World Water Scarcity: Conservation and Desalination

WATER STRESS

Apart from the global overpopulation problem, water scarcity is as announced by the World Economic Forum in January 2015 : “The water crisis is the number one global risk based on impact to society as a measure of devastation”. The UN defines water stress when an area’s annual water supplies drop below 1700 cubic meters per person. When it is below 1000 cubic meters it has water scarcity. It is estimated that 10% of the world’s population does not have access to safe drinking water. This will increase as the world’s population is fast growing. The global demand for fresh water is rising by 640 billion cubic meters a year. A UNESCO report said that the world’s shortage of freshwater will rise to 2000 billion cubic meter by 2025. UN warns that if we continue our current trajectory, we will only have 60% of the water we need in 2030.

Where is this water going to come from? The worse hit areas are in the semi arid areas of Asia, Middle East and North Africa. An IAEA study showed that 2.3 billion people ( 1/3 of world’s population) live in water stressed areas, and 1.7 billion of them have less than 1000 cubic meter of drinking water per year. By 2025 this number could rise to 3.5 billion.

Such water scarcity is extremely worrying as it has great effect on the sustainability of the economic development of our world. As water is indispensable in all industries – agriculture, mining, energy production, etc as well as in human well being.

To put a human face on these statistics. One cubic meter is 1000 liters. A person everyday drinks about 4 liters. But for agriculture to produce the food we eat, a person needs 2000 liters a day. So water scarcity of 1000 cubic meters translates to 2740 liters/day person. On the whole 70% of this goes to agriculture, More than 20% for industry and this does not leave much for personal use.

The fundamental reason of water scarcity in China is the fact that though China has 21% of the world’s population, it has only 7% of the world’s freshwater supplies. While 80% of rainfall and snow melt occurs in the South, only 20% of moisture occur in the mostly desert regions of the North. North China is particularly dry. The average annual rainfall of Beijing, for example, is only 57 cm per year. ( 4.8 cm per month) Therefore the The South-North Water Transfer Project is bringing water from the Yangtze river, whose water come from ice melt of the Himalayas, to the North. Demand is fast outstripping supply as already the consumption levels are 70% higher than in 2012. It is projected that by 2020 water demand will reach 670 billion cubic meters a year while the resources are dwindling with time.

According to state media reports, before the arrival of infusions from the South-North Water Diversion Project Beijing’s annual per-capita water volume was just 100 cubic meters, 1.25% of the world’s average level. With the water from the south, that figure will go up to 150 cubic meters per person ( 411 liters/day). The average personal residential use of water is 86 liters/day compared to UK with 150 and US 560 liters/day.

Air pollution in China is a well known problem. While this results in acid rain, not many are aware that water scarcity and water pollution pose a greater threat to china’s thirst wellbeing, as well as for food security, energy use, urbanization, modernization and overall economic development.

However, adding to water scarcity is the nation wide water pollution problem. The Chinese government reported that nearly 60 percent of China’s groundwater is polluted. with 35% of water so low quality that it is not fit for industry, agriculture or human consumption. Yet it is used. There are reports that 10% of the rice produced is contaminated with cadmium.

CONSERVATION

We should concentrate on more efficient use of existing resources:
* Better water sustainable management.
* Pollution control.
* Water reclamation.
* Reducing leakage of agriculture irrigation.
* Collection of rainwater on rooftops and streets.
* Recyling of urban residential waste. This is an imperative for the future. Many countries are experimenting with this problem, The top 5 wastewater treatment plants are:
-USA. Stickney Metropolitan Water Reclamation District of Greater
Chicago produces 5.45 million cubic meters/day, serving
2.4 million people. With an annual budget of $450 million,
it comes to $0.22/cubic meters. This is about 1/2 to
1/3 of the cost of desalination ( see section on Desalination)
-USA Boston 4.8 million cubic meters/day
-USA Detroit 3.48 million cubic meters/day
-China. Shanghai 2.0 million cubic meters/day
-Mexico. Atotonilco plant 2.0 million cubic meters/day.
* Increase the price of water. This has negative effects such as
driving away local industrial developments.
* Upgrading storm water systems.

DESALINATION

As world’s glaciers are melting fast, the drying of aquifers through overpumping and pollution of rivers, the world does not have many options left.

DESALINATION TECHNOLOGY
there are basically 2 principles

* Reverse Osmosis – RO
Sea water is forced across a semi-permeable membrane by applying high pressure with electric pumps. The water diffuses through the membrane while the salts are left behind. This process is electricity intensive, around 3-8 kWh/cubic meter ( = one ton) of water produced. This accounts for 60% of the world’s capacity in 2011
Pumping seawater to pressures of more than 70 kg/ per square cm takes less energy than boiling it—but it is still expensive.

There are new technologies coming on line which are more efficient than standard RO and hence reduce energy cost:
1) Use of nanotechnoloy in the form of graphene membrane will save cost and produce greater efficiency.
2) Use of nanotubes through the membrane. An electric charge at the nanotube mouth repels positively charged salt ions. The uncharged water molecules slip through with little friction, reducing pumping pressure
3) Water molecules pass through channels made of aquaponne proteins that efficiently conduct water in and out of living cells. A positive charge will repel salt molecules near each channels center. Repelling salt.

* Multi-Flash Distillation (MFD) and Multi-Effect distillation(MED)
It is a brute force method needing much energy. This is a simple distillation process where sea water is heated and distilled. It is capable of using waste heat from power plants. This process requires 10 kWh/cubic meter.

Desalination is a great solution for the residential drinking usage problem. But is now becoming widely used for agriculture and industrial uses. However it is energy, mostly electricity, intensive and is therefore an expensive business Both in the capital cost and in the running cost. It is about two to three times as expensive as treating rainwater and waste water.

It energy costs are around 3-10 kWh per cubic meter. But that depends on some variables such as distance transferred of sea water and distance traveled to pump fresh water to the cities. In Israel, for example, 3.5 kWh is needed for electricity of desalination – 1.3 kWh to pump seawater to the plant and 2.2 kWh for the RO desalination process. At the present price of electricity at $0.12/kWh, 3.5 kWh comes to $0.42 /cubic meters. This ia about twice the cost of waste treatment plants. For Multi FlashDistillation systems the cost is even more.

According to International Desalination Association ( IDA), which is world’s most reputable authority on desalination. We get the following figures: By 2013 there are are altogether more than 17,000 desalination plants in the world. The global capacity commissioned as of 2013 is more than 80 million cubic meters per day. So far, water produced is more than 66.5 million cubic meters per day. Most of this goes to industry such as agriculture, electricity generation power plants, refining, oil and gas, mining for coal and metals etc. There are more than 300 million people who rely on desalination for whole or part of their daily use.

The break down by country is :
Country – Commissioned seawater desalination capacity (m³/d)
Saudi Arabia – 9,170,391
UAE – 8,381,299
Spain – 3,781,314
Kuwait – 2,586,761
Algeria – 2,364,055
Australia – 1,823,154
Qatar – 1,780,708
Israel – 1,532,723
China – 1,494,198
Libya – 1,048,424
————————————–
Total = 30 million cubic meters/day

However, if we look at only the largest plants, the figure are roughly half that given by IDA. Of course, the difference comes from small units scattered in the countries.

WORLD’S LARGE NEW DESALINATION PROJECTS

Desalination plants operate in more than 120 countries in the world, including Saudi Arabia, Oman, United Arab Emirates, Spain, Cyprus, Malta, Gibraltar, Cape Verde, Portugal, Greece, Italy, India, China, Japan, and Australia.

Many are just coming on line. The largest are the following:

* SAUDI ARABIA
In Ras Al Khair. it uses a hybrid of RO and MSF technology with a gigantic capacity of 1.025 million cubic meters per day. The construction cost was also a huge $7.2 billion.
Yet another plant is in plan in Rabigh by the Red sea that will have a capacity to make 0.6 million cubic meters.

*UNITED ARAB EMIRATES, UAE
Capacity 4.6 million cubic meters/day. Construction cost $2.7 billion. It is actively pursuing the use of solar energy.

*AUSTRALIA
With its long standing drought, it generates combined 1.45 million cubic meters/day with 6 plants using RO technology and some renewable energy from wind. In total, allowing for small plants, the capacity is around 2.2 million cubic meters/day

* SPAIN
It has 40 years of history in desalination and is actively selling its expertise around the world. It has 900 small desalination plants producing a total of 1.5 million cubic meters/day. In project is a plan to produce 1.7 million cubic meters/day, using where possible renewable energy

* CHINA
Currently production is 0.75 million cubic meters/day. It is building a 3 million cubic meters/day RO plant to supply Beijing by 2020. The construction plant will cost $1.1 billion . But the pipeline to Beijing will cost an additional $1.6 billion.

* ISRAEL
Sorek was built in 2013 with a output capacity of 0.627 million cubic meters per day. By 2016, some 50 percent of the country’s water is expected to come from desalination. It uses highly efficient much improved RO membranes so it saves energy. Construction cost: $400 million.

* ALGERIA
Has a large desalination plant using RO producing 0.5 million cubic meters/day.

* USA
In Carlsbad, San Diego, California To open in 2016 using RO. Will produce 0.19 million cubic meters per day at a capital cost of $ 1 billion.

DESALINATION IN CHINA

In China, about 400 cities face serious water shortage problems. It has 112 seawater desalination plants in 2014, which could produce 0.93 million cubic meters/day, according to the State Oceanic Administration. The government aims to quadruple its seawater desalination capacity to 3.6 million cubic meters/day by 2020.

Key industrial sectors such as thermal/nuclear power plants, steel and metal production plants, or centralized industrial parks take up more than 90% of the overall desalinated water in China

A 100,000 cubic meter/day seawater RO plant supplied by Abengoa of Spain started operating early in 2013 at Qingdao in Shandong province. Another project is for a 330,000 cubic meter/day plant near Daya Bay.

A 50,000 cubic meter/day Aqualyng plant was completed in October 2011 at Caofeidian on Bohai Bay in Hebei province, and a second stage doubled this in 2012. The Hong Kong based Beijing Enterprises Water Group (BEWG) with Aqualyng is building a 1 million cubic meter/day RO plant at Caofeidian for RMB 7 billion($ 1.06 billion) to supply Beijing through a 270 km pipeline by 2019, providing water for 1/3 of its residents. A 3 million cubic meter/day plant is planned to expand this to supply the capital. The pipeline, itself a major part of the project, will cost about RMB 10 billion($ 1.5 billion), and supply desalinated water at RMB 8 ($ 1.22) /cubic meter.

In March 2013 the National Development and Reform Commission announced new plans for seawater desalination, including for the cities of Shenzhen and Zhoushan, Luxixiang Island in Zhejiang Province, Binhai New Area in Tianjin, Bohai New Area in Hebei, and several industrial parks and companies. The cost is likely to be some RMB 21 billion ($3.2 billion). China aims to produce 2.2 million cubic meter/day of desalinated water by 2015, more than three times the 2011 level. More than half of the freshwater is channelled to islands and more than 15% of water delivered to coastal factories will come from the sea by 2015, according to the plan. This plan will have an investment cost around $21 billion RMB ( $3.35 billion).

A 300,000 cubic meter/day seawater desalination plant at Tianjin is under construction and will be the first zero-liquid discharge (ZLD) plant in the world. The freshwater is due to supply petrochemical plants from 2017.

NUCLEAR DESALINATION

We point out here a fast growing resource – nuclear desalination- which has high potentials that will last throughout the 21st century. Its advantage is it does not emit Green House Gases GHG. And its price is very competitive with water generated from other fuels – especially coal.

The affordability question all boils down to the cost of energy. Since coal power stations produce too much GHG and are out of favor. China is turning to nuclear power stations and there is much research on the project of building 50 thorium molten salt reactors which are safer and economical than standard plutonium reactors.

Large-scale deployment of nuclear desalination on a commercial basis will depend primarily on economic factors. Indicative costs are US$ 70-90 cents per cubic meter, much the same as fossil fuel plants in the same areas.

China is looking at the feasibility of a nuclear seawater desalination plant in the Yantai area of Shandong Peninsula, producing 80,000-160,000 cubic meter/day by MED ( Multi-Effect Distillation) process, using a 200 MWt NHR-200 reactor.

COMPARISON OF DESALINATION COSTS FOR DIFFERENT FUELS
Following are just some typical values.

A B C D E F
—————————————————————————————————-
coal $4 billion 400,000 $3 (RO) 0 6 million tons
$22(MFD)
natural gas $3 billion 400,000 $7.30 0 3 million tons

Wind $6 billion 45,000 $12.50 0 carbon credit

nuclear $3 billion 400,000 $0.5-1.0 (RO) 700 MWe carbon credit
$1.5 (MED)
—————————————————————————————————-
A= Nature of plant. Capacity 1100 MWe
B= Approximate cost of plant
C= Water produced in cubic meters/day
D= Water price / cubic meters including cost of fuel
E= Additional energy output
F= Yearly GHG emission

As can be seen from the table. nuclear desalination is very price competitive as well as having advantages of not using fossil fuel.

COGENERATION

For cogeneration we can use power stations fueled by thermal power plants or nuclear reactors

Lack of freshwater along the many coastal cities of China makes it very suitable for the installation of small and medium sized reactors for cogeneration. The hot water from the final cooling system is used to drive turbines for electricity generation. The low pressure steam from the turbines is then used for desalination. The beauty of the cogeneration setup is when the grid is busy, reactor is used for generating electricity. When the grid demand is low at night, it switches to desalination. so there is no waste energy

An IAEA preliminary feasibility study on nuclear desalination in Algeria was published in 2015 for Skikda on the Mediterranean coast, using cogeneration. The nuclear energy option was very competitive compared with fossil fuels.
WORLD COGENERATION EXPERIENCE WITH NUCLEAR POWER
The feasibility of integrated cogeneration nuclear desalination plants has been proven with over 150 reactor-years of experience, chiefly in Kazakhstan, India and Japan.
*Kazakhstan
The BN-350 fast reactor at Aktau, successfully supplied up to 135 MWe of electric power while producing 80,000 cubic meter/day of potable water over some 27 years, about 60% of its power being used for heat and desalination. It established the feasibility and reliability of such cogeneration plants. (In fact, oil/gas boilers were used in conjunction with it, and total desalination capacity through ten MED units was 120,000 cubic meters/day.)
*Japan
some 10 desalination facilities linked to pressurized water reactors operating for electricity production yield some 14,000 cubic meter/day of potable water, and over 100 reactor-years of experience have accrued.

*India
It has been engaged in desalination research since the 1970s. In 2002 a demonstration plant coupled to twin 170 MWe nuclear power reactors (PHWR) was set up at the Madras Atomic Power Station, Kalpakkam. This hybrid Nuclear Desalination Demonstration Project (NDDP) comprises a reverse osmosis (RO) unit with 1800 cubic meters/day capacity and a multi-stage flash (MSF) plant unit of 4500 cubic meter/day costing about 25% more. This is the largest nuclear desalination plant based on hybrid MSF-RO technology using low-pressure steam and seawater from a nuclear power station. They incur a 4 MWe loss in power from the plant.
A low temperature (LTE) nuclear desalination plant uses waste heat from the nuclear research reactor at Trombay has operated since about 2004 to supply make-up water in the reactor.
*Pakistan
In 2010 commissioned a 4800 cubic meter/day MED desalination plant, coupled to the Karachi Nuclear Power Plant (KANUPP, a 125 MWe PHWR) though in 2014. It has been operating a 454 cubic meter/day RO plant for its own cooling.
*China
General Nuclear Power (CGN) has commissioned a 10,080 cubic meter/day seawater desalination plant using waste heat to desalinate and provide cooling water at its new Hongyanhe project at Dalian in the northeast Liaoning province.
* Much relevant experience comes from nuclear plants in Russia, Eastern Europe and Canada where district heating is a by-product.

CONCLUSION
As the global population is fast growing, water scarcity is becoming more and more acute. How will 9 billion people in 2050 manage with so little water which is already present with us today? Conservation, in particular recycling of urban waste water is imperative. Desalination is expensive and energy intensive. But more countries are now building large desalination plants not just for drinking water but for irrigation in agriculture and for industrial uses like mining for coal which is water intensive. In China, pollution control is number one priority. Both in air pollution leading to acid rain, and pollution in the water system – dumping of waste in rivers for example. Nuclear cogeneration of fresh water using improved new RO technique is for our future. However, we must not forget that the world’s energy resources are NOT limitless.

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