|Central Eurasian Water Crisis: Caspian, Aral, and Dead Seas (UNU, 1998, 203 pages)|
|Part IV: The Dead Sea|
|11. Alternative strategies in the inter-state regional development of the Jordan Rift Valley|
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.
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.
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.
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).