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Renewable Desalination System
The theme focuses primarily on desalination system based on the use of renewable sources. Desalination has become the most important source of water for drinking and agriculture. The population standards of living, and the quick development of the agricultural and industrial sectors have a huge impact to the water and energy shortages . Fundamental needs of power and water in remote regions can be covered by Renewable energy sources (RES) tied to desalination which offers a promising vision where connection to the public electrical web is either not cost effective or not feasible, and where the water lack is severe. There is a lack of fresh water where, 3 percent is fresh water while 97 percent of earth’s water is saline which meaning it has low concentrations of dissolved salts and other total dissolved solids. This small percentage of the earth’s water not enough most of human and animal needs exists in ground water, lakes and rivers. It would be feasible to address the water-shortage problem with seawater desalination; however, the separation of salts from seawater requires large amounts of energy which, when produced from fossil fuels, can cause harm to the environment.

The availability of renewable energy resources (RES) likely has more efficient economically way to utilize the Desalination systems.

Design
The system design is based on the renewable resources as major feed for producing freshwater. The integration of renewable resources in desalination and water purification is becoming increasingly attractive. This is justified by the fact that areas of fresh water shortages have plenty of solar energy and these technologies have low operating and maintenance costs. The selection of the appropriate desalination technique is based on an overall assessment of the available water sources (brackish and seawater) in both quantity and quality. If brackish water sources are available, their desalination must be preferred, since, due to low salinity, energy requirements are much lower. Usually brackish water sources are available in inland regions, whereas seawater desalination is mainly employed in coastal sites. The selection of the appropriate desalination technique differs according to the type and potential of the local RES, remoteness, feed water salinity, required product water quality, and the water demand that is to be covered which defines the plant capacity. One must note for example that distillation processes are used for the production of distillate water while membrane processes are used for the production of potable water.

Method
The methods of desalination system can be divided into two main categorizes which can use renewable energy to desalinate the water. The first categorize are often referred to as “direct solar desalination” and usually involve different types of solar stills. The second categorize are known known as “indirect solar desalination” .The second categorize are include many ways of the thermal energy from the sun is used for either heating the seawater or generating steam in conventional distillation plants.

DIRECT SOLAR DESALINATION
This method is principally appropriate for the low functional temperature and pressure of the steam which can make production value rate be low. Direct solar desalination can be describe to be a device basin with a transparent cover of with glass which the seawater is heated by solar radiation heated by solar radiation until it is begin to evaporate and the formed the water surface.

Direct solar desalination include three ways:


 * Single-effect solar stills
 * Multi-effect solar stills
 * Water desalination with humidification-dehumidification (HD)

INDIRECT SOLAR DESALINATION
This desalination systems method is been created to increase the production value scale that required from industry. This system uses fossil fuels as the energy basis for either heating or electric power generation to desalinate the water

Indirect solar desalination ways:


 * Multi-Effect (ME)
 * Multi-Stage Flash (MSF)
 * Reverse Osmosis (RO)
 * Salinity-gradient Solar ponds
 * Parabolic through collectors



Procedures
Renewable energies for use in desalination processes include:

Desalinate water by photovoltaic:
This photovoltaic reverse osmosis (PVRO) desalination system will fit the needs of off-power grid communities that face drinking water shortages due to saline water problems. In the PVRO system a high-pressure pump capable can be used which can make the flow was united directly to photovoltaic panels. This eliminates which can result with a low-cost, energy-efficient system.

Desalinate water by wind:
The wind turbine that can be used to power desalination plants which can generate the electrical and mechanical power for RO and ED desalination unit s. With the system power variations could occur due to wind fluctuations. These power variations would decrease the performance of desalination equipment and possibly reduce the life cycle of specific components. In the Mechanical Vapor Compression (MVC), the mechanical energy of the wind turbine is used directly for MVC without further conversion into electricity. Wind Powered Desalination is highly applicable to locations with ample wind energy resources such as islands. Wind power desalination can be one of the most hopefully options for seawater desalination especially in specific areas with high wind potential.



Desalinate water by Geothermal:
This process can describe as the production of fresh water using heat energy. Geothermal energy is the 3rd largest renewable resource currently utilized around the world. The power generation that based on geothermal sources are growing at many parts around the world. An excellent heat sources choice for thermal desalination processes can be help us is like geothermal sources. Since thermal desalination processes require large quantities of heat sources, geothermal based energy source represents a feasible, sustainable, and an environmentally friendly option. Geothermal resources can both be used to heat the greenhouses and to provide fresh water needed for irrigation of the crops cultivated inside the greenhouses. The energy can be used directly as heat or converted into electricity making very useful in most desalination process, such as reverses osmosis (RO), Multiple Effect Distillation (MED), Multi Stage Flash (MSF) and Vapor Compression (VC) . Many statuses of the worldwide geothermal desalination and the potential for possible future projects in this industrial area were discussed in detail for Australia, Caribbean Islands, Central America India, the Kingdom of Saudi Arabia, UAE, USA, and Sub-Saharan Africa.

Desalinate water by Solar-thermal:
The only limitless natural source of energy that desalination possess abundantly, is solar energy. It is well known that other forms of renewable energy, like the wind energy, wave energy and Geothermal have limited potential in water desalination industry. In this section a solar field is used which provides thermal energy to multiple effect distillation (MED) evaporator to produce fresh water. This solar heat can be given directly to the MED unit or in days with good irradiation the excess energy can be stored for use in periods of low sunshine and during the night. The system can also be hybridized using conventional fuel to run the desalination subsystem during the night. A very small quantity of electrical energy (compared to thermal) is required by the MED unit to drive the pumps.

Renewable energy driven desalination systems fall into two categories. The first category includes distillation processes driven by heat produced by the renewable energy systems, while the second includes membrane and distillation processes driven by electricity or mechanical energy produced by RES.