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Seawater desalination in China: Retrospect and prospect
Chemical Engineering Journal 242 (2014) 404–413
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Seawater desalination in China: Retrospect and prospect Xiang Zheng a,b,⇑, Di Chen a, Qi Wang a, Zhenxing Zhang c,⇑ a
School of Environment & Natural Resources, Renmin University of China, Beijing 100872, PR China State Key Laboratory of Urban Water Resource and Environment (SKLUWRE), Harbin Institute of Technology, Harbin 150090, PR China c Susquehanna River Basin Commission, Harrisburg, PA, USA b
h i g h l i g h t s Comprehensively review the history of seawater desalination in China. Desalination is a key strategy to address water resources shortage in China. Perform techno-economic analysis of desalination technologies. Present outlook of seawater desalination in China.
a r t i c l e
i n f o
Article history: Received 29 August 2013 Received in revised form 28 December 2013 Accepted 31 December 2013 Available online 8 January 2014 Keywords: Seawater desalination RO MED Economic analysis Prospect
a b s t r a c t China has been and will be facing water shortage issues due to the disparity between water supply and demand, especially within Chinese coastal areas. Seawater desalination can increase the total water supply and is an important component in addressing water shortage issues in China. With the development of the last six decades, seawater desalination technologies and applications have been advanced remarkably. Total seawater desalination capacity has increased from 10,000 m3/d in 2000 to approximately 660,000 m3/d in 2011. Seawater desalination has been primarily used in power generation, steel manufacturing, petrochemical industry, and public water supply. 75 desalination plants have been constructed in China, among which 16 desalination plants have capacities of 10,000 m3/d or more. Nine desalination plants are under construction, which will provide capacity of 408,000 m3/d. Most of the desalination applications (99.5% of the desalination capacity) are located within five provinces: Liaoning, Shandong, Hebei, Tianjin, and Zhejiang. The dominant desalination technologies are reverse osmosis (RO) and multi-effect distillation (MED). 80.3% of desalination plants employ RO and 14.5% of desalination plants adopt MED. The desalination capacities of RO and MED are 348,000 and 232,000 m3/d, respectively. Facing the challenge of water shortage, seawater desalination is of necessity in China and is increasingly an inevitable national strategy to address the issue. China is one of the most promising market for seawater desalination. However, international desalination companies will still dominate seawater desalination market for the foreseeable future. Ó 2014 Elsevier B.V. All rights reserved.
1. Introduction China started research on seawater desalination about 60 years ago. Studies on electro-dialysis (ED) technology started in 1958 and investigations on reverse osmosis (RO) and distillation technologies started in 1965 [1]. To facilitate research on seawater desalination technologies and development strategies, China’s State Oceanic Administration founded the Institute of Seawater Desalination and Multipurpose Utilization in 1984. The institute
⇑ Corresponding authors. Address: School of Environment & Natural Resources, Renmin University of China, Beijing 100872, PR China (X. Zheng). Tel.: +86 10 6276 4261; fax: +86 10 6284 3276. E-mail addresses: [email protected] (X. Zheng), [email protected] (Z. Zhang). 1385-8947/$ - see front matter Ó 2014 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.cej.2013.12.104
was located in Tianjin City, a northern port city. Since then, distillation and RO technologies in China has remarkably advanced, which has placed China at the front of advanced seawater desalination technologies, along with the USA, France, Japan, and Israel [2–4]. While research on seawater desalination technologies has attracted much attention for over six decades, the applications of these technologies only took off in the last decades [5,6]. The research on the applications of seawater desalination technologies has been focused on the following facets. (1) A comparison of seawater desalination and long distance water transfer. Long distance water transfers are a key solution to uneven temporal–spatial distribution of Chinese water resources [7]. Long distance water transfers coupled with exclusive institutional arrangements have been the
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primary focus of both government and academia, to the detriment of research and applications of seawater desalination. The Institute of Seawater Desalination and Multipurpose Utilization was founded in 1984, the same year that the Luanhe-Tianjin Water Diversion Project was completed and began supplying water to Tianjin city. Seawater desalination became a kind of ‘‘strategic reserve technology’’. The advancement of seawater desalination technologies reduced the capital and operational cost of seawater desalination in the 1980s and 1990s with more promising applications on the horizon [8]. The Chinese government started to implement the South–North Water Diversion Project in 2002, which made seawater desalination even less economically attractive. The provincial and local governments lost interest in large-scale seawater desalination. Long distance water transfer could only redistribute water resources from wet regions to the water-starved regions but could not increase total available fresh water. Seawater desalination could provide extra fresh water for the country. Thus policy and economic stimulus should be provided to facilitate the applications of seawater desalination [9]. Seawater desalination has not been as competitive as long distance water transfer due to the following factors: long distance water transfer projects are funded by government and water is underpriced due to government price control. Seawater desalination projects are usually funded and operated based on market forces. The misconception that the cost of seawater desalination is too high compared with long distance water transfer is very common in public and media, primarily because seawater desalination is not subsidized [10]. Due to the emphasis only on long distance water transfer and lack of investment in seawater desalination industry, seawater desalination industry in China still has a big gap compared with that of the USA and Japan [11]. (2) Selection of seawater desalination technologies based on techno-economic analysis. Feng [12] concluded that the capital and operational cost of multi-effect distillation (MED) is higher than that of RO for large-scale municipal water plants [13]. With the advancement of new energy recovery technologies, the energy consumptions of RO are less than 3.9 kWh/m3. Liu and Huang [14] reached the same conclusion as Feng based on his cost benefit analyses on Shandong Huangdao Power Plant which has both MED and RO seawater desalination facilities with the same capacity of 3000 m3/d. Liu et al. [15] compared MED and RO and found that MED is competitive in the production of boiler make-up water for coal-fired power plants if the cost of steam generation is ignored and RO is favored in providing municipal public water. Generally, the factor that limits seawater desalination applications is relatively high cost [16,17]. (3) The impact of seawater desalination and its mitigation measures. In the process of seawater desalination, a large amount of concentrated seawater will be produced [18,19]. The discharge of concentrated seawater will damage the seashore environment [20]. Nie and Tao [21] simulated the impact of a seawater desalination system with the capacity of 100,000 metric tons/d on Bohai water quality using a hydraulic and water quality model, and found that the area with increased salinity with 10-day continuous discharge is four times of that with 3-day continuous discharge. In addition, the waste heat discharge of seawater desalination process could increase seawater temperature and result in harmful algal blooms. Seawater desalination facilities were determined as the potential reason of harmful algal blooms in the sea area of 1600 square kilometers around Huanghua, Hebei Province [22]. Applications of combined water and
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power and coupled MED–RO technology are commonly used to mitigate these impacts. The development of combined water and power and coupled MED–RO technology could decrease the cost of steam generation by using the low grade superheated steam and reduce energy consumption by using cooling water. Many researchers proposed to utilize concentrated seawater by combining the process of seawater desalination and salt production [23]. Concentrated seawater utilization and zero-discharge technology is warranted to facilitate sustainable development of seawater desalination industry [24]. However, application of zero-discharge technology is currently limited due to the high cost [25]. On the global scale, about 16,000 desalination plants now operate in over 125 countries with a total capacity of 40 million m3 of water per day. 80% of the seawater desalination capacity is employed to provide drinking water for about 100 million people [63]. It is projected that additional desalination capacity 24 million m3 of water per day will be materialized in the next decade. The three commonly used technologies in worldwide for seawater desalination include multi-phase flash (MSF), MED, and RO. MSF was applied for water generation in 1950s and was advanced remarkably since 1980s. MSF is employed for 26% of total desalination capacity worldwide [64]. Interestingly MSF has seen limited applications in China due to its massive capital cost and high energy consumption. MED was the primary technique for seawater desalination before 1960s. MED is applied in more desalination plants but generate less water than that of MSF [23]. RO was applied in seawater desalination in 1950s. With the higher permeability membranes, installation of energy recovery devices, and the use of more efficient pumps, the cost has decrease from $2.1 per m3 water in 1975 to $0.5 per m3 water, and the energy consumption decreased from 15–20 kWh/m3 to 1.5–2.4 kWh/m3 [65–68]. Development of seawater desalination in China has been hindered by the aforementioned factors in the last six decades. Recently, with the move of iron & steel and petrochemical industries to coastal areas, the development of seawater desalination has been ramped up. It is critical to systematically review the history of the development of seawater desalination. In this paper, we examine the need for seawater desalination in China, review seawater desalination applications, and outline the prospect of the industry.
2. The need for seawater desalination in China With the economic development, population growth and increasing urbanization, water demand has been increased substantially. 22% of the world’s population lives in China which has only 8% of the world’s water resources. The supply and demand imbalance in Chinese coastal areas is even worse, compared with Chinese inland areas, because of the need to support more population and industry with less water resources. The average water resources per capita in 11 Chinese coastal provinces are only 1915 m3 (by the end of 2010). The 11 coastal provinces lay along the 1800 km coastal line, occupying 13.7% of China’s territory with 43.0% of China’s population (by the end of 2010). 49.0% of China’s urban population lives in the 11 coast provinces (by the end of 2009). Table 1 shows the urbanization level in the 11 provinces compared with the national level. In 2009, the urbanization level in the coastal areas was 57.7%, compared with 48.3% national average urbanization level. Table 2 compares water supply in coastal areas with the country. It is easy to see that the stress on water resources in coastal areas is more intensive than that of the whole country. The total
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Table 1 The urbanization level of 11 coastal provinces in China.a
a
Provinces
2000 (%)
2005 (%)
2009 (%)
Liaoning Hebei Tianjin Shandong Jiangsu Shanghai Zhejiang Fujian Guangdong Guangxi Hainan Average National
54.3 26.1 72.0 38.0 41.5 88.3 48.7 41.6 55.0 28.2 40.0 48.5 36.2
58.7 37.7 75.1 45.0 50.1 89.1 56.0 47.3 60.7 33.6 45.2 54.4 43.0
60.4 43.0 78.0 48.3 55.6 88.6 57.9 51.4 63.4 39.2 49.1 57.7 48.3
Data from Chinese Statistical Yearbook, 2010 [26].
water supply accounts of 51.1% water supply capacity in coastal areas while the national water supply is 50.4% of the water supply capacity. In coastal areas, there is also a higher percentage of population served by public water. The average water use per capita in coastal area is 185.2 liters/person/d, compared with national average water use of 171.4 liters/personal/d. Economic development and industry are much more advanced in coastal areas compared with inland China. This results in more stress on water resources in coastal areas. Table 3 shows the water resources and theirs utilization in coastal areas compared with the national average. The Gross Domestic Production (GDP) in coastal areas in 2010 is 24.6 trillion Chinese yuan, accounting for 61.3% of the national GDP. However, the total water resources in coastal areas only account for 28.6% of the national total water resources. The total water use in coastal area is 248 trillion m3 which is about 41.2% of the national total water use. 28.1% of the water resources have been utilized in coastal areas while the national average water efficiency is only 19.5%. In general, the water supply and demand imbalance in coastal areas has deteriorated for decades due to economic development, population growth, and urbanization. These three factors will be intensified in the next two decades in the coastal areas, especially in the regions of Pearl River Delta, Yangtze River Delta, and Bohai Rim. Thus, the water resources stress in coastal areas will not be relieved in the near future. One of the most challenging issues facing water resources professionals in China is how to address the increasing imbalance between water supply and demand. 3. Retrospect of seawater desalination Based on scales of the subject seawater desalination projects under research and development [28], the last 6 decades are divided into 3 phases which are described in details below. (1) 1958–1996, laboratory experiments and pilot-scale. Researchers in the Institute of Chemistry, Chinese Academy of Sciences started investigating ED technology in 1958 and RO technology in 1965 [1]. In 1980, an ED seawater
desalination facility with a capacity of 200 m3/d was completed in Xisha, Hainan province, the energy consumption of which was as high as 18 kWh/m3. Pilot-scale tests of MSF technology with a capacity of hundreds m3/d were conducted through late 1980s [29]. (2) 1997–2004, 500–5000 m3/d. During this period, practical applications on the scale of hundreds to thousands of m3/d were developed, primarily to serve residential and industrial need. The first seawater reverse osmosis (SWRO) desalination station was constructed in 1997 in Shengshan Island of Zhoushan, Zhejiang province [30,31]. The station had a capacity of 500 m3/d and employed mainly imported technologies and instruments. A seawater desalination plant with a capacity of 1000 m3/d, using RO technology, was completed in 1999 in Dachangshan Island of Dalian [32]. In 2003, a seawater desalination system using RO technology with capacity of 5000 m3/d was constructed in Shidao Island, Rongcheng, Shandong province [33]. In 2004, a seawater desalination system using low temperature MED (LT-MED) technology with capacity of 3000 m3/d was completed in Huangdao Power Plant of Qingdao [34]. After nearly 40 years of research and development and demonstrations, Chinese seawater desalination technology has become increasingly mature, which make it possible for large scale application. (3) 2005–present, large-scale of over 10,000 m3/d. Large-scale desalination plants with a capacity of over 10,000 m3/d have been developed and constructed in this period. In 2005, the first large-scale seawater desalination system (10,800 m3/d) was completed at the Datang Wangtan Power Plant [41]. In 2006, 2 10,000 m3/d LT-MED device was introduced to China [35]. The existing independent LT-MED device ranges from 3000 to 12,500 m3/d [29,36–39] and are mainly used for power plant boiler make-up water supplies [40]. In 2009, the first desalination plant with a capacity of over 100,000 m3/d was completed in Tianjin [34]. Presently there are 60 SWRO desalination plants with a total capacity of 348,000 m3/d and 11 LT-MED desalination plants with a total capacity of 222,300 m3/d [42]. 4. Present seawater desalination in China In 2005, China developed ambitious goals for its seawater desalination industry [43]. The goal for total capacity of desalination was set at 0.8–1 million m3/d by 2010, and 2.5–3 million m3/d for 2020. However, by the end of 2010, the total completed capacity was only 583,000 m3/d and the amount under construction was 408,000 m3/d, well under the goal for 2010. Fig. 1 shows the annual and cumulative completed desalination capacity [9,60]. It demonstrates that desalination capacity expanded remarkably since 2005. Annual completed desalination capacities in both 2009 and 2010 were more than 100,000 m3/d. By 2010, there were 75 completed desalination plants in China. Table 4 shows the 10 largest desalination plants in China. Fig. 2 shows the geographic distribution of the 10 largest desalination plants in China. The cumulative desalination capacity in China has been growing in the annual rate of
Table 2 The coastal area and national water supply in 2010.a
a b
Area
Total water supply (billion m3/d)
Total water supply/water supply capacity (%)
Urban population (million)
Population served with public water (million)
Average water use (liter/ person/d)
Coastal areas China
27.6
51.1
304.6b
198.9
185.2
50.8
50.4
669.8
381.6
171.4
Data from Chinese Statistical Yearbook, 2011 [27]. Date of 2009, from Chinese Statistical Yearbook, 2010 [26].
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X. Zheng et al. / Chemical Engineering Journal 242 (2014) 404–413 Table 3 Water resources and its utilization for coastal areas and entire China in 2010.a
a b
Area
Total water resources (billion m3)
Total water use (billion m3)
Average water resources per capita (m3/person)
Industry water useb (billion m3)
GDP (trillion yuan)
Water use efficiency
Coastal area China
884
248
1915.7
206
24.6
28.1%
3091
602
2310.4
514
40.1
19.5%
Data from Chinese Statistical Yearbook, 2010 [26]. Industrial water use includes agriculture water use.
Hebei with the capacity of 123,000 m3/d; and 6 plants were located in Tianjin with the capacity of 218,000 m3/d. Only 5 plants were constructed in the other coastal provinces with a negligible capacity of 3000 m3/d. Fig. 2 shows the geographic distribution of the ten largest desalination plants along Chinese coastal line. 4.2. Industry sectors
Fig. 1. Capacity growth of seawater desalination in China.
70%. By September 2011, 16 desalination plants with over 100,000 m3/d capacity have been constructed and the total capacity is about 660,000 m3/d. There are presently 9 desalination plants under construction in China as listed in Table 5. The total capacity of these 9 plants is 408,000 m3/d. RO technology is employed in 8 of these plants. Fig. 3 shows the locations of these plants. 4.1. Geographic distribution Most of the completed desalination plants were located in five provinces, i.e. Liaoning, Shandong, Hebei, Tianjin, and Zhejiang [44]. These five provinces have total capacity of 580,000 m3/d which accounts for 99.5% of the national total capacity. Fig. 4 shows the desalination capacity for each of the provinces. Among the 75 completed desalination plants, 20 plants were in Shandong with the total capacity of 68,000 m3/d; 23 plants were in Zhejiang with the total capacity of 100,000 m3/d; 14 plants were in Liaoning with the capacity of 66,000 m3/d; 7 plants were in
The distribution of desalination plants in industry sectors is shown in Fig. 5. Seawater desalination primarily is used in public water supply, power generation, steel manufacturing, and petrochemical sectors. Public water supply, electricity, steel manufacturing, and petrochemical industry account for 53.9%, 26.3%, 3.9%, and 5.3% of the total number of desalination plants, respectively. Desalination plants in the power generation industry produce the most capacity, accounting for 51.6% of the total capacity. Petrochemical, public water supply, and steel manufacture provide 21.4%, 13.7% and 8.6% of the total desalination capacity. Desalination plants in these 4 sectors are summarized below. In the power generation industry, desalination plants are commonly used to produce boiler makeup water. This is due to the incentive policy that requires new power plants within coastal areas to adopt seawater desalination technology to provide water. New power plants with a total generation capacity of over 35,000 MW which are planned for construction in coastal areas, will need high quality boiler makeup water of 180,000 m3/d. Due to both the incentive policy and desalination technology advancement, seawater desalination would provide the majority of boiler makeup water for power plants in the future. Desalination plants can reuse the water steam and heat generated in petrochemical and steel manufacturing sectors. Thus desalination plants not only can provide reliable water but also can reuse waste steam and heat, reducing costs. It is expected that more petrochemical and steel manufacturing facilities will adopt seawater desalination technology for a water source. With the more restrictive requirements of drinking water and the costs associated with public water distribution system updates and maintenance, the water price in China will keep increase. With advancement of seawater desalination technologies and construction of larger scale desalination plants, the unit cost of desalination
Table 4 Ten largest desalination plants in China.a
a
Plants
Capacity (m3/d)
Technology
Manufacturer
Start-up year
Tianjin North Power Plant Phase I of Tianjin Dagang Xinquan Hebei Huanghua Power Plant Hebei Caofeidian Shougang Jingtang Iron Works Yuhuan Huaneng Power Plant in Zhejiang Yueqing Power Plant in Zhejiang Qingdao Soda Ash Industrial Company Limited Dalian Chemical Industry Company Huangdao Power Plant in Shandong ZhuangHe Power Plant in Liaoning
100,000 100,000 57,500 50,000 35,000 21,600 20,000 20,000 16,000 14,400
MED RO MED MED RO RO RO RO MED, RO RO
IDE Hyflux SIDEM SIDEM CNC N/A N/A CNC Hyflux N/A
2010 2009 2006 2009 2006 2007 2010 2009 2004 2008
Data from [60,61].
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Fig. 2. Geographic distribution of the 10 largest desalination plants in China.
Table 5 Desalination plants under construction in China.a
a
Plants
Capacity (m3/d)
Technology
Location
Caofeidian Industrial Park Lubei Enterprise Group Qingdao Baifa Huizhou Pinghai Power Plant Ningde Nuclear Power Station in Fujian Phase II of Tianjin Dagang Xinquan Phases II, III, and IV of Zhoushan Liuheng Dalian Beiliangchu Zhejiang Sanmen Nuclear Power Station Project Total
50,000 40,000 100,000 17,000 11,000 50,000 100,000 30,000 10,000 408,000
RO RO RO RO MSF RO RO RO RO
Hebei Shandong Shandong Guangdong Fujian Tianjin Zhejiang Liaoning Zhejiang
Data from [60,61].
will decrease. It is possible in the future that desalination plants will produce large amounts of water to feed public water supply systems. 4.3. Technologies Fig. 6 shows the plants and capacity of desalination with various technologies. It is evident that most desalination plants employ RO and/or MED technologies. For the number of desalination plants, 80.3% desalination plants, i.e. 61 plants, adopt RO technology to desalinize seawater. Only 11 desalination plants, 14.5% of total plants, employ MED technology. The capacity of desalination plants with RO technology is 348,000 m3/d, accounting for 59.3% of the national total desalination capacity, while
MED technology is used in desalination plants with capacity of 232,000 m3/d which is about 39.6% of the national total capacity. This is due to the fact that MED is generally used for larger scale desalination plants than RO is [45]. On average, the capacity of a desalination plant with MED is 21,000 m3/d and that with RO is only 6000 m3/d. The capacity of desalination plants with other technologies such as MSF and ED only accounts for 1.1% of the total capacity.
5. Techno-economic analysis One of the key factors in the selection of seawater desalination technologies is techno-economic analysis. In this section, we
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Fig. 3. Geographic distribution of desalination plants under construction in China.
Fig. 4. Seawater desalination output capacities for coastal provinces.
conducted a thorough techno-economic analysis of the most commonly used seawater desalination technologies, i.e. RO and MED. 5.1. Techno-economic analysis of RO technology The costs of 5 desalination plants with capacities of 500– 35,000 m3/d were analyzed to compare the impact of capacity on the cost of desalination plants. Tables 6 and 7 show the results of the analysis. Due to the cost of heating in winter, the total unit cost of Changhai County Seawater Desalination Plant is higher than that
of Shengshan Seawater Desalination Project. Generally, the unit total cost usually decreases as the capacity increases [51]. Electricity consumption per cubic meter water decreases while the capacities of desalination plants increase. Interestingly, unit capital cost is relatively stable with varying desalination capacities. In addition to the capital cost of desalination, the operation and maintenance cost includes electricity, membrane, chemicals, maintenance, and labor [49,50]. It is evident that electricity is the largest cost component. The electricity cost account for 50.7%, 37.7%, 44.4%, 52.2%, 27.9% of the total unit costs for the 5 desalination plants, respectively. The percentage of electricity generally decreases with larger scale desalination plants. Reduction of electricity consumption in desalination process is the key to reduce the unit cost of desalination as it is the major cost component. Capital cost is the second largest cost component. For the 5 desalination plants in Table 7, the percentages of capital cost with respect to total unit cost are 28.0%, 26.5%, 23.8%, 25.4%, and 27.9%, respectively. The capital cost generally accounts for 25% of total unit cost, either for small scale or large scale desalination plants. The costs for periodic membrane replacement for the 5 desalination plants accounts for 6.5%, 16.1%, 10.7%, 7.8%, and 20.5%, respectively. With the advancement of membrane technology, it is expected that the cost for replacing membrane will decrease [12,52]. The Huangneng Yuhuan Power Plant is analyzed in depth to examine cost component of desalination [53]. The desalination capacity of Huangneng Yuhuan Power Plant is 35,000 m3/d to provide water for the cooling system and boilers. RO coupled with MSF technology is adopted in the plant. The cost analysis is based
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(b) Cap pacity (m3 / daay)
(a) Number of plants
Fig. 5. Industry sectors with desalination plants in China.
(b) Capacity (m3 / daay)
(a) Number of plants
Fig. 6. Number and capacity of desalination plants with various technologies in China.
Table 6 The cost of RO desalination with various scale capacity. Seawater desalination project
Shengshan [30]
Tianjin [46]
Changhai County [32,47]
Rongcheng [33]
Yuhuan Power Plant [48]
Capacity (m3/d) Start-up year Total capital cost (million yuan) Electricity consumption (kwh/m3) Cost of electricity (yuan/m3) Capital cost (yuan/m3) Total unit cost (yuan/m3)
500 1997 6.16 5.20 3.12 1.72 6.15
1000 2004 7.50 4.16 2.08 1.46 5.52
1500 2001 15.94 4.00 2.80 1.50 6.30
5000 2003 20.00 3.54 2.40 1.17 4.60
35,000 2006 192.44 3.30 1.20 1.48 4.30
Table 7 Components of cost of RO desalinization with various scale capacity. Seawater desalination project
Shengshan [30]
Tianjin [46]
Changhai Country [32,47]
Rongcheng [33]
Yuhuan Power Plant [48]
Membrane (yuan/m3) Chemicals (yuan/ m3) Labor (yuan/m3) Maintenance (yuan/m3) Electricity (yuan/m3) Investment (yuan/m3) Total unit cost (yuan/m3) Percentage of electricity and investment
0.40 0.30 0.25 0.36 3.12 1.72 6.15 78.7%
0.89 0.45 0.24 0.34 2.08 1.46 5.52 64.1%
0.68 0.22 0.13 0.97 2.80 1.50 6.30 68.3%
0.36 0.36 0.13 0.18 2.40 1.17 4.60 77.6%
0.88 0.23 0.07 0.22 1.20 1.61 4.30 65.3%
on the loan period of 15 years with total loan of 144 million yuan. The total capital cost is 192 million yuan and the period of depreciation is assumed 30 years which is commonly used in China. The detailed cost of the plant is shown in Table 8. 5.2. Techno-economic analysis of MED technology Table 9 shows the cost for different scale MED desalination plants, ranging from 3000 to 25,000 m3/d. Generally, the unit
cost of MED technology is lower than that of RO for plants of the same scale. Furthermore, Phase I for Huanghua Power Plant is analyzed in depth to examine cost component of desalination. Phase I for Huanghua Power Plant has the capacity of 2 10,000 m3/d, using TVC-MED technology. The detailed cost components are shown in Table 10. After the application of seawater desalination, this plant does not need other fresh water, and save 20.1 million yuan for using fresh water and pretreated water.
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The factor that limits MED applications is electricity consumption. Most of the MED desalination plants were constructed together with power plants. With many more nuclear power plants expected to be constructed in China, MED desalination will receive more attention and market share [39,54]. China’s steel industry consumes a lot of electricity, and the production process produces a large amount of waste heat and gas. The waste heat and gas can be used to drive MED seawater desalination devices, to increase the thermal efficiency from less than 40% to nearly 60% [55]. Using the waste energy to produce fresh water, seawater desalination applications in the iron and steel industry can achieve the co-production of water and electricity for plant. If waste energy can be used for seawater desalination, unit cost for desalination would be decreased substantially and make the technology much more economically competitive [40,56,57]. 6. Prospect of seawater desalination applications In February 2012, the Chinese government issued a memo that outlined the most recently updated goals and prospects of seawater desalination for 2015. The Chinese government and provincial governments also developed long-term goals of seawater desalina-
Table 8 Cost for desalination in Yuhuan Power Plant (3,5000 m3/d).a
Interestb Depreciation of fixed assets Membrane Maintenance Labor Electricity Chemicals Total unit cost a b
Annual cost (thousand yuan)
Unit cost (yuan/m3)
1104 12,829 9800 1930 600
0.13 1.48 0.88 0.22 0.07 1.20 0.32 4.30
Data from [48]. Based on annual interest rate of 6.12%.
Table 9 Cost for different scale MED desalination plants.a
a
Seawater desalination project
Huangdao Power Plant
Huanghua Power Plant
Caofeidian Shougang
Capacity (m3/d) Operational year Total capital cost (million yuan) Unit capital cost (yuan/m3) Total unit cost (yuan/m3)
3000 2004 24
20,000 2006 228
25,000 2008 250
8000
11,400
10,000
4.73
3.80
6.00
Data from [19,14,38].
Table 10 Cost of desalination for Huanghua Power Plant (20,000 m3/d).a Cost (yuan/m3) Depreciation of fixed assets Electricity Chemicals Steam Labor Maintenance Total unit cost a
Data from [38].
0.99 0.20 0.28 2.20 0.05 0.08 3.80
tion for 2020. Based on these goals and planning, the prospect for seawater desalination application in China for the next decade is summarized below. By 2015, the total seawater desalination capacity is projected to be 2.2–2.6 million m3/d. Considering the total seawater desalination at 2010 is only about 0.6 million m3/d, almost 2.0 million m3/d capacity will be needed. By 2015, seawater desalination is projected to provide more than 50% of new water supply for Chinese islands and more than 15% of new water supply for Chinese coastal areas. For 2020, each coastal province has its own planning and goals which are shown in Table 11. By 2020, the total seawater desalination capacity will reach 2.5 to 3.1 million m3/d which is only slightly higher than the goal of 2015. This is because the goals of 2020 were developed earlier than those of 2015. It is expected that individual provinces will update their provincial planning and goal for 2020 based on the revised national goal. It can be expected that Chinese seawater desalination capacity will substantially increase in the next decade. RO and MED will still be the dominant technologies employed in most seawater desalination projects [12]. With the advancement of last six decades, the membrane industry China has been well developed. Comprehensive applications of microfiltration (MF), Ultrafiltration (UF), and RO technologies in seawater desalination have been increased a lot. Benchmark seawater desalination plants with RO technology have been constructed. As an emerging industry, membrane industry has received unprecedented attention in China. In 2010, China central government released ‘‘Decision of the State Council on Accelerating the Fostering and Development of Strategic Emerging Industries’’ and high performance membrane materials was listed as strategic emerging industry in the decision. This unprecedentedly stimulates the development and advancement of membrane technology, membrane industry, and membrane application market. In ‘‘National 12th Five-Year Science and Technique Development Plan’’ released in 2011, the specific requirement for membrane materials have been outline which included ‘‘primarily develop of membranes for water treatment, gas separation, and specialty separation. Promote applications of membrane technologies in water treatment, iron and steel manufacturing, petrochemical industry, and environment protections’’. It is foreseeable that membrane technologies especially RO technology will play an increasing role in seawater desalination in China [58]. There are the following challenges that China has to face to develop seawater desalination. (1) The membrane technologies for seawater desalination (e.g. waste power recycle and RO membrane) and the manufacturing of key equipment for desalination (e.g. seawater evaporators, condensers, and steam ejector etc.) in China have yet to be improved remarkably. (2) There is significant lack of practices and experiences in seawater desalination engineering, large-scale desalination equipment design, manufacturing, operation, and maintenance. (3) The guidance on testing, evaluating, and designing seawater desalination is not well developed and thus it does not provide complete industry standards and technique guidance for seawater desalination. (4) The existing and planned desalination plants could cause adverse environmental
Table 11 Goals of seawater desalination capacity for 2020 (in thousand m3/d).a
a
Liaoning
Hebei
Tianjin
Shandong
Jiangsu
Shanghai
300400
200–250
450–500
800–900
10–20
30–50
Zhejiang
Fujian
Guangdong
Guangxi
Hainan
Total
550–650
60–100
80–150
10–20
30–50
2520–3090
Data from [62].
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impact. Seawater desalination consumes a large amount of thermoelectric energy and results in emission of air pollutants and green-house gases [66]. It could also cause impingement and entrainment of marine organisms [66,69,70]. The elevated salinity of brines and the chemicals used in desalination process poses environmental risks to marine ecosystem [66,69,70]. The other potential environmental impact of desalination is the increased seawater temperature cause by the process. Detailed analysis of these potential environmental impacts should be required and mitigation measures shall be identified for desalination plants. Many large-scale desalination plants (100,000 m3/d plus) have been proposed to be constructed in Chinese coastal areas recently. The total capacity under construction and draft is 1.4 million m3/d and China has become a most promising market for seawater desalination. The projected annual increase rate of total desalination capacity is about 50%. International giant desalination companies will still dominate Chinese desalination market in the foreseeable future as domestic companies is not competitive in large-scale whole sets of equipment, RO technology, MED technology and equipment.
7. Conclusions Economic development and urbanization are the major causative factors in the disparity between water supply and demand within coastal areas, especially the Pearl River Delta, Yangtze River Delta, and Bohai Rim. Water shortage has become a limiting factor of sustainable development in China. In the next two decades, the water shortage problem in Chinese coastal areas will only be intensified [7]. Water resources development and utilization in most streams and rivers in northern China have exceeded the corresponding water resources carrying capacity. Seawater desalination is of extreme importance for increasing water supply in China. We strongly recommend that seawater desalination be prioritized to the Chinese national water resources key strategy to promote seawater desalination in the near future. Seawater desalination can increase total water supply and is the inevitable national strategy to address water shortage issue in China. This is beyond the consideration of water price and cost or pros and cons of various technologies. It is of necessity due to sustainable social and economic development in coastal areas in China. Seawater desalination in China has been applied primarily in the municipal public water supply, power generation, steel manufacturing, and petrochemical sectors. Seawater desalination applications in the power generation industry are primarily intended to provide boiler makeup water. The metallurgical and chemical industries have seen rapidly increasing applications of seawater desalinations recently and are expected to apply numerous seawater desalination projects in the future. As the gap between water price and seawater desalination cost shrinks steadily, though slowly, it will become practical that water generated by seawater desalination will become an important component in public water supply systems. The inappropriate cost accounting system has confined the development and applications of seawater desalination in China for the last two decades. Long distance water transfer projects are usually funded and financed by central or local governments and water are underpriced. Applications of seawater desalination have to be financed through market and thus it is not as competitive as long distance water transfer. With the relocation of many iron and steel manufacturing and petrochemical facilities to coastal areas, the applications of seawater desalination have been promoted as infrastructure. The mainstream technologies for seawater desalination include RO and MED. Though the amount of MED applications is less than
RO, the average generated water per application of MED is four times as RO. Power consumption in MED is the major factor that limits MED applications. As MED technology is very well coupled with the nuclear power generation process and many nuclear power plants will be built in the next two decades in China based on the long-term national planning of nuclear power, it is expected that more seawater desalination applications will employ MED technology [59]. China now is one of the most promising market for seawater desalination. The annual increase rate is projected to be about 50%. However, due to the fact that domestic companies are not competitive in large-scale whole sets of equipment, RO technology, MED technology and equipment, international desalination companies will still dominate Chinese seawater desalination market in the foreseeable future.
Acknowledgements The research was supported by Program for New Century Excellent Talents in University (NCET-12-0531), Open Project of State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology (No. ES201005) and Beijing Science & Technology Star Plans (2008A110). Any opinions, findings, and conclusions are those of the authors and no official endorsement should be inferred. The authors would like to thank Bob Pody and Pierre MaCoy for proofreading and reviewing the revised manuscript. The comments of anonymous reviewers and editor of CEJ helped us to refine and improve this manuscript.
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Chemical Engineering Journal journal homepage: www.elsevier.com/locate/cej
Seawater desalination in China: Retrospect and prospect Xiang Zheng a,b,⇑, Di Chen a, Qi Wang a, Zhenxing Zhang c,⇑ a
School of Environment & Natural Resources, Renmin University of China, Beijing 100872, PR China State Key Laboratory of Urban Water Resource and Environment (SKLUWRE), Harbin Institute of Technology, Harbin 150090, PR China c Susquehanna River Basin Commission, Harrisburg, PA, USA b
h i g h l i g h t s Comprehensively review the history of seawater desalination in China. Desalination is a key strategy to address water resources shortage in China. Perform techno-economic analysis of desalination technologies. Present outlook of seawater desalination in China.
a r t i c l e
i n f o
Article history: Received 29 August 2013 Received in revised form 28 December 2013 Accepted 31 December 2013 Available online 8 January 2014 Keywords: Seawater desalination RO MED Economic analysis Prospect
a b s t r a c t China has been and will be facing water shortage issues due to the disparity between water supply and demand, especially within Chinese coastal areas. Seawater desalination can increase the total water supply and is an important component in addressing water shortage issues in China. With the development of the last six decades, seawater desalination technologies and applications have been advanced remarkably. Total seawater desalination capacity has increased from 10,000 m3/d in 2000 to approximately 660,000 m3/d in 2011. Seawater desalination has been primarily used in power generation, steel manufacturing, petrochemical industry, and public water supply. 75 desalination plants have been constructed in China, among which 16 desalination plants have capacities of 10,000 m3/d or more. Nine desalination plants are under construction, which will provide capacity of 408,000 m3/d. Most of the desalination applications (99.5% of the desalination capacity) are located within five provinces: Liaoning, Shandong, Hebei, Tianjin, and Zhejiang. The dominant desalination technologies are reverse osmosis (RO) and multi-effect distillation (MED). 80.3% of desalination plants employ RO and 14.5% of desalination plants adopt MED. The desalination capacities of RO and MED are 348,000 and 232,000 m3/d, respectively. Facing the challenge of water shortage, seawater desalination is of necessity in China and is increasingly an inevitable national strategy to address the issue. China is one of the most promising market for seawater desalination. However, international desalination companies will still dominate seawater desalination market for the foreseeable future. Ó 2014 Elsevier B.V. All rights reserved.
1. Introduction China started research on seawater desalination about 60 years ago. Studies on electro-dialysis (ED) technology started in 1958 and investigations on reverse osmosis (RO) and distillation technologies started in 1965 [1]. To facilitate research on seawater desalination technologies and development strategies, China’s State Oceanic Administration founded the Institute of Seawater Desalination and Multipurpose Utilization in 1984. The institute
⇑ Corresponding authors. Address: School of Environment & Natural Resources, Renmin University of China, Beijing 100872, PR China (X. Zheng). Tel.: +86 10 6276 4261; fax: +86 10 6284 3276. E-mail addresses: [email protected] (X. Zheng), [email protected] (Z. Zhang). 1385-8947/$ - see front matter Ó 2014 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.cej.2013.12.104
was located in Tianjin City, a northern port city. Since then, distillation and RO technologies in China has remarkably advanced, which has placed China at the front of advanced seawater desalination technologies, along with the USA, France, Japan, and Israel [2–4]. While research on seawater desalination technologies has attracted much attention for over six decades, the applications of these technologies only took off in the last decades [5,6]. The research on the applications of seawater desalination technologies has been focused on the following facets. (1) A comparison of seawater desalination and long distance water transfer. Long distance water transfers are a key solution to uneven temporal–spatial distribution of Chinese water resources [7]. Long distance water transfers coupled with exclusive institutional arrangements have been the
X. Zheng et al. / Chemical Engineering Journal 242 (2014) 404–413
primary focus of both government and academia, to the detriment of research and applications of seawater desalination. The Institute of Seawater Desalination and Multipurpose Utilization was founded in 1984, the same year that the Luanhe-Tianjin Water Diversion Project was completed and began supplying water to Tianjin city. Seawater desalination became a kind of ‘‘strategic reserve technology’’. The advancement of seawater desalination technologies reduced the capital and operational cost of seawater desalination in the 1980s and 1990s with more promising applications on the horizon [8]. The Chinese government started to implement the South–North Water Diversion Project in 2002, which made seawater desalination even less economically attractive. The provincial and local governments lost interest in large-scale seawater desalination. Long distance water transfer could only redistribute water resources from wet regions to the water-starved regions but could not increase total available fresh water. Seawater desalination could provide extra fresh water for the country. Thus policy and economic stimulus should be provided to facilitate the applications of seawater desalination [9]. Seawater desalination has not been as competitive as long distance water transfer due to the following factors: long distance water transfer projects are funded by government and water is underpriced due to government price control. Seawater desalination projects are usually funded and operated based on market forces. The misconception that the cost of seawater desalination is too high compared with long distance water transfer is very common in public and media, primarily because seawater desalination is not subsidized [10]. Due to the emphasis only on long distance water transfer and lack of investment in seawater desalination industry, seawater desalination industry in China still has a big gap compared with that of the USA and Japan [11]. (2) Selection of seawater desalination technologies based on techno-economic analysis. Feng [12] concluded that the capital and operational cost of multi-effect distillation (MED) is higher than that of RO for large-scale municipal water plants [13]. With the advancement of new energy recovery technologies, the energy consumptions of RO are less than 3.9 kWh/m3. Liu and Huang [14] reached the same conclusion as Feng based on his cost benefit analyses on Shandong Huangdao Power Plant which has both MED and RO seawater desalination facilities with the same capacity of 3000 m3/d. Liu et al. [15] compared MED and RO and found that MED is competitive in the production of boiler make-up water for coal-fired power plants if the cost of steam generation is ignored and RO is favored in providing municipal public water. Generally, the factor that limits seawater desalination applications is relatively high cost [16,17]. (3) The impact of seawater desalination and its mitigation measures. In the process of seawater desalination, a large amount of concentrated seawater will be produced [18,19]. The discharge of concentrated seawater will damage the seashore environment [20]. Nie and Tao [21] simulated the impact of a seawater desalination system with the capacity of 100,000 metric tons/d on Bohai water quality using a hydraulic and water quality model, and found that the area with increased salinity with 10-day continuous discharge is four times of that with 3-day continuous discharge. In addition, the waste heat discharge of seawater desalination process could increase seawater temperature and result in harmful algal blooms. Seawater desalination facilities were determined as the potential reason of harmful algal blooms in the sea area of 1600 square kilometers around Huanghua, Hebei Province [22]. Applications of combined water and
405
power and coupled MED–RO technology are commonly used to mitigate these impacts. The development of combined water and power and coupled MED–RO technology could decrease the cost of steam generation by using the low grade superheated steam and reduce energy consumption by using cooling water. Many researchers proposed to utilize concentrated seawater by combining the process of seawater desalination and salt production [23]. Concentrated seawater utilization and zero-discharge technology is warranted to facilitate sustainable development of seawater desalination industry [24]. However, application of zero-discharge technology is currently limited due to the high cost [25]. On the global scale, about 16,000 desalination plants now operate in over 125 countries with a total capacity of 40 million m3 of water per day. 80% of the seawater desalination capacity is employed to provide drinking water for about 100 million people [63]. It is projected that additional desalination capacity 24 million m3 of water per day will be materialized in the next decade. The three commonly used technologies in worldwide for seawater desalination include multi-phase flash (MSF), MED, and RO. MSF was applied for water generation in 1950s and was advanced remarkably since 1980s. MSF is employed for 26% of total desalination capacity worldwide [64]. Interestingly MSF has seen limited applications in China due to its massive capital cost and high energy consumption. MED was the primary technique for seawater desalination before 1960s. MED is applied in more desalination plants but generate less water than that of MSF [23]. RO was applied in seawater desalination in 1950s. With the higher permeability membranes, installation of energy recovery devices, and the use of more efficient pumps, the cost has decrease from $2.1 per m3 water in 1975 to $0.5 per m3 water, and the energy consumption decreased from 15–20 kWh/m3 to 1.5–2.4 kWh/m3 [65–68]. Development of seawater desalination in China has been hindered by the aforementioned factors in the last six decades. Recently, with the move of iron & steel and petrochemical industries to coastal areas, the development of seawater desalination has been ramped up. It is critical to systematically review the history of the development of seawater desalination. In this paper, we examine the need for seawater desalination in China, review seawater desalination applications, and outline the prospect of the industry.
2. The need for seawater desalination in China With the economic development, population growth and increasing urbanization, water demand has been increased substantially. 22% of the world’s population lives in China which has only 8% of the world’s water resources. The supply and demand imbalance in Chinese coastal areas is even worse, compared with Chinese inland areas, because of the need to support more population and industry with less water resources. The average water resources per capita in 11 Chinese coastal provinces are only 1915 m3 (by the end of 2010). The 11 coastal provinces lay along the 1800 km coastal line, occupying 13.7% of China’s territory with 43.0% of China’s population (by the end of 2010). 49.0% of China’s urban population lives in the 11 coast provinces (by the end of 2009). Table 1 shows the urbanization level in the 11 provinces compared with the national level. In 2009, the urbanization level in the coastal areas was 57.7%, compared with 48.3% national average urbanization level. Table 2 compares water supply in coastal areas with the country. It is easy to see that the stress on water resources in coastal areas is more intensive than that of the whole country. The total
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Table 1 The urbanization level of 11 coastal provinces in China.a
a
Provinces
2000 (%)
2005 (%)
2009 (%)
Liaoning Hebei Tianjin Shandong Jiangsu Shanghai Zhejiang Fujian Guangdong Guangxi Hainan Average National
54.3 26.1 72.0 38.0 41.5 88.3 48.7 41.6 55.0 28.2 40.0 48.5 36.2
58.7 37.7 75.1 45.0 50.1 89.1 56.0 47.3 60.7 33.6 45.2 54.4 43.0
60.4 43.0 78.0 48.3 55.6 88.6 57.9 51.4 63.4 39.2 49.1 57.7 48.3
Data from Chinese Statistical Yearbook, 2010 [26].
water supply accounts of 51.1% water supply capacity in coastal areas while the national water supply is 50.4% of the water supply capacity. In coastal areas, there is also a higher percentage of population served by public water. The average water use per capita in coastal area is 185.2 liters/person/d, compared with national average water use of 171.4 liters/personal/d. Economic development and industry are much more advanced in coastal areas compared with inland China. This results in more stress on water resources in coastal areas. Table 3 shows the water resources and theirs utilization in coastal areas compared with the national average. The Gross Domestic Production (GDP) in coastal areas in 2010 is 24.6 trillion Chinese yuan, accounting for 61.3% of the national GDP. However, the total water resources in coastal areas only account for 28.6% of the national total water resources. The total water use in coastal area is 248 trillion m3 which is about 41.2% of the national total water use. 28.1% of the water resources have been utilized in coastal areas while the national average water efficiency is only 19.5%. In general, the water supply and demand imbalance in coastal areas has deteriorated for decades due to economic development, population growth, and urbanization. These three factors will be intensified in the next two decades in the coastal areas, especially in the regions of Pearl River Delta, Yangtze River Delta, and Bohai Rim. Thus, the water resources stress in coastal areas will not be relieved in the near future. One of the most challenging issues facing water resources professionals in China is how to address the increasing imbalance between water supply and demand. 3. Retrospect of seawater desalination Based on scales of the subject seawater desalination projects under research and development [28], the last 6 decades are divided into 3 phases which are described in details below. (1) 1958–1996, laboratory experiments and pilot-scale. Researchers in the Institute of Chemistry, Chinese Academy of Sciences started investigating ED technology in 1958 and RO technology in 1965 [1]. In 1980, an ED seawater
desalination facility with a capacity of 200 m3/d was completed in Xisha, Hainan province, the energy consumption of which was as high as 18 kWh/m3. Pilot-scale tests of MSF technology with a capacity of hundreds m3/d were conducted through late 1980s [29]. (2) 1997–2004, 500–5000 m3/d. During this period, practical applications on the scale of hundreds to thousands of m3/d were developed, primarily to serve residential and industrial need. The first seawater reverse osmosis (SWRO) desalination station was constructed in 1997 in Shengshan Island of Zhoushan, Zhejiang province [30,31]. The station had a capacity of 500 m3/d and employed mainly imported technologies and instruments. A seawater desalination plant with a capacity of 1000 m3/d, using RO technology, was completed in 1999 in Dachangshan Island of Dalian [32]. In 2003, a seawater desalination system using RO technology with capacity of 5000 m3/d was constructed in Shidao Island, Rongcheng, Shandong province [33]. In 2004, a seawater desalination system using low temperature MED (LT-MED) technology with capacity of 3000 m3/d was completed in Huangdao Power Plant of Qingdao [34]. After nearly 40 years of research and development and demonstrations, Chinese seawater desalination technology has become increasingly mature, which make it possible for large scale application. (3) 2005–present, large-scale of over 10,000 m3/d. Large-scale desalination plants with a capacity of over 10,000 m3/d have been developed and constructed in this period. In 2005, the first large-scale seawater desalination system (10,800 m3/d) was completed at the Datang Wangtan Power Plant [41]. In 2006, 2 10,000 m3/d LT-MED device was introduced to China [35]. The existing independent LT-MED device ranges from 3000 to 12,500 m3/d [29,36–39] and are mainly used for power plant boiler make-up water supplies [40]. In 2009, the first desalination plant with a capacity of over 100,000 m3/d was completed in Tianjin [34]. Presently there are 60 SWRO desalination plants with a total capacity of 348,000 m3/d and 11 LT-MED desalination plants with a total capacity of 222,300 m3/d [42]. 4. Present seawater desalination in China In 2005, China developed ambitious goals for its seawater desalination industry [43]. The goal for total capacity of desalination was set at 0.8–1 million m3/d by 2010, and 2.5–3 million m3/d for 2020. However, by the end of 2010, the total completed capacity was only 583,000 m3/d and the amount under construction was 408,000 m3/d, well under the goal for 2010. Fig. 1 shows the annual and cumulative completed desalination capacity [9,60]. It demonstrates that desalination capacity expanded remarkably since 2005. Annual completed desalination capacities in both 2009 and 2010 were more than 100,000 m3/d. By 2010, there were 75 completed desalination plants in China. Table 4 shows the 10 largest desalination plants in China. Fig. 2 shows the geographic distribution of the 10 largest desalination plants in China. The cumulative desalination capacity in China has been growing in the annual rate of
Table 2 The coastal area and national water supply in 2010.a
a b
Area
Total water supply (billion m3/d)
Total water supply/water supply capacity (%)
Urban population (million)
Population served with public water (million)
Average water use (liter/ person/d)
Coastal areas China
27.6
51.1
304.6b
198.9
185.2
50.8
50.4
669.8
381.6
171.4
Data from Chinese Statistical Yearbook, 2011 [27]. Date of 2009, from Chinese Statistical Yearbook, 2010 [26].
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X. Zheng et al. / Chemical Engineering Journal 242 (2014) 404–413 Table 3 Water resources and its utilization for coastal areas and entire China in 2010.a
a b
Area
Total water resources (billion m3)
Total water use (billion m3)
Average water resources per capita (m3/person)
Industry water useb (billion m3)
GDP (trillion yuan)
Water use efficiency
Coastal area China
884
248
1915.7
206
24.6
28.1%
3091
602
2310.4
514
40.1
19.5%
Data from Chinese Statistical Yearbook, 2010 [26]. Industrial water use includes agriculture water use.
Hebei with the capacity of 123,000 m3/d; and 6 plants were located in Tianjin with the capacity of 218,000 m3/d. Only 5 plants were constructed in the other coastal provinces with a negligible capacity of 3000 m3/d. Fig. 2 shows the geographic distribution of the ten largest desalination plants along Chinese coastal line. 4.2. Industry sectors
Fig. 1. Capacity growth of seawater desalination in China.
70%. By September 2011, 16 desalination plants with over 100,000 m3/d capacity have been constructed and the total capacity is about 660,000 m3/d. There are presently 9 desalination plants under construction in China as listed in Table 5. The total capacity of these 9 plants is 408,000 m3/d. RO technology is employed in 8 of these plants. Fig. 3 shows the locations of these plants. 4.1. Geographic distribution Most of the completed desalination plants were located in five provinces, i.e. Liaoning, Shandong, Hebei, Tianjin, and Zhejiang [44]. These five provinces have total capacity of 580,000 m3/d which accounts for 99.5% of the national total capacity. Fig. 4 shows the desalination capacity for each of the provinces. Among the 75 completed desalination plants, 20 plants were in Shandong with the total capacity of 68,000 m3/d; 23 plants were in Zhejiang with the total capacity of 100,000 m3/d; 14 plants were in Liaoning with the capacity of 66,000 m3/d; 7 plants were in
The distribution of desalination plants in industry sectors is shown in Fig. 5. Seawater desalination primarily is used in public water supply, power generation, steel manufacturing, and petrochemical sectors. Public water supply, electricity, steel manufacturing, and petrochemical industry account for 53.9%, 26.3%, 3.9%, and 5.3% of the total number of desalination plants, respectively. Desalination plants in the power generation industry produce the most capacity, accounting for 51.6% of the total capacity. Petrochemical, public water supply, and steel manufacture provide 21.4%, 13.7% and 8.6% of the total desalination capacity. Desalination plants in these 4 sectors are summarized below. In the power generation industry, desalination plants are commonly used to produce boiler makeup water. This is due to the incentive policy that requires new power plants within coastal areas to adopt seawater desalination technology to provide water. New power plants with a total generation capacity of over 35,000 MW which are planned for construction in coastal areas, will need high quality boiler makeup water of 180,000 m3/d. Due to both the incentive policy and desalination technology advancement, seawater desalination would provide the majority of boiler makeup water for power plants in the future. Desalination plants can reuse the water steam and heat generated in petrochemical and steel manufacturing sectors. Thus desalination plants not only can provide reliable water but also can reuse waste steam and heat, reducing costs. It is expected that more petrochemical and steel manufacturing facilities will adopt seawater desalination technology for a water source. With the more restrictive requirements of drinking water and the costs associated with public water distribution system updates and maintenance, the water price in China will keep increase. With advancement of seawater desalination technologies and construction of larger scale desalination plants, the unit cost of desalination
Table 4 Ten largest desalination plants in China.a
a
Plants
Capacity (m3/d)
Technology
Manufacturer
Start-up year
Tianjin North Power Plant Phase I of Tianjin Dagang Xinquan Hebei Huanghua Power Plant Hebei Caofeidian Shougang Jingtang Iron Works Yuhuan Huaneng Power Plant in Zhejiang Yueqing Power Plant in Zhejiang Qingdao Soda Ash Industrial Company Limited Dalian Chemical Industry Company Huangdao Power Plant in Shandong ZhuangHe Power Plant in Liaoning
100,000 100,000 57,500 50,000 35,000 21,600 20,000 20,000 16,000 14,400
MED RO MED MED RO RO RO RO MED, RO RO
IDE Hyflux SIDEM SIDEM CNC N/A N/A CNC Hyflux N/A
2010 2009 2006 2009 2006 2007 2010 2009 2004 2008
Data from [60,61].
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Fig. 2. Geographic distribution of the 10 largest desalination plants in China.
Table 5 Desalination plants under construction in China.a
a
Plants
Capacity (m3/d)
Technology
Location
Caofeidian Industrial Park Lubei Enterprise Group Qingdao Baifa Huizhou Pinghai Power Plant Ningde Nuclear Power Station in Fujian Phase II of Tianjin Dagang Xinquan Phases II, III, and IV of Zhoushan Liuheng Dalian Beiliangchu Zhejiang Sanmen Nuclear Power Station Project Total
50,000 40,000 100,000 17,000 11,000 50,000 100,000 30,000 10,000 408,000
RO RO RO RO MSF RO RO RO RO
Hebei Shandong Shandong Guangdong Fujian Tianjin Zhejiang Liaoning Zhejiang
Data from [60,61].
will decrease. It is possible in the future that desalination plants will produce large amounts of water to feed public water supply systems. 4.3. Technologies Fig. 6 shows the plants and capacity of desalination with various technologies. It is evident that most desalination plants employ RO and/or MED technologies. For the number of desalination plants, 80.3% desalination plants, i.e. 61 plants, adopt RO technology to desalinize seawater. Only 11 desalination plants, 14.5% of total plants, employ MED technology. The capacity of desalination plants with RO technology is 348,000 m3/d, accounting for 59.3% of the national total desalination capacity, while
MED technology is used in desalination plants with capacity of 232,000 m3/d which is about 39.6% of the national total capacity. This is due to the fact that MED is generally used for larger scale desalination plants than RO is [45]. On average, the capacity of a desalination plant with MED is 21,000 m3/d and that with RO is only 6000 m3/d. The capacity of desalination plants with other technologies such as MSF and ED only accounts for 1.1% of the total capacity.
5. Techno-economic analysis One of the key factors in the selection of seawater desalination technologies is techno-economic analysis. In this section, we
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409
Fig. 3. Geographic distribution of desalination plants under construction in China.
Fig. 4. Seawater desalination output capacities for coastal provinces.
conducted a thorough techno-economic analysis of the most commonly used seawater desalination technologies, i.e. RO and MED. 5.1. Techno-economic analysis of RO technology The costs of 5 desalination plants with capacities of 500– 35,000 m3/d were analyzed to compare the impact of capacity on the cost of desalination plants. Tables 6 and 7 show the results of the analysis. Due to the cost of heating in winter, the total unit cost of Changhai County Seawater Desalination Plant is higher than that
of Shengshan Seawater Desalination Project. Generally, the unit total cost usually decreases as the capacity increases [51]. Electricity consumption per cubic meter water decreases while the capacities of desalination plants increase. Interestingly, unit capital cost is relatively stable with varying desalination capacities. In addition to the capital cost of desalination, the operation and maintenance cost includes electricity, membrane, chemicals, maintenance, and labor [49,50]. It is evident that electricity is the largest cost component. The electricity cost account for 50.7%, 37.7%, 44.4%, 52.2%, 27.9% of the total unit costs for the 5 desalination plants, respectively. The percentage of electricity generally decreases with larger scale desalination plants. Reduction of electricity consumption in desalination process is the key to reduce the unit cost of desalination as it is the major cost component. Capital cost is the second largest cost component. For the 5 desalination plants in Table 7, the percentages of capital cost with respect to total unit cost are 28.0%, 26.5%, 23.8%, 25.4%, and 27.9%, respectively. The capital cost generally accounts for 25% of total unit cost, either for small scale or large scale desalination plants. The costs for periodic membrane replacement for the 5 desalination plants accounts for 6.5%, 16.1%, 10.7%, 7.8%, and 20.5%, respectively. With the advancement of membrane technology, it is expected that the cost for replacing membrane will decrease [12,52]. The Huangneng Yuhuan Power Plant is analyzed in depth to examine cost component of desalination [53]. The desalination capacity of Huangneng Yuhuan Power Plant is 35,000 m3/d to provide water for the cooling system and boilers. RO coupled with MSF technology is adopted in the plant. The cost analysis is based
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(b) Cap pacity (m3 / daay)
(a) Number of plants
Fig. 5. Industry sectors with desalination plants in China.
(b) Capacity (m3 / daay)
(a) Number of plants
Fig. 6. Number and capacity of desalination plants with various technologies in China.
Table 6 The cost of RO desalination with various scale capacity. Seawater desalination project
Shengshan [30]
Tianjin [46]
Changhai County [32,47]
Rongcheng [33]
Yuhuan Power Plant [48]
Capacity (m3/d) Start-up year Total capital cost (million yuan) Electricity consumption (kwh/m3) Cost of electricity (yuan/m3) Capital cost (yuan/m3) Total unit cost (yuan/m3)
500 1997 6.16 5.20 3.12 1.72 6.15
1000 2004 7.50 4.16 2.08 1.46 5.52
1500 2001 15.94 4.00 2.80 1.50 6.30
5000 2003 20.00 3.54 2.40 1.17 4.60
35,000 2006 192.44 3.30 1.20 1.48 4.30
Table 7 Components of cost of RO desalinization with various scale capacity. Seawater desalination project
Shengshan [30]
Tianjin [46]
Changhai Country [32,47]
Rongcheng [33]
Yuhuan Power Plant [48]
Membrane (yuan/m3) Chemicals (yuan/ m3) Labor (yuan/m3) Maintenance (yuan/m3) Electricity (yuan/m3) Investment (yuan/m3) Total unit cost (yuan/m3) Percentage of electricity and investment
0.40 0.30 0.25 0.36 3.12 1.72 6.15 78.7%
0.89 0.45 0.24 0.34 2.08 1.46 5.52 64.1%
0.68 0.22 0.13 0.97 2.80 1.50 6.30 68.3%
0.36 0.36 0.13 0.18 2.40 1.17 4.60 77.6%
0.88 0.23 0.07 0.22 1.20 1.61 4.30 65.3%
on the loan period of 15 years with total loan of 144 million yuan. The total capital cost is 192 million yuan and the period of depreciation is assumed 30 years which is commonly used in China. The detailed cost of the plant is shown in Table 8. 5.2. Techno-economic analysis of MED technology Table 9 shows the cost for different scale MED desalination plants, ranging from 3000 to 25,000 m3/d. Generally, the unit
cost of MED technology is lower than that of RO for plants of the same scale. Furthermore, Phase I for Huanghua Power Plant is analyzed in depth to examine cost component of desalination. Phase I for Huanghua Power Plant has the capacity of 2 10,000 m3/d, using TVC-MED technology. The detailed cost components are shown in Table 10. After the application of seawater desalination, this plant does not need other fresh water, and save 20.1 million yuan for using fresh water and pretreated water.
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The factor that limits MED applications is electricity consumption. Most of the MED desalination plants were constructed together with power plants. With many more nuclear power plants expected to be constructed in China, MED desalination will receive more attention and market share [39,54]. China’s steel industry consumes a lot of electricity, and the production process produces a large amount of waste heat and gas. The waste heat and gas can be used to drive MED seawater desalination devices, to increase the thermal efficiency from less than 40% to nearly 60% [55]. Using the waste energy to produce fresh water, seawater desalination applications in the iron and steel industry can achieve the co-production of water and electricity for plant. If waste energy can be used for seawater desalination, unit cost for desalination would be decreased substantially and make the technology much more economically competitive [40,56,57]. 6. Prospect of seawater desalination applications In February 2012, the Chinese government issued a memo that outlined the most recently updated goals and prospects of seawater desalination for 2015. The Chinese government and provincial governments also developed long-term goals of seawater desalina-
Table 8 Cost for desalination in Yuhuan Power Plant (3,5000 m3/d).a
Interestb Depreciation of fixed assets Membrane Maintenance Labor Electricity Chemicals Total unit cost a b
Annual cost (thousand yuan)
Unit cost (yuan/m3)
1104 12,829 9800 1930 600
0.13 1.48 0.88 0.22 0.07 1.20 0.32 4.30
Data from [48]. Based on annual interest rate of 6.12%.
Table 9 Cost for different scale MED desalination plants.a
a
Seawater desalination project
Huangdao Power Plant
Huanghua Power Plant
Caofeidian Shougang
Capacity (m3/d) Operational year Total capital cost (million yuan) Unit capital cost (yuan/m3) Total unit cost (yuan/m3)
3000 2004 24
20,000 2006 228
25,000 2008 250
8000
11,400
10,000
4.73
3.80
6.00
Data from [19,14,38].
Table 10 Cost of desalination for Huanghua Power Plant (20,000 m3/d).a Cost (yuan/m3) Depreciation of fixed assets Electricity Chemicals Steam Labor Maintenance Total unit cost a
Data from [38].
0.99 0.20 0.28 2.20 0.05 0.08 3.80
tion for 2020. Based on these goals and planning, the prospect for seawater desalination application in China for the next decade is summarized below. By 2015, the total seawater desalination capacity is projected to be 2.2–2.6 million m3/d. Considering the total seawater desalination at 2010 is only about 0.6 million m3/d, almost 2.0 million m3/d capacity will be needed. By 2015, seawater desalination is projected to provide more than 50% of new water supply for Chinese islands and more than 15% of new water supply for Chinese coastal areas. For 2020, each coastal province has its own planning and goals which are shown in Table 11. By 2020, the total seawater desalination capacity will reach 2.5 to 3.1 million m3/d which is only slightly higher than the goal of 2015. This is because the goals of 2020 were developed earlier than those of 2015. It is expected that individual provinces will update their provincial planning and goal for 2020 based on the revised national goal. It can be expected that Chinese seawater desalination capacity will substantially increase in the next decade. RO and MED will still be the dominant technologies employed in most seawater desalination projects [12]. With the advancement of last six decades, the membrane industry China has been well developed. Comprehensive applications of microfiltration (MF), Ultrafiltration (UF), and RO technologies in seawater desalination have been increased a lot. Benchmark seawater desalination plants with RO technology have been constructed. As an emerging industry, membrane industry has received unprecedented attention in China. In 2010, China central government released ‘‘Decision of the State Council on Accelerating the Fostering and Development of Strategic Emerging Industries’’ and high performance membrane materials was listed as strategic emerging industry in the decision. This unprecedentedly stimulates the development and advancement of membrane technology, membrane industry, and membrane application market. In ‘‘National 12th Five-Year Science and Technique Development Plan’’ released in 2011, the specific requirement for membrane materials have been outline which included ‘‘primarily develop of membranes for water treatment, gas separation, and specialty separation. Promote applications of membrane technologies in water treatment, iron and steel manufacturing, petrochemical industry, and environment protections’’. It is foreseeable that membrane technologies especially RO technology will play an increasing role in seawater desalination in China [58]. There are the following challenges that China has to face to develop seawater desalination. (1) The membrane technologies for seawater desalination (e.g. waste power recycle and RO membrane) and the manufacturing of key equipment for desalination (e.g. seawater evaporators, condensers, and steam ejector etc.) in China have yet to be improved remarkably. (2) There is significant lack of practices and experiences in seawater desalination engineering, large-scale desalination equipment design, manufacturing, operation, and maintenance. (3) The guidance on testing, evaluating, and designing seawater desalination is not well developed and thus it does not provide complete industry standards and technique guidance for seawater desalination. (4) The existing and planned desalination plants could cause adverse environmental
Table 11 Goals of seawater desalination capacity for 2020 (in thousand m3/d).a
a
Liaoning
Hebei
Tianjin
Shandong
Jiangsu
Shanghai
300400
200–250
450–500
800–900
10–20
30–50
Zhejiang
Fujian
Guangdong
Guangxi
Hainan
Total
550–650
60–100
80–150
10–20
30–50
2520–3090
Data from [62].
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impact. Seawater desalination consumes a large amount of thermoelectric energy and results in emission of air pollutants and green-house gases [66]. It could also cause impingement and entrainment of marine organisms [66,69,70]. The elevated salinity of brines and the chemicals used in desalination process poses environmental risks to marine ecosystem [66,69,70]. The other potential environmental impact of desalination is the increased seawater temperature cause by the process. Detailed analysis of these potential environmental impacts should be required and mitigation measures shall be identified for desalination plants. Many large-scale desalination plants (100,000 m3/d plus) have been proposed to be constructed in Chinese coastal areas recently. The total capacity under construction and draft is 1.4 million m3/d and China has become a most promising market for seawater desalination. The projected annual increase rate of total desalination capacity is about 50%. International giant desalination companies will still dominate Chinese desalination market in the foreseeable future as domestic companies is not competitive in large-scale whole sets of equipment, RO technology, MED technology and equipment.
7. Conclusions Economic development and urbanization are the major causative factors in the disparity between water supply and demand within coastal areas, especially the Pearl River Delta, Yangtze River Delta, and Bohai Rim. Water shortage has become a limiting factor of sustainable development in China. In the next two decades, the water shortage problem in Chinese coastal areas will only be intensified [7]. Water resources development and utilization in most streams and rivers in northern China have exceeded the corresponding water resources carrying capacity. Seawater desalination is of extreme importance for increasing water supply in China. We strongly recommend that seawater desalination be prioritized to the Chinese national water resources key strategy to promote seawater desalination in the near future. Seawater desalination can increase total water supply and is the inevitable national strategy to address water shortage issue in China. This is beyond the consideration of water price and cost or pros and cons of various technologies. It is of necessity due to sustainable social and economic development in coastal areas in China. Seawater desalination in China has been applied primarily in the municipal public water supply, power generation, steel manufacturing, and petrochemical sectors. Seawater desalination applications in the power generation industry are primarily intended to provide boiler makeup water. The metallurgical and chemical industries have seen rapidly increasing applications of seawater desalinations recently and are expected to apply numerous seawater desalination projects in the future. As the gap between water price and seawater desalination cost shrinks steadily, though slowly, it will become practical that water generated by seawater desalination will become an important component in public water supply systems. The inappropriate cost accounting system has confined the development and applications of seawater desalination in China for the last two decades. Long distance water transfer projects are usually funded and financed by central or local governments and water are underpriced. Applications of seawater desalination have to be financed through market and thus it is not as competitive as long distance water transfer. With the relocation of many iron and steel manufacturing and petrochemical facilities to coastal areas, the applications of seawater desalination have been promoted as infrastructure. The mainstream technologies for seawater desalination include RO and MED. Though the amount of MED applications is less than
RO, the average generated water per application of MED is four times as RO. Power consumption in MED is the major factor that limits MED applications. As MED technology is very well coupled with the nuclear power generation process and many nuclear power plants will be built in the next two decades in China based on the long-term national planning of nuclear power, it is expected that more seawater desalination applications will employ MED technology [59]. China now is one of the most promising market for seawater desalination. The annual increase rate is projected to be about 50%. However, due to the fact that domestic companies are not competitive in large-scale whole sets of equipment, RO technology, MED technology and equipment, international desalination companies will still dominate Chinese seawater desalination market in the foreseeable future.
Acknowledgements The research was supported by Program for New Century Excellent Talents in University (NCET-12-0531), Open Project of State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology (No. ES201005) and Beijing Science & Technology Star Plans (2008A110). Any opinions, findings, and conclusions are those of the authors and no official endorsement should be inferred. The authors would like to thank Bob Pody and Pierre MaCoy for proofreading and reviewing the revised manuscript. The comments of anonymous reviewers and editor of CEJ helped us to refine and improve this manuscript.
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