This study focuses on accurate performance as well as the cost analysis of reverse osmosis desalination powered with PV connected to the grid in the region of Saudi Arabia. Data from the Hybrid Optimization Model for Electric Renewables approximate 2.81 Energy Modeling Software and Desalination Economic Evaluation Program software is used to examine the technological economic probability of plants. The total cost is higher as compared to the price of diesel-based grid electricity in region as diesel fuel has been subsidized in Saudi Arabia. Report summarizes the various factors and prospects of business with the deployment of PVRO plants in Middle East and reduction in CO2 emissions.

This study focuses on accurate performance as well as the cost analysis of reverse osmosis desalination powered with PV connected to the grid in the region of Saudi Arabia. Data from the Hybrid Optimization Model for Electric Renewables approximate 2.81 Energy Modeling Software and Desalination Economic Evaluation Program software is used to examine the technological economic probability of plants. The total cost is higher as compared to the price of diesel-based grid electricity in region as diesel fuel has been subsidized in Saudi Arabia. Report summarizes the various factors and prospects of business with the deployment of PVRO plants in Middle East and reduction in CO2 emissions.

As the scarcity of freshwater endures to upsurge the episodes of drought and the increasing population, as desalinating seawater is very essential for meeting the needs of freshwater. Water scarcity is a risk to greater than 45% of population and availability to the freshwater resources is anticipated to deteriorate in the future. Amongst the other applications, solar electricity is able to produce cost-effective fresh water for the regions deprived of water by driving the seawater desalination plants and propelling the water inland. Traditionally, powered desalination is not the sustainable process, owing to the use of fossil fuel-based power for supplying high energy needs for the recovery of freshwater. For instance, Saudi Arabia uses an approximate 3.4 Mn m3 of desalinated water per day, utilizes greater than 1.6 Mn barrels of oil every day to influence its desalination plants.

Photovoltaics (PV) delivers a sustainable option for water desalination as compared to conventional means, for being the pollution-free and fuel-free during operation, where PV do not need a large amount of water rather than thermoelectric generation requires. In the year 2013, global desalination capacity was predicted to be more than 85 Mn m3 each day, with two-thirds of capacity allotted to the Middle East and predicted that about 0.8% of the desalination capacity is supplemented by the generation of solar power, as renewables include more than 2% of capacity and solar-assisted generation includes greater than 85% of the renewable market.

Desalination Technologies: Overview

The procedure of desalination irrespective of the technology used includes the seawater separation into the component of freshwater and brine concentrate component. Desalination technologies are mainly categorized as chemically-driven, membrane driven or thermal desalination processes. Thermal desalination processes involve solar ponds, dehumidification and humidification, vapor compression, multi-effect distillation, multi-stage flash distillation and solar distillation. Membrane-driven processes consist of membrane distillation, electrodialysis and reverse osmosis. Technologies with the exception of ED are used for desalinating seawater or brackish water, though brackish water desalination is less energy intensive. The most widely used technologies are RO and MSF. An MSF distillation plant is using thermal energy to evaporate saline feed water and gather the distillate through several chambers operating at low pressure. MSF plants are anticipated to preserve the dominant role in the market of desalination, specifically in oil-rich countries that advantage from locating MSF plants with the thermal cogeneration plants to use waste heat. Though RO is considered to be the leading global competitor as it is the most effective energy of all the desalination processes and improvements in technology like energy recovery devices and improved membranes have boosted the performance of RO and reduce prices.

PV-powered RO (PVRO) is been observed as not present in the competitive solution on comparing the powered desalination, restricting PVRO to small-scale applications in remote areas. For instance, PVRO large plants are planned for the installation in Dubai and Saudi Arabia, with expected production capacities per day respectively.

Reverse osmosis: Overview

Reverse osmosis of saline water in the form of pressurized filtration where the filter is the semi-permeable membrane that permits water, but not salts, to pass through. The feed water is preserved and then pressurized to overcome the osmotic pressure, permitting its separation by the membrane in two flows: a brine that is rejected at high pressure and flow that passes through membranes. Electricity is required for the post and pretreatment processes and pressurization of saline water. The membrane elements are stored in pressure vessels with every vessel comprising the elements connected in series. Cleaning of the membrane through chemical treatment is essential, and the cleaning frequency depends on the quality of feed water and the operating conditions. The predominant RO membrane materials include polyamides, cellulose acetate and aramids. These membranes can be used and treated as secondary nanofiltration or micro-membranes, permitting the enhancement of environmental sustainability. For instance, reused membranes can be incorporated in the desalination plant for pretreatment and reused in other less intensive applications like brackish water desalination.

Subsidies and use of fuel in Saudi Arabia desalination plants:

Saudi Arabia uses an approximate 3.4 Mn m3 of desalinated water per day, utilizes greater than 1.6 Mn barrels of oil every day to influence its desalination plants. A large fraction of diesel required by country is imported as local refineries having the everyday generation capacity of more than 5,00,000 barrels and demand reaches to more than 8,00,000 barrels every day in summer. The prices of fuels and extension of electricity in Saudi Arabia are highly sponsored. When photovoltaic electricity transfers diesel-based electricity, reserves from evaded fuel subsidies amount to greater than 18cts/kWh.

Methodology:

Technical data from a KAUST study was used for suggesting a CPV-RO plant on the coast of the Red Sea in Saudi Arabia. The study described the stipulations of demonstration size pilot RO plant associated with 3-MW and 1-MW CPV power plants providing the fraction of annual electricity load needed by RO plant. Desalination Economic Evaluation Program (DEEP) and Hybrid Optimization Model for Electric Renewables (HOMER) software are used and the performance is replicated and financial analysis of the design plant of KAUST pilot-scale. Later, prices of electricity and energy outputs of the designs were compared with the power plants using First Solar’s CdTe PV effective modules in one-axis and fixed tilt tracking configurations.

In the second phase of an investigation, large and small RO plant and PV plant sizes that generate the complete electricity load needed yearly. A grid was used as a backup for PV, with inoculations and withdrawals to and from grid balancing from years. In this manner, it was assumed that grid functions as storage without experiencing losses and the purchase and selling price of electricity are equivalent. HOMER 2 (v2.81) was used to analyze the economic and technical performance of the power plants integrated with PV-grid and software DEEP 4.0 for analyzing the economic performance of desalination plants powered by associated PV-grid systems. The volumes of diesel fuel evaded by PV electricity were determined on the basis of predictions of subsidies of diesel for the period of 2011 and 2012 in Saudi Arabia, determining the subsidy cost savings related to PV displacing diesel. Hybrid Optimization Model for Electric Renewable, established at National Renewable Energy Laboratory is the tool used for analyzing and designing the hybrid energy systems, permitting users to choose renewable and conventional energy technologies.

Results:

By using HOMER and DEEP displays that the balanced water production prices for around 3-MW CPV with the tracking through the dual axis and CdTe PV at fixed latitude tilt and single-axis tracking are greater than $1.31/m3 respectively. These costs are large than the costs of RO systems powered by 1 MW systems because of the smaller purchases of subsidized grid electricity. The breakdown includes capital costs of the RO plant, power costs, material costs, labor and management costs, and insurance costs. In this scenario, power accounts for 20% of the water production cost.

Conclusion:

The charges of photovoltaic electricity have been suddenly decreased in past 5 years to level with unsubsidized electricity rates in the regions of high solar irradiation in the Middle East and other regions essential to increase the water desalination capacity. PV electricity transfers electricity from diesel power plants, each kilowatt-hour of solar electricity shows greater than 0.30 l of diesel, and preserving evaded fuel subsidies amount to more than 18cts/kWh. Thus, by applying PV powered-desalination plants, demand for freshwater in sunny and arid regions can be met cost-effectively during the reduction of air pollution from combustion. The next phase of this activity would be to design off-grid, PV-RO systems with minimal electrical storage, which would be a solution for remote coastal areas.