IEA’s prediction, according to National Energy Administration’s plan,27 the production of SNG will be 50 bcm in 2020. We take this as the target in CPS in 2020 and use the increase rate of total natural gas production to make the prediction in other scenarios. There was no prediction for coal washing under the three scenarios in the IEA report. According to the “Action Plan for the Control of Air Pollution”(70% in 2017)28 and the average growth rate per annum between 2000 and 2010 (1.3%, data sources see SI Table S2), we assumed that the ratio of raw coal for washing under the three scenarios would be 73% in 2020 and 80% in 2030. We assumed that the oil demand in IEA’s projection was equated to the amount of oil refining, which means the available crude oil will all be refined based on the ratio of oil refining to the total available crude oil in 2010 (97.6%) and the annual growth rate between 2000 to 2010 (0.26%) (data derived from China Energy Statistical Yearbook 2001−201129). At province level, the data of energy production in 2011 mainly came from China Energy Statistical Yearbook 201230 (see SI Table S3). For the future energy production at province level, we assumed that the amount of energy production of each processes for each provinces as a share of the entire nation would be the same as that in 2015 (detailed information about energy production in 2015 can be found in SI Table S4). We used this share to make the prediction about the amount of energy production for each processes at province level under three scenarios in 2020 and 2030. For comparisons with the historical water withdrawal for energy production, we used energy production data for 2000−2010 from the China Energy Statistical Yearbook29 (detailed information about energy production between 2000 and 2010 and be found in SI Table S2).

Hydraulic fracturing used for shale gas extraction requires significant amounts of water. The water used for shale gas extraction in Texas accounts for approximately 1.15% of the local water consumption.14 Production of SNG is also very water-intensive.15 Thus, the energy sector is vulnerable to physical constraints on water availability,16 and the choice of technology, sites, and types of energy production facilities is impacted by water availability.17 China has also been facing water scarcity problems in recent decades. China’s annual per capita availability of renewable water resources is roughly a quarter of the world average.18 The magnitude and frequency of water scarcity events has shown an increasing trend as a result of rapid economic development and urbanization processes,7,19 and these events have begun to threaten food security, economic development, and the quality of life in China.20,21 From 2000 to 2010, water withdrawal increased from 5497 to 6022 billion cubic meters (bcm),22 which aggravated the water scarcity. In addition to water scarcity, the uneven distribution of water resources and energy resources may pose a significant challenge to energy production in China. Nearly 80% of the mineral energy resources are located in the north and west, where water scarcity has been severe.23,24 For example, Shanxi, Shaanxi, Inner Mongolia, and Xinjiang account for 74% of China’s coal resources but only 7% of the nation’s water resources.25 Thus, the water supply is crucial for China’s future energy strategies.6 Therefore, this study examines the water withdrawal for energy production based on possible policy scenarios in China for the period 2011−2030. The following section describes the methodology for the calculation of water withdrawn by energy strategies. Section 3 shows the results of energy production for the period 2011−2030 based on different scenarios and the corresponding water withdrawn by different sectors and provinces. Section 4 provides discussions of the results and their policy implications.

2. MATERIALS AND METHODS 2.1. Accounting Scope. To measure the water withdrawal during energy production processes, this study includes the amount of water used for the extraction of the primary energy and the processing and conversion of primary energy. Primary energy production contains coal, oil, and natural gas extraction, whereas the processing of primary energy entails the processes of coal washing, oil refining, and biofuel production. In addition, the conversion of primary energy production includes electricity generation from coal, natural gas, biomass power, nuclear power, hydropower, wind power, and solar photovoltaic (PV) power and heat supply. Moreover, we divide energy production into different sectors based on the energy type. The coal sector includes coal mining, coal washing, and electricity generation from coal-fired plants. The oil sector includes oil exploitation and refining. The natural gas sector includes natural gas extraction and electricity generation from gas-fired plants. The biomass sector includes biofuel production and electricity generation from biomass power. The nuclear, hydro, wind, and solar sector only includes electricity generation from nuclear power, hydropower, wind power, and solar PV power. 2.2. Energy Production Scenarios. This study selected the energy production scenarios presented by the International Energy Agency (IEA) in its report “World Energy Outlook 2012” (WEO 2012). Based on the level of economic activity, demographic changes, energy prices, and efficiency of energy use, the IEA projected the energy production of China. To 11761

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Figure 1. Energy Production and Its Water Withdrawal for the Entire Nation Between 2000 and 2030. E denotes energy production; W denotes water withdrawal for energy production.

2.3. Water Withdrawal for Energy Production. The calculation of water withdrawal for energy production is measured by the water withdrawn by energy production per unit based on the data from Environmental Statistics Database 2011 and the quantity of energy production. The following section discusses the water withdrawal for energy production in different sectors. Water for Coal. In coal mining processes, a large volume of water is required for steps including cooling mining equipment, dedusting, washing tunnels, and extinguishing. A significant amount of water is withdrawn for the coal washing process of slime water treatment. Water used for thermal power from coalfired plants includes supplementary water to compensate for the loss of circulating cooling water and to reduce the dust caused by coal fired.31 In addition, the application of CCS for thermal power from coal-fired needs additional water (1.85 m3/ MWh) due to the CCS equipment needs extra electricity during its operation.32,33 As our study focus on freshwater withdrawal, we have subtracted the amount of seawater utilization for the thermal power from coal-fired (detailed information about seawater use can be found in SI Table S5). Water for Oil. Waterflooding or enhanced oil recovery is a key process during the exploitation of oil that involves the injection of large quantities of water into a well to force oil to separate from rock formations and reach oil wells. Oil refining includes crude oil distillation, which accounts for a significant amount of water withdrawn for the production of steam and cooling.17 Water for Natural Gas. Although conventional natural gas extraction requires little water,9 hydraulic fracturing for shale gas extraction requires significant amounts of water. Moreover, production of SNG needs a lot of water.15 The thermal power from gas-fired plants uses supplementary water to compensate for the loss of circulating cooling water. Water for Biomass. In China, currently, the feedstock for bioethanol primarily comprises crop residue34,35and the raw materials for biodiesel primarily comprise kitchen waste and drainage oil without direct water consumption.34,35 Moreover, in 12th Five-Year Plan for Bioenergy Development36 and Medium and Long-term Development Plan for Renewable Energy37 Chinese government have regulated that using the crop residue or nonfood crop as the materials for biomass due

to China’s food security concern. In future, many provinces have presented the plan of development for nonfood biomass fuel, like cassava, sweet sorghum, and Jatropha. These plants do not need direct blue water (equal to irrigation) during their growing stage,38 which means rainwater can satisfy their water requirement. Therefore, the water withdrawal for the materials of biofuel production has not been considered, and this study only reports on the water withdrawn used during biofuel production. Producing bioethanol and biodiesel requires water for grinding, liquefaction, fermentation, separation, and drying. Biomass power plants also need supplementary water as a result of the loss of circulating cooling water. Water for Nuclear. The nuclear fuel for China’s nuclear power is primarily imported from Australia and other countries.39 Therefore, the water used for uranium mining has not been considered in this study. Moreover, similar as thermal power plant, nuclear power plant needs the supplementary water to compensate for the loss of circulating cooling water.40 As our study focus on freshwater withdrawal, we have subtracted the amount of seawater utilization for the nuclear power (detailed information about seawater use can be found in SI Table S5). Water for Hydropower. The water consumption by hydroelectricity primarily results from evaporation. However, reservoirs often serve many purposes, including the provision of hydroelectric power, so all the evaporates cannot be calculated, and the size of different reservoirs may have significant differences. Consequently, the evaporation may be diverse, and it is difficult to ascertain the portion of water consumption that results from evaporation for hydropower. Therefore, this study considered the water used for hydroelectricity to be zero.41 Water for Wind and Solar Power. The operation of wind and solar PV power for the generation of electricity requires negligible amounts of water.9,42 Therefore, this study considered the water used for wind and solar PV power to be zero. Water for Heat Supply. The operation of heat supply system need supplementary water to generate steam for translate heat. There are many energy sources for heat supply includes coal, oil, natural gas, etc. no matter what sources the heat supply 11762

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Figure 2. Water withdrawal for different energy production under three scenarios (bcm). Coal includes the amount of water withdrawal for coal mining, washing, and electricity generation from coal-fired plants. Oil includes the amount of water withdrawal for oil exploitation and refining. Nature gas includes the amount of water withdrawal for shale gas extraction and electricity generation from gas-fired plants. Biomass includes the amount of water withdrawal for biofuels production and electricity generation from biomass plants. The water withdrawal for heat production had not been included in this figure for we do not know the future energy sources for heal supply.

The percent of renewable energy from the nuclear, biomass, hydro, wind, and solar which contribute to a reduction of CO2 emissions will increase to 12% and 21% under the NPS and 450S in 2030, respectively. At province level, Shanxi, Inner Mongolia, Shaanxi, Shandong, and Henan are the main energy producers and account for approximately 60% of the energy production for the entire country. Shanxi, Inner Mongolia, and Shaanxi are the largest coal mining areas, and the quantity of coal mined from these three provinces accounts for 57% of the production for the entire country. Shaanxi, Tianjin, and Heilongjiang produce the greatest amount of oil, accounting for approximately 50% of the oil exploited for the entire country. Coal is primarily washed in Shanxi, Henan, Shandong, and Inner Mongolia, accounting for approximately 52% of the processing for the entire country. Oil refining primarily occurs in Liaoning, Shandong, Guangdong, Jiangsu, and Zhejiang, with approximately 50% of the refining for the entire country. A large amount of electricity generation from coal-fired plants occurs in Shandong, Jiangsu, Inner Mongolia, Guangdong, Shanxi, Henan, and Hebei, accounting for approximately 51% of the entire nation (detailed information about energy production at province level were listed in SI Table S3). 3.2. Water Withdrawal for Energy Production. The increased energy production also impacts the water demand. The water withdrawal for energy production has increased from 8.98 to 28.78 bcm from 2000 to 2011 (see Figure 1). In addition, the water withdrawal will increase to 39.70, 35.86, and 31.33 bcm in the CPS, NPS and 450S, respectively, by 2020 and will be 50.90, 42.53, and 33.45 bcm, respectively, by 2030. If the Chinese government adopts its current policies without change, the water withdrawal for energy production will increase by 38% and 77% in 2020 and 2030, respectively, which will place significant pressure on the limited water resources. However, if China adopts new climate policies such as increasing its nonfossil fuel share and implementing CO2 pricing from 2020, the water withdrawal for energy production will be reduced by 16% (8.36 bcm)and 34% (17.45 bcm)under the NPS and the 450S. Nonetheless, the water withdrawal will have not peaked under the 450S and will have increased by 16% in 2030. Under the 450S, new technologies, such as CCS, will be adopted to reduce CO2 discharge, which will require more water withdrawal. The implementation of the new technologies

system all need water. In this study, we did not distinguish the water withdrawal of different energy sources for heat supply. 2.4. Data Collection. The water withdrawal for energy production per unit for each provinces was calculated based on the data from Environmental Statistics Database 2011. In this database, there are data of water withdrawal for each company related with energy production and the amount of product output at province level. We can get water withdrawal for energy production per unit for each company though dividing the amount of water withdrawal by product output. And then we get the value of water withdrawal for energy production per unit for each provinces based on the average of each company in a certain province. Based on this method we can get all the value of water withdrawal for each energy production processes per unit cross all the provinces except the inland nuclear power, shale gas production and SNG production. Currently, there is no inland nuclear power, while according to Guo et al.43 average water withdrawal of nuclear power is 150% of thermal power from coal-fired and we use this rate to calculate the value of water withdrawal for nuclear power for each provinces. China has not begun to extract shale gas, so we applied the average water usage for the period 2009−2011 in Texas.14 The value of water withdrawal for SNG production derived from previous research about water use for SNG production in China.15 Detailed information about water withdrawal for energy production per unit for each provinces can be found in SI (Tables S6 and S7).

3. RESULTS 3.1. Energy Production. The primary energy production of China increased from 976 Mtce/year in 2000 to 2916 Mtce/ year in 2011, as shown in Figure 1. In addition, according to IEA projections, the energy production will significantly increase under the CPS and NPS compared with the level of 2011. Under the 450S, the amount of energy production shows a weak decreasing trend between 2011 and 2030. Specifically, under the CPS, NPS, and 450S, energy production will reach, respectively, 3466, 3247, and 2917 Mtce in 2020 and 3949, 3364, and 2450 Mtce in 2030. The percent of production in the coal sector shows a decreasing trend in the NPS and 450S, but it still accounts for the largest percent of energy production (more than 60%) among all sectors. Coal will obviously not change as the main energy source for the period 2011−2030. 11763

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Figure 3. Distribution of water withdrawal for energy production and water scarcity in different provinces. a, Water withdrawal for energy production in different provinces in 2011; Darker backgrounds indicate more water withdrawal for energy production. b-d, Water scarcity and variation of water withdrawn for energy production in different provinces under the CPS, NPS, and 450S in 2030 compared with 2011; Darker backgrounds indicate worse water scarcity. Size of the circle show the variation of water withdrawn for energy production (bcm), blue shows the increase and green shows the decrease.

will offset part of the reduction of water withdrawal by other methods. Although the percentage of water withdrawal for coal shows a decreasing trend under the NPS and 450S, it still has a dominant position in the three scenarios (see Figure 2). The water withdrawal for coal sector comprises more than 60% of the total water withdrawal for energy production in the different scenarios. The key strategy to reduce CO2 for China is to change the energy structure and reduce coal consumption under the NPS and 450S. Thus, the water withdrawal for coal sector will decrease by 23% and 51% under NPS and 450S, respectively, when compared to that of the CPS in 2030. Based on the spatial distribution of energy production, the spatial distribution map of water withdrawal for energy production can be drawn (see Figure 3). As Figure 3 shows that, because of the coal sector is the largest contributor to water withdrawal, provinces with a greater number of coal mines (Shanxi, Inner Mongolia) and provinces with a greater number of coal-fired plants (Jiangsu, Shandong, Guangdong, and Zhejiang) need more water for energy production. If the local government does not alter its energy strategies, The amount of water withdrawn by these six provinces mentioned above will increase by more than 0.5 bcm under the CPS,

mainly due to the increase in coal mining and the generation of electricity from coal-fired plants However, if China were to institute low-carbon development, such as increasing its nonfossil fuel share to 15% by 2020 and reducing coal consumption, energy production would place less pressure on local water resources. For example, under the 450S, the water withdrawal for energy production of Jiangsu, Zhejiang and Guangdong showed a decreasing trend between 2011 and 2030, mainly due to the decrease of electricity generation from coal-fired (decreased by more than 45%). Not only the water withdrawal for energy production has reduced, but also the composition of water withdrawal has changed when compared NPS and 450S with CPS. As Figure 4 show that, water withdrawal for renewable energy like nuclear and biomass hold more proportion when compared NPS and 450S with CPS at province level. Moreover, it is important to note that the inland nuclear power make great contribution (more than 30%) to the water withdrawal for energy production in Hubei, Hunan and Jiangxi province under the three scenarios (see Figure 4). 11764

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Figure 4. Composition of water withdrawal for energy production at province level in 2011 and three scenarios in 2030 (bcm).

Figure 5. Comparison of energy production and water withdrawal in 2015 with the three scenarios. E means energy production, and W means water withdrawal; Nation plan denotes the energy production target in 12th Five Year Plan for the country. Provincial plans denotes the summary of energy production targets in the 12th Five Year plan for each province.

4. DISCUSSION

450S. We chose the energy strategies in the 12th Five-Year Plan of Energy Development for China44 and provincial energy plans to compare the energy production trend with the projections for China. The detailed data for 2015 are provided in the SI (Table S4). The national energy production target for 2015 is 3581 Mtce, which is more than that of the CPS in 2020

4.1. Energy Production and Water Withdrawal Trends. This study used the projection of energy production based on the IEA’S WEO 2012 report; however, the energy production trend is overly optimiztic in this report and China’s energy strategies differ substantially from the NPS and the 11765

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Figure 6. Ratio of water withdrawal for energy production to the total water withdrawal at the provincial level in 2011 and under the three scenarios in 2030. The total water withdrawal remains unchanged. Data of the total water withdrawal for each province are listed in SI (Table S8).

(3466 Mtce/year), whereas the sum of the provincial energy production targets is approximately 24% higher than that of the CPS in 2020 (see Figure 5). Most provinces still plan to increase the production of coal and build coal-fired plants. Specifically, raw coal production is projected to reach 4968 million tons, and the electricity generated by coal-fired plants is projected to reach 5096 TWh in 2015; these values are equal to 126% and 137%, respectively, of those in 2011. The increasing demand for energy will also result in additional water demands. The water withdrawal required for energy production according to the national plan and the provincial plans will be 5% and 15% greater than that of the CPS in 2015. 4.2. Water Scarcity and Energy Production. To show the impact of water used for energy production on limited water resources, we calculated the ratio of water withdrawal for energy production to the total water withdrawal at the province level (data sources see SI Table S8). Although water withdrawal for energy production comprises only a small portion (4.7%) of total water withdrawal at the national level, it has a significant impact on local water resources. The ratio of water withdrawal for energy production to the total water withdrawal at the province level in 2011 showed that Shanxi and Zhejiang each utilize more than 10% of their water withdrawal for energy production (see Figure 6). In addition, in 2030, besides the aforementioned two provinces, Tianjin, Shanghai, Shaanxi, Jiangsu, Inner Mongolia, Guangxi, and Chongqing will be over 10% under the CPS. The water withdrawal rate for thermal power from coal-fired plants of Zhejiang, Shanghai, Guangxi, Jiangsu and Chongqing are much higher than other provinces for the more proportion use of once through cooling technology, so the corresponding water withdrawal are much

larger than other provinces. Shanxi, Inner Mongolia and Shaanxi are the main producer of coal mining, these three provinces hold 57% of the total coal production in China. As a result, the increase in energy production especially coal mining and electricity generation from coal-fired plants and thus water demand will squeeze the water that has been allocated for agriculture and other industrial production processes and cause a high risk of water scarcity at local level. The NPS and the 450S will mitigate such a trend and reduce such uneven water withdrawal for energy production. Moreover, the spatial distribution of water resources is inconsistent with the energy production in China. Most of energy production located at those provinces have already face water scarcity problems (detailed information about water resources at province level can be found in SI Table S8) in China according to the standard of the United Nations45(see Figure 4). Overall, 67% of energy production located in water scarcity regions and these regions hold only 24% water resources of the whole nation and the spatial distribution of water resources and energy production are seriously mismatched. The increase of water withdrawal for energy production will inevitably aggravate the water scarcity problem in future, especially for the regions which have been experiencing absolute water scarcity, like Henan, Shanxi, Shandong, Hebei and Jiangsu. In addition, new energy resources, such as shale gas and SNG which are heavy water-intensive also planned in water scarcity regions. As SI Figure S1 showed the 27% of the total shale gas extraction and 58% of the total SNG production located in the regions face water scarcity. The water withdrawal for unconventional nature gas production in these regions would 11766

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Figure 7. The impact of technological innovation on water withdrawal for energy production during 2011−2030 under different scenarios (bcm). CT indicate current technology.

domestic water use, other industrial water use and service industry water use et al. (detailed information about the calculation of economic value of water saving for energy production can be found in SI). Therefore, low-carbon development in China is not only urgent because of climate challenges and air pollution but also essential to reducing the pressure of water scarcity. China’s government should adopt stricter polices to direct energy production to the trend of the NPS at least and to reduce the pressure on limited water resources. In addition, the regions that already face water scarcity should reduce their energy production (especially for coal sector). Moreover, the regions with a higher value of water withdrawal for energy production should update technology to get water saving for energy production. Any energy production plan should carefully implement a water scarcity risk assessment. Additionally, methods for reduction of CO2 emissions such as CCS, inland nuclear power and the unconventional energy used to replaces the coal consumption like shale gas and SNG, which require a large amount of water should be developed carefully in regions with existing water scarcity. 4.5. Limitation. There are mainly two limitations in this study. First, we only considered the direct water withdrawal for energy production, so our results may be conservative; indirect water withdrawal should be considered in future research through a life cycle perspective. Second, water resources are not stationary under the impact of climate change8,46 and future research should also consider the impact of climate change on water resources.

be more than 377.79 million cubic meters under three scenarios in 2030 and inevitably result in more pressure on local limited water resources of water scarcity regions (see SI Figure S1). 4.3. Technological Innovation. The time scale of the projection is about 20 years which is long enough to update the technology which taken by each energy production processes. Moreover, the potential technological innovation differs between regions for the different technology base. As a result, We designed three scenarios about the technological innovation. We ordered the company for each energy production processes based on the value of water withdrawal for energy production per unit from the lowest to highest at province level. The value of water withdrawal for energy production per unit will be the average of former 95%, 90% in 2020 and 2030 respectively (T1 scenarios), and the former 90%, 80% (T2 scenario) and the former 80%, 60% (T3 scenario). As Figure 7 shows that the decrease rate of water withdrawal for energy production would be more than 17% between different scenarios due to technological innovation in 2030. Especially, in T3 scenario the technological innovation could offset the increase of water withdrawal for energy production under CPS in 2030. Thus, the potential technological innovation will bring significant water saving for energy production. 4.4. Policy Implication. The results presented here characterize the future water withdrawal for China’s energy strategies. As the results show that future water scarcity risk induced by energy strategies and the uneven distribution of water resources have a number of important implications. The projection of water withdrawal for energy production will increase by 77% based on the current energy strategy, which will aggravate China’s water scarcity risk. However, China’s 12th Five-Year Plan of Energy Development does not change existing energy strategies, and the planned total energy production is much higher than the IEA’s projection. The spatial distribution of China’s water resources and energy production are severely mismatched, and we observed that 67% of China’s energy production occurs in areas that are already facing water scarcity. Thus, an increase in water withdrawal for energy production will cause significant water scarcity risk in China. However, if China adopts low-carbon development and alters its energy structure, a significant reduction in water withdrawal will result, compared with the CPS, and the water scarcity risk will be mitigated. Besides the low-carbon energy strategies, updating technological also would lead to significant water saving for energy production. In addition, the water saving for energy production will bring CNY 15.80 to CNY 79.38 billion benefits in 2030 if those water will be used as

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ASSOCIATED CONTENT

S Supporting Information *

Additional information includes data of energy production and water resources and supplementary tables and figures. This material is available free via the Internet at http://pubs.acs.org.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This study was supported by the National Science Foundation of China (71322303 & 71433007). 11767

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Policy Analysis

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dx.doi.org/10.1021/es502655m | Environ. Sci. Technol. 2014, 48, 11760−11768