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Canal schemes for co-generation
The best aspects of two types of projects - the regional approach with emphasis on international economic cooperation, and the comparatively safe and clean energy applications of the Med-Dead (Mediterranean-Dead Sea; MDS) Canal or the Red-Dead (Red Sea-Dead Sea) Canal - might be combined, integrated with new co-generation technology, and expanded for a new hybrid project for water and power. The project could also be incorporated into a badly needed regional water development plan for the Middle East, in particular to supply fresh and safe drinking water in the region.
The core of the complex might be either a Med-Dead or a Red-Dead Canal (see fig. 11.1), with a new emphasis on reverse osmosis desalination fuelled by direct hydro-pressure in a topographical head difference. In contrast to earlier plans, which focused on power generation and unilateral development, a new approach would make available, in sparsely populated areas, power and water for fish ponds, industry, and even recreation on artificial lakes, to the benefit of populations from Egypt, Israel, Jordan, Gaza, and the West Bank. The scope of the project could expand, depending on cost, financing, and which of the countries and territories of the region were to be involved; greater benefits would accrue with larger-scale involvement. Either way, the focus on water, rather than power, and an emphasis on cooperative regional development instead of unilateral benefits, could add both the economic and the political viability that earlier plans lacked.
Fig. 11.1 Map of Med/Red-Dead Sea canals and Peace Drainage Canal
The original Med-Dead salt-water canal would have been sited in a particularly favourable position to foster regional cooperation. The intake would have been located in or near the Gaza Strip, which is the site of some of the most squalid and densely populated refugee camps in the world, as well as of severe groundwater overdraft. The Canal itself would have run parallel to the Egyptian-Israeli border and then into the Negev and Sinai deserts. A Red-Dead route would provide similar opportunities for Jordanians and Israelis.
The Med-Dead route and the Red-Dead route would each face obvious obstacles in terms of political viability, as have all plans for regional cooperation. The Mediterranean (Gaza)-Dead Sea Canal was revived in the "Declaration of Principles" on 13 September 1993, in which the Annex on the Protocol on Israeli-Palestinian cooperation concerning regional development programmes suggests as a priority the techno-political project of the Med-Dead Canal.
The 400 m drop at the Dead Sea could be used not only for hydropower generation but also for reverse osmosis desalination. This single pressure of 40-60 kg/cm2 would be directly used to convert sea water for drinking purposes at a reasonable treatment cost of less than US$1/m3. The topography and geology of the Red-Dead route do not favour the combination of hydropower generation with a reverse osmosis desalination plant in a single-pressure pipeline system that requires terminal end pressure of 40-60 kg/m2. The Med-Dead conduit route (Gaza-Masada), on the other hand, is ideal for adding a reverse osmosis desalination plant at the end of the pressure pipeline system on the existing design.
Co-generation refers to the use of waste heat from a conventional (oil or coal) energy-producing plant for the desalination of sea water. The co-generation scheme was first conceived to provide both hydroelectricity and fresh water from reverse osmosis sea-water desalination plants in the early 1980s (Glueckstern, 1982). The use of a part of the hydro potential to make reverse osmosis desalination cost-effective was shelved, however, owing to high costs and a poor understanding of membrane technologies at the time (WPDC, 1980, 1983).
Discussion of the MDS in the early 1980s might not have sufficiently emphasized the idea of shared resources and the benefit of joint development, given political limitations at the time. Indeed, until now, there had been no attempt at comprehensive development of the Jordan River system, which includes the linkage of MDS and the Al-Wuheda dam on the Yarmouk tributary. This new co-generation approach to the MDS scheme thus takes into account both recent innovative developments in membrane technology for reverse osmosis (RO) desalination, which aim to save energy and to make reverse osmosis desalination more cost-effective, and recent changes in the Middle East political situation following the Gulf War in March 1992, the Israel-PLO Declaration of Principles in September 1993, and the Jordan-Israel Treaty of Peace in October 1994, which may make comprehensive basin development not only technically and financially feasible but politically desirable and, indeed, urgent.
Hydro-powered sea-water reverse osmosis desalination for co-generation would exploit the elevation difference of 400 m between the Mediterranean and the Dead Sea (see figs. 11.1 and 11.2). The Dead Sea water level would be maintained at a steady-state level with some seasonal fluctuations of about 2 metres to sustain the seawater level between 402 m and 390.5 m below mean sealevel, during which inflow into the Dead Sea should balance evaporation.
The bilateral (or trilateral) development plan of the Israel/Palestine (Jordan) Mediterranean-Dead Sea conduit scheme (IJMDS) is a co-generation alternative that would combine a solar-hydro scheme with a hydro-powered sea-water reverse osmosis desalination plant as illustrated in fig. 11.2. The IJMDS scheme would have six major structural components:
- an upstream reservoir (the Mediterranean) at zero sealevel, with essentially an infinite amount of water,
- a sea-water carrier by tunnel, canal, and pipeline, with booster pumping station,
- an upper reservoir and surge shaft at the outlet of the sea-water carrier to allow or regulate the water flow,
- a storage-type hydroelectric unit capable of reverse operation to allow the system to work also as a pumped-storage unit, if required,
- a downstream reservoir (the Dead Sea), at a present surface elevation of approximately 400 m below sealevel,
- a hydro-powered reverse osmosis desalination plant, including a pre-treatment unit, a pressure control unit, the reverse osmosis unit, an energy recovery unit, a post-treatment unit, and regulating reservoirs for distribution.
Fig. 11.2 Schematic profile of MDS canal for co-generation (Note: a. pumped storage alternative)
The theoretical hydro potential to exploit the head difference between the Mediterranean Sea (=0 m) and Dead Sea (= -400 m) by diverting 56.7m3/sec. (1.6 billion m3 per year) of sea water is estimated to be 194 MW. The hydropower plant would produce 1.3 billion kWh per year of electricity with installed capacity of 495 MW assuming peak-power operation. These figures coincide with the plan of the Tahal consultancy company in 1981 (Tahal, 1982).
A booster pumping alternative could be applied to make an effective head difference of 500 m, taking into account the operating water pressure at 50 kg/cm2 and cheap electricity during off-peak periods. The sea-water diversion capacity is estimated to be 50 m3/sec., comprising 39 m3/sec. of intake water for the hydropower unit and 11 m3/sec. of feed water for the desalination unit.
The hydropower unit has a theoretical hydro potential of 160 MW, and it generates 1.2 billion kWh per year of electricity with installed capacity of 480 MW and operating at peak power for 8 hours a day. To produce 100 million cubic meters (MCM) per year of permeate (water filtered through a membrane), the installed capacity of the reverse osmosis plant is estimated to be 322,300 m3/day (with a load factor of 85 per cent; Murakami, 1991, 1993).
Marginal operation of the reverse osmosis system is designed to use the hydro-potential energy in a tunnel conduit (penstock) with 481.5 m of effective head of water for 16 hours a day off-peak (see fig. 11.3). The feedwater requirements to produce 100 MCM per year of permeate with 1,000 mg/litre of total dissolved solids (TDS) are estimated to be 333 MCM per year, assuming a 30 per cent recovery ratio. The brine reject of 233 MCM a year, whose salinity is 57,000 ma/litre of TDS, is then discharged into the Dead Sea (Murakami, 1991, 1993). The energy recovery potential from the brine reject is estimated to be 28,280 kW, assuming 20 per cent of friction loss in the reverse osmosis circuit.
The annual production of electricity from the reverse osmosis brine reject is estimated to be 168 million kWh with a load factor of 68 per cent. The recovered energy (electricity) will be used to supply electricity for the post-treatment process or other purposes to save electricity on the national grid.
Fig. 11.3 Marginal operation of pumped-storage and hydro-powered reverse osmosis desalination (Note: a
. reverse osmosis desalination operating for 16 hours per day)
These estimates of hydra potential are based on conventional equations as shown below:
Pth = 9.8*Ws*Q*He (1)
P = Pth*Ef (2)
Pp = P*(24/8) (3)
Py = 365*24*Gf*P (4)
Per = 9.8*Ws*Qbr*He*(1 - Fro)*Ef, (5)
Pth = theoretical hydra potential (kW)
Ws = specific weight of feed water (= 1.03-1.05)
Q = flow discharge (m3/sec.)
He = effective head of water difference (m)
P = installed capacity (kW)
Ef = synthesized efficiency (= 0.85)
Pp = installed capacity for 8 hours a day of peak operation (kW)
Py = potential power generation (output) per year (kWh)
Gf = generating efficiency (= 0.85)
Per = installed capacity of energy recovery unit (kW)
Qbr = brine reject water from reverse osmosis membrane module (m3/sec.)
Fro = hydraulic friction loss in the reverse osmosis circuit (=0.2or20%)
The project costs of the proposed reverse osmosis unit are preliminarily estimated to be US$389.4 million capital expenditure and US$44.4 million per year for operation and maintenance. The cost estimates are based on 1990 prices, assuming: a plant life of 20 years, a membrane life (replacement) of 3 years, 8 per cent interest during the three years of construction, the exclusion of cost benefits from energy recovery, and the exclusion of the costs of source water and pipeline/distribution (Murakami, 1991, 1993). The unit water cost of hydro-powered sea-water reverse osmosis desalination to produce 100 MCM/yr is estimated to be US$0.63/m3, which is reasonable when compared with international water tariffs and the estimated unit water cost of US$0.85-1.07/m3 in the "Peace Pipeline" project, and/or the estimated unit water cost of US$1.6/m3 by conventional reverse osmosis desalination using electricity to create pressure of 50-60 kg/cm2 (Murakami, 1991,1993).
The Peace Drainage Canal scheme and eco-political decision-making
The lower Jordan system (including the Dead Sea), which is shared by three riparians - Israel, Palestine (West Bank), and Jordan (East Bank) - will be an area of focus to demonstrate the willingness for peace through economic development. The "Peace Drainage Canal" (PDC) scheme, which would salvage brackish water, including saline spring water and irrigation return in the Jordan Valley, is proposed not only to protect the water quality of the lower Jordan mainstream but also to produce new fresh potable water (Murakami and Musiake, 1994). The PDC scheme would have an 85 km drainage canal along the lower Jordan River in either the West Bank or the East Bank, and a brackish water reverse osmosis desalination plant with an installed capacity of 200,000 m3 day at the terminal end of the canal system (fig. 11.4). The reverse osmosis desalination plant would convert useless or harmful saline waters into safe potable water at reasonable cost, taking into account incentives generated by ecopolitical decision-making to share the resources and benefits among the three riparians.
The PDC scheme is being proposed to take into account the following six planning elements with eco-political decision-making initiatives:
1. Water environment. Freshwater quality and the ecosystem of the lower Jordan system would be conserved by diverting the harmful saline water that at present is being wasted in the mainstream, adversely affecting downstream users in Palestine (West Bank) and Jordan (East Bank).
2. Feedwater source. Brackish waters including saline spring water, base flow, and brackish groundwater in the Jordan Valley would be collected from the three riparian states. Israel would salvage saline spring water in Lake Tiberias and in and around Beit She'an. Palestine and Jordan would collect saline spring water, irrigation returnflow, deep percolation, saline groundwater in the shallow sandy aquifer, and brackish groundwater in the Jordan Rift Valley in the deep sandstone aquifer.
3. Joint water management. Diversion intake, infiltration pond, and a dual-purpose well system would be incorporated in a plan to salvage 50-100 MCM of residual winter flows in the lower Jordan system for joint use. The dual-purpose wells would mainly be sunk in the sandy shallow aquifer system. Tubewells that could pump 25-50 MCM per year of brackish groundwater from the deep sandstone aquifer system would be added to supply feed water during the dry season (fig. 11.5).
4. Drainage canal system and reverse osmosis plant. An 85 km drainage canal would collect saline water from Israel, the West Bank, and the East Bank. The canal route would run alongside the lower Jordan mainstream in either the West Bank or the East Bank. The reverse osmosis desalination plant, including a pre-treatment and post-treatment unit, would be installed at the end of the canal system.
5. Water pipeline system. A main waterpipe along the coast of the Dead Sea, to link the major towns of Suwayma, Qumran, Ein Gedi, Ein Bokek, and Al-Mazra'a, would be constructed to share the fresh potable water from the reverse osmosis plant among the three riparian states.
6. Wastewater treatment system and re-use. Wastewater treatment facilities in the major towns would be incorporated not only to re-use treated waste water for tree crops or garden irrigation but also to protect the clean water environment of the Dead Sea.
Fig. 11.4 The Jordan River system and the Peace Drainage Canal
Fig. 11.5 System flow diagram of the Peace Drainage Canal scheme (MCM) (Notes: PDC = Peace Drainage Canal, EGMC = East Ghor Main Canal, INWC = Israel National Water Carrier; a. brackish groundwater in shallow aquifer - summer period; b. brackish groundwater in deep aquifer - drought period; c. allocation of RO permeate in "Treaty of Peace," October 1994. Source: plans in "Treaty of Peace," October 1994, including Adashlya dam, Deganya Gate dam, and RO desalination plant in Israel)
Reverse osmosis desalination
The heart of the Peace Drainage Canal project is the reverse osmosis desalination plant to salvage brackish water. The treatment process includes three phases: pre-treatment, processing, and post-treatment.
Before being desalted, the water will pass through three pre-treatment steps to remove all solids that would quickly clog the expensive desalting membranes if they were not removed. Pre-treating the water will ensure a membrane life of three to five years. As the water flows into the plant, chlorine will be added to prevent the growth of algae and other organisms. The water will then go through a grit sedimentation basin to remove heavy grit, sediment, and suspended sands in the water. The water will also be softened by removing some of the calcium. Lime and ferric sulphate are both used in solid contact reactors. In the last step in the pre-treatment process, dual-media filters will be used to remove any fine particles or organisms remaining in the water.
Reverse osmosis is the separation of one component of a solution from another (in this case, salt from water) by means of pressure exerted on a semi-impermeable plastic membrane. A total of about 6,750 membrane elements inserted into fibreglass pressure vessels will desalt the water. Although the pressure tubes will all be 6 m (20 ft) in length, some membranes will have a diameter of 30 cm (12 in.), while the diameter of others will be 20 cm (8 in.). The element will be made up of a number of sheets rolled into a spiral-wound membrane. The separation of salt is a chemical process as well as a physical diffusion process. The water will be forced through the walls of cellulose acetate or synthesized membranes by applying pressure at about 15-25 kg/cm2, allowing only the freshly desalted water to pass through. This process will filtrate 75 per cent of the feed water and remove about 97 per cent of the salts from it. The fresh water will be forced by the downward pressure toward the centre tube.
Post-treatment and energy recovery
The water, with a salinity level of 300-500 mg per litre of TDS, will then be treated to make it safe for drinking in accordance with WHO standards. The water pressure in the brine reject (25 per cent of the feed water with 10,000 mg/litre salinity) will be used to generate electricity with a 1 MW mini hydropower plant at the end of the reverse osmosis module circuit. After retrieving energy of 6.4 million kWh per year, the brine will be directly released to the Dead Sea, where it will mix with this extremely saline water body (300,000 ma/litre of TDS).
Project costs and the unit water cost
The unit cost of the brackish-water reverse osmosis desalination, including the construction of an 85 km drainage canal, is roughly estimated to be US$0.48/m3. This includes the following four cost elements, assuming a construction period of three years for the reverse osmosis plant and an interest rate of 8 per cent:
- capital cost: US$211,518,000
- design and construction management: US$52,911,000
- financial expenditure: US$68,672,000
- annual operation and maintenance costs: US$20,551,000
The operation and maintenance costs of reverse osmosis desalination would likely be reduced by using less expensive off-peak electricity and by developing low-pressure, high-efficiency membrane modules.
The 75 MCM/yr of water produced from the reverse osmosis plant could be shared equitably among Israel, Palestine, and Jordan (see table 11.1). This water would be mainly used for municipal and industrial water supplies, with the aim of supplying fresh potable water exclusively to the major towns and cities along the shore of the Dead Sea. The Peace Drainage Canal scheme with a reverse osmosis desalination plant and water pipeline system should have the highest priority in a basin-wide master plan for an environmentally sound sustainable water development project to foster peaceful cooperation and regional economic development.
Table 11.1 Inter-state water allocation plans for the Jordan River system (MCM per year)
|Main Plan (1953)||45||774||394||1,213|
|Arab Plan (1954)||35||132||698||182||1,047|
|Cotton Plan (1954)||451||30||575||1,290||2,346||including Litani diversion to Jordan|
|Johnston Plan (1955)|
|Jordan mainstream||22||100||375||497||Israel uses mainstream after Arab states use it|
|East Bank wadis||243||243|
|Treaty of Peace (October 1994)|
|Yarmouk River (Adashiya)||25||45||70||Israel: 13 in summer, 33 in winter; Jordan: remainder|
|Jordan River (Deganya gate)||20||excess||50||Jordan: 20 in summer|
|RO desalination of saline springs in Israel||10||10||20|
|Integrated Joint Plan: Jordan-Palestine-Israel-(Egypt): M. Murakamia|
|Aqaba hybrid pumped-storageb|
|Hydroelectricity (million kWh/yr)||500||500||500||1.5 billion kWh of electricity is shared by the three|
|MDS canal for co-generationc|
|Hydroelectricity (million kWh/yr)||400||400||400||1.2 billion kWh is shared by the riparians with Gaza|
|Peace Drainage Canal with RO desalination||25||25||25||75||Brackish water desalination by RO|
a. Simply assumes an equal allocation of water and electricity. b. Aqaba pumped-storage facilities with hydro-powered desalination plant are situated in the Hashemite Kingdom of Jordan. c. The MDS canal has an retake in Gaza, a conduit in Gaza and Israel, a hydropower station with RO plant in Israel, and a hydro-solar reservoir (Dead Sea) in Jordan, Palestine, and Israel.
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