5.4 Joint Israel/Palestine/Jordan Mediterranean-Dead Sea conduit development with co-generation

A new co-generation method for Israel and Jordan is proposed here, which would produce both electricity and fresh water from the sea by means of a cogeneration system combining solar-hydro power generation and hydropowered RO desalination, based on exploitation of the 400 m elevation difference between the Mediterranean and the Dead Sea.

The co-generation system would produce 500 MW of electricity and 100 million m³ of fresh water per year from the Mediterranean Sea. The benefits would be shared by the riparians, including Gaza. It is assumed that the product of 100 million m³ of fresh water per year would be used exclusively to supply the central Ghor (the Jordan valley, in and around the Dead Sea), where the ground elevation is as low as 210-400 m below sea level.

The application of solar-hydro generation with RO desalination, which is a new type of co-generation system proposed here, is likely to be a key technological development in this region for the strategic objective of saving fossil energy and the global environment.

5.4.1 Background

This particular type of hydroelectric power development, also known as hydrosolar power, is made possible by the existence of a vast depression at a distance not too far from the sea, and the region's characteristically arid climate (with the resulting high degree of evaporation). Two such hydro-solar projects have been studied in depth: the Mediterranean-Qattara canal scheme in Egypt (discussed in section 2.11 above) and the Mediterranean-Dead Sea canal scheme in Israel (fig. 5.4). Both plans would involve an initial development stage during which the basins would be filled with water from the Mediterranean Sea up to a certain design level, which would be maintained thereafter by transfer of water to replace the amount evaporated.

Fig. 5.4 Locations of the Mediterranean-Qattara and Mediterranean-Dead Sea hydro-solar schemes

THE ISRAELI PLAN. Israel announced a feasibility study on a seawater hydroelectric power generation project in 1980, but this had been preceded by pre-feasibility studies over many years before that. The Mediterranean-Dead Sea Canal hydro-power project was designed to exploit the 400 m elevation difference between the Mediterranean Sea 0 m) and the Dead Sea ( - 402 m) by linking the two seas.

Various routes for the conduit to connect the seas were studied (fig. 5.5). The shortest, the central route, would be 72 km long, including a 15-km section of open canal and a 57-km tunnel 5 m in diameter. The first 30-km section would have crossed Israeli territory, and the second 42-km section would traverse the West Bank (occupied Palestine). This option was, however, put aside for fear of possible saline (seawater) water leakage through the tunnel which could contaminate fresh groundwater aquifers in the Judaea mountain range.

Fig. 5.5 Israel-Jordan Mediterranean-Dead Sea hydro-solar scheme project

After considering 27 alternative routes, the Gaza-Ein Bokok route with an 80-km tunnel length was selected in 1982 to minimize the capital cost. That route, however, would cross the occupied Gaza Strip. For political reasons, an alternative route was considered which would move the entrance of the canal northwards into Israeli territory; this would have added US$60 million to the cost and 20 km to the planned 100-km length (WPDC 1980). However, even if political problems in the Gaza Strip could be avoided, they would certainly have been encountered in Jordan, which shares the Dead Sea with Israel and also extracts minerals such as potassium from it. The planned effect of the canal would have been to raise the level of the Dead Sea by 17 m, from 402 to 385 m below sea level. This would have meant that the mineral processing plants in both countries would have had to be moved, and potash production could have fallen by 15% (WPDC 1980).

COST OF THE MDS PROJECT. The Israeli MDS solar-hydro development project with booster pumping would have generated 800 MW of electricity with annual generated electricity of 1.4-1.85 x 10⁹ kWh, assuming a gross water head of 444-472 m and maximum discharge of 200 m³/sec with an annual average flow intake of 1.23-1.67 x 10⁹ m³ (Tahal 1982). The total project cost was estimated to be US$1.89 x 10⁹ (at 1990 prices), assuming a 140% price escalation from 1982 to 1990, with the following major cost elements:

• main tunnel (80.4 km), US$732 million,
• power station (400 MW x 2) US$385 million,
• other facilities and structures, US$310 million,
• design and supervision, etc., US$142 million,
• financial expenditure, US$319 million.

JORDAN'S COUNTER-PROPOSAL. Jordan vied with Israel over the canal power scheme in 1981 by proposing to bring seawater from the Gulf of Aqaba to the Dead Sea. This scheme would also have exploited the 400 m drop between the Gulf of Aqaba and the Dead Sea to generate electricity. Seawater would have been pumped into a series of canals and reservoirs from Aqaba to Gharandal, 85 km further north (fig. 5.5). From there, the water would fall into the Dead Sea to generate about 330 MW for eight hours a day at peak demand (WPDC 1983).

ENVIRONMENTAL PROBLEMS AND POLITICAL CONFLICT. The flow of water from the Jordanian carrier would have forced Israel to cut back its own influx of water into the Dead Sea, or the level would have risen so high as to flood the potash works (of both Israel and Jordan) and the surrounding hotels on the Israeli side. The Mediterranean-Dead Sea hydropower project was then put aside. Israeli interest then turned to seawater pumped-storage from the Dead Sea (WPDC 1989; Gaff and Matson 1984).

It should be noted that a United Nations mission found that the maximum level to have been reached by the Dead Sea would have been-390.5 m, which would not have flooded any religious or archaeological remains, nor would it have triggered earthquakes, as this level was comparable with previous equilibrium levels, and would not increase reflectivity. These studies therefore demonstrated that the project would not have had any adverse environmental effects (WPDC 1983). The possible increased evaporation through the introduction of Mediterranean water as discussed below could indeed have had additional beneficial effects.

DEAD SEA PUMPED-STORAGE SCHEME BY ISRAEL. Israel's Energy Ministry has recently shown renewed interest in a pumped-storage scheme on the Dead Sea, first proposed in the early 1980s but shelved in favor of a similar project proposed for the Sea of Galilee. Power could be produced even more cheaply and efficiently from pumped-storage on the Sea of Galilee in northern Israel, but the project could damage plant and animal life. The interest has therefore shifted back to the Dead Sea because of its almost total absence of flora and fauna. The Dead Sea pumped-storage scheme could produce 400-800 MW, equivalent to 7%-14% of the Israeli national grid's generation capacity of 5,835 MW in 1991. The total production of electricity amounted to 20.8 x 10⁹ kWh in 1991.

CO-GENERATION WITH JOINT DEVELOPMENT: THE opportunity FOR THE FUTURE While Israel's MDS canal scheme was conceived to provide hydroelectric power, it did not offer any solution to the urgent need for fresh water supply (Glueckstern 1982). The use of hydroelectric power to make desalination cost-effective was a consideration of the scheme in the early 1980s, but it was not considered sustainable to use valuable clean energy from hydroelectricity for conventional desalination because the substantial energy losses that would be incurred through conversion and transmission. Discussion of the MDS canal scheme in the early 1980s overlooked the concept of shared resources and the benefit of joint development. Indeed up until 1991 there was no attempt to conceive a comprehensive development plan for the Jordan River system including linkage of the MDS canal and the Al-Wuheda dam on the Yarmouk (Murakami 1991).

The new co-generation approach to the MDS canal scheme proposed here takes into account (1) recent innovative developments in membrane technology for RO desalination which aim to save energy and to make RO desalination more cost-effective and (2) recent changes in the Middle East political situation following the Gulf war that may make comprehensive basin development not only technically and financially feasible but politically desirable and urgent.

5.4.2 Hydrology of the Dead Sea and evaporation from it

The climate of the watershed ranges from "hot arid" in the bottom of the Jordan valley to "Mediterranean semi-arid" in the surrounding highlands. The Dead Sea is a brine water body with the extremely high salinity of 250,000 mg of TDS per litre. It is a closed lake with no outlet except by evaporation, which at present amounts to 1,500-1,600 mm per year (Carder and Neal 1984).

Evaporation from the surface of the saline lake is the key factor in estimating the capacity for generating electricity by solar-hydro development. For the same meteorological inputs and aerodynamic resistance, a decrease in salt concentration will increase evaporation rates and reduce lake temperature, whereas an increase in concentration will have the reverse effect. Increased use of water from the Jordan River, especially for irrigation, has increased salt concentrations, whereas the proposed introduction of Mediterranean Sea water into the Dead Sea via a canal for hydroelectric purposes would reverse this trend (Weiner and Ben-Zvi 1982).

A model analysis to predict the annual evaporation rate and surface temperature as a function of aerodynamic resistance and thermodynamic activities of water (Carder and Neal 1984) assumed that on an annual longterm basis the heat flux into the lake was negligible and that the available energy could be equated to the net radiation calculated from the following parameters for the Dead Sea: air temperature (T) = 23.6°C, vapour pressure of air (e) = 15.9 mbars, saturation vapour pressure of water at temperature T (e_s(T)) = 29.05 mbars, and total available energy (H) = net radiation flux density (R_n) = 146 W-m². The activity of the water in solution (a_w; the a_w of pure water = 1.00) was assumed to have changed from 0.75 before 1958 to 0.71 in the 1980s. If the proposed canal development were completed, the formation of an unmixed Mediterranean water surface layer (a_w = 0.98) overlying the denser Dead Sea water would (possibly on a localized scale in the vicinity of the canal outlet) decrease the surface water salt concentration and raise the a_w values. The model prediction suggests a large increase in the (local) mean annual evaporation rate by 345 mm, from a present 1,563 mm to 1,908 mm, and a marked decrease in surface water temperature of 3.3°C, to 23.4°C. These estimated rates of evaporation are conceived to be conservative and are comparable to those measured at Lake Mead in Arizona, in the United States, which amount to 2,000 mm per year (Sellers 1965).

This study assumes 1,600 mm of mean annual evaporation for present conditions. The evaporation rate after impounding water from the Mediterranean is assumed to be 1,900 mm per year for the cogeneration plan proposed in the following sections.

5.4.3 Co-generation plan: Solar-hydro and hydro-powered reverse osmosis desalination

The proposed solar-hydro development plan would exploit the elevation difference of 400 m between the Mediterranean Sea and Dead Sea. The water in the Dead Sea would be maintained at a steady-state level, with some seasonal fluctuations of about 2 m, between 402 and 390 m below mean sea level, with the inflow into the Dead Sea balancing evaporation.

The Israel/Jordan Mediterranean-Dead Sea conduit plan is a co-generation alternative that would combine solar-hydro and hydro-powered seawater RO desalination (fig. 5.6). It would have the following major components:

>> an upstream reservoir (the Mediterranean) at sea level (0 m), with an essentially unlimited amount of water,

>> a seawater carrier, in tunnel, canal, and pipeline, with a booster pump,

>> an upper reservoir and surge shaft at the outlet of the seawater carrier to allow for regulating the water flow,

>> a storage-type hydroelectric unit capable of reverse operation to allow the system to also work as a pumped-storage unit if required,

>> a downstream reservoir (the Dead Sea), at a present surface elevation of approximately 402 m below sea level,

>> a hydro-powered RO desalination plant, including a pre-treatment unit, a pressure-converter unit, the RO unit, an energy-recovery unit, a posttreatment unit, and regulating reservoirs for distribution.

Fig. 5.6 MDS hydro- solar conduit development alternatives

5.4.4 Estimate of hydro-power

The theoretical hydro-potential to exploit the head difference between the Mediterranean Sea (0 m) and Dead Sea ( - 400 m) by transferring 56.7 m³ of seawater per second (1.6 x 10⁹ m³ per year) is estimated to be 194 MW, or, with an installed capacity for peak-power operation at 495 MW, to provide 1.3 x 10⁹ kWh of electricity per year. Another option for exploiting the gross head at 444-472 m (Tahal 1982) by transferring 43 m³ of seawater per second would have 198 MW of theoretical hydro-potential, or, with an installed capacity for peak-power operation at 505 MW, to provide 1.33 x 10⁹ kWh of electricity per year. These estimates are based on the following conventional equations for theoretical hydro-potential (P_th) and installed capacity (P), both in kW, and potential power generation (W_p) in kWh per year:

P_th = 9.8 x Ws x Q x He,
P= P_th X E_f,
W_p= 365 x 24 x G_f x P.

where

W_s = specific weight of seawater ( = 1.03),
Q = Flow discharge (m³/sec),
H_e = effective difference head of water (m),
E_f = synthesized efficiency (=0.85),
G_f = generating efficiency (=0.30; 8 hours a day of peak operation).

5.4.5 Hydro-powered seawater reverse-osmosis desalination

The co-generation system is an application of seawater RO annexed to a solarhydro-power system requiring eight hours a day of peak operation. Marginal operation of the RO system is designed to use the hydropotential energy in the pipeline-tunnel (penstock) system (481.5 m of differential head of water) for 16 hours a day during the off-peak time. The feed-water requirements to produce 100 million m³ of permeate per year with 1,000 mg of TDS per litre are estimated to be 333 million m³ per year, assuming at least a 30% recovery ratio. The installed capacity is estimated to be 322,300 m³ per day, with a load factor of 85%. The energy recovery from the brine reject is estimated to be 24,000 KW, with annual generation of 134.7 million kWh of electricity, with a load factor of 68%. The recovered energy (electricity) will be used to supply electricity for the post-treatment process or other purposes, as shown in fig. 5.7.

COST ESTIMATES. The total investment cost for the proposed hydropowered seawater RO desalination unit, based on 1990 prices with 8% interest during three years' construction, is preliminarily estimated to be US$389,355,000, with an annual capital cost at US$18,568,000, with the following major elements:

• pre-treatment, US$44,195,000,
• desalting plant, US$70,414,000,
• RO membrane and equipment, US$84,835,000,
• control and operating system, US$5,952,000,
• appurtenant works, US$27,013,000,
• power line and substation, US$11,427,000,
• energy recovery/turbine, US$2,999,000,
• sub-total (US$246,835,000);
• design and construction management, US$62,250,000;
• financial expenditure, US$80,270,000.

The annual cost of operation and maintenance is estimated to be US$44,387,000, with the following major elements:

• labour, US$3,718,000,
• material supply, US$1,860,000,
• chemicals, US$7,440,000,
• power (pumped-storage for RO feed water), US$3,100,000,
• membrane replacement, US$28,269,000.

These cost estimates are based on 1990 prices and the following assumptions:

• plant life, 20 years;
• membrane life (replacement), 3 years;
• cost benefit from energy recovery not included;
• costs for source water and pipeline/distribution not included.

Fig. 5.7 Schematic diagram of a co-generation system for the MDS conduit scheme

Table 5.1 Water and electricity tariffs in six world metropolises

	Water		Electricity
	Yen/montha	US$/m³	Yen/montha	US$/kWh
Tokyo	4,070	1.23	4,962	0.18
New York	746	0.23	12,000	0.44
Los Angeles	4,800	1.45	3,600	0.13
London	2,860	0.87	3,913	0.14
Paris	2,513	0.76	4,700	0.17
Cairo	12,892	3.91	1,055	0.04

Source: LAJ 1989.

a. Japanese yen for 22 m³ of water and 180 kWh of electricity per month.

The unit water cost of the hydro-powered seawater reverse-osmosis desalination for the design annual product water of 100 million m³ is estimated to be US$0.68/m³, which may be reasonable value when compared with international water tariffs, as shown in table 5.1.

The project cost of the Israeli MDS canal for the hydro-power scheme was estimated at US$1.9 x 10⁹ as described in section 5.4.1 above.

5.4.6 Method of sharing and allotment

The Dead Sea surface, which is the source of evaporation for the MDS solar-hydro scheme, is the joint heritage of the riparian states: Israel (300 km², 30%) and Palestine and Jordan (700 km², 70%). The route of the MDS conduit would pass through Palestine (Gaze) (10 km) and Israel (90 km).

The water balance of the Dead Sea for the co-generation scheme to produce 500 MW of electricity and 100 million m³ of fresh water is estimated follows:

• evaporation after impounding seawater, 1,900 million m³,
• seawater intake for MDS hydro-power at steady-state level, 1,220 million m³,
• brine reject water from proposed hydro-powered RO plant, 233 million m³,
• inflow from catchments, 447 million m³.

The riparians, Israel, Palestine, and Jordan, share the resources and must find a way of sharing the benefits. If the cost sharing were to be split fifty-fifty between the riparian states to assure fifty-fifty benefit allotment, project formulation including financing, construction, operation, and maintenance could be done by an international consortium sponsored by an international agency such as the Middle East Development Bank. The possible benefits and their allocation are discussed further in Appendix D.

5.4.7 Remarks

This study of hydro-solar development has been made to test the technical feasibility of exploiting seawater resources by taking into account the distinctive nature of the arid zone hydrology and topography in and around the Dead Sea. Reverse osmosis is the cheapest process for desalination today, but it may not be the optimum solution in the twenty-first century. Further research will be needed to evaluate its technical feasibility, including (1) the actual rate of evaporation from the Dead Sea surface after impounding, (2) the design of materials to avoid corrosion of hydraulic structures from seawater and brine reject water, (3) tunnel-boring-machine methods of construction for the seawater conduit tunnel, (4) application of low-pressuretype (3050 kg/cm²) RO-membrane modules for seawater desalination, (5) an improved energy-recovery system in RO, (6) methods of hybrid desalination, and (7) the potential development of technology for power generation by a solar pond.