Int. J. of Sustainable Water and Environmental Systems Volume 4, No. 1 (2012) pp. 15-22
Energy and water linkage in Mexico Claudia Sheinbaum-Pardoa, Carlos Chávez-Baezab, Sebastián Lelo de Larreaa a
b
Instituto de Ingeniería, Universidad Nacional Autónoma de México, Mexico DF, Mexico, 04510 Programa de Energía, Universidad Autónoma de la Ciudad de Mexico, Mexico DF, Mexico, 03100
Abstract The following study analyzes the relationship between water and energy in Mexico, from the standpoint of water being needed for energy production and use, as well as energy being needed for diverse water uses. The extraction and processing of fuels, along with electricity generation, account for most of the water consumption and pollution in the energy system. According to official data, the share of water use for the energy sector reaches 6% of National consumption in 2008, and the consumption of electricity for different water uses added up to 7% of national electricity use. Even though these figures might seem low, it appears clear that the energy sector cannot operate under water stress scenarios, and without energy, potable water supply and water treatment cannot function. It important to develop an information system that allows us to understand with greater detail the relationship between these two resources, and in consequence promote policies that minimize risks and encourage a more efficient and sustainable use of both water and energy. Keywords: Water, energy, Mexico
1. Introduction Water and energy are essential for human welfare. Without water, life is not possible, and energy allows us to obtain water in the desired quality and quantity for either consumption or productive activities. Energy is vital for modern life, and water is necessary for its production. Adequate availability of water resources is linked to the adequate availability of energy resources, and vice-versa. Water pumping and water treatment require energy, whose production, transformation, and consumption rely on water in return. Water is also fundamental in electricity generation. It is used directly in hydroelectric plants, and it is used for cooling, and emission control in thermo-electric plants. In 2008, power generation in Mexico through thermo-electric plants represented 5% of total water consumption, while in the United States, it represented 39% in the year 2000, figure that is similar to the agricultural sector [1, 2]. Water and energy are necessary for agriculture, industrial and commercial activities. Basic services of water and electricity are required to diminish poverty. Water and energy scarcity is a limitation to economic growth and human development. In addition, climate change puts more stress on the relation between water and energy. Climate change is likely to have a destabilizing effect on the world’s water systems. Climate change represents strain to areas that already struggle to meet their need for fresh water. This is also true for water needed to energy production and transformation. This study analyzes the relationship between water and energy
in Mexico, from the standpoint of water being needed for energy production and use, as well as energy being needed for diverse water uses. To put this study in context, it is important to mention other studies on the energy and water relation that have been conducted in recent years. Some of them are discussion papers of both, governmental and non governmental agencies that raised the importance of this linkage. For example, the California Energy Commission [3] published a very important report on problems related to energy and water in this US state. The US Department of Energy [4] presented a report to US Congress, on US energy demands on water resources. Also, USDOE through the National Energy Technology Laboratory, investigated water issues related to coal mining, coal to liquids, oil shale, and carbon capture and sequestration [5]. The Australian government published a discussion paper that inform and promote discussion of the links between climate variability and change, energy production and use, and water-resource management in Australia [6]. The World Economic Forum [7] presented an important assessment on energy and water linkage. Other analysis that present case studies are for example, the discussion on how the US plan to raise their thermo-electric capacities could face water shortages if linked management is not seriously considered [8]. Also, how the Middle East and North Africa face increasing energy demands and decreasing freshwater supplies in many areas, due to a strong dependence on energy for water abstraction and production systems [9]. In China, combining seawater desalination with industrial processes is being proposed as a feasible and promising way of solving problems of freshwater shortages, while simultaneously enhancing middle and low thermal energy
*
Corresponding author. Tel.: +525556233693 ; E-mail:
[email protected] © 2012 International Association for Sharing Knowledge and Sustainability DOI: 10.5383/swes.04.01.002
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Sheinbaum-Pardo et. al. / Int. J. of Sustainable Water and Environmental Systems, 4 (2012) 15-22 efficiency [10]. Spain, whose use of biofuels in the transport sector reaches 1.42%, is compromised to reach a European Union objective of 10% by 2020; this without taking into consideration the intensive consumption of water resources needed for biofuel production, this puts additional pressure in already water-stressed areas [11, 12]. With exception of hydroelectricity, linked management of energy and water is minimal in Mexico. For this reason, there is very little data available on energy for water and water for energy. The paper is divided in three parts. The first part addresses the water demand necessary for production, transformation, and use of energy. The second one treats the topic of the necessary energy for potable water consumption and sanitation. In both cases, quantitative estimations are presented. The last part presents risks and opportunities of the energy-water linkage.
2. Energy supply and water needs
that water quantity, 75% was re-injected, and the rest was disposed of, in some countries, without treatment [7]. In Mexico, the petroleum activity is restricted to Pemex by constitutional mandate. Pemex uses surface, subterranean, treated, and reused water, as well as water from the ocean which is subject to desalination, as sources for water supply of the diverse petroleum activities. The main sources of water for Pemex’s operations are the Coatzacoalcos, Huazuntlan, Ramos and Tamesi rivers, as well as the Salamanca, Cadereyta, and Tula aquifers [14, 15, 16, 17]. In 2008, Pemex´s total water input reached 237.8 millions of cubic meters (Mm3). Pemex Exploration and Production (PEP) accounts for 3% of the water consumption, followed by Pemex Gas and Basic Petro chemistry (PGPB) that accounts for 18%, Pemex Petrochemical (PPQ) 24%, and Refineries (PR) 55% (Fig. 1). Close to 52% of the water consumption for refineries comes from ground sources and 42% from surface water, while in the case of gas, basic, and secondary petrochemical, most of the water consumption comes from surface sources (Fig. 2).
Water is used for several activities of the energy sector, from extraction to processing of fossil fuels, power generation, and final use. These activities have an impact on water quality through chemical and thermal pollution, or through atmospheric emissions that precipitate and pollute water. The biggest water consumption is related to the extraction and processing of fuels, while the final energy use implies minimal water requirements. 2.1 Water for hydrocarbon extraction and production Water consumption for the extraction of coal, petroleum, and natural gas, along with their transformation and processing reached 6% of the national total in 2008, and represented 3.3 km3 [1].1 Exploration is an activity that in the final stage includes well drilling to verify the existence of the product. During this activity, and along with well exploitation, water is used in different stages of the process: it is a fundamental ingredient of most perforation mud; it can be injected in mature wells to push hydrocarbons into the wells; it can be pumped into the wells as steam to strip bitumen and heavy petroleum from surrounding sand, and, it is also used as fracture fluid to break clay, and allow natural gas to freely flow through rock [13]. The volume of water consumption depends on the location and quality of the fuel deposit. Future natural gas and petroleum reservoirs, like the ones on bituminous sands, will most likely require intensive water use for their exploitation. Additional water pollution might occur during hydrocarbon extraction, where water located in the subterranean formations is liberated alongside petroleum and gas. The quality of this water varies according to each deposit; nevertheless, most cases present various pollutants, among which high salinity stands out [7]. This water is generally disposed of, either by deep injection on earth, or by posterior discharge into the environment, previous treatment. Both activities signify great monetary cost. The injection must be done in geologically isolated formations, to avoid subterranean sources of potable water, and in several occasions it requires previous treatment to avoid obstruction of the receiving formation and damage to the injection equipment [13]. As a well matures, the produced water quantity reaches 40 times the amount of petroleum extracted. In 1999, it was estimated that 210 million barrels of subterranean water were produced daily, this associated with the production of around 72 million barrels of petroleum. From
Source: Informe de Desarrollo Sustentable Pemex [17]. PPQ: Petrochemical; PEP: Production; PR: Refinery; PGPQ: Gas a basic petrochemicals Fig. 1. Water input per petroleum activity (2008).
As a general trend, water input for the various activities of the petroleum industry, has been diminishing; however, the water utilized for petroleum refineries increased between 2005 and 2008, in spite that refinery capacity has not changed (Fig. 3). Specific water consumption per activity has decrease in PEP2 and in PPQ, but not in PR, where water input showed a great variation in the last few years (Table 1).
100% Others
80% 60% 40% 20% 0%
Source: Informe de Desarrollo Sustentable de Pemex [17]. Fig. 2. Water consumption by source and petroleum activity
1
CNA category of self-supplied industry. The data refers to water extracted from water bodies but does not account for water that comes from municipal grids.
2
Excluding year 2000, because of information inconsistencies.
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Sheinbaum-Pardo et. al. / Int. J. of Sustainable Water and Environmental Systems, 4 (2012) 15-22 Table 1. Water consumption per production unit (input minus output)
Exploration and production Water input Water consumption Oil Production input/production
Units
2000*
2001
2002
2003
2004
2005
2006
2007
2008
Mm3 Mm3 Mbb/day
11.91 9.78 3.45
37.01 26.02 3.56
36.49 27.02 3.59
30.33 19.85 3.79
27.38 16.19 3.83
9.22 14.51 3.76
16.44 12.83 3.68
9.77 7.14 3.47
8.46 2.16 3.16
m3/m3
0.06
0.18
0.18
0.14
0.12
0.04
0.08
0.05
0.05
m /m
0.05
0.13
0.13
0.09
0.07
0.07
0.06
0.04
0.01
Mm3
149.04
132.39
111.4
112.22
106.62
86.47
117.29
119.87
130.04
3
3
consumption/production
3
Refining Water input Water consumption
Mm
79.07
73.25
82.90
90.72
82.20
85.18
88.16
79.83
88.95
Petroleum products
Mbb/day
1.45
1.47
1.48
1.56
1.59
1.55
1.55
1.51
1.49
1.8
1.5
1.3
1.2
1.2
1.0
1.3
1.4
1.5
m3/m3
0.94
0.86
0.96
1.00
0.89
0.94
0.98
0.91
1.03
Mm3
36.82
40.39
39.24
47.48
46.81
42.13
43.30
41.49
42.00
Water consumption
3
Mm
24.10
23.25
24.98
23.16
24.05
22.96
21.88
20.73
21.82
Production
Mft3
2791
2804
2916
3029
3144
3147
3445
3546
3461
Input/production Consumption/production Gas and basic petrochemicals Water input
3
3
1.28
1.39
1.30
1.52
1.44
1.30
1.22
1.13
1.17
3
3
m /1000 m gas
0.84
0.80
0.83
0.74
0.74
0.71
0.61
0.57
0.61
Mm3
66.56
60.433
58.015
59.178
59.002
53.227
51.418
54.021
56.935
Water consumption Petroleum products
3
Mm Mt
39.60 6.84
38.32 5.99
42.43 5.89
34.36 6.09
34.03 6.22
29.31 6.22
24.60 6.57
32.19 7.50
36.54 7.84
Input/production
m3/t
9.74
10.08
9.85
9.73
9.48
8.56
7.82
7.21
7.26
5.79
6.39
7.20
5.65
5.47
4.71
3.74
4.29
4.66
Input/production Consumption/production Petrochemicals Water input
m /1000 m gas
Consumption/production m3/t Data based on Informe Estadístico de Pemex [17,19]
According to Pemex, the amount of treated water for reuse has been increasing. In 2008, it reached 30 Mm3 [14-17]. Table 2 shows the volume of water discharge per activity . According to Pemex´s statistics, this volume decreased between 2000 and 2004, and increased between 2005 and 2008 . On the other hand, the quantity of congenital water, which refers to the water produced during hydrocarbon exploitation, is in a vast majority injected. In 2004 this quantity reached 88.9% . In 2003, the Mexican official norm that establishes the environmental specifications for the management of congenital water associated to hydrocarbons was published, it establishes the upper permissible boundaries of different pollutants for the discharge of congenital water, as well as the characteristics that a well must have for its re-injection [18]. According to Pemex plans, a new refinery will have the capacity to produce 300,000 barrels per day of petroleum products. If the average water input of other Pemex refineries is taken into consideration as basic information (Table 1), for each barrel of petroleoum derivates produced, 1.5 barrels of
Table 2. Pemex total water discharge Year
Mm3
2000
111.8
2001
91.7
2002
61.3
2003
57.7
2004
59.7
2005
n.a.
2006
74.0
2007
79.5
2008 83.7 Source: Based on [14-17].
water input will be required3. This would imply an extraction of water from the aquifer of 0.83 m3/s4. 3
According to DOE (2006), for every unit of produced petroleum derivates in a refinery, between 1 and 2.5 units of water volume are required.
4
This is a calculation based on historical information.
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Sheinbaum-Pardo et. al. / Int. J. of Sustainable Water and Environmental Systems, 4 (2012) 15-22 Regarding Pemex´s discharge of pollutants, they have been diminishing because of water treatment plants. In year 2000, the total pollutant discharge was of 5,541 ton, 23% of this total corresponded to oil and fats (O and F), 61% to Total Suspended Solids (SST), 14% to total Nitrogen (Ntot) and the rest to other organic residues. The activity that generates the most water contaminants is refinery of petroleum. It is alarming that, even though, organic residues are the most risky, even in low quantities they are not reported with greater detail
Source: Informe de Desarrollo Sustentable de Pemex [14-17] Fig. 3. Trends of the water input per activity in Pemex (Mm3)
2.2 Water for coal mining Water needed for coal mining varies by mining method. Typical mining processes that require water include coal cutting in underground mines and dust suppression for mining and hauling. According to USDOE [4], coal mining requires from 1 to 6 gallons of water for every million Btu (1 to 6 liters of water for every 279 MJ) [20, 21]. According to the Mexican National Energy Balance, in the year 2008 251.2 PJ of coal were produced, which would imply, based on USDOE data, estimated annual water consumption for coal mining of 0.9 and 5.4 Mm3. 2.3 Water for thermo-electric generation Thermo-electric generation technologies that need vapor to move turbines require coolers to condense the vapor. The operation and cooling, imply a significant quantity of water consumption. In Mexico, in the year 2008, the thermo-electric centrals, including private production, generated 198.79 TWh, which represented 87% of the total of electricity production in the country. The oldest thermo-electric plants were built near surface water bodies. These plants normally use open-loop cooling systems. This means they withdraw water from the source, and then return it at a higher temperature, which produces inefficient consumption of the resource and thermal pollution into the water bodies. In 1988, the first Mexican standard, that established the upper permissible boundaries, and the proceedings for the determination of the contaminants present in the residual water from conventional thermo-electric centrals that discharge into national water bodies, was published. This standard was updated in 1993, and then absorbed into the norm NOM-001 in 1996, in which the upper permissible boundaries of contaminants present in water discharged into national water bodies, are established. In every case, a maximum temperature of the discharge is established [22]. Because of the contaminants involved in these cases, the situation is to be taken into serious consideration. The more modern thermo-electric plants use closed-loop systems, in which the water utilized is cooled through a cooling tower or pond. These systems withdraw less than 5% of the
water withdrawn by open-loop cooling systems, but most of it is lost due to evaporation [4]. In 2008, water consumption of the thermo-electric plants (that includes the water utilized in steam power plants, combined cycle, gas turbine, and internal combustion) reached the value of 4.1 km3, of which 88% has a surface water origin, and the rest an underground one. However, 76% of the water granted to thermo-electric plants in the country, corresponds to the carboelectric plant of Petacalco, located in the Guerrero coast, near the mouth of the Balsas river [1]. The most important carboelectric plant (Petacalco) alone, consumed 3.1 km3 of water, to generate 13.4 TWh. Meanwhile, the rest of the plants generated 185.5 TWh and consumed only 1 km3 of water. In addition to surface and ground water, CFE utilizes seawater and black treated waters. For the 15 centrals with 40 units in coastal sites, seawater is utilized in the steam cycle, through filtration, evaporation, distillation, and demineralization. In the center, and north of the country, municipal treated waters are utilized in thermoelectric plants as a source of water supply for cooling of the condenser in closed-loop systems with cooling tower [23]. According to CFE [22], from 1990 to 2004, subterranean water consumption dropped 70% from 1 l/s per MWh to 0.3 l/s. In the future, it is projected that the installed capacity of the national power sector will increase by 17,942 MW for 2018, of which 2,078 MW will be based on imported coal. This has serious implications not just for water consumption, but also, for other environmental impacts [24]. 2.4 Water for hydroelectricity Waterfall is the source for hydroelectricity. In 2008, 150.7 km3 of water were used by hydroelectric centrals to produce 12% of the electricity generated in the country. It should be noted, that in this process, the same water goes through the turbines and is accounted for, several times. However, it is reckoned that, more water is lost to evaporation in the hydroelectric central’s reservoirs, than what would be lost in the natural flowing river; hence water consumption in hydroelectric centrals could be discussed. On the other hand, the water stock in water dams, necessary for hydroelectric generation, has other uses as well, and its control is essential to avoid floods. 2.5 Water and energy for renewable resources The water quantity used to operate the technology based on renewable energy sources is variable. In the case of electricity generation, the use of water for wind turbines or photovoltaic panels is practically none. However, in the case of geothermal energy, and solar thermal power with integrated storage, water is indispensable for the cooling of turbines. It is estimated that the average consumption of water reaches 5.3 m3 per MWh in the case of geothermal power, and from 2.8 to 3.5 m3 per MWh in the case of the solar thermal power with integrated storage [7]. In the case of bioenergy sustained in grain crops, water consumption is very significant, it obviously depends on the type of crop, where and how it is cultivated, and above all, if it utilizes irrigation. It is calculated that the water consumption can go from 9 m3/GJ in the case of corn, and 250 m3/GJ in the case of soy [7]. Ethanol production is based on a fermentation process in which more water is consumed in comparison with biodiesel.
Table 3. Comparison between WEF and national information
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Sheinbaum-Pardo et. al. / Int. J. of Sustainable Water and Environmental Systems, 4 (2012) 15-22
Primary production Oil Traditional
WEF (1) lt/GJ
National estimation (2) lt/GJ
3-7
1.2
Enhanced Oil Recovery
50-9000
Oil. Bituminous sands
70-1800
Biofuel. Corn Biofuel. Soy Coal
9,000-100,000 50,000-270,000 0.9 a 5.4
5-70
Gas. Traditional Gas. Shale
Average consumption (3) Mm3 8.5 a 36.5
Minimal
0.005
36.4 a 47.5
36-54
Transformation Petroleum refining
25-65
Petrochemical Ethanol
39 3.2
86.5 a 149.0 51.4 a 66.6
47-70
Biodiesel
14
Coal liquefaction
140-220
Gas processing
7 lt/MWh
Electricity generation
lt/MWh
Primary production Coal
20-270
Uranium
170-570 4100
Electricity generation Close cooling system Geothermal Evaporation in hydroelectric plants Solar concentrators Wind Photovoltaic
720-2700
1
5,300 17,000 2,800-3,500 Minimal MInimal 4284 a 4405 6%
TOTAL % national
(1) WEF [7], and USDOE [4], CEC [3]: (2) Adapted from SENER [27] and CFE [28]; (3) Minimum and maximum values: 2000 a 2008.
3. Water supply and energy needs 2.6 Comparative analysis Table 3 shows water consumption for diverse energy production sources and technologies published by the World Economic Forum [7] and the calculations for the national water consumption according to information previously presented. In the case of water consumption for petroleum production, the figure is very low, perhaps because seawater is not taken into account. The refinery values are in range. The value of the calculated water consumption for electricity generation, based on CFE figures, turns out to be very low in international comparison, perhaps because CFE only reports water consumption for cooling and cooling tower refill.
3.1 Energy and water consumption in Mexico In the year 2008, Mexico consumed 7,698 PJ of primary energy, of which 44% corresponded to petroleum, 40% to natural gas, 5% to coal, 4% to hydro-electricity, 1% to geothermal energy, 1% to cane bagasse, and less than 1% to wind energy. About 35% of this energy was destined to generate electricity (including petroleum derivates and cane bagasse). Electricity is the main source of secondary energy utilized for water pumping, supply, transport, and treatment. On the other hand, in 2008, 77% of fresh water consumption was for agriculture, 14% municipal, 4% industry and 5% to thermoelectric plants (Fig.4). In the following sub-sections an estimation of electricity needs for water consumption is developed.
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Sheinbaum-Pardo et. al. / Int. J. of Sustainable Water and Environmental Systems, 4 (2012) 15-22 3.3 Energy demands for municipal water supply and drainage
Source: [1] Fig. 4. Water uses (km3/year)
3.2 Energy demand for water supply in the agricultural sector Agriculture is the principal use of water in Mexico. In 2008, it represented 77% of the extracted water (61.2 km3) Even though agricultural productivity in irrigated areas is 3.7 times higher than in non-irrigated areas [25], land aptitude, lack of water availability for irrigation in some areas of the country, the high prices of infrastructure, and the energy requirements, provoke that from the 21 million hectares destined to agriculture (11% of the national territory), only 6.5 million hectares are irrigated. Two thirds of the irrigation is done by surface waters throughout reservoirs, river derivations and gravity canals. This represents low irrigation efficiency (40-60%) due to high evaporation indexes, but minimum energy consumption (most of the irrigation is by gravity). The electricity use for agricultural irrigation has four specific electricity tariffs (Table 4). In 2008, the group of registered users in these rates ascended to 113,584, whose consumption was 8,049 GWh, quantity that signified 4.6% of the national consumption [26]. The tariffs for agricultural irrigation, 9 and 9M had an average price of around 0.01 USD/kWh (one US cent per kilowatt-hour), while the tariffs 9CU and 9N, denominated stimuli tariffs had an average price of 0.04 USD/kWh. The stimuli rates are applied to those producers that commit to achieve higher productivity and higher energy efficiency. Part of the required energy for irrigation is supplied through gasoline and diesel pumps, but there is no information to calculate its consumption. Also, windmills have been used successfully in Mexican land for decades, especially in the southeast of the country [27]. Also, there are schemes to promote water pumping by renewable resources (wind power, photovoltaic, and hybrid pumping). There is a fund trust called Fideicomiso de Riesgo Compartido (FIRCO, Shared Risk Trust) that bring financial incentives. It is estimated that in total about 19 MW of photovoltaic systems were installed in 2008 [29]. Table 4. Electricity consumption for agricultural pumping in México, 2008 Consumption Tariff 9 9M
(GWh) Water pumping in low tension Water pumping in middle tension
9CU Unit charge Water pumping during night middle 9N tension Total Source: [29]
60.2 1,125.0 1,680.4 5,183.4 8,049.0
The public water supply includes domestic, commercial, industrial, and services, and it represented 14% of the national water consumption in 2008 (the rest corresponds to agricultural, self-supplied industries and thermo-electric plants). The municipal systems require energy to pump water for its extraction, transportation, distribution, and storage. Energy is also needed for water treatment. In 2008, 11.2 km3 of water were used for municipal supply, of those, 62% came from ground sources, and 38% came from surface waters [25]. Water pumping for public services uses electricity. There is a specific tariff for potable water and black water pumping that according to CFE, reached a consumption of 1,514 GWh in 2008. The Mexican larger cities, however, do not contract electricity for water pumping in this tariff but in high tension tariffs. Unfortunately CFE do not published disaggregate data on high tension tariffs. Therefore indirect estimations have to be done. An estimation of electricity use of the Cutzamala system, which supplies a volume close to 10 m3/s to the Metropolitan Area of the Mexico Valley can be made. The water volume must go through a distance of more than 160 km, and needs to be pumped 1,100 m high. The corresponding energy consumption estimation reaches 2.85 kilowatts-hour per cubic meter (kWh/m3), which is to say, close to 900 GWh a year [30]. Also, Table 8 shows indirect estimation of electricity consumption for potable and water treatment in Mexico based on specific consumption data from [7]. 3.4 Energy supply demand, and water treatment in industry and thermoelectric plants The industrial water use reached 3.2 km3 in 2008, of which 45% comes from ground water and 55% from surface water sources [25]. The required water quality for industrial use is usually less than the quality needed for domestic use, excepting specific industries like the food industry, in which potable water is essential. The water is used for several porpoises: to clean, heat and cool, to generate steam, to transport substances or dissolved particles, as raw material, as a dissolvent, and as a part of the product, like on the beverages industry. In 2000, almost 80% of the water consumption in this sector corresponds to six industrial branches: sugar, chemistry, petroleum, cellulose and paper, textile, and beverages [31]. Of the total industrial water consumption, 50% is destined to cooling, 35% to processing, 5% to boilers, and 10% to services. In 2007, the industry treated 29.9 m3/s of residual waters of which 35.6% were primary treatment (pH is adjusted and organic materials are removed); 50.5% secondary treatment (includes removing organic, dissolved, and colloidal materials); and 2.1% tertiary treatment (dissolved organic materials that include gases, natural and synthetic organic substances, ions, bacteria, and virus). The level of treatment of the remaining 11.8% is not specified [32]. Based on the same value published by WEF [7] for the treatment of municipal waters (660 kWh per million liters) the electricity consumption of the industry responsible for water treatment reaches 0.62 TWh. In the case of thermoelectric plants, the energy consumption for water use is vast, and can include the process of electricity production itself, since it relates to steam. Table 5, presents a summary of the calculations of electricity consumption for the diverse water uses.
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Sheinbaum-Pardo et. al. / Int. J. of Sustainable Water and Environmental Systems, 4 (2012) 15-22
Table 5. Estimated electricity consumption for supply, treatment, and water pumping (2008) Energy consumption Use
TWh
Irrigation (tariff 9)
8.05
Municipal water pumping
1.51
Cutzamala
0.89
Municipal potable process
0.71
Municipal water treatment
1.65
Water treatment in industry
0.62
TOTAL % of National consumption
13.43 Electricity 7.1%
Source: [7, 30-32].
4. Risk and opportunities of the energy-water linkage Electricity consumption for water uses represents around 7% of the national energy consumption, and water consumption of the energy sector represents 6% of the total national water consumption. In spite of these small figures, the relationship between these resources is essential for the country’s development. The energy sector cannot operate without water or under water stress conditions, and the supply of potable water and sanitation depends on energy to operate. Climate change puts additional stress on the water and energy linkage. The impacts of climate change in the world’s hydro balances are very well documented [33,34, 35]. These impacts can vary from droughts to floods see level increase and extreme events. Energy and water planning must take into account vulnerability and adaptation to climate change, especially in hydroelectric plants. There is an important potential for water savings in the energy sector, particularly in refineries, petro chemistry industry, and thermo-electric plants. Even when Pemex, and the CFE have made some effort towards these ends, they are minor in comparison to the potential of reusing water in their processes. Opportunities for water efficiency might create additional energy demand such as substitution of gravity channels for more efficient irrigation systems that includes water pumping. However the use of photovoltaic systems for his matter is economically feasible. Finally, it is obvious that a mechanism for the coordinated administration of the available resources should be established between CONAGUA, CFE, the Energy Regulation Commission, and Pemex. Furthermore, there is a necessity for a national information system for water to energy and energy to water. For example more information is needed to analyze the extent of the potential freshwater savings in energy activities as well as environmental impacts. Data is also needed in the rubric of electricity consumption for water pumping, and sanitation in order to evaluate the saving potential for water and energy.
References [1] Comisión Nacional del Agua (CONAGUA). Estadísticas del agua en México. SEMARNAT, México, 2009. [2] U.S. Departament of Energy (USDOE). Energy demands on water resources. Report to Congress on the Interdependency of Energy and Water. 2008.
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