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close this bookCentral Eurasian Water Crisis: Caspian, Aral, and Dead Seas (UNU, 1998, 203 pages)
close this folderPart IV: The Dead Sea
close this folder11. Alternative strategies in the inter-state regional development of the Jordan Rift Valley
View the document(introductory text...)
View the documentIntroduction
View the documentCanal schemes for co-generation
View the documentThe Peace Drainage Canal scheme and eco-political decision-making
View the documentThe Aqaba hybrid scheme
View the documentTechno-political assessment of the Peace Drainage Canal and the Med/Red-Dead Sea canal
View the documentConclusion
View the documentAcknowledgements
View the documentReferences

The Aqaba hybrid scheme

Construction of any new thermal or nuclear power station in the region would benefit from a pumped-storage scheme for efficient off-peak energy use. Hybrid water-energy co-generation is the application of sea-water pumped-storage with reverse osmosis desalination 1993; Murakami and Musiake, 1994). The Aqaba scheme (see fig. 11.6) would pump sea water during off-peak periods to store it in an upper reservoir at the top of an escarpment 600 m above sealevel. The stored sea water would be discharged into a penstock shaft to yield an effective water pressure of 60 kg/cm2 at the end of the pressure pipe system, simultaneously generating 600 MW of peak electricity and producing 100 MCM of fresh potable water (see fig. 11.7). Off-peak electricity to lift the sea water to 600 m above sealevel would be supplied not only from a steam power plant at Aqaba but also from steam power plants in either Egypt or Israel, or from other regional electricity grids.


Fig. 11.6 Aqaba regional development plan with hybrid sea-water pumped-storage scheme for co-generation

Conceptual design

The volume of sea water pumped for co-generation is estimated to be 50 m3/s, comprising 39 m3/sec. for peak power electricity generation and 11 m3/sec. of feed water for reverse osmosis desalination. The theoretical hydro potential to exploit the head difference of 600 m with 39 m3/sec. of pumped sea water is estimated to be 200 MW, assuming a specific weight of sea water of 1.03 and a synthesized efficiency of 0.85. The discharge and installed capacity of the hydropower plant are preliminarily estimated to be 116 m3/sec. and 600 MW, respectively, assuming 8 hours a day of marginal peak operation. The annual power output from the 600 MW plant would amount to 1.5 billion kWh with a generating efficiency of 0.85.

Marginal operation of the reverse osmosis system would make use of the hydro-potential energy in a penstock pipeline with 600 m of head difference for 16-24 hours a day. The feed sea-water requirements for producing 100 MCM of permeate per year (with 5001,000 mg/litre of TDS) are estimated to be 333 MCM, assuming a 30 per cent recovery ratio (70 per cent for brine reject water with 53,000 mg/litre of TDS). The installed capacity of the reverse osmosis unit is estimated to be 322,300 m3/d with a load factor of 85 per cent.

The potential energy recovery from the brine reject is estimated to be 29.5 MW, 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 175 million kWh with a load factor of 68 per cent. The brine would then be discharged into the Dead Sea (Murakami and Musiake, 1994). The recovered energy would be used to supply electricity for the post-treatment process or to other pumps to save electricity on the national grid.


Fig. 11.7 Schematic profile of the Aqaba hybrid sea-water pumped-storage scheme with reverse osmosis desalination

Table 11.2 The major cost elements of the Aqaba hybrid sea-water RO desalination unit (preliminary estimates in 1990 prices)

Major capital cost element (US$)

Pre-treatment

44,195,000

Desalting plant

70,414,000

RO membrane/equipment

84,835,000

Control and operating system

5,952,000

Appurtenant works

27,013,000

Powerline and substation

11,427,000

Energy recovery/turbinea

2,999,000

Sub-total

246,835,000

Design and construction management

62,250,000

Financial expenditure

80,270,000

Total

389,355,000

Major O&M cost element (US$/yr)

Labour

3,718,000

Material supply

1,860,000

Chemicals

7,440,000

Power (pumped-storage for RO feedwater/permeateb)

3,100,000

Membrane replacement

28,269,000

Total

44,387,000

a. Energy recovery unit generates electricity from brine reject water of 233 MCM.
b. Assuming US$0.02/kWh of off-peak electricity tariff for pumping 100 MCM.

Cost estimates and water economy

The cost of a unilateral 600 MW pumped-storage scheme is estimated to be US$1 billion at 1990 prices. The total investment cost of the proposed hydro-powered sea-water reverse osmosis desalination plant is preliminarily estimated to be US$389.4 million 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 annual costs are estimated to be US$18.6 million in financing the major capital cost element and US$44.4 million in operation and maintenance (O&M) elements, as shown in table 11.2.

Water economy is examined by comparing the unilateral pumped-storage scheme and the hybrid pumped-storage scheme with reverse osmosis desalination. The annual benefit of the hybrid scheme is 1.4 times greater than the unilateral scheme, assuming tariffs of US$0.1/kWh of peak electricity and US$1.0/m3 of fresh potable water. The cost and benefit elements are shown in table 11.3.

The unit water cost of hydro-powered sea-water reverse osmosis desalination, which assumes a shadow benefit of using 11 m3/sec. of feed water for the sole purpose of hydroelectricity generation, is estimated to be US$0.69/m3 (= 0.63+0.059). The economy of this method can be seen when it is compared with either US$1.6-2.7/m3 for conventional desalination such as reverse osmosis and multi-stage flush (Murakami 1991, 1995) or unilateral hydropower (see table 11.3).

Method of sharing resources and benefits

The Aqaba hybrid sea-water pumped-storage scheme for co-generation would include the following inter-state cooperation scenarios to share the resources and benefits:

1. An inter-state electricity grid or network that would include Egypt, Israel, Palestine, Jordan, and Saudi Arabia is incorporated in the plan to transfer inexpensive night and morning off-peak electricity to the pumped-storage scheme (buying) and to deliver valuable day and evening peak electricity to neighbouring states (selling).

2. An inter-state water pipeline system connecting three states (Egypt, Israel, and Jordan) along the Aqaba coastline is constructed in order to share fresh potable water from the hydro-powered reverse osmosis desalination plant at Aqaba, Jordan.

3. An inter-state sanitation and water environment management programme, which includes treated wastewater recovery for tree crop and garden irrigation as well as for protecting the clean water environment of Aqaba bay, will be incorporated in the plan. The application of membrane separation technology, including microfilter and/or ultra-filter techniques, will also be adopted in the process of tertiary wastewater treatment for re-use for limited irrigation (Murakami and Musiake 1994; Murakami, 1995).

Fresh potable water amounting to 100 MCM per year from the Aqaba hydro-powered reverse osmosis desalination plant in the pumped-storage scheme could be shared among Jordan (Aqaba), Israel (Eilat), Egypt (Taba), and Saudi Arabia (Haq) in accordance with a possible agreement within the inter-state regional economic development programme (see fig. 11.6). The non-oil-producing state of Jordan, whose national economy is not as strong as those of Israel and Saudi Arabia, would have an exclusive chance to export 100 MCM per year of fresh, potable water. It would also be able to export valuable peak electricity as well as to import cheap off-peak electricity from Israel, Egypt, and Saudi Arabia. The Aqaba hydro-powered sea-water desalination plant would also save 17.5 MCM of fossil groundwater currently being pumped from the Disi aquifer to Aqaba for its municipal water supply (Murakami and Musiake, 1991).

Table 11.3 Cost and benefit elements between unilateral and co-generation schemes (assuming tariffs of US$0.1/kWh of peak electricity and US$1.0/m3 of potable fresh water)


Feed water

Electricity

Permeate

Output/Salea

Project cost

Annual cost element (US$m.)

Type

(MMC/sec)

(million kWh/yr)

(MMC/yr)

(US$m./yr)

(US$m.)

Capital

O&M

Total

Differenceb

Unilateral pumped-storage (for power generation only):

Hydroelectricity

50

1,482

148.2

1,000

50.0

10.0

60.0

88.2


Hybrid pumped-storage with hydro-powered RO desalination:

Hydroelectricity

39

1,156


139.6

905

39.0

10.0

49.0


RO desalination

11

175

100

100.0a

390

18.6

44.4

63.0


Total

50

1,331

100

239.6

1,295

57.6

54.4

112.0

127.6

a. Output/Sale does not include the benefit of energy recovery of 175 million kWh in the RO unit.
b Difference = (Annual output/sale - Annual cost in total).

Inter-state cooperation for joint development and use among the riparian parties (including Jordan, Israel, Egypt, and Saudi Arabia) takes into account the following: efficient use and/or saving of energy or oil, with an initiative for global environment perspectives; a long-term flexible supply of peak electricity and fresh water; and fewer political constraints, with geo-political initiatives, incentives, and favours for Jordan. The pumped-storage facility would pump water up to a higher elevation for storage during off-peak hours and would simultaneously produce fresh water and hydroelectricity whenever demand peaked. This facility would be conceived for initial incorporation into the canal project. The hybrid sea-water pumped-storage scheme for co-generation is at the planning stage, but it will be important to spell out the coordination required, including international cooperation, in the next phase of projects that will also need innovative research including membrane separation technologies.