WATER SUPPLY MANAGEMENT APPROACHES USING RES IN ISLAND,

E. Manoli, D. Assimacopoulos1 and C. A. Karavitis2 National Technical University of Athens, Chemical Engineering Department, Process Analysis and Plant Design Section, 9 Heroon Polytechniou, Zografou Campus, GR-15780, Athens, Greece

ABSTRACT: Desalination powered by Renewable Energy Sources (RES) is presented in order to augment the water supply in the semi-arid region of Rhodes island.. The island of Rhodes was chosen as a case study as it relies mostly on the exploitation of groundwater resources and faces serious water shortage problems due to the aquifers depletion. Alternatives are discussed and compared in contrast to the construction of storage dams so as to meet the urban demand up to the year 2040. Results may indicate that by using also financial incentives and management approaches, desalination powered by RES could be an attractive and environmentally friendly option in an effort to solve problems related to water quantity and quality in semi-arid regions with adequate Renewable Energy potential.

1. INTRODUCTION resources problems. The whole scheme should be incorporated in an overall management framework in an In the South Mediterranean region water is used in an effort to ensure the long term sustainability of the region. unsustainable manner. The South European Mediterranean landscape, as a whole, is ecologically fragile and seriously endangered by prevailing social and economic trends. In 2. THE ISLAND OF RHODES this regard, the future of the region may be threatened by increasing coastal area stress, by expanding differences 2.1 Physiography, Social and Economic Profile between tourist areas and the rural hinterlands, and by the sensitivity between the water and soil equilibrium. Most of The island of Rhodes is located in the SE corner of the the population is concentrated in the coastal zone, and Greece and is one of the largest and most populated of the increasing tourism causes a strong, seasonal water demand. Aegean Islands, with an area of 1400 km2. Thus uneven water demands in both space and time greatly The permanent population of the island was 98,181 increase the cost of making water accessible [1]. A most inhabitants (NSCG, 1991). The most densely populated illustrating example of the above is the island of Rhodes. and urbanized area is the north of the island around the Desalination, compared to more conventional water municipality of Rhodes per se and its coastal suburbs. The supply related interventions, can take an advantageous remaining of the island is mainly rural with decreasing position in terms of economic costs and environmental population density from the north to the south. impacts. Amongst the various desalination techniques, The predominant economic activity is tourism. Reverse Osmosis (RO) has been widely used during the Approximately half of the labour force is occupied with last years. The recent technology advances in the field of tourism related activities, thus strongly contributing to the energy recovery have managed to reduce the specific coastal development schemes and the accompanying energy consumption at 2.0 kWh/m3 for seawater intensive use of water resources. The rural hinterland, desalination [2]. The low energy requirements are expected which has been affected by tourism development to a far to render the particular desalination technology more lesser degree relies still on agriculture and confronts competitive compared to other desalination techniques and serious depopulation problems [3]. conventional interventions. Under these conditions, wind- Despite the fact that agriculture is the second most powered RO desalination units could offer an effective, important economic activity, the local market demand is economic and environmentally friendly solution in water not satisfied, and agricultural products have to be imported stressed areas where adequate wind potential exists. from the mainland. The reasons for such a case as well as The island of Rhodes, presents a unique challenge of a the corresponding declining future trend may be attributed semi-arid region, where shoddy water resources to the lack of capital investments, to the ageing of the rural management and uncontrolled development have led to population and to the shift towards the service sector. severe water shortages and environmental stresses. The island with an excellent wind potential seems ideal for the 2.2 Water Resources Issues implementation of Desalination powered by Renewable Energy Sources in order to confront proliferating water

1 Corresponding author, email: [email protected], Fax: +301-7723155

2 Faculty affiliate, Water Resources Planning of Management. Dep. of Civil Engineering, Colorado State University, Fort Collins, Co.; U.S.A.

The average annual precipitation for the whole island is 586 mm resulting in 753 x 106 m3 of potential water volume from which about 70% is lost to evapotranspiration. From the remaining volume, 108 x 106 m3 (14.4%) and 120 x 106 m3 (15.9%) constitute the infiltration and the surface runoff respectively [5]. Other estimates produce an overall annual average rainfall of 712 mm and a surface runoff coefficient of 0.20 [3]. Urban water supplies in Rhodes are still, solely, obtained from groundwater resources and in most cases do not require treatment other than chlorination to meet the urban water supply sanitation requirements. Water Demand (2000) (MCM) 5.84 to 5.85 2.79 to 5.84 1.46 to 2.79 0.7 to 1.46 , RODOS 0.03 to 0.7

TRIANTA PARADEISION, , Water Demand Distribution , 7.1 , , , , THEOLOGOS, MARITSA , Χ Χ Χ , FANAI , KALYTHIAI , Χ , PSINTHOS Irr igation Springs , Domes tic needs , SALAKOS , DIMYLIA Χ , ARCHIPOLIS , APOLONAΧ , PLATANIA , Χ Figure 2. Water Demand Distribution (2000) , EMPONAS , ARCHANGELOS Χ , MALON Χ Following a moderate scenario for the permanent and AGIOSΧ ISIDOROS, LAERMA , , MASARI , SIANA seasonal population increase, which assumes small and Χ , KALATHOS Χ Χ , MONOLITHOS Χ decreasing growth rates for the highly developed areas, , ISTRIOS , PYLON Apolakia Dam , PROFILIA Χ , , ! urban water demand is expected to reach 25.15 MCM. by Χ , ASKLIPIEION , , ARNITHA , VATION the year 2020 and 32.45 MCM by the year 2040, which

, GENNADION accounts for almost 70% of the total water demand (46.23 Settlements/Towns , MESANAGROS ,

Boreholes MCM). Water demand growth and the need for , Χ Springs LACHANIA sustainability of the water resources point towards the , ! Dams Water Network Main Water Transfer Pipe necessity for the application of water supply policy

Sea Intrusion Front alternatives in an effort to ensure the island’s future economic and social growth. Figure 1. Water Supply Sources 2.3 Water resources management approaches Water supply for irrigation is similarly dependent on groundwater except for the case of the southwest part of In order to delineate alternatives confronting the severe the island where the possibility exists for the use of surface water supply problems in Rhodes island, it is important to water impounded from the Apolakkia storage dam and understand the broader context of Greek water resources reservoir (7.3 MCM/yr). management . The most pressing issue is the existence of The strong dependence on groundwater resources many government departments dealing with water along with the large urban population concentration and problems with compartmentalized and not well- tourist development in the northern part of the island has coordinated activities. Added to this is a water law system led to the depletion and overexploitation of the adjacent which is not responsive to modern issues of an urbanized mostly coastal aquifers. From Figure 1, it can be deduced society and widely scattered, thus permitting overlapping that safe yield has been exceeded in most aquifers in the functions, multiple advisory bodies and insufficiently northern part of the island and in the southern irrigated decentralized management responsibilities through areas. In addition, the sea intrusion front is advancing or regional organizations [4]. The most striking element so as seriously threatening the groundwater resources. A to describe the state of water resources management foreseeable increase in water demand and the further options in Rhodes, is that a crisis seems imminent development of the tourist sector are expected to aggravate regarding water supplies and their usage. Such a crisis, the situation and they are strongly eliciting the need for the present also in other similar parts of the world, may be implementation of integrated water resources management demarcated by the following: (a) the annual fluctuation of efforts. water supply exacerbated by periodic droughts or floods; The total water demand for the year 2000 has been (b) the rapid water consumption increase and highly estimated at 32.66 MCM of which 80% is attributed to the consumptive water demands, especially as a result of highly urbanized northern part and the tourist coastal zone dramatic shifts from the rural areas to urban developments; [3]. The remaining 20% refers to the irrigation demand, (c) the trend towards more intensive irrigation needs in the mainly concentrated in the rural southern and central parts remaining agricultural sector; (d) the deterioration of the of the island (Figure 2). water quality, as a result of both water intensive life styles and tourist uses; (e) the decreasing groundwater availability joint with the contamination of most of the aquifers; and (f) the increasing ecosystemic considerations,

including natural changes and the entire gamut of anthropogenic impacts in the surrounding environment. In this regard some guidelines may emerge for a sustainable development of urban water systems. Such guidelines may be demarcated in the following central pivotal principles [5]: (a) The principle of urban water Ρ Ρ management with a full range of tools to address environmental, social and economic considerations; (b) the Ρ principle of policy integration incorporating the Ρ subsidiarity principle with the wider concept of shared Ρ responsibility; (c) the principle of an ecosystemic approach combining the idea of a complex system that is characterised by continuous processes of change and development; and, (d) the principle of cooperation and partnership among the various users groups and stakeholders including community consultation and Ρ Ρ Wind park sites participation. Average Wind Speed Hence, the above mentioned principles may lead to the Ρ 7 m/s formulation of an integrated management framework so to 8 m/s delineate alternative water supply policy options for the island of Rhodes, and by extension to other parts of the Figure 3. Potential Wind Park Sites world facing similar problems, in the next sections.

2.4 Emerging water supply policy options 3. WATER SUPPLY AUGMENTATION RESPONSES

A series of water supply policy options focus on the 3.1 Construction of dams and storage reservoirs development of the potential surface water resources. In this context, Table I presents the water resources balance The UNEP Water Resources Master Plan which has of the island. The significant quantity of surface run-off is been formulated for the island, focuses on the exploitation favourable towards the construction of dam and storage of the surface run-off for the satisfaction of the urban water reservoirs in an effort to satisfy the increasing water supply demand [3]. It proposes the construction of 2 dams and needs. It should be noted that with the exception of the storage reservoirs, in Kritinia and Gadouras areas and the Apolakkia dam, all of the potential surface run-off is use of the existing Apolakkia reservoir for the service of currently lost as outflow to the sea. urban water needs of the neighboring areas (Figure 4).

Table I. Potential water resources balance PPT EVT Run-Off Infiltration , RODOS WS (mm) (MCM) (MCM) (MCM) , , , Χ Χ , , KOSKINOU 1 495 49.6 4.2 11.8 Χ , Χ , , , , , 2 635 41.9 7.1 18.8 , Χ Χ Χ Χ , 3 645 82.3 23.2 20.0 Χ Χ , Χ , , Χ , , Kritinia Χ 4 517 28.7 9.4 0.1 , , 5 585 61.1 20.0 3.4 , Χ Χ, , Gadouras 6 628 189.6 49.4 42.0 , , , 7 489 71.8 6.5 12.4 , , , , , , LINDOS Apolakkia , , Another series of water supply options are Χ , , , concentrated, on alternative sources of water supply , Χ , , Settlements coupled with recently developed technologies and other , Χ Water Supply Solution natural resources exploitation guided by the sustainability Χ Irrigation Supply , Χ concepts. In the regard, the construction of desalination , Proposed Surface Storage Reservoirs Domestic Supply units is examined. Χ Existing Surface Storage Reservoirs Domestic Use Besides conventionally powered desalination, the Agricultural Use excellent wind potential of the island points towards the possibility of coupling reverse osmosis with wind energy. Figure 4. Construction of surface storage reservoirs Figure 3 presents the sites favorable for wind park construction. The presented sites are far from areas of The Gadouras dam with a total annual storage capacity special interest (coastal zone, archaeological sites), near of 30 MCM/yr should cover the urban water demand of the the local electricity grid and with a relative low altitude northern part of the island, the south and the touristic areas (<800 m) in order to ensure easy access. of Lindos and up to 2040. The smaller dam of Kritinia with a capacity of 2.5 MCM/yr will cover the

irrigation and potable water needs of the villages of Kritinia and Emponas. In the proposed scheme, the central Table V. Desalination and wind park costs part of the island and all local irrigation needs will be Desalination Unit 3 3 supplied through the existing boreholes and springs. The Capacity (m /d) Capital Cost O& M Costs (€/m 3 southeast part of the island (the area of the Apolakkia dam) (€/m -d) produced) will rely for urban water supply on the existing dam, which Small (<5000) 1275 0.425 is currently used only for irrigation purposes. Medium (<15000) 1105 0.425 Large (> 15000) 935 0.425 Almost 98% of the total cost will be allocated for the Wind Park construction of Gadouras dam and the related waterworks. General costs (€) Specific O & M Costs The analytical cost estimation for the pertinent dam and Costs (€/WT) (€/WT/yr) reservoir is presented in Table II. 74,000 711,000 17,000

Table II. Cost estimation for Gadouras Dam and Reservoir Figures 5a and 5b present the basic economic indices 6 Cost (10 €) for all supply augmenting options that have been Total Investment Cost 121.771 considered so far. For the estimation the average water Operational Costs (/yr) 3.653 selling price was set at 1.08 €/m3 and an amortization rate Replacement of 0.092 (at 25 yrs) equipment of 4% has been assumed.

Water production cost 3.2 Desalination 1.0 0.9 0.8 Another series of water supply policy options focuses 0.8 on technology alternatives and mainly desalination. In 0.6 contrast to the construction of the Gadouras dam and 0.4 0.4 reservoir two different options are discussed and evaluated: (a) conventional desalination and (b) desalination powered 0.2 by Renewable Energy Sources. 0.0 Gadouras Dam Conventional RES Powered Due to the very low energy requirements and the Desalination Desalination experience in similar units, reverse osmosis (RO) is selected as the optimal desalination process. The overall Benefit to cost ratio energy consumption is estimated at 3.5 kWh/m3 of potable water and the units will be rebuilt in 2016 and 2031. The 2.5 2.0 capacity of the unit for each option ensures that urban 2.0 demand of the target area will be covered up to the year 1.5 1.3 2040 and is presented in Table III. The desalination unit in 1.0 any case is placed near the village of Massari and the 1.0 length of distribution network needed is estimated at 95 0.5 km. 0.0 Gadouras Dam Conventional RES Powered Desalination Desalination Table III. Capacity of desalination unit Year Capacity (m3/d) Figure 5. (a) Water Production Cost (b) Benefit to Cost Ratio for 2001 47300 Gadouras dam, conventional and RES – powered desalination. 2016 58000 2031 66650 As it can be educed from the previous figures, the construction of the proposed surface storage reservoir is As mentioned, energy requirements for the second the most economically attractive option. However, the option will be covered through the exploitation of the local significant evaporation losses and the annual fluctuation of wind potential. The wind turbine selected is Tacke rainfall makes the acquisition of the promised water supply (Nominal Power: 600 kW), with a lifetime of 20 years. The rather difficult. In addition, with a constant storage wind park is proposed to be constructed in the southern capacity, the dam neither can adjust to water demand part of the island, in the greater area of Kattavia village, growth patterns nor respond to unexpected seasonal and the installed power, escalating with the desalination demand fluctuations. The long construction period ( at least unit capacity is presented in Table IV. 5 years) and the environmental impacts in the area of construction are two additional disadvantages. On the other Table IV. Installed power hand, the desalination units can follow water demand Year Installed power (MW) Wind turbines growth. Specifically, desalination powered by RES, as 2001 12.0 20 opposed to conventional desalination, is an attractive 2016 14.4 24 solution in terms of profitability and environmental 2031 16.2 27 impacts. However the realization of one desalination unit in order to meet potable water needs of the entire area can Table V presents the data used for the analytical cost pose significant problems in cases of failure or shutting estimation for both alternatives. Electricity selling and down for maintenance purposes. The high capital and buying prices are equal to 0.044 and 0.066 €/kWh O&M costs of the unit should discourage private respectively. involvement.

In the second scheme (joint venture) the financing 3.3 Small Scale Desalination Units parameters for the private investor are identical. However, the public sector in the form of the local water company, The conclusions of the previous section indicate that assumes 40% of the total capital cost, 50 % of the O&M the construction of smaller desalination units, located near expenses and receives 40% of the water sales. The the demand sites, will present less operational problems. amortization rate is at 10 % for the private investor and at 4 Therefore it is proposed that instead of one, six % for the public company while the water selling price is desalination units are constructed. The spatial distribution estimated at 1.2 €/m3. Table VI and Figure 8 present the of the units is presented in Figure 6 and will be as follows: results for each alternative. • 1 unit for the Northwest coast (Paradeisi- ) Table VI. Water Production Cost (small scale desalination units) Water Production Cost (€/m3 • 1 unit for the Southeast coast (Gennadi – Unit Kattavia) Private Investment (A) Joint Venture (B) Average 0.797 0.812 • 1 unit for the East coast (Lindos area) NW Coast 0.834 0.843 • 3 units for the Northeast coast (Koskinou – East Coast 0.777 0.806 Archangelos) and the capital of Rhodes South Coast 0.723 0.770 North Coast - 1 0.885 0.862 North Coast - 2 0.783 0.796 , RODOS North Coast - 3 0.781 0.795 KREMASTI , PARADEISION , , , , KOSKINOU , Private Investor , , , MARITSA % KALAVARDA , , KALYTHIAI% 29% ,% 30% , ,%AFANTOU 25% 19% 20% , 20% 18% 18%

15% 14% 15% , ARCHANGELOS , LAERMA MASARI 10% , , % 5% , KALATHOS PYLON 0% , Average NW Coast East Coast South Coast North Coast - 1 North Coast - 2 North Coast - 3 ASKLIPIEION , , LINDOS , Joint Venture , Private Investor 34% , Settlements 35% Public Company , GENNADION , Existing Water Netw ork 30%

% 25% LACHANIA Exis ting Electric Grid 22% , 22% 21% 21% , 20% KATTAVIA Desalination Unit 17% % 15% Proposed Water Netw ork 15% Wind Park 10% Figure 6. Spatial Distribution of small scale desalination units 5% 0% Average NW Coast East Coast South Coast North Coast - 1 North Coast - 2 North Coast - 3 Figure 7 presents the total capacity of the units.

Figure 8. Internal Rate of Return (IRR) for small scale

30.0 desalination units

25.0 Due to economies of scale, water production cost is 20.0 higher in the case of small desalination units. However, the 15.0 construction of smaller units, near demand sites, ensures Million m3 10.0 lower network and operational costs. The investment cost

5.0 is lower and private investment risks are almost eliminated. Results indicate that the joint venture scheme seems the 0.0 2001 2016 2031 2040 most attractive option for both the private investor and the North Coast - 1 North Coast - 2 North Coast - 3 NW Coast public company. East Coast South Coast Dam Capacity Demand

Figure 7. Capacity of small scale desalination units 3. CONCLUDING REMARKS

For the cost benefit analysis of the proposed scheme, two different alternatives are evaluated, differing on the Desalination with the use of Renewable Energy degree of involvement of the public sector. Sources can be an attractive solution in cases of arid or In the first scheme (private investor), the investment is semi-arid regions who experience severe water stress a completely private one. The financing for the capital conditions. It offers a reliable water supply which is also costs is as follows adjustable to water demand growth patterns while it is an environmental friendly solution. The further reduction of • Desalination unit: 50 % loan of the total cost, with the specific energy consumption of the Reverse Osmosis an interest rate of 4.5% and a payback period of 9 desalination process is expected to lower significantly years water production costs. • Wind Park: 40 % grant of the total cost

In comparison to centralized solutions, small scale Programme and European Investment Bank (EIB), desalination units, located near demand sites present a Mediterranean Environmental Technical Assistance rather increased water production cost. However with the Program, 1996. MAP Coastal Area Management use of appropriate financing mechanisms and the active Programme “The Island of Rhodes”, Activity: No. 5 involvement of the public sector (joint venture schemes), – Water resources Master Plan, Split, Croatia. financial risk is eliminated, the profitability of the [4] Karavitis, C.A., 1999. ΄΄Drought and Urban Water investments is increased and the option is fully competitive Supplies: the Case of Metropolitan Athens΄΄. Water with conventional supply-side interventions. Policy, Vol. 1, Iss. 5, pp. 505-524, Elsevier Science. [5] European Commission (1996). European Sustainable REFERENCES Cities, Brussels, Belgium.

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