Water desalination systems powered by renewable energy sources: Review

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Renewable and Sustainable Energy Reviews 16 (2012) 1537 1556Contents lists available at SciVerse ScienceDirectRenewable and Sustainable Energy Reviewsj ourna l h o mepage: www.elsev ier .com/ locate / rserWater A.M.K. ElEngineering Coa r t i c lArticle history:Received 15 JuReceived in reAccepted 6 NoAvailable onlinKeywords:Renewable enDesalinationSeawater reveMembrane sysThermal systePhotovoltaicSolar collectorSolar stillSolar towerSolar parabolic troughSolar dishContents1. Introd1.1. 1.2. 1.3. 1.4. 1.5. 1.6. 2. Water2.1. 2.2. 3. Renew3.1. 3.2. 3.3. 3.4. Tel.: +966 E-mail add1364-0321/$ doi:10.1016/j.uction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1538Natural water resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1538Water demand and consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1538The need for desalination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1539Desalination and energy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1539Desalination market . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1539Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1539 desalination techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1539Thermal processes (phase change) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15402.1.1. Multistage ash evaporation (MSF) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15402.1.2. Multiple effect boiling (MEB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15412.1.3. Vapour compression (VC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15422.1.4. Freezing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15432.1.5. Solar distillation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1543Membrane processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15452.2.1. Reverse osmosis (RO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15452.2.2. Electro-dialysis (ED) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1546able energy systems (RES) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1546Potential of solar energy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1547Photovoltaic (PV) energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1547Thin-lm photovoltaic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1548Concentrating photovoltaic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1549595188023.ress: amghonemy@yahoo.com see front matter 2011 Elsevier Ltd. All rights reserved.rser.2011.11.002desalination systems powered by renewable energy sources: Review-Ghonemy llege, Al-Jouf University, Saudi Arabia e i n f one 2011vised form 27 October 2011vember 2011e 18 January 2012ergy sources (RES)rse osmosis (SWRO)tems (RO&ED)ms (phase change)sa b s t r a c tWater and energy are two of the most important topics on the international environment and develop-ment agenda. The social and economic health of the modern world depends on sustainable supply of bothenergy and water. Many areas worldwide that suffer from fresh water shortage are increasingly depen-dent on desalination as a highly reliable and non-conventional source of fresh water. So, desalinationmarket has greatly expanded in recent decades and expected to continue in the coming years. The inte-gration of renewable energy resources in desalination and water purication is becoming increasinglyattractive. This is justied by the fact that areas of fresh water shortages have plenty of solar energy andthese technologies have low operating and maintenance costs.The present paper presents a review for the work that has been achieved during the recent yearsin the eld of desalination by renewable energies, with emphasis on technologies and economics. Thereview also includes water sources, demand, availability of potable water and purication methods.A comparative study between different renewable energy technologies powered desalination systemsas well as performance and economics have been done. Finally, some general guidelines are given forselection of desalination and renewable energy systems and the parameters that need to be considered. 2011 Elsevier Ltd. All rights reserved.1538 A.M.K. El-Ghonemy / Renewable and Sustainable Energy Reviews 16 (2012) 1537 15564. Concentrating solar thermal power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15495. Different combination between RES and desalination systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15505.1. Photovoltaic and RO (PV/RO) combination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15505.2. Concentrating solar thermal driven desalination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15515.3. Wind energy and RO (WIND/RO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.4. Hybrid units (PV/wind/batteries/RO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6. Economic analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7. Decision support tool (DST) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8. Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Appendix A. Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .NomenclatureAC alternative currentADS autonomous desalination systemBOE barrel of oil equivalentBW brackish waterBWRO brackish water reverse osmosisCdS compounds of cadmium sulphideCLFR compact linear Fresnel reectorCPC compound parabolic collectorsCTC cylindrical trough collectorCPV concentrating photovoltaicCR concentration ratio is dened as the aperture areadivided by the receiver/absorber area of the collec-torCu2S cuprous sulphideDC direct currentDOD maximum depth of discharge (for batteries)DST decision support tool softwareEL load energyED electro-dialysisER-RO energy recovery reverse osmosis systemsETC evacuated tube collectorFPC at plate collectorGaAs gallium arsenideGCC gulf cooperation councilGOR gain output ratiothe ratio of fresh water output(distillate) to steam.GWp gega watt (as peak load)HFC heliostat eld collectorkW kilowattkWh kilowatt-hourKJC operating company of Kramer Junction, CaliforniaRO reverse osmosis (RO)LFR linear Fresnel reectorLTV long tube vertical (MEB plant)ME multiple effectMEB multiple-effect boilingMEE multiple-effect evaporationMES multiple effect stackMF micro-ltrationMSF multi-stage ashMW megawattNF nanoltrationNREL5 US National Renewable Energy LaboratoryO&M operation and maintenancePPM parts per million (milligram per liter)PR performance ratioPTC parabolic trough collector(PV-RO) photovoltaic-powered reverse osmosis systemPV/RO photovoltaic and RO combinationRE/RORES RO SCA SEGS Si SW SW-RO SWCC TDS UF V VC W WIND/RGreek sym Subscripte p 1. Introdu1.1. NaturaWater isthree-fourtis salt watepoles (in thsupply mostiny 3% of tsnow coveris undergroand rivers twater; lake1.2. Water Man hawater reserculture andby agricultuconsumed wHowevetion explosfresh water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1551 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1553. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1553. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1554. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1555 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1555 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1556renewable energy and reverse osmosis combina-tionsrenewable energy sourcesreverse osmosissolar collector assemblysolar energy generating systemssiliconseawaterseawater reverse osmosisSaline Water Conversion Corporationtotal dissolved solids contained in waterultraltrationvoltvapor compression which can be thermal (TVC) ormechanic (MVC)wattO wind energy and reverse osmosis combinationsbolefciencyseffectivepeakctionl water resources one of the most abundant resources on Earth, coveringhs of the planets surface. About 97% of the Earths waterr in the oceans and 3% is fresh water contained in thee form of ice), ground water, lakes and rivers, whicht of human and animal needs. Nearly, 70% from thishe worlds fresh water is frozen in glaciers, permanent, ice and permafrost. Thirty percent of all fresh waterund, most of it in deep, hard-to-reach aquifers. Lakesogether contain just a little more than 0.25% of all freshs contain most of it [1,2].demand and consumptions been dependent on rivers, lakes and undergroundvoirs for fresh water requirements in domestic life, agri- industry. About 70% of total water consumption is usedre, 20% is used by the industry and only 10% of the waterorldwide is used for household needs [1].r, rapid industrial growth and the worldwide popula-ion have resulted in a large escalation of demand for, both for the household needs and for crops to produceA.M.K. El-Ghonemy / Renewable and Sustainable Energy Reviews 16 (2012) 1537 1556 1539adequate quantities of food. Added to this is the problem of pollu-tion of rivers and lakes by industrial wastes and the large amountsof sewage discharged. In total, water demand doubles every 20years, so the water emergency situation is certainly very alarming[1,2].1.3. The neeThe onlyTheir mainit would bedesalinationDesalinigenerally s(WHO), themillion (ppof the wateseawater noin the formExcess wlems and lato clean orwith total dor less. Thiswill be anal1.4. DesalinIn generof good stantion all humquantities oThe dramatseries of proto energy couse of fossilsources thais that they harmful eftechnologiea viable soluby lack of pand electricnation pilotsuccessfullyare customor geothermexperience bility and codesalinationin terms of tain areas ain the near 1.5. DesalinMany arare increasand non-cohas greatlycontinue exSeawateity worldwifor 23% of incapacity ran. 1. Gjectis papter dable able d, forors, s.ter dter dn berane tion . Theuel s soucity iion omerstagepor nicalat sus is ue tcuatesivelsupptemp andB, va by t to hs at aB ancts. Mraturratenical onlyg an of saline water to fresh water by freezing has always existedre and has been known to man for thousands of years. Ination of water by freezing, fresh water is removed and leave concentrated brine. It is a separation process related to theiquid phase change phenomenon. When the temperature ofwater is reduced to its freezing point, which is a functionity, ice crystals of pure water are formed within the saltn. These ice crystals can be mechanically separated from thetrated solution, washed and re-melted to obtain pure water.d for desalination nearly inexhaustible sources of water are the oceans. drawback, however, is their high salinity. Therefore, attractive to tackle the water-shortage problem with of this water.ze in general means to remove salt from seawater oraline water. According to World Health Organization permissible limit of salinity in water is 500 parts perm) and for special cases up to 1000 ppm, while mostr available on Earth has salinity up to 10,000 ppm, andrmally has salinity in the range of 35,00045,000 ppm of total dissolved salts [1,2].ater salinity causes the problem of taste, stomach prob-xative effects. The purpose of a desalination system is purify brackish water or seawater and supply waterissolved solids within the permissible limit of 500 ppm is accomplished by several desalination methods thatyzed in this paper.ation and energyal, energy is as important as water for the developmentdards of life because it is the force that puts in opera-an activities. Desalination processes require signicantf energy to achieve separation of salts from seawater.ic increase of desalinated water supply will create ablems, the most signicant of which are those relatednsumption and environmental pollution caused by the fuels. Renewable energy systems produce energy fromt are freely available in nature. Their main characteristicare friendly to the environment, i.e. they do not produceuents. Production of fresh water using desalinations driven by renewable energy systems is thought to betion to the water scarcity at remote areas characterizedotable water and conventional energy sources like heatity grid. Worldwide, several renewable energy desali- plants have been installed and the majority has been operated for a number of years. Virtually, all of them designed for specic locations and utilize solar, windal energy to produce fresh water. Operational data andfrom these plants can be utilized to achieve higher relia-st minimization. Although renewable energy powered systems cannot compete with conventional systemsthe cost of water produced, they are applicable in cer-nd are likely to become more widely feasible solutionsfuture.ation marketeas worldwide that suffer from fresh water shortageingly dependent on desalination, as a highly reliablenventional source of fresh water. Desalination market expanded in recent decades and they are expected topanding in the coming years.r desalination is being applied at 58% of installed capac-de, followed by brackish water desalination accountingstalled capacity [1,2]. Fig. 1 outlines the global desaltingked according to feed water sources.Fig1.6. ObThifor warenewrenewbe usecollectenergy2. WaWathat camembdistillasourcefossil-fenergyelectriionizatCommulti-and vamechastages procesbrine dan evasuccessteam imum scalingOn MEenergyis ablestage ithe MEor effetempeis genemechaNotfreezinversionin natudesalinbehindsolidlsaline of salinsolutioconcenlobal installed desalination capacity by feed-water sources [1].veser presents a description of the various methods usedesalination. Special attention is given to the use ofenergy systems in desalination. Among the variousenergy systems, the ones that has been used, or can desalination are reviewed. These include solar thermalolar ponds, photovoltaic, wind turbines and geothermalesalination techniquesesalination can be achieved by different techniques classied under two categories: called as thermal andprocesses. In the thermal processes (phase-change), theof seawater is achieved by utilizing a thermal energy thermal energy may be obtained from a conventionalource, nuclear energy or from a non-conventional solarrce or geothermal energy. In the membrane processes,s used either for driving high-pressure pumps or forf salts contained in the seawater.cial desalination processes based on thermal energy are ash (MSF) distillation, multiple effect boiling (MEB)compression (VC), which could be thermal (TVC) or (MVC). MSF and MEB processes consist of a set ofccessively decreasing temperature and pressure. MSFbased on the generation of vapor from seawater oro a sudden pressure reduction when seawater entersd chamber. The process is repeated stage by stage aty decreasing pressure. This process requires an externally, normally at a temperature around 100 C. The max-erature is limited by the salt concentration to avoid this maximum limits the performance of the process.pors are generated due to the absorption of thermalhe seawater. The steam generated in one stage or effecteat the salt solution in the next stage because the next lower temperature and pressure. The performance ofd MSF processes is proportional to the number of stagesEB plants normally use an external steam supply at ae of about 70 C. On TVC and MVC, after initial vapord from the saline solution, this vapor is thermally orly compressed to generate additional production. distillation processes involve phase change, but alsod humidication/dehumidication processes. The con-1540 A.M.K. El-Ghonemy / Renewable and Sustainable Energy Reviews 16 (2012) 1537 1556Table 1Desalination processes [2].I-Phase-change processes:I-1. Multi-stage ash (MSF)I-2. MultipI-3. VaporI-4. FreeziI-5. HumidI-6. Solar sa. Conveb. Speciac. Cascad. Wick-e. MultipII-MembranII-1. Revera. RO wib. RO wiII-2. ElectrII-3. NanoTherefore, ttion systema refrigeratihumidicatair can be mthe vapor caIn this prochumidity. Tface of whicollected astechnical pthese technincluded inThe otheinvolve phasis (RO) andor shaft powsaline solutthe salt connormally arED also cleaned by tively chargbrackish wtion procesare MSF andity, respectof the thermore than 8processes apresent secSolar enproducing tprocesses obrane procetwo categoname impliduce distillcollection senergy collnation systeequipment either a conor mains elwhereas ining and appcombinatioTable 2The most promising and applicable RESdesalination combinations [2].RES technology Feed water salinity Desalination technologyhermal Seawater Multiple effect boiling (MEB)Seawater Multi-stage ash (MSF)voltaic Seawater Reverse osmosis (RO)Brackish water Reverse osmosis (RO)Brackish water Electrodialysis (ED)energy Seawater Reverse osmosis (RO)Brackish water Reverse osmosis (RO)Seawater Mechanical vapor compression (MVC)ermal Seawater Multiple effect boiling (MEB)g. 2. P opeheatnde of thte prhichmenR [2direc is ussed ierma ther.Multistage ash evaporation (MSF) MSF process is composed of a series of elements called. In each stage, condensing steam is used to preheat theter feed. By fractionating the overall temperature differen-tween the warm source and seawater into a large numberes, the system approaches ideal total latent heat recovery.ion of this system requires pressure gradients in the plant.le effect boiling (MEB) compression (VC)ngication/dehumidicationtills:ntional stillsl stillsded type solar stillstype stillsle-wick-type stillse processesse osmosis (RO):thout energy recoveryth energy recovery (ER-RO)o-dialysis (ED)ltrationhe basic energy input for this method is for the refrigera- [2]. Humidication/dehumidication method also useson system but the principle of operation is different. Theion/dehumidication process is based on the fact thatixed with large quantities of water vapor. Additionally,rrying capability of air increases with temperature [2].ess, seawater is added into an air stream to increase itshen this humid air is directed to a cool coil on the sur-ch water vapor contained in the air is condensed and fresh water. These processes, however, exhibit someroblems which limit their industrial development. Asologies have not yet industrially matured, they are not this paper.r category of industrial desalination processes does notse change but membranes. These are the reverse osmo- electro-dialysis (ED). The rst one requires electricityer to drive the pump that increases the pressure of theion to that required. The required pressure depends oncentration of the resource of saline solution and it isound 70 bar for seawater desalination.requires electricity for the ionization of water which isusing suitable membranes located at the two apposi-ed electrodes. Both of them, RO and ED are used forater desalination, but only RO competes with distilla-ses in seawater desalination. The dominant processes RO, which account for 44 and 42% of worldwide capac-ively [1,2]. The MSF process represents more than 93%mal process production, while RO process represents8% of membrane processes production [2]. All the abovere listed in Table 1 and described in more detail in thetion [18].ergy can be used for seawater desalination either bySolar tPhotoWind GeothFiThelatent time comentsdistillainput wThis diratio, Pto the whichexpres2.1. ThThecesses2.1.1. Thestagesseawatial beof stagOperathe thermal energy required to drive the phase changer by producing electricity required to drive the mem-sses. Solar desalination systems are thus classied intories, i.e. direct and indirect collection systems. As theires, direct collection systems use solar energy to pro-ate directly in the solar collector, whereas in indirectystems, two sub-systems are employed (one for solarection and one for desalination). Conventional desali-ms are similar to solar systems since the same type ofis applied. The prime difference is that in the former,ventional boiler is used to provide the required heatectricity is used to provide the required electric power, the latter, solar energy is applied. The most promis-licable renewable energy systems (RES) desalinationns are shown in Table 2.The principcial installadrop per stA practiFig. 3. The srinciple of operation of the multi-stage ash (MSF) system [2].rating principle of thermal processes entails reusing the of evaporation to preheat the feed while at the samensing steam to produce fresh water. The energy require-ese systems are traditionally dened in terms of units ofoduced per unit mass (kg) of steam or per 2326 kJ heat corresponds to the latent heat of vaporization at 73 C.sional ratio in kg/2326 kJ is known as the performance]. The operating principle of membrane processes leadst production of electricity from solar or wind energy,ed to drive the plant. Energy consumption is usuallyn kWhe/m3 [2].l processes (phase change)mal processes can be subdivided into the following pro-le of operation is shown in Fig. 2 Current commer-tions are designed with 1030 stages (2 C temperatureage).cal cycle representing the MSF process is shown inystem is divided into heat-recovery and heat-rejectionFig. 3. A multi-stage ash (MSF) process plant [2].A.M.K. El-Ghonemy / Renewable and Sustainable Energy Reviews 16 (2012) 1537 1556 1541sections. Seawater is fed through the heat-rejection section, whichrejects thermal energy from the plant and discharges the productand brine at the lowest possible temperature. The feed is thenmixed with a large mass of water, which is re-circulated around theplant. This water then passes through a series of heat exchangersto raise its temperature. The water next enters the solar collectorarray or a conventional brine heater to raise its temperatureto nearly the saturation temperature at the maximum systempressure. The water then enters the rst stage through an oriceand in so doing has its pressure reduced. Since, the water wasat the saturation temperature for a higher pressure, it becomessuperheated and ashes into steam. The vapor produced passesthrough a wire mesh (demister) to remove any entrained brinedroplets and thence into the heat exchanger, where it is condensedand drips into a distillate tray. This process is repeated throughthe plant as both brine and distillate streams ash as they entersubsequent stages, which are at successively lower pressures.In MSF, the number of stages is not tied rigidly to the PR requiredfrom the plant. In practice, the minimum must be slightly greaterthan the PRelevation. Tthe boilingThis is advathe terminincreases ansavings in pMSF is tcapacity. Thcharacteristprecise pretherefore sorunning optively unsuiis used for tMoustafsolar MSF dsisted of a storage andage systemallowed thelow radiatioto be over collection a2.1.2. MultiThe MEBelements, was heating evaporationthrough thesome of theFig. 4. Prito be possibthan that ofsolutions coIn this procjoritthe Mt a la reduith thoue, inect, wion t eith are es, iat suceiveated dowdownre arcombemened onevapsignorm ave vwo t tubshowses conde.h mu the ationtherMES). This is the most appropriate type for solar energy appli- It has a number of advantages, the most important of whichtable operation between virtually 0 and 100% output evensudden changes are made and its ability to follow a varyingsupply without upset [2]. In Fig. 6, a four-effect MES evapora-hown. Seawater is sprayed into the top of the evaporator andds as a thin lm over the horizontally arranged tube bundle effect. In the top (hottest) effect, steam from a steam boiler a solar collector system condenses inside the tubes. Becauseow pressure created in the plant by the vent-ejector system,n seawater lm boils simultaneously on the outside of the, while the maximum is imposed by the boiling-pointhe minimum inter-stage temperature drop must exceed-point elevation for ashing to occur at a nite rate.ntageous because as the number of stages is increased,al temperature difference over the heat exchangersd hence less heat transfer area is required with obviouslant capital cost [2].he most widely used desalination process in terms ofis is due to the simplicity of the process, performanceics and scale control [2]. A disadvantage of MSF is thatssure levels are required in the different stages andme transient time is required to establish the normaleration of the plant. This feature makes the MSF rela-table for solar energy applications unless a storage tankhermal buffering [2].a et al. [8] reported on the performance of a 10 m3/dayesalination system tested in Kuwait. The system con-220 m2 parabolic trough collectors, 7000 L of thermal a 12-stage MSF desalination system. The thermal stor- was used to level off the thermal energy supply and production of fresh water to continue during periods ofn and night-time. The output of the system is reported10 times the output of solar stills for the same solarrea.ple effect boiling (MEB) process shown in Fig. 4 is also composed of a number ofhich are called effects. The steam from one effect is useduid in another effect, which while condensing, causes of a part of the salty solution. The produced steam goes following effect, where, while condensing, it makes other solution evaporate and so on. For this procedurenciple of operation of a multiple-effect boiling (MEB) system [2].the maplant, withoudesign[1,2].As wpassesof thestop effsaturatsteam,boiler,then gothe heand reis repepassestravel Theon the arrangand usof low lm dein the fmay hare of tor longplants condensteam outsidWituse ofevaporAno(MEB-cation.is its swhen steam tor is sdescenin eachor fromof the lthe thiFig. 5. Long tube vertical (LTV) MEB plant [2].le, the heated effect must be kept at a pressure lower the effect from which the heating steam originates. Thendensed by all effects are used to preheat the feed [5].ess, vapor is produced by ashing and by boiling, buty of the distillate is produced by boiling. Unlike an MSFEB process usually operates as a once through systemrge mass of brine re-circulating around the plant. Thisces both pumping requirements and scaling tendenciesthe MSF plant, the incoming brine in the MEB processgh a series of heaters but after passing through the laststead of entering the brine heater, the feed enters thehere the heating steam raises its temperature to theemperature for the effect pressure further amounts ofer from a solar collector system or from a conventionalused to produce evaporation in this effect. The vaporn part, to heat the incoming feed and, in part, to providepply for the second effect, which is at a lower pressures its feed from the brine of the rst effect. This processall the way through (down) the plant. The distillate alson the plant. Both the brine and distillate ash as they the plant due to progressive reduction in pressure [2].e many possible variations of MEB plants, dependinginations of heat-transfer congurations and ow-sheetts used. Early plants were of the submerged tube designly two to three effects. In modern systems, the problemoration rate has been resolved by making use of the thins with the feed liquid distributed on the heating surfaceof a thin lm instead of a deep pool of water. Such plantsertical or horizontal tubes. The vertical tube designsypes: climbing lm, natural and forced circulation typee, vertical (LTV), straight falling lm type. In the LTVn in Fig. 5, the brine boils inside the tubes and the steamoutside. In the horizontal tube, falling-lm design, theenses inside the tube with the brine evaporating on theltiple evaporation, the underlying principle is to makeavailable energy of the leaving streams of a single- process to produce more distillate. type of MEB evaporator is the multiple effect stack type1542 A.M.K. El-Ghonemy / Renewable and Sustainable Energy Reviews 16 (2012) 1537 1556Fig. 6. Schem(MEB-MES) [2tubes, thuscondensingThe seawashing thrpressure. Thof the tubesthe productexternal coThe evapto effect in inside the tis condensewater. Mosbut a smaltreated witwater passuse a little gradually, bproduced frso that it cthe stack. Tof the stackautomaticasuddenly apIt is a oncemation wittypical prodorate as thetype evaporwith solar eUnlike the MSF plant, the performance ratio for an MEB plant ismore rigidly linked to and cannot exceed a limit set by the numberof effects in the plant. For instance, a plant with 13 effects might typ-ave a PR of 10. However, an MSF plant with a PR of 10 could335 stages depending on the design. MSF plants have a max-PR of approximately 13. Normally, the gure is between 6. MEB plants commonly have performance ratios as high as [2]. The main difference between this process and the MSF the steam of each effect just travels to the following effect, it is immediately used for preheating the feed. This processs more complicated circuit equipment than the MSF; on theand, it has the advantage that is suitable for solar energy uti-n because the levels of operating temperature and pressurerium are less critical [2].4-effect MEB plant with a nominal output of 3 m3/h andd with 2672 m2 parabolic trough collectors (PTC) has beented by Kalogirou [2]. The system is installed at the plataformae Almeria in Southern Spain. It also incorporates a 155 m3-cline thermal storage tank. The circulated uid through theollectors is a synthetic oil heat-transfer uid (3M Santotherme performance ratio (PR) obtained by the system varies from10.7, depending on the condition of the evaporator tube- surfaces. The authors estimated that the efciency of the can be increased considerably by recovering the energy when part of the cooling water in the nal condenser isd. Enat puash2 ev Unit optiits praturximatic of the MEB process with the multi effect stack type evaporatorically hhave 1imum and 101214is thatwhererequireother hlizatioequilibA 1couplepresensolar dthermosolar c55). Th9.3 to bundlesystemwastedrejectetion heEl-N1862 mDhabi,for theaffect tempeThe ma]. creating new vapor at a lower temperature than the steam.ater falling to the oor of the rst effect is cooled byough nozzles into the second effect, which is at a lowere vapor made in the rst effect is ducted into the inside in the second effect, where it condenses to form part of. Furthermore, the condensing warm vapor causes theoler seawater lm to boil at the reduced pressure.orationcondensation process is repeated from effectthe plant, creating an almost equal amount of productubes of each effect. The vapor made in the last effectd on the outside of a tube bundle cooled by raw sea-t of the warmer seawater is then returned to the sea,l part is used as feed-water to the plant. After beingh acid to destroy scale forming compounds, the feed-es up the stack through a series of pre-heaters thatof the vapor from each effect to raise its temperatureefore it is sprayed into the top of the plant. The waterom each effect is ashed in a cascade down the plantan be withdrawn in a cool condition at the bottom ofhe concentrated brine is also withdrawn at the bottom. The MES process is completely stable in operation andlly adjusts to changing steam conditions even if they areplied, so it is suitable for load-following applications.-through process that minimizes the risk of scale for-hout incurring a large chemical scale dosing cost. Theuct purity is less than 5 ppm TDS and does not deteri- plant ages. Therefore, the MEB process with the MESator (MEB-MES) appears to be the most suitable for usenergy.mum operabe obtained2.1.3. VapoIn a VC pthe steam fcondensatioused to prostages [17in the rstwhich is at Fig. 7. Schemnation processergy recovery is performed with a double-effect absorp-mp.ar [8] gives details of a MEB-MES system powered withacuated tube collectors. The system is installed in Abued Arab Emirates. A computer program was developedmization of the operating parameters of the plant thaterformance, i.e. the collector area in service, the highe collector set point and the heating water ow rate.um daily distillate production corresponding to the opti-ting conditions was found to be 120 m3/day, which can for 8 months of the year.ur compression (VC)lant, heat recovery is based on raising the pressure ofrom a stage by means of a compressor, see Fig. 7. Then temperature is thus increased and the steam can bevide energy to the same stage it came from or to other]. As in a conventional MEB system, the vapor produced effect is used as the heat input to the second effect,a lower pressure. The vapor produced in the last effectatic diagram of a single stage mechanical vapor compression desali- [1].A.M.K. El-Ghonemy / Renewable and Sustainable Energy Reviews 16 (2012) 1537 1556 1543is then passed to the vapor compressor, where it is compressed andits saturation temperature is raised before it is returned to the rsteffect. The compressor represents the major energy input to thesystem and since the latent heat is effectively recycled around theplant, the pParametout and shounless it is cFurthermments haveengine, andthan enougmaking theVC system operated atVapor cogories: meccompressiosystems emwhereas thproblems a(i) Vapor cleads to(ii) There acapacitiThermalavailable. Ththe relativecondenser hThermalpresented b(1) Operativapor cmance rtwice thplant.(2) The pernumbercompre(3) Energy desalinacomparmulti-e(4) The suball threbecausesystem,defect b(5) Energy numberratio (vtor), or temperaFinally, EVC process (compressoheat exchanwarmed byenters the ethe evaporacompressedTable 3Relative power requirements of desalination processes (assumed conversion ef-ciency of electricity generation of 30% [2]).Process Heat input (kJ/kg of Mechanical power Prime energytill to tt, seFreezs onendart. Frete ancoolebrine is bd lofree lf ofis th the w ice w by ts poswasemovtanepresslter elteer to rela procted iotal [1,2]Solar othor seale teso duere wd cod on pertdiaticontapresnal solar still, which uses the greenhouse effect to evaporateater. It consists of a basin, in which a constant amount ofer is enclosed in a V-shaped glass envelope, see Fig. 8. Theays pass through the glass roof and are absorbed by the black-ottom of the basin. As the water is heated, its vapor pressureased. The resultant water vapor is condensed on the under- the roof and runs down into the troughs, which conduct thed water to the reservoir. The still acts as a heat trap becausef is transparent to the incoming sunlight, but it is opaque torocess has the potential for delivering high PR [2].ric cost estimates and process designs have been carriedw that this type of plant is not particularly convenient,ombined with an MEB system.ore, it appears that the mechanical energy require- to be provided with a primary drive such as a diesel cooling the radiator of such an engine provides moreh heat for the thermal requirements of the process, solar collector system redundant [2]. Therefore, thecan be used in conjunction with an MEB system and periods of low solar radiation or overnight.mpression systems are subdivided into two main cate-hanical vapor compression (MVC) and thermal vaporn (TVC) systems. The mechanical vapor compressionploy a mechanical compressor to compress the vapor,e thermal one utilize a steam jet compressor. The mainssociated with the MVC process are [2]:ontaining brine is carried over into the compressor and corrosion of the compressor blades.re plant-size limitations because of limited compressores. vapor systems are designed for projects, where steam ise required pressure is between 2 and 10 bar and due toly high cost of the steam, a large number of evaporative-eat recovery effects are normally justied. performance and energy analysis of a TVC system isy Hamed et al. [9] and they found that:onal data of a four-effect, low temperature thermalompression desalination plant revealed that perfor-atios of 6.56.8 can be attained. Such ratios are almostose of a conventional four effect boiling desalinationformance ratios of the TVC system increase with the of effects and with the entrainment ratio of the thermo-ssor and decrease with the top brine temperature.analysis reveals that the thermal vapor compressiontion plant (TVC) is the most energy-efcient whened with the mechanical vapor compression (MVC) andffect boiling (MEB) ones.-system most responsible for energy destruction ine desalination systems investigated is the rst effect, of the high temperature of its heat input. In the TVC this amounts to 39%, with the second highest energyeing that of the thermo-compressor, equal to 17%.losses can be signicantly reduced by increasing the of effects and the thermo-compressor entrainmentapor taken from evaporator and compressed by ejec-by decreasing the top brine and rst-effect heat inputtures.ltawil et al. [1] explained simply the basic theory of athat, the input energy is accomplished by a work devicer). Seawater feed is initially heated in a liquid/liquidger by the blow down and product streams and further thermal rejection from the compressor. The feed thenvaporator where it evaporates. The produced vapor intor is then passed to the vapor compressor where it is; its temperature is being raised in this process. It thenMSF MEBVC ED Solar sROER-ROpassedproduc2.1.4. Thias secoing facnucleais pre-waste butaneizes anof salt-one-haslurry withinbed ofcausedscreenbed is then rThe buis comthe meice is mtogethThenationpresenmore twater 2.1.5. Thewater a simpers. Alanywhtion anis basethe proThis rawater A reventiosalty wseawatsuns rened bis increside ofdistillethe rooproduct) input (kWh/m3) cons. (kJ/kg)a294 2.5:4 338.4123 2.2 149.4N/A 8:16 192N/A 12 1442330 0.3 2333.6N/A 5:13 120N/A 4: 6 60he heater/condenser section where it is condensed toe Fig. 7.ing of commonly used freezing methods which use butaney refrigerant. Freezing process is based on the follow-ezing a saline solution causes crystals of pure water tod grow leaving brine concentrate behind. Seawater feedd by heat exchange between the product water and the streams. The feed then enters the freezer where liquidubbled through the seawater feed. The butane vapor-wers the water temperature. This result in formationice crystals in more concentrated brine. Approximately the seawater is frozen into ice crystals. The ice-brineen pumped to a washer-melter where the slurry risesasher and the ice crystals are compacted into a poroushich is removed upward by a slight positive pressurehe brine owing through the bed and outward throughitioned near the middle of the column. The rising icehed with less than 5% of the total product. The ice ised by means of mechanical scrapper into the melter. vapor which contains the heat removed to form the iceed in the primary compressor and then introduced intowhere it condenses on the ice. Heat is given up and thed. The condensed butane and the product water ow descanting unit where the two liquids are separated.tive power requirements for the various types of desali-esses are listed in Tables 3 and 4. It is clear from the datan the table that thermal desalination process requiresenergy than RO processes per unit volume of treated. distillationer non-conventional methods to desalinate brackishwater, is solar distillation. Comparatively, this requireschnology which can be operated by non-skilled work-e to the low maintenance requirement, it can be usedith lesser number of problems. It utilizes the evapora-ndensation processes. The principle of solar distillationthe fact that glass and other transparent materials havey of transmitting incident short-wave solar radiation.on can pass through the glass into the still and heat theined in it [1021].entative example of direct collection systems is the con-1544 A.M.K. El-Ghonemy / Renewable and Sustainable Energy Reviews 16 (2012) 1537 1556Table 4Relative power requirements of desalination processes [1].Process Gain output ratio (GOR) Electric energy. cons. (kWh/m3) Thermal energy Cons. (kWh/m3) Total energy cons. (kWh/m3)MSF 08:12 3.25:3.75 6.75:9.75 10.5:13MED 08:12 2.5:2.9 4.5:6.5 7.4:9MED-TVC 08:14 2:2.5 6.5:12 9:14MVC N/A 9.5:17 N/A 9.5:17BWRO N/A 1:2.5 N/A 1:2.5SWRO N/A 4.5:8.5 N/A 4.5:8.5the infrared radiation emitted by the hot water (greenhouse effect).The roof encloses the entire vapor, prevents losses, and keeps thewind from reaching and cooling the salty water.Fig. 8 shows the various components of a conventional doubleslope symmetrical solar distillation unit (also known as roof typeor greenhouse type solar still). The still consists of an air tight basin,usually constructed out of concrete/cement, galvanized iron sheet(GI) or ber reinforced plastic (FRP) with a top cover of transparentmaterial like glass or plastic. The inner surface of the base known asthe basin liner is blackened to absorb efciently the solar radiationincident on it. There is a provision to collect distillate output at thelower endsthe basin foThe stilling the nig[2]. Design vapor tightnmal insulatstill efcienizing the wglass cover34 L/m2 [1Several aas plastics. portation, ais their shoin Fig. 8 hasolar stills [The clasby many auand mode these are clstills, an exthe basin oequipment energy from[1,2]. If no sstill is knowable in the lstill with passive condenser, double condensing chamber solar still,vertical solar still, conical solar still, inverted absorber solar still andmultiple effect solar still [2].The following other techniques to increase the production ofstills has been recommended as reviewed by Kalogirou [2]:1. using various dyes to enhance performance. These dyes darkenthe water and increase its solar radiation absorptivity. With theuse of blstill outpthese dyreaseasin presime.uid ce thelopi55% i still use tpletens. S coms [2].elopikenees ofethyes aridesr eneve codentle conn thsing ries onsistwn in of top cover. The brackish or saline water is fed insider purication using solar energy.s require frequent ushing, which is usually done dur-ht. Flushing is performed to prevent salt precipitationproblems encountered with solar stills are brine depth,ess of the enclosure, distillate leakage, methods of ther-ion, and cover slope, shape and material [1,2]. A typicalcy, dened as the ratio of the energy utilized in vapor-ater in the still to the solar energy incident on the, is 35% (maximum) and daily still production is about,2].ttempts have been made to use cheaper materials suchThese are less breakable, lighter in weight for trans-nd easier to set up and mount. Their main disadvantagerter life [2]. Many variations of the basic shape shownve been developed to increase the production rates of2]. Some of the most popular ones are shown in Fig. 9.sication of solar distillation systems has been studiedthors [1,2,10,11]. On the basis of various modicationsof operations introduced in conventional solar stills;assied as passive and active. In the case of active solartra-thermal energy by external equipment is fed intof passive solar still for faster evaporation. The externalmay be a collector/concentrator panel, waste thermal any chemical/industrial plant or conventional boileruch external equipment is used then that type of solarn as passive solar still. Different types of solar still avail-iterature are conventional solar stills, single-slope solarwhe2. IncrTheup ta liqredu3. Dev40dardis tocomtitiowhostill4. DevblacpiecpolyedgprovsolaaboEviand thence odecreacategoThis coas shoFig. 8. The basic design of a solar distillation [1].ack napthalamine at a concentration of 1725 ppm, theut could be increased by as much as 29%. The use ofes is safe because evaporation in the still occurs at 60 C, the boiling point of the dye is 180 C.g the production of a still by lining its bed with charcoal.ence of charcoal leads to a marked reduction in start- Capillary action by the charcoal partially immersed inand its reasonably black color and surface roughnesse system thermal inertia.ng a two-basin type solar still. This still provides ancrease in fresh water produced as compared to a stan-, depending on the intensity of solar radiation. The ideawo stills, one on top of the other, the top one being madely from glass or plastic and separated into small par-imilar results were obtained by other two researches,pared the performance of single and double-basin solarng a simple multiple-wick-type solar still in whichd wet jute cloth forms the liquid surface. Jute-cloth increasing lengths were used, separated by thin blacklene sheets resting on foam insulation. Their uppere dipped in a saline water tank, where capillary suction a thin liquid sheet on the cloth, which is evaporated byrgy. The results showed a 4% increase in still efciencynventional stills.y, the distance of the gap between the evaporator traydensing surface (glass cover) has a considerable inu-e performance of a solar still which increases withgap distance. This led to the development of differentf solar stills, namely, the cascaded type solar still [2].s mainly of shallow pools of water arranged in cascade, Fig. 10, covered by a slopping transparent enclosure.Fig. 9. Common designs of solar stills [2].A.M.K. El-Ghonemy / Renewable and Sustainable Energy Reviews 16 (2012) 1537 1556 1545The evaporminum sheThe metradiation, stion, algae affect signiformance owere sugge- Reducing - Reducing - Using re- Using inte- Using bac- Use of dye- Use of cha- Use of ene- Use of spo- Multi-wic- Condensin- Inclined s- IncreasingIt is obsdaily yield oparametersThe genetioned by mthe cost of wthe total carequiremenrequired tofer the watein solar disproduction means the regardless oconditions fnation metcapacity dedistillation sizes. Also, having capaother plantIn concluinitial cost, is a direct coperate. Thimplies thatwhether soavailable neor brackish where wateFig. embr ther.Rever RO ranesllow uens appnto tmenic pre080h a ud is pthe mrane,ainre. Ind briled er en drivthrouo becity ped Rtput brae conne lcal f necerane me dire devernatatmimizemovent ser thFig. 10. Schematic of a cascaded solar still [2].ator tray is usually made of a piece of corrugated alu-et (similar to the one used for roong) painted at black.eorological parameters, namely wind velocity, solarky temperature, ambient temperature, salt concentra-formation on water and mineral layers on basin linercantly the performance of solar stills. For better per-f a conventional solar still, the following modicationssted by various researchers [2]:bottom loss coefcient.water depth in basin/multi-wick solar still.ector.rnal and external condensers.k wall with cotton cloth..rcoal.rgy storage element.nge cubes.k solar still.g cover cooling.olar still. evaporative area.erved that there is about a 1015% change in overallf solar stills due to variations in climatic and operational within the expected range.ral comments about usage of solar stills have been men-any authors as reviewed by Kalogirou [2]. Generally,ater produced in solar distillation systems depends onpital investment to build the plant, the maintenancets, and the amount of water produced. No energy is operate the solar stills unless pumps are used to trans-r from the sea. Thus, the major share of the water costtillation is that of amortization of the capital cost. Therate is proportional to the area of the solar still, whichcost per unit of water produced is nearly the samef the size of the installation. This is in contrast withor fresh water supplies as well as for most other desali-hods, where the capital cost of equipment per unit ofcreases as the capacity increases. This means that solarmay be more attractive than other methods for smallit has been reported that the solar distillation plantscity less than 200 m3/day are more economical thans.sion, solar stills are the cheapest, with respect to their2.2. MThecesses2.2.1. Themembtion, athe invalue ibrine irequireosmotcally 5througthe feeacross membThe rempressurejecteare calSolasourcetricity can alselectripowerThe ouof memand thvery biologifeed ismembOnebeforemarilyan altepre-tre1. Minby r2. Prev3. Lowof all available desalination systems in use today. Thisollection system, which is very easy to construct ande disadvantage of solar stills is the very low yield, which large areas of at ground are required. It is questionablelar stills can be viable unless a cheap, desert-like land isar the sea. However, obtaining fresh water from salinewater with solar stills is useful for arid and remote areas,r supply is available.feed-watThe moreviewed a1. Analysis panels orthe high11. Schematic of a simple reverse osmosis (RO) system [1].ane processesmal processes can be subdivided into the following pro-se osmosis (RO)system depends on the properties of semi-permeable which, when used to separate water from a salt solu-fresh water to pass into the brine compartment underce of osmotic pressure. If a pressure in excess of thislied to the salty solution, fresh water will pass from thehe water compartment. Theoretically, the only energyt is to pump the feed water at a pressure above thessure. In practice, higher pressures must be used, typi- bar, in order to have a sufcient amount of water passnit area of membrane [2]. With reference to Fig. 11,ressurized by a high-pressure pump and made to owembrane surface. Part of this feed passes through the where the majority of the dissolved solids are removed.der, together with the remaining salts, is rejected at high larger plants, it is economically viable to recover thene energy with a suitable brine turbine. Such systemsnergy recovery reverse osmosis (ER-RO) systems.ergy can be used with RO systems as a prime movering the pumps [1] or with the direct production of elec-gh the use of photovoltaic panels [13]. Wind energy used as a prime mover source. As the unit cost of theroduced from photovoltaic cells is high, photovoltaic-O plants are equipped with energy-recovery turbines.of RO systems is about 5001500 L/day per square meterne, depending on the amount of salts in the raw waterdition of the membrane. The membranes are in effectters, and are very sensitive to both biological and non-ouling. To avoid fouling, careful pre-treatment of thessary before it is allowed to come in contact with thesurface.thod used recently for the pre-treatment of seawatercted to RO modules is nana-ltration (NF). NF is pri-loped as a membrane softening process which offersive to chemical softening. The main objectives of NFent are [2]:e particulate and microbial fouling of the RO membranesal of turbidity and bacteria.caling by removal of the hardness ions.e operating pressure of the RO process by reducing theer total dissolved solids (TDS) concentration.st important results obtained by many authors werend summarized as follows [18]:of a system using an RO desalination unit driven by PV from a solarthermal plant. It is concluded that due to cost of the solar equipment the cost of fresh water is1546 A.M.K. El-Ghonemy / Renewable and Sustainable Energy Reviews 16 (2012) 1537 1556Fig. 12. Principle of operation of a reverse osmosis (RO) system [2].about the same as with an RO system operated from the mainpower supply.2. Performing an energy analysis of a 7250 m3/day reverse osmosis(RO) desalination plant in California. The analysis of the systemwas conducted by using actual plant operation data. The RO plantis described in detail, and the energies across the major compo-nents of the plant are calculated and illustrated using energyow diagdistributdestructiwater is throttlinsure dropchamberenergy dthis amoenergy daccounteatively smcalculatethe seconducing abrine strthe pumRO procthe seawategreater thanthe feed thrthe concentas indicatedis spiral wofouling botherally requiFFig. 14. 2.2.2. ElectThis sysinityh mence. bracted ie ionde ime nesitivepermtre gn an mems thaw-sp owd wh.the etersater rly, dmenof leshe prlectrd w elecrente to tlace b will will allow only the passage of negative ions then alternates of high salinity and low salinity will be created betweenropriate membranes. The product water can then be movedhe low salinity region and the brine from the high salinity. Fig. 14 shows the process arrangement.rams in an attempt to assess the energy destructionion. It was found that the primary locations of energyon were the membrane modules in which the salineseparated into the brine and the permeate, and theg valves, where the pressure of liquid is reduced, pres-s through various process components, and the mixing, where the permeate and blend are mixed. The largestestruction occurred in the membrane modules, andunted to 74.1% of the total energy input. The smallestestruction occurred in the mixing chamber. The mixingd for 0.67% of the total energy input and presents a rel-all fraction. The second law efciency of the plant wasd to be 4.3%, which seems to be low. It is shown thatd law of efciency can be increased to 4.9% by intro- pressure exchanger with two throttling valves on theeam, and this saved 19.8 kW of electricity by reducingping power of the incoming saline water.ess is based on what is known as osmotic pressure. Ifr solution is fed to one side of membrane at a pressure the osmotic pressure, the pure water will migrate fromough the membrane to the other side. In the mean timerated brine is extracted from the inlet side of seawater in Figs. 11 and 12. The most used type of membranesund and hollow ne ber. They are very sensitive to biological and non-biological. Therefore RO plants gen-re pre-treatment system.ing salthrougdifferein the separachlorinelectrogo to ththe pocation-the cen[1,2]. Ianion spacering owhichare use20 minAs the wafeed wSimilarequirewater As twith erequireTheDC curmigratIf we pwhichwhichregionthe appfrom tregionig. 13. Principle of operation of electro-dialysis (ED) [2].3. RenewaAll the ed into twenergy is destantly (elehydropowegen derivePrinciple of electro dialysis under constant DC current eld [1].ro-dialysis (ED)tem, shown schematically in Fig. 13, works by reduc- by transferring ions from the feed water compartment,mbranes, under the inuence of an electrical potentialThe process utilizes a dc electric eld to remove salt ionskish water. Saline feed-water contains dissolved saltsnto positively charged sodium and negatively chargeds. These ions will move toward an appositively chargedmersed in the solution, i.e. positive ions (actions) willgative electrode (cathode) and negative ions (anions) to electrode (anode). If special membranes, alternativelyeable and anion-permeable, separate the electrodes,ap between these membranes will be depleted of saltsactual process, a large number of alternating cation andbranes are stacked together, separated by plastic owt allow the passage of water. The streams of alternat-acers are a sequence of diluted and concentrated water in parallel to each other. To prevent scaling, invertersich reverse the polarity of the electric eld every aboutnergy requirements of the system are proportional to salinity, ED is more feasible when the salinity of theis not more than about 6000 PPM of dissolved solids.ue to the low conductivity, which increases the energyts of very pure water, the process is not suitable fors than about 400 PPM of dissolved solids.ocess operates with DC power, solar energy can by usedo dialysis by directly producing the voltage differenceith photovoltaic (PV) panels.tro-dialysis process is based on the fact that when a is passed through an ionic solution, positive ions willhe cathode and negative ions will migrate to the anode.etween the anode and cathode alternately, membranesallow only the passage of positive ions and membranesble energy systems (RES)energy sources we are using today can be classi-o groups; renewable and non-renewable. Renewablerived from natural processes that are replenished con-ctricity and heat generated from solar, wind, ocean,r, biomass, geothermal resources, bio-fuels and hydro-d from renewable resources) [22]. Non-renewableA.M.K. El-Ghonemy / Renewable and Sustainable Energy Reviews 16 (2012) 1537 1556 1547Table 5The annual horizontal solar energy available in some countries [24].Country Annual solar energy (kWh/m2) Peak radiation (W/m2)Yemrn Saudi ArabiaOmanEgypt JordanLibya U.A. EmirateIsrael SyriaMalta MoroccoAlgeria Tunisia energy is ensuch as corenewable esources incThis sectbe used forusable enerment. Thesesolar pondsSolar energcollectors. Suated tube,into imaginand compoToday, trange of MWmercial solain 1979. It cThe secondoutput of 35process heaof 673 K. Thsmall capacor electrica3.1. PotentiEnergy eall electricitthe potentiplants are cThe undlenges will drawbacks.and relative[24]. The folnologies [223.2. PhotovPhotovosunlight envoltaic cellsin a three dAlthough, telectricity, costs for silituring wafebulky and rtypical PV cquerhe coas 1e ras noequial mt proratioV celal, mlectry me singcapsa pan PV pmbecal of theg systovoare mcity. undslliumproddulevoltatly oationn eag, waty of applted t easdalon2170 9402160 9402140 9302050 10302050 10202010 1040s 1980 9101930 10101910 10401900 10401860 9601840 9501750 980ergy sources that cannot replenish in the near futureal, petroleum and natural gas. Renewable and non-nergy sources can be used to produce secondary energyluding electricity and hydrogenion presents a review of the possible systems that can renewable energy collection and transformation intogy, which may be used to power desalination equip- cover solar energy which includes thermal collectors, and photovoltaic, wind energy and geothermal energy.y thermal collectors include stationary and trackingtationary collectors include the at-plate and the evac- whereas concentrating collectors are further dividedg and non-imaging collectors like the parabolic troughund parabolic, respectively.here exist many large solar plants with output in the for producing electricity or process heat. The rst com-r plant was installed in Albuquerque, New Mexico, USA,onsisted of 220 heliostats and had an output of 5 MW. was erected at Barstow, CA, USA, with a total thermal MW. Most of the solar plants produce electricity and/ort for industrial use and they provide superheated steamus, they can provide electricity and/or steam to driveity conventional desalination plants driven by thermall energy [22,23].al of solar energyxperts expect that in the year 2050, over 50% and 80% ofy could be generated by renewable energy [9]. Amongal sources of renewable energy, solar thermal poweronsidered to be one of the most economic.erstanding of each technology and its associated chal-provide a suitable basis to recognize advantages and The Annual horizontal solar energy available (kWh/m2) peak value (W/m2) in some countries is given in Table 5lowing sections will outline various existing solar tech-,23].Bec1839. T1958 w[22]. Thcost wPV minimwithouits opeA Pmaterilight, eaway bfrom aand encalled Theany nuelectritage oexistinPhowhich electricompoand gawhich PV molarger pendenApplic(both olightincapaciPV connecare noA stanoltaic (PV) energyltaic cells are semi-conductor devices, which convertsergy directly to electrical energy. Conventional photo- are made of crystalline silicon that has atoms arrangedimensional array, making it an efcient semiconductor.his material is most commonly used for generation ofit also has associated drawbacks, such as high materialcon, costly processes for purifying silicon and manufac-r, additional processes for assembly of modules and theigid nature of the photovoltaic panels. Fig. 15 depicts aell under illumination [22].the energy stand-aloneteries and cthe systemmodules toFor gridconnect PVthat duringeither be usin ofces, oor can be somore commFig. 15. Photovoltaic cell under illumination [22].el had discovered the photovoltaic effect in selenium innversion efciency of the new silicon cells developed in1% although the cost was prohibitively high ($1000/W)st practical application of solar cells was in space, wheret a barrier as no other source of power is available.pment has no moving parts and as a result requiresaintenance and has a long life. It generates electricityducing emissions of greenhouse or any other gases, andn is virtually silent.l consists of two or more thin layers of semi-conductingost commonly silicon. When the silicon is exposed toical charges are generated and this can be conductedtal contacts as direct current (DC). The electrical outputle cell is small, so multiple cells are connected togetherulated (usually glass covered) to form a module (alsoel).anel is the principle building block of a PV system andr of panels can be connected together to give the desiredutput. This modular structure is a considerable advan- PV system, where further panels can be added to antem as required.ltaic (PV) cells are made of various semiconductors,aterials that are only moderately good conductors ofThe materials most commonly used are silicon (Si) and of cadmium sulphide (CdS), cuprous sulphide (Cu2S), arsenide (GaAs). These cells are packed into modulesuce a specic voltage and current when illuminated.s can be connected in series or in parallel to produceges or currents. Photovoltaic systems can be used inde-r in conjunction with other electrical power sources.s powered by PV systems include communicationsrth and in space), remote power, remote monitoring,ter pumping and battery charging. The global installedphotovoltaic at the end of 2002 was near 2 GWp [22].ications are: either Stand-alone applications or Grid-systems. Standalone PV systems are used in areas thatily accessible or have no access to main electricity.e system is independent of the electricity grid, withproduced normally being stored in batteries. A typical system would consist of PV module or modules, bat-harge controller. An inverter may also be included in to convert the direct current (DC) generated by the PV alternating current (AC) required by normal appliances.-connected systems. Nowadays, it is usual practice to systems to the local electricity network. This means the day, the electricity generated by the PV system caned immediately (which is normal for systems installedther commercial buildings and industrial applications),ld to one of the electricity supply companies (which ison for domestic systems, where the occupier may be1548 A.M.K. El-Ghonemy / Renewable and Sustainable Energy Reviews 16 (2012) 1537 1556out during the day). In the evening, when the solar system is unableto provide the electricity required, power can be bought back fromthe network. In effect, the grid is acting as an energy storage sys-tem, which means the PV system does not need to include batterystorage.For PV sof individusuitable curCommon5080 W eatherefore caround 15entation of Most povolts (V), wtrial proces(120 V in thvert the lowinverters arpower backOther cothe array mneeded to eAttractivno pollutiotechnologythe grounding technolglobal envirinstalled, unbest applicathan $0.1/kto ve timesystems, PVtechnologyOn the otheNovember 2silicon solarretail price watt, from aPV industryHowever, cature rise adevices inteefciency.3.3. Thin-PV thincrystalline, [22,23].Mono-crcrystalline lattice strucadvantage ically arounto produceslightly higMulti-crgrains of mmolten polthen cut intDue to the are cheapertend to be s12%.Amorphous silicon cells are composed of silicon atoms in a thinhomogenous layer rather than a crystal structure. Amorphous sili-con absorbs light more effectively than crystalline silicon, so thecells can be thinner. For this reason, amorphous silicon is also as ated o makhousith tre cfor m coson anive mon isrphory thd tocing lm mater the (Cused theyrocesy typ.tovo harsnts. porsitio atomline)ed Ple-crodues a tiblee wiran 1the mnt apay bees. Nles mally,ratinulateso, aientls ma disee eitteriaal ins evichnot of nce sing ion oystem conguration. The PV array consists of a numberal photovoltaic modules connected together to give arent and voltage output. power modules have a rated power output of aroundch. As an example, a small system of 1.52 kWp mayomprise some 2030 modules covering an area of25 m2, depending on the technology used and the ori-the array with respect to the sun.wer modules deliver direct current (DC) electricity at 12hereas most common household appliances and indus-ses operate with alternating current (AC) at 240 or 415 Ve United States). Therefore, an inverter is used to con- voltage DC to higher voltage AC. Numerous types ofe available, but not all are suitable for use when feeding into the mains supply.mponents in a typical grid-connected PV system areounting structure and the various cables and switchesnsure that the PV generator can be isolated.eness of the PV technology is low maintenance, andn, and has positioned PV to be the preferred power for many remote applications for both space and on. Photovoltaic (PV) technology is expected to be a lead-ogy to solve the issues concerning the energy and theonment due to several advantages of the PV system. Thesubsidized costs, now coming close to $0.2/kWh in thetions while average electric rates from utilities are lessWh [22,23]. Although, photovoltaic electricity is threes more expensive than other conventional grid power is turning into a mainstream. The average cost for PV in 2006 was roughly $710 per peak watt installed [22].r hand, the average module cost is about $4.34/W on009 [22]. The lowest retail price for a multi-crystalline module is $2.48 per watt from a US retailer. The lowestfor a monocrystalline silicon module is also $2.70 pern Asian retailer [9]. Sun Power Corporation, a leader in is currently offers PV modules at 18% peak efciency.limatic effects such as dirt accumulation and temper-s well as aging, which causes a gradual increase of thernal leakage conductance, and consequently lowers thelm photovoltaic lm technology are usually divided into mono-multi-crystalline silicon and amorphous silicon cellsystalline silicon cells are made from very pure mono-silicon. The silicon has a single and continuous crystalture with almost no defects or impurities. The principleof mono-crystalline cells is their high efciency, typ-d 15%, although the manufacturing process required mono-crystalline silicon is complicated, resulting inher costs than other technologies.ystalline silicon cells are produced using numerousono-crystalline silicon. In the manufacturing process,ycrystalline silicon is cast into ingots; these ingots areo very thin wafers and assembled into complete cells.simpler manufacturing process, multi-crystalline cells to produce than mono-crystalline ones. However, theylightly less efcient, with average efciencies of aroundknowndeposiwhichAmorpcells, wtherefosuited and lowof silicattract1. Silic2. Amoa vepareredu3. ThinportOthtelluridbeing is thattrial pyet thesiliconPhosuch aronmehave imcompoThecrystalproducin singA mprovidsuscepdelicatless thing on differeules mclimatroof-tiUsuan opeencapsrial. AlconvenCelindiumbecomPV mamateriIt ilm teamouncell. Siogy, usreduct thin lm PV technology. Amorphous silicon can ben a wide range of substrates, both rigid and exible,es it ideal for curved surfaces and fold-away modules. cells are, however, less efcient than crystalline basedypical efciencies of around 6%, but they are easier andheaper to produce. Their low cost makes them ideallyany applications, where high efciency is not requiredt is important. Amorphous silicon (a-Si) is a glassy alloyd hydrogen (about 10%). Several properties make it anaterial for thin-lm solar cells: abundant and environmentally safe.us silicon absorbs sunlight extremely well, so that onlyin active solar cell layer is required (about 1 mm as com- 100 mm or so for crystalline solar cells), thus greatly solar-cell material requirements.s of a-Si can be deposited directly on inexpensive sup-erials such as glass, sheet steel, or plastic foil.in lms which are promising materials such as cadmiumdTe) and copper indium diselenide (Cu In Se2) are now for PV modules. The attraction of these technologies can be manufactured by relatively inexpensive indus-ses, in comparison to crystalline silicon technologies,ically offer higher module efciencies than amorphousltaic panels or modules are designed for outdoor use inh conditions as marine, tropic, arctic, and desert envi-The choice of the photovoltaically active material cantant effects on system design and performance. Both then of the material and its atomic structure are inuential.ic structure of a PV cell can be single-crystal (mono-, multi-crystalline, or amorphous. The most commonlyV material is crystalline silicon, either polycrystalline orystals.le is a collection of PV cells that protects the cells andusable operating voltage. PV cells can be fragile and to corrosion by humidity or ngerprints and can havee leads. Also, the operating voltage of a single PV cell is V, making it unusable for many applications. Depend-anufacturer and the type of PV material, modules havepearances and performance characteristics. Also, mod- designed for specic conditions, such as hot and humidowadays, the panels come in a variety of shapes likeade from amorphous silicon solar cells. the cells are series-connected to other cells to produceg voltage around 1416 V. These strings of cells are thend with a polymer, a front glass cover, and a back mate- junction box is attached at the back of the module for wiring to other modules or other electrical equipment.de of amorphous silicon, cadmium telluride, or copperlenide are manufactured on large pieces of material thather the front or the back of the module. A large area ofl is divided into smaller cells by scribing or cutting theto electrically isolated cells.dent that since the past 1520 years various thin-logies have been under development for reducing thelight absorbing material required in producing a solarilicon is the key contributor to the cost of PV technol-less silicon will have a considerable effect on the costf the PV technology.A.M.K. El-Ghonemy / Renewable and Sustainable Energy Reviews 16 (2012) 1537 1556 1549Conversion efciency is one major metric for solar material,which represents how much of the suns energy the material canconvert into electricity. Today, the laboratory efciency of theamorphous silicon (a-Si) is 12.3%, cadmium telluride (CdTe) is 16.5%and copper indium gallium selenide (CIGS) is 19.9% [22,23].Advantages of Thin Film Technologies over Conventional Crys-talline Silicon are lower cost of production than conventionalsilicon processes, lower production facility cost per watt, use offar less material, as little as 1/500th the amount used in standardsilicon cells, and lower energy payback. It also produces more use-able power per rated watt, provides superior performance in hotand overcast climates, has the ability to be attractively integratedinto buildings and produces the lowest cost of power. The thin-lmmodule manufacturing cost decreased to 98 cents per watt, break-ing the $1 per watt price barrier [22,23]. Although, thin-lm cellsare not as efcient as conventional crystalline silicon-especially asthey are not used in tandem devices, it is believed that thin-lmwill be a dominant PV technology in the future. Many also believethat, the likelihood of signicant reduction of module cost has manyopportunities to increase the efciency that surely will reduce theoverall cost of thin-lm technology.3.4. Concentrating photovoltaicConcentlenses or mvoltaic cellsin the samdoes The atttechnologying most oreduce the will improvshown in FiConcentadvantages(a) Potentia(b) No mov(c) No inter(d) Near-am(e) No ther(f) Reducti(g) ScalabilFig. 16. A consilicon cells [2Despite the advantages of CPV technologies, their applicationhas been limited by the complexity and due to the cost of focusing,tracking and cooling equipment; it is now only reaching com-mercial viability. Even if using expensive cells, a CPV system withconcentration ratio of 500 (or 500 suns) generally uses 1/500, theamount of PV cell surface area as does conventional PV. So theprice of the PV cell constitutes a smaller cost consideration forCPV. Energy Innovations and SolFocus are two leading companiespursuing serious research efforts in CPV technology. SolFocus Com-pany offered the cost of its Gen1 CPV system to become as low as$1/W at 1 GW production level [9]. Further, SolFocus Gen2 systemsare expected to achieve 26% efciency and a record cost less than$0.50/W [22,23].4. Concentrating solar thermal powerConcentrating solar thermal power plants have the capabilityfor thermal energy storage and alternative hybrid operation withfossil or bio-fuels, allowing them to provide rm power capacity ondemand. The core element is a eld of large mirrors reecting thecaptured sun rays to a small receiver element, thus concentratingthe solar radiation intensity by 80 to several 100 times and pro-ducing high temperature heat at several 100 to over 1000 C. Thisheat can be either used directly in a thermal power cycle based onturbines, gas turbines or Stirling engines, or stored in moltenncrete or phase-change material to be delivered later to the cycle for night-time operation [33]. principle of operation of a concentrating solar collector andP plant is drafted in Figs. 17 and 18, showing the option fored generation of heat and power. use of a simple power cycle for electricity generation onlyurse also possible. From the point of view of a grid operator,Princiicity arating photovoltaic (CPV) systems uses a large area ofirrors to focus a large area of sunlight on a small photo-, which converts sunlight energy into electrical energye way that the conventional photovoltaic technologyractiveness of the CPV technology over the standard PV is that it uses less semi-conducting material by replac-f the PV cell area with a set of reectors in order tocost. Additionally, increasing the concentration ratioe the performance of general photovoltaic materials asg. 16.rating photovoltaic technology offers the following [9]:l for solar cell efciencies greater than 40%.ing parts.vening heat transfer surface.bient temperature operation.mal mass and a fast response.on in the cost of cells relative to optics.ity to a range of sizes.centrating photovoltaic system uses a dense array of high-efciency2].steam salt, copowerTheof a CScombinTheis of coFig. 18. of electrFig. 17. Principle of a concentrated solar collector.ple of a concentrating solar thermal power station for co-generationnd process steam.1550 A.M.K. El-Ghonemy / Renewable and Sustainable Energy Reviews 16 (2012) 1537 1556Fig. 19. Conce(top left), linedish-Stirling eTable 6Cost of concenSpecicationStandard plaMax efcienSpecic powBasic plant cTotal US instLargest unit DemonstratCSP behavewith less orgrid stabilitmainly on rfrom 5 MWFor concat glass miing and lineThese systebut not the by mirrors.concentratihence achieTherefore, lsteam cycleadditionallyTable 6 givpower tech5. DifferensystemsThere arnation comframeworkcesses [1,2renewable requiremenDistribution of renewable energy powered desalination technologies [1].ake up between 50% and 70% of the total operating costis thus not surprising that many of the large-scale thermalation plants are co-located with power stations or industriesermal process energy waste. The globally installed desaltingty byotovdesaable ted wrespdepeesignre aris (Red a arentrating solar collector technology mainstreams: parabolic troughar Fresnel (bottom left), central receiver solar tower (top right), andngine (bottom right) [33].trated solarthermalelectric technologies [22]./type SolardishengineParabolictroughSolar powertowernt size, MW 2.5100 100 100Fig. 20. can mand it desalinwith thcapaci5.1. PhRO renewpresenthe corwater tems dTheosmosdescriband EDcy, % 30 24 22er, W/m2 200 300 300ost, $/W 2.65 3.22 3.62allation, MW 0.118 354 10in the USA, MW 0.025 80 10ed system, h 80,000 300,000 2000s just like any conventional fuel red power station, but no fuel consumption, thus being an important factor fory and control in a future electricity supply system basedenewable energy sources. CSP plants can be designed to several 100 MW of capacity [33].entration of the sunlight, most systems use curved orrrors because of their very high reectivity. Point focus- focusing collector systems are used, as shown in Fig. 19.ms can only use the direct portion of solar radiation,diffuse part of the sunlight that cannot be concentrated Line focusing systems are easier to handle than pointng systems, but have a lower concentration factor andve lower temperatures than point focusing systems.ine concentrating systems will typically be connected to power stations, while point concentrating systems are capable of driving gas turbines or combustion engines.es a comparison of the main features of solar thermalnologies.t combination between RES and desalinatione numerous renewable energy sources (RES)desali-binations have been identied and tested in the of ongoing research for innovative desalination pro-,22]. Table 7 and Fig. 20 show the distribution ofenergy powered desalination technologies [1]. Energyt in the form of thermal as well as electrical energythe feasibilfor desalinathere are cotion systemcost and, foearly PV-RORO system,power, butapproach teproduct, duand in the batteries wrather highpowered ROFig. 22 osmosis (PVThe systemsince the raaccording twith the mowater at apF process in 2002 is shown in Fig. 21.oltaic and RO (PV/RO) combinationlination unit can be coupled with different types ofenergy. Table 8 summarizes several studies which wereith various possible combinations and Table 9 presentsonding costs. As shown in Table 9, the cost of desalinatednds on few factors including plant capacity, RES/RO sys-, feed water quality, site location, etc.e mainly two PV driven membrane processes, reverseO) and electro-dialysis (ED). Both techniques arebove, and from a technical point of view, PV as well as RO commercially available technologies. At present time,ity of PV-powered RO or ED systems, as valid optionstion at remote sites, has also been proven [2]. Indeed,mmercially available standalone, PV powered desalina-s [2]. The main problem of these technologies is the highr the time being, the availability of PV cells. Many of the demonstration systems were essentially a standard which might have been designed for diesel or mains powered from batteries that were charged by PV. Thisnds to require a rather large PV array for a given ow ofe to poor efciencies both in the standard RO systemsbatteries. Large PV arrays and regular replacement ofould tend to make the cost of water from such systems. Table 8 shows a selection of some brackish-water PV system.shows diagram of photovoltaic-powered reverse--RO) system to desalinate seawater without batteries. is operated from seawater and requires no batteries,te of production of freshwater varies throughout the dayo the available solar power. Initial testing of the system,dest solar resource available in the UK, provided fresh-proximately, 1.5 m3/day. Nearer to the equator and withig. 21. Global installed desalting capacity by process [1].A.M.K. El-Ghonemy / Renewable and Sustainable Energy Reviews 16 (2012) 1537 1556 1551Table 7General combinations technologies of RES and desalination methods [1].Renewable energy sources1-Solar 2-Wind 3-GeothermalPV Solar thermal Shaft Electricity Heat Shaft ElectricityRO ED MVC TVC MED MSF MVC RO ED RO MVC MVC RO Table 8Selection of some brackish-water PV-RO systems [1].Location Feed water (ppm) Capacity (m3/day)Sadous Riyadh {Saudi Arabia} 5800 15 Haifa {Israel) 5000 3Elhamrawie {Egypt} 3500 53 Heelat ar Rakah {Oman} 1000 5 White Cliffs {Australia} 3500 0.5 Solarow {Australia} 5000 0.4 Table 9Water cost for desalination by renewable energies [25].Combination Water Plant capacity (m3/day) PV/BAT/RO Seawater 12 PV/BAT/RO 120 PV/BAT/RO PV/RO WIND/BAT/RWIND/GRIDPV/GRID/ROa PV array oproduction 5.2. ConcenThe diffesolar powerA concepgeneration The lowfeed water the feed wais determining parameFig. 22teamlectrre anes paind e elecBrackish water 250 Seawater 1.5 O Brackish water 250/RO Seawater 300 Seawater f only 2.4 kWp, a software model of the system predictsof over 3 m3/day throughout the year [1].trating solar thermal driven desalinationrent congurations for desalination by concentrated are shown in Fig. 23(ac).tual layout for a solar dish based system with power[1,2]: serate epressuprovid5.3. WTheand RO desalination is shown in Fig. 24 [1]. temperature waste heat is shown as an input to theas a reduction in RO energy consumption is achieved ifter temperature is raised (but only up to a limit whiched by the membrane characteristics and other operat-ters). A modication of this arrangement is described in. PV-RO system to desalinate seawater without batteries [1].input for thor a wind faogy due to of the variaoutput. So,are requiredtion load. Tin the desigThere wereRO process.however, thfore, this arexpertise. Opromising, Remote islands can nation for fis a reducedporting theas power sotems are poconnected coupling ofcase, the deinterruptioations, howcomponentElectricity Electricity HeatRO ED MVC RO ED MVC TVC MED MSF PV (kWp) Battery (kWh)10 2643.5 plus 0.6 wind 3618 2003.25 9.60.34 None0.12 NoneWater cost (US$/m3) Year27 19967.4 19966.7 19912.95 20032.7 20031.8 20021.9 2005 is used primarily to power a steam turbine and gen-icity, but is also extracted from the turbine (at reducedd temperature) and used to drive a booster pump, whichrt of the RO high pressure pumping demand.nergy and RO (WIND/RO)trical or mechanical energy required as primary energye RO unit can be provided from a single wind turbinerm. However, reverse osmosis is the preferred technol-the low specic energy consumption [1,2,25]. Becausebility of wind speed, it is difcult to predict the energy appropriate power control and conditioning systems in order to match the ratio of power input to desalina-he design of the control system is the most critical stepn of a desalination RO unit powered by wind energy. a number of attempts to combine wind energy to the Several units have been installed and tested worldwide,ese studies remain at the research level [2630]. There-ea suffers from lack of information and data in terms ofn the other hand, the prospects of this combination aremainly due to the low cost of wind energy, see Table 9.areas with potential of wind energy resources such asemploy wind energy systems to power seawater desali-resh water production. The advantage of such systems water production cost compared to the costs of trans- water to the islands or to using conventional fuelsurce. Different approaches for wind/desalination sys-ssible. First, the wind turbines/desalination system areto a grid system. The second option is based on direct the wind turbine(s) and the desalination system. In thissalination system is affected by power variations andns caused by the power source (wind). These power vari-ever, have an adverse effect on the performance and life of certain desalination equipment. Hence, backup1552 A.M.K. El-Ghonemy / Renewable and Sustainable Energy Reviews 16 (2012) 1537 1556Fig. 23. (a) Hcongurationssystems, suintegrated iof an RO dtemperaturthe water toturbines is fing pressur5080 bars permeationing brine aleat only. (b) Power only. (c) Combined heat and power. Different for desalination by concentrated solar power [33].ch as batteries, diesel generators, or ywheels might bento the system. Fig. 25 shows a schematic presentationesalination plant. The process takes place in ambiente. The only electrical energy required is for pumping a relatively high operating pressure. The use of specialor energy recovery from concentrate pressure. Operat-es vary between 10 and 25 bars for brackish water andfor seawater. High pressure is needed to allow sufcient at relatively high concentrations of the concentrat-ong the membrane axis located in the pressure vessel.Fig. 24. Combined dish based solar thermal power generation and RO desalination[1].Water recoas high as 9ery is betwis obtainedthe PersianThe Euroand demonand SpanishThe inst1986. It is system. Besoperation oFinally, Eura. Island ofb. Ile du Plac. Island ofd. Island ofe. Island ofIn additcoupling ofpower has Island (OahRO plant wpower of a 13 L/min caThe ED since it is ait is most simental tesCanaria, Spwas 19272Fig. 25. Scvery (permeate water divided by feed water%) can go0.95% in the case of light brackish water, while recov-een 35 and 50% in the case of seawater. Low recovery especially in a relatively closed sea, like the Red Sea or Gulf [2].pean Community funded different research programsstration projects of wind desalination systems on Greek islands. Other wind-driven RO systems are as follows.allation of WIND/RO in the Middle East was started ina 25 m3/day-plant connected to a hybrid winddieselides that, in Drepanon, Achaia, near Patras (Greece), thef other wind powered RO system started in 1995 [2].opean Commission (1998) presented other facilities at: Suderoog (North Sea), with 69 m3/day;nier, France Pacic Islands, with 0.5 m3/h; Helgoland, Germany (2.4 m3/h); St. Nicolas, West France (hybrid wind-diesel) and Drenec, France (10 kW wind energy converter).ion, interesting experimental research about the direct a wind energy system and a RO unit by means of shaftbeen carried out at the Canary Islands. Also, in Coconutu, Hawai), a brackish water desalination wind-poweredas analyzed. The system was coupling directly the shaftwindmill with the high pressure pump. The result wasn be maintained for wind speed of 5 m/s [2].process is interesting for brackish water desalinationble to adapt to changes of available wind power anduitable for remote areas than RO. Modeling and exper-ts results of one of such system installed at the Granain is presented by [2]. The capacity range of this plant3 m /day.hematic presentation of a reverse osmosis desalination plant [1].A.M.K. El-Ghonemy / Renewable and Sustainable Energy Reviews 16 (2012) 1537 1556 15535.4. Hybrid units (PV/wind/batteries/RO)Another interesting RES/RO conguration is the hybridPV/wind/batteries/RO systems which have greater exibility com-pared to pexperimentwith a capwind. A spfacility opeThe code ctery chargetree was dsolar and wadditional auxiliary (dwater reversources (hyLibya (300 moperation orecovery), twind energof this inveconsumptio6. EconomThe econof the life cyment of theall signicaeach optioncommon ba(i) recurrin(ii) non-recCost anaally aims towater, and ccost. This idattracts theimprovemeated with imdepend on (i) quality water (ecompar(ii) Plant capumpinLarge cacomparscale, thlower [1(iii) Site chasuch as plant lois anothbe subssource awater b(iv) Costs astrate diexpansiconstruTable 10Percent distribution of cost factors [1].Cost name Brackish water (%) Seawater (%)Fixed costs 54 37c powrane renanccals ulatal/sta difggreablesalinauctio costhe d strud coapacirecirect onst opend vcosts costajord maaboue asally le 10 of borteed fre xawate maater ag facsts arts a thechnoerall coss. Thwil e solar4), wuctir disote isolated areas with a water demand less than 50 m3/day.ther technologies are more expensive at this small scale.le other researcher believes that solar stills are the technol-of choice for water production needs up to 200 m3/day. dominant competing process is RO that has an energyirement of between 6 and 10 kWh/m3 of water treated andrevious congurations. Weiner et al. [31] studied,ally and numerically, an autonomous desalination plantacity of 9 m3/day supplied by solar photovoltaic andecially adapted code was developed to simulate theration to allow an appropriate choice of components.ontinuously updates water level in the tank and bat- state. Based on these two variables, a logical decisionesigned to determine whether the combination ofind energy can meet the burden of the unit or if anenergy must be supplied by batteries or a generatoriesel engine). Kershman et al. [32] investigated a sea-se osmosis (SWRO) powered from renewable energybrid PV/wind/grid/RO) for small-scale desalination in3/day). While the expected nominal power load for thef the RO desalination system is 70 kW (net power afterhe solar PV system is designed for 50 kWpeak and they conversion for 200 kW nominal output. The objectivestigation was a reduction of the non-renewable energyn to about 40%.ic analysisomic analysis made in this section is based on the usecle cost (LCC). The life cycle cost is an economic assess- cost for a number of alternatives by taking into accountnt costs over the lifetime of each alternative, addings costs for every year and discounting them back to ase. These costs can be categorized into two types:g cost (operation cost and maintenance cost)urring cost (batteries and replacement costs) [1,2]:lysis of autonomous desalination system (ADS) usu- estimate the cost of a liter or a cubic meter of freshalculates the contribution of each cost item to the totalenties immediately the most signicant cost items and attention to what should rst be examined for possiblent and cost reduction. In general, cost factors associ-plementing a desalination plant are site specic andseveral variables. The major cost variables are:of feed water, where, the low TDS concentration in feed.g. brackish water) requires less energy for treatmented to high TDS feed water (seawater).pacity where it affects the size of treatment units,g, water storage tank, and water distribution system.pacity plants require high initial capital investmented to low capacity plants. But due to the economy ofe unit production cost for large capacity plants can be,2].racteristics where it can affect water production costavailability of land and land condition, the proximity ofcation to water source and concentrate discharge pointer factor. Pumping cost and costs of pipe installation willtantially reduced if the plant is located near the waternd if the plants concentrate is discharged to a nearbyody.sociated with water intake, pretreatment, and concen-sposal can be substantially reduced if the plant is anon of an existing water treatment plant as compared tocting a new plant.ElectriLaborMembMaintChemi(v) ReglocIt isat an aof variDesconstr(O&M)costs. Tintakeings anplant cThe indtotal dance, cThecosts azation capitalused. Mcals, anrate is could bis typic[1].Tabnationare repobserv(i) Thse(ii) Thwin(iii) CopaonteovTheauthorby Elta1. The(199prodsolaremAll oWhiogy 2. Therequer 11 449 4eplacement 7 5e and parts 9 710 3ory requirements which associated with meetingte permits and regulatory requirements [2].cult to compare the costs of desalination installationsgated level because the actual costs depend on a range specic to each site [1].tion plant implementation costs can be categorized as:n costs (starting costs) and operation and maintenances. Construction costs include direct and indirect capitalirect cost includes land, production wells, surface watercture, process equipment, auxiliary equipment, build-ncentrate disposal (type of desalination technology,ity, discharge location, and environmental regulations).t capital cost is usually estimated as percentages of thecapital cost. Indirect costs may include freight and insur-ruction overhead, owners costs, and contingency costs.rating and maintenance (O&M) costs consist of xedariable costs. Fixed costs include insurance and amorti-. Usually, insurance cost is estimated as 0.5% of the total. Typically, an amortization rate in the range of 510% is variable costs include the cost of labor, energy, chemi-intenance. For low TDS brackish water, the replacementt 5% per year. For high TDS seawater, the replacement high as 20%. The cost for maintenance and spare partsless than 2% of the total capital cost on an annual basis shows the percent cost of various factors for desali-rackish water and seawater in RO plants. These datad in the Sandia National Laboratories report. It can beom these data, that:ed costs are a major factor for both, brackish water ander.jor difference in cost between desalination of brackishnd seawater is energy consumption, while the remain-tors are decreased proportionally.ssociated with membrane replacement, maintenance &nd consumables are relatively small. These costs depend status of technology and may be further reduced aslogy evolves, but will not have signicant impact on the cost of desalination.t and energy gures have been estimated by manye summary is given below as reviewed and reportedt al. [1]: still distillation system can produce water for $20/m3hile other researcher estimated solar distilled wateron costs as low as $2.4/m3. Recent improvements intillation technology make it the ideal technology for1554 A.M.K. El-Ghonemy / Renewable and Sustainable Energy Reviews 16 (2012) 1537 1556Fig. 26. Typical cost structure for RO desalination of seawater [1].investment costs of between US$600 and US$2000/m3 of pro-duction c3. The RO tleast amopared toa potentinicantlyUsing EDcosts for seahave showncapital costthermal desical water c(Fig. 27). Itfor thermalsources of hIn additresistant henergy costthe differenThe dataimately 0.90.03 milliona 30 millionRO remacapacities iimportant tspecic, so tis not as strSolar thermclean electrbest-suitedreduction. TFig. 27. TypicTable 11Unit product costs for conventional and novel desalination processes by capacity[1].System, type Capacity millionsgallons/dayUnit product cost$Cent/gallonI-Novel processesMEE-VS, 30 effects,aluminum alloy, uted tubes90.53 0.182MEE-ABS, absorption heatpump and gas turbine2.5 0.133II-Mechanical vaporcompression (MVC)0.03 1.8940.13 1.221.06 0.9391.2 0.925.28 0.174III-Reverse osmosisSingle stage 5.28 0.242Two stage 5.28 0.2880.03 0.8981.06 0.75ltistagl purple purturbintiple-l-purple purturbinerE-TVCle purpose 5.85 0.886l-purpose 5.85 0.4965.85 0.587e order of 0.5 years, while the economic lifetime is at leastrs [2]. cycle emissions of greenhouse gases amount to0.015 kg/kWh, which is very low in comparison to thosered combined cycles (0.500 kg/kWh) or steam/coal power(0.900 kg/kWh).ision support tool (DST)id the process of cost calculation for a specic desalinationlogy, a decision support tool (DST) software is used for costtion during any project. For analysis, the DST authors [1] sug- to divide the cost of ADS into following categories as follows):apacity [2].echnologies with energy recovery systems require theunt of energy to process seawater (46 kWh/m3) com- all other technologies. If brackish water is included asal input, then the energy requirements for RO drop sig- and are basically equivalent to (0.52.5 kWh/m3). treatment for brackish water Comparison of typicalwater desalination by RO and typical thermal processes that for RO, the largest cost reduction potential lies ins and energy costs (Fig. 26). For a typical large-scalealination plant, energy cost represents 59% of the typ-osts with the other major expense being capital cost would seem that the most effective cost reduction desalination can be achieved by utilizing alternativeeat or energy, such as dual purpose plants.ion, the development of less costly and corrosion-eat transfer surfaces could reduce both capital ands [1]. There is more detailed cost comparisons betweent desalination technologies are given in Table 11. show that the costs of RO systems ranging from approx-0 cents/gallon (US$2.37/m3) for a plant with capacity of gallons per day to 0.21 cents/gallon (US$0.55/m3) for gallons/day capacity system.ins the cheaper option at both low and high productionn comparison to the other technologies. However, it iso restate that desalination cost data is extremely sitehe comparison of costs across the different technologiesaight forward as it may appear in the presented data.al power plants may acquire a considerable share onicity generation in the 21st century. They are one of the technologies to achieve the global goals of CO2 emissionhe energy payback time of a solar thermal power plantIV-MuDuaSingGas V-MulDuaSingGas boilVI-MESingDuais in th25 yeaLife0.010of gas plants 7. DecTo atechnoestimagested(Fig. 28al cost structure for large thermal desalination of seawater [1].1.2 0.4899.99 0.41310.56 0.31412 0.25830 0.208e ash desalination (MSF)ose 7.13 0.292pose 7.13 0.621e, waste-heat boiler 8.45 0.5457.13 0.5959.99 0.473effect evaporation (MEE)ose 6 0.33pose 6 0.7396 0.5296 0.479.99 0.409e, waste-heat 9.99 0.496Fig. 28. DST cost categories [1].A.M.K. El-Ghonemy / Renewable and Sustainable Energy Reviews 16 (2012) 1537 1556 1555i. Cost of feed water system and pre-treatment, including all nec-essary investment and related expenses required for the supplyof brackish or seawater to the desalination main system.ii. Cost of desalination unit itself.iii. Cost of sufor the deiv. Cost of brimal to vv. Other cosand (b) acost of puwhile thevarious cm3 of frealized involume oIt shouldis a site-spein other situby ADS is nnologies drienergy. Howfresh watertourism, theunderway swide spreadAn effectechnologielems with pollution oMeanwhiletems are stsupplies arerenewable and electrictructure is c8. ConclusThe use days as a reemerging aFor low-fresh waterfore, the chand oceansemerging reThe conndesalinationnation systavailable, itbrackish waturbines arlation may other renewGeotherat reasonabable becaussystems reqdevelopmeThe mostion in desaand direct aof renewabAlso, the new pretreatments may improve the performance by per-mitting a considerable increase of the operating temperature indistillation plants.Environmental issues are associated with brine concentrateal, enn. Onancerial adix Ackishore se: Wrges preenerag wor excentrmbreratiatioolve planillatiuce withtrodilectrpuritterms a pily fodwat wateling:is mehwag/L)ed sh-preressuressultrati the S in ted sexcher exltipleare pate wof thapoltista thenurati the w exteter. Tre, wsatiopporting source (RES), supplying all the energy needssalination unit, feed water pumps and brine disposal.ine water disposal, which could be anything from min-ery expensive depending upon specic conditions.ts. Most of the above categories have (a) an investment running cost. The investment cot reects the annualrchasing and installing equipment or other xed asset, running cost relates to annual expenses and the cost ofonsumables which are necessary. The cost per liter orsh water is estimated by dividing the sum total annu-vestment plus running costs of all categories by thef fresh water produced. be noted, that for a given ADS technology, cost analysiscic and usually cannot be generalized for applicationsations. As a general rule, the cost of the produced waterormally higher than conventional desalination tech-ven by network electricity or conventional fuel thermalever, in the remote areas far from electricity, fuel and resources as well as areas where the economic driven is water price is acceptable. The developments currentlyuggest that ADS applications are going to become more.tive integration of desalination and renewable energys will allow countries to address water shortage prob-a domestic energy source that does not produce airr contribute to the global problem of climate change. the costs of desalination and renewable energy sys-eadily decreasing, while fuel prices are rising and fuel decreasing. Finally, the desalination units powered byenergy systems are uniquely suited to provide waterity in remote areas where water and electricity infras-urrently lacking.ionof renewable energies for desalination appears nowa-asonable and technically attractive option toward thend stressing energy and water problems.density population areas worldwide there are lack of as well as electrical power grid connections. There-eap fresh water may be produced from brackish, sea water by using wind turbines, solar panels and othernewable energy technologies.ection of photovoltaic cells to membrane processes in is an interesting alternative for stand-alone desali-ems in remote areas. Nevertheless, if wind power is exhibits lower energy cost than solar PV energy. Forter desalination, both of RO and ED powered by winde usually the best selection. Nevertheless, solar distil-be advantageous for seawater desalination, althoughable energy resources have to be taken into account.mal energy is suitable for different desalination processle cost wherever a proper geothermal source is avail-e there is no energy storage is required. Moreover, otheruire further analysis for evaluating their potentials ofnt, applications and performance.t attractive technologies of renewable energy applica-lination are wind and PV-driven membrane processesnd indirect solar distillation. Nevertheless, the couplingle energy and desalination systems has to be optimized.disposductioacceptindustAppenBrasalt-mBrindischaused inCogby usinpose, fwater.Conthe meDeadesalinDissnationDistto prodwater Elecized (ethe imThe inchargeprimarFeesourceFouosmosFresliter (mdissolvuses.Highigh-phigh-pInenterspatternsaturatIon polymMurators evaporforms tube evMuheatedthe sattion ofon theuct wapressucondenergy consumption and associated greenhouse gas pro- the other hand, social issues may include the public of using recycled water for domestic dual-pipe systems,nd agricultural purposes.. Glossary: Water that typically contains less than 10,000 ppmalt than freshwater but less than the open seawater.ater that contains greater than 50,000 ppm salt. Brinefrom desalination plants may also include constituentstreatment processes. See also Concentrate.tion: A power plant that is designed to conserve energyaste heat from generating electricity for another pur-ample to thermal desalination or to warm SWRO feedate: Water containing concentrated salts rejected byane. See also Brine.on: Removal of oxygen. A pretreatment process inn plants to reduce corrosion and fouling.d air otation (DAF): A pretreatment process in desali-ts to remove solids and organics.on: A process of desalination where the water is heatedsteam. The steam is then condensed to produce product low salt concentration.alysis: Most impurities in water are present in an ion-ically charged) state. When an electric current is applied,ies migrate toward the positive and negative electrodes.ediate area becomes depleted of impurities and dis-uried stream of product water. This technology is usedr brackish waters.er: Water fed to the desalination equipment. This can ber with or without pretreatment. Contamination or biological growth on the reversembranes or pretreatment lters.ter: Water that contains less than 1000 milligrams per of dissolved solids; generally, more than 500 mg/L ofolids is undesirable for drinking and many industrialssure differential pressure (HP DP): The pressure at there inlet port of the PX device minus the pressure at there outlet port of the PX device.on gallery: A method used for the area where seawaterWRD process. Perforated pipes are arranged in a radialhe sand onshore below the water level. Water in theand enters the perforated pipes.ange: A reversible water treatment process. A chargedchanges Na+, H+, Cl, or OH for other ions in a solution. effect distillation (MED): A form of distillation. Evapo-laced in series, and vapor from one effect is used toater in the next lower pressure effect. There are severalis technology, one of the most common is the verticalrator (VTE).ge ash (MSF): A form of distillation. Intake water is discharged into a chamber maintained slightly belowon vapor pressure of the incoming water, so that a frac-ater content ashes into steam. The steam condensesrior surface of heat transfer tubing and becomes prod-he unashed brine enters another chamber at a lowerhere a portion ashes to steam. Each evaporation andn chamber is called a stage.1556 A.M.K. El-Ghonemy / Renewable and Sustainable Energy Reviews 16 (2012) 1537 1556Nanoltration (NF): A lower pressure membrane ltration tech-nology sometimes used for pretreating reverse osmosis feed-water.Permeate: Water puried by a reverse osmosis membrane.Product water: The desalted, post-treated water (or permeate)delivered to the water distribution system.Recovery: Ratio of permeate to membrane feed ows, typicallyexpressed as a percentage.Reverse osmosis (RO): A process where pressure is appliedcontinuously to feedwater, forcing water molecules through asemi-permeable membrane. Water that passes through the mem-brane leaves the unit as permeate or product water; most of thedissolved impurities remain behind and are discharged in a con-centrated brine or waste stream.Salinity increase: The increase in the salinity of the membranefeed stream caused by the energy recovery device. Salinity increasevaries with the membrane recovery rate. It is typically expressedas a percentage increase of the membrane inlet stream above thesalinity of the system feed-water according to the following equa-tion:Salinity in= membrSeawateof seawaterScaling: Total disscentration iVacuum perature anwater formduce the prand is not cVapor cofeed-water Mechanicalincreases itproduct wawater.References[1] Eltawil Mgies integReviews 2[2] Kalogirouin Energy[3] Moustafatistage u[4] Buros OK[5] Howe ED1974.[6] Al-Sahlawi MA. Sea water desalination in Saudia Arabia: economic review anddemand projection. Desalination (Elsevier) 1999;123:1437.[7] El-Sadek A. Water desalination: an imperative measure for water security inEgypt. Desalination (Elsevier) 2010;250:87684.[8] El-Nashar AM. Optimising the operating parameters of a solar desalinationplant. Solar Energy 1992;48(4):20713.[9] Hamed OA, Zamamiri AM, Aly S, Lior N. Thermal performance and energy anal-ysis of a thermal vapour compression desalination system. Energy Conversionand Management 1996;37(4):37987.[10] Harding J. Apparatus for solar distillation. Proceedings of the Institution of CivilEngineers London 1883;73:2848.[11] Telkes M. Solar stills. In: Proceedings of world symposium on applied solarenergy. 1956. p. 739.[12] Rajvanshi AK. Effects of various dyes on solar distillation. Solar Energy1981;27:5165.[13] Akinsete VA, Duru CU. A cheap method of improving the performance of rooftype solar stills. Solar Energy 1979;23(3):2712.[14] Lobo PC, Araujo SR. A simple multi-effect basin type solar still, SUN. In: Pro-ceedings of the international, solar energy society, vol. 3. 1978. p. 202630.[15] Al-Karaghouli AA, Alnaser WE. Experimental comparative study of theperformances of single and double basin solar stills. Applied Energy2004;77(3):31725.[16] Al-Karaghouli AA, Alnaser WE. Performances of single and double basin solar-stills. Applied Energy 2004;78(3):34754.k G, S3;14(ha Mlysis aari GN Mancunanolved ari GNrgy Cadir rgy d0;14:el MRdemyad aptiannagemrouniosis pe Enerer AMrgy 2tana I syste4;160ta JA,ered3;75:las Pven de CCK, erse o2;150iner Dolar- 1;137shmaewaball-scab F, S Desantriescreaseane inlet salinity system feed water salinitysystem feed water salinity 100%r reverse osmosis (SWRO): Reverse osmosis desalination.Salt deposits on the surfaces of a membrane.olved solids (TDS): Total salt and calcium carbonate con-n a sample of water.freezing (VF): A process of desalination where the tem-d pressure of the seawater is lowered so that the pures ice crystals. The ice is then washed and melted to pro-oduct water. This technology is still being developed,ommercially viable.mpression (VC): A form of distillation. A portion ofis evaporated, and the vapor is sent to a compressor. or thermal energy is used to compress the vapor, whichs temperature. The vapor is then condensed to formter and the released heat is used to evaporate the feed-A, Zhengming Z, Yuan L. A review of renewable energy technolo-rated with desalination systems. Renewable and Sustainable Energy009;13:224562. SA. Seawater desalination using renewable energy sources. Progress and Combustion Science 2005;31:24281. SMA, Jarrar DI, Mansy HI. Performance of a self regulating solar mul-sh desalination system. Solar Energy 1985;35(4):33340.. The USAID desalination manual. IDA; 1981.. Fundamentals of water desalination. New York: Marcel Dekker, Inc.;[17] Fric197[18] Sodana[19] Tiwand[20] Satinv[21] TiwEne[22] AbKene201[23] PatAca[24] AhmEgyMa[25] Bouosmabl[26] OmEne[27] Pestion200[28] Carpow200[29] Kokdri[30] Liurev200[31] Wea s200[32] Kerrensm[33] TrieandCouommerfeld Jv. Solar stills of inclined evaporating cloth. Solar Energy4):42731.S, Kumar A, Tiwari GN, Tyagi RC. Simple multiple-wick solar still:nd performance. Solar Energy 1981;26(2):12731.. Demonstration plant of multi-wick solar still. Energy Conversionagement 1984;24(4):3136.athan S, Hanses HP. An investigation of some of the parametersin solar distillation. Solar Energy 1973;14:35363., Yadav YP. Economic analysis of large-scale solar distillation plant.onversion and Management 1985;25(14):4235.MZA, Rafeeu Y, Adam NM. Prospective scenarios for the full solarevelopment in Malaysia. Renewable and Sustainable Energy Reviews302331.. Wind and solar power systems. Kings Point, NY: US Merchant Marine; 1999. GE, Schmid J. Feasibility study of brackish water desalination in the deserts and rural regions using PV systems. Energy Conversion andent 2002;43:PP26419. K, Barek T, Taee A. Design and optimization of desalination reverselants driven by renewable energies using genetic algorithms. Renew-gy 2011;36:93650.. Overview of renewable energy sources in the Republic of the Sudan.002;27:PP52347.DLN, Latorre FJG, Espinoza CA, Gotor AG. Optimization of RO desalina-ms powered by renewable energies. Part I. Wind energy. Desalination(293):9. Gonzalez J, Subiela V. Operational analysis of an innovative wind reverse osmosis system installed in the Canary Islands. Solar Energy15368.A, Papathanassiou SA. Component sizing for an autonomous windsalination plant. Renewable Energy 2006;31:212239.Park JW, Migita R, Qin G. Experiments of a prototype wind-drivensmosis desalination system with feedback control. Desalination:27787., Fisher D, Eduard J, Katz B, Meron G. Operation experience ofand wind-powered desalination demonstration plant. Desalination:713.n SA, Rheinlander J, Gabler H. Seawater reverse osmosis powered fromle energy sources e hybrid wind/photovoltaic/grid power supply forle desalination in Libya. Desalination 2002;153:17e23.charfe J, Kern J, Nieseor T, Glueckstern P. Combined Solar Powerlination Plants: Techno-Economic Potential in Mediterranean Partner (MED-CSD). Work Package 1 Leader Organization, DLR; 2009.Water desalination systems powered by renewable energy sources: Review1 Introduction1.1 Natural water resources1.2 Water demand and consumption1.3 The need for desalination1.4 Desalination and energy1.5 Desalination market1.6 Objectives2 Water desalination techniques2.1 Thermal processes (phase change)2.1.1 Multistage flash evaporation (MSF)2.1.2 Multiple effect boiling (MEB)2.1.3 Vapour compression (VC)2.1.4 Freezing2.1.5 Solar distillation2.2 Membrane processes2.2.1 Reverse osmosis (RO)2.2.2 Electro-dialysis (ED)3 Renewable energy systems (RES)3.1 Potential of solar energy3.2 Photovoltaic (PV) energy3.3 Thin-film photovoltaic3.4 Concentrating photovoltaic4 Concentrating solar thermal power5 Different combination between RES and desalination systems5.1 Photovoltaic and RO (PV/RO) combination5.2 Concentrating solar thermal driven desalination5.3 Wind energy and RO (WIND/RO)5.4 Hybrid units (PV/wind/batteries/RO)6 Economic analysis7 Decision support tool (DST)8 ConclusionAppendix A GlossaryReferences

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