CSP (Concentrated Solar Power)-Tower Solar Thermal Desalination Plant

The main goal of this paper is that achieve 1.48 US $/m for LCOW (Levelized Cost of Water) and 0.016 US $/kWhth for LCOH (Levelized Cost of Heat). For this goal, the paper suggests an integrated CSP (Concentrated Solar Power)Tower Solar thermal desalination facility with steam storage. The plant includes heliostat area, solar receiver, and thermal desalination unit and steam storage system. When sun shine, steam that is produced from the CSP heliostat field will be sent to steam storage system and the thermal desalination unit via steam reducer. Also, extra heat will be again used to charge the steam storage during the peak hours. The fresh water that is output of the desalination unit will be for public utilization. The brine (excessively salty water) that is output of the desalination unit will be processed for to obtain precious minerals with ZLD (Zero Liquid Discharge) technologies. Assumptions that is to calculate unit price are type of return schedule, type of interest rates for every year; and amortization and taxation are ignored With these assumptions, the methodology achieves the goal with 1.48 US $/m and 0.016 US $/kWhth for 12 years return time, %3 interest rate without subsidizing.


Introduction
This paper introduces production of fresh water through solar thermal desalination. Most of the currently operational desalination plants use reverse osmosis, Delyannis [1], Khawaji et al. [2], Al-Shammiri and Safar [3], and Warsinger et al. [4]. Solar thermal desalination is superior to this and other methods of desalination for a number of reason, Crittenden et al. [5]. First, unlike these plants that burn fossil fuels and other un-renewable energy sources to run the plant, a solar thermal desalination plant runs entirely on solar energy; and the steam that it generates during the desalination process, Further, a solar thermal desalination plant can operate and produce water far more cheaply than the current technology, Panagopoulos [6],. García-Rodríguez et al [7], Kalogirou [8] and Qiblawey and Banat [9]. Thus, a solar thermal desalination plant provides the environmental benefit of a reduced the carbon footprint, lessens the United States' dependence on foreign fossil fuels, and provides water to the American public at lower costs.
Widespread commercialization of the solar thermal desalination process also addresses a critical, life-and-death issue namely, the scarcity of fresh water in various parts of the country. Indeed, the growth of the U.S. population, coupled with lengthy droughts, has created significant fresh water shortages in certain states. These shortages have not only threatened human life at the most basic level but also they have had significant socio-economic impacts. For instance, because of fresh water shortages, farming has had to be scaled back in certain U.S. states, which has led to job loss and shortages of farming products. Building thermal plants in these areas is a clean, cost-effective way to address provides immeasurable benefits to human health, safety, and prosperity.
The highlights of the paper are as follows: 1) Utilize CSP-Towers to operate desalination plants based on renewable sources; 2) Generate and store steam by using the lowest number of heliostats at high temperature and pressure; 3) Utilize steam generated by the solar thermal desalination plant to provide energy for the desalinization process during periods of no sunshine; 4) Achieve the lowest LCOW (Levelized Cost of Water) and LCOH (Levelized Cost of Heat) on the market today; 5) Utilize successful solar thermal desalination plant as a model for future use.

System Description
CSP field will be installed with 1500 heliostats; and during periods of sunshine, steam produced from the CSP heliostat field will be sent to steam storage system and thermal desalination unit via steam reducer. During periods of no sunshine, the steam storage system will discharge and thermal the desalination unit will continue to work. The brine that is output from the desalination unit will be processed to obtain precious minerals with ZLD (Zero Liquid Discharge) technologies. The fresh water output from the desalination unit will be for public consumption and utilization. The fresh water output from the desalination unit will be for public consumption and utilization. Figure 1 represents a diagram for proposed CSP facility.

The Heliostat Field
1) 1500 heliostats (each heliostat is 16 m 2 ; total field is 24,000 m 2 ). 2) Main goal is production cost of heliostat less than 100 US $/m 2 , including simple site assembly and erections designs including. 3) Smart and independent heliostat system with wireless communications and autonomic calibrations. 4) Automated interactive heliostat field control management using auxiliary software. 5) An analysis is conducted based on solar conditions that are typical in areas in which the proposed solar thermal desalination plant would operate. 6) Figure 2 presents the design data for a heliostat field derived from an engineering analysis. 7) Figure 3 presents the calculation of production hours and power using the design data. 8) Figure 4 presents a graph of seasonal production times for identified performance points. 9) Figure 5 represents the seasonal average thermal energy production graph derived from the design data and seasonal working hours.

The Thermal Desalination System
A "MEP (Multi-Effect Plate Evaporator)" is considered, and the MEP desalination process consists of a series of evaporation and condensation chambers known as effects. Each effect is fitted with heat transfer, and in the plate channels of an effect, seawater or brackish water on one side is heated up and partially evaporated to distillate vapor, which is used in the next effect; on the other side, the distillate vapor from the previous effect is condensed, giving up its latent heat, into pure distillate. By maintaining a partial pressure difference across the effects, the process is able to yield maximum efficiency from available low-grade thermal energy sources. The performance and the capital cost of the system are proportional to the number of effects contained in a unit. The system flow diagram of a four effect MEP is shown by Figure 6.

The Steam Storage System
The proposed methodology will be implementing the design and pilot scale application of the steam storage system to increase availability in concentrated solar energy systems. The sensible heat storage, steam production and heat loss rate will be measured. Additional improvements will also be made to optimize the steam storage system.

The Operating Principle of the System
1) Seawater or brackish water is pumped into the system via a seawater pump to a condenser. Here, the seawater acts as a coolant, removing the heat supplied to the system and thereby maintaining the proper energy balance. 2) In the condenser, the vapor produced in the last effect is condensed into pure distillate. 3) As distillate vapor is condensed, heat is transferred to the seawater. 4) The seawater or brackish water pump also transports preheated seawater or brackish water downstream of the condenser to the various effects of the unit for evaporation. 5) The seawater or brackish water is led towards the evaporation side of the plate stack, creating a uniform and controlled thin film on the plate. 6) To minimize scaling, the special design of the plate surfaces ensures a uniform flow without any dry areas.
On the evaporation side of the plate stack, the seawater or brackish water is partially evaporated by the heat from the condensation side of the plate stack. 7) The vapor thus produced is passed through a demister to separate salt from the water droplets before the vapor enters the condensation side of the subsequent heat exchanger plates. Here, the vapor condenses into distilled water while transferring its latent heat through the plates to the evaporation side. The process is repeated in all effects. 8) Finally, distillate and brine are extracted from the last effect. 9) The evaporation takes place at sub-atmospheric conditions, and vacuum conditions are created and maintained by a venting system. 10) The venting system is a water-driven ejector, and as shown on the flow diagram. The venting system removes air from the plant at start-up and extracts non-condensable gases during operation of the plant.

Feasibility
We performed detailed feasibility studies for the proposed CSP-Tower Desalination facility within the scope of the paper. As a sample, we selected an area that would have conditions typical of the conditions in which the proposed solar thermal desalination plant would operate. The "Nevada Area" was selected for a feasibility analysis. In this area, there will be 3142 available solar hours per year. The number of heliostats to be used for the corresponding CSP-Tower field is 1500 when looking at the DNI data in the relevant area. This will correspond to 24,000 m 2 . Also the height of the tower is 50 m. In the desalination unit, 37.5 m 3 per hour fresh water will be generated. Because of the steam storage system, water production will continue for 24 hours in a day.
This design can be used in similar sunny areas like California or other states.
When all this design data and field design are taken into account, the conditions for reaching the target cost are created. All details for the scenarios are taken into consideration. The way to follow the scenario is as follows: 1) The cost of equipments and other components (cabling, electrical components, piping, etc.) to be used for the installation of the CSP plant has been calculated. For Levelized Cost of Water and Thermal Power, CAPEX (Capital expenditures) and estimated OPEX (annual expenses) are taken into consideration.
2) The generated amount of water and heat is calculated.
3) While the plant was is constructed, 80% of the cost is bank loans and the rest (20%) is organizations equity. 4) It was accepted that the credit will have a return time of 5, 10, 12 or 20 years. 5) At each return time, 3 different interest rates were settled. These ratios are: 0.03, 0.04 and 0.05. 6) For each return time and the interest rate within it, a unit price of 0.5 to 1.5 US $/ m 3 was given. 7) Income is calculated for each payback time, interest rate and unit price. 8) OPEX cost was assumed to be similar to an equivalent plant's field data. 9) For the accepted 4 years and 3 different interest rates, the interest and principal payment was determined based on the relevant return time. Also, equal equity payments are calculated for equity. 10) Amortization and taxation are ignored in all calculations made. In addition, no subsidizing has been considered when calculating the lowest cost. The assumptions can be changed according to agreements between banks and the organization's management. The information used for the scenarios is shown by Table  1 [11], Burenstam-Linder [12], Manzhos [13] and Cekirge and Erturan [14].

Innovations and Impacts
This paper has multiple unique strengths. First, the cost of the heliostats, which is one of the thermal facility's major components, is reduced by virtue of the optimum and experimental design. Second, the steam storage system, another critical component, is developed at low cost and enables the desalination plant to function 24 hours/day, including in no sunlight conditions. The goal of this paper is to prove CSP-Tower plants using steam storage as a feasible desalination method.

Objectives of the Plan
The goal of this paper is to use develop a method for delivering fresh water using a method that uses renewable energy. This serves the dual process of solving water shortage problems while avoiding the environmental harm that plants that rely on fossil fuels or other non-renewable sources create.
Specific objectives for the paper are: 1) To supply fresh water from sea water or brackish water; 2) To provide fresh water when the sun does not shine; 3) To use renewable energy sources to minimize carbon emissions; 4) To deal with solar intermittency via steam storage; 5) To obtain precious minerals and salt from brine with brine recovery; 6) To minimize negative impact on marine life with no discharge of brine to the sea or ocean; 7) To low cost and maintains free steam storage system design; 8) To reduce CAPEX (Capital Expenditures) and OPEX (Operating Expenses); 9) To increase solar beam emissivity and lightweight design criteria; and 10) To achieve the lowest LCOW and LCOH.

Technical Scope Summary
Phase 1. Initiate Phase Activities: The legal obligation and other all related documents are investigated and necessary actions are taken. Phase 2. CSP System Design and Engineering Phase Activities: The most appropriate design, system details, all purchases and transportation are investigated. Phase 3. Installation Phase Activities: Installation will be completed using the data of the selected location and design, and the requirements of the site of plant area are provided. The problems of mobilization can create Difficulties in terms of efficiency. Successfully mobilization of the field must be chosen as a milestone, since it will affect the future activities of the plant. At the end, the CSP and desalination plant will be ready for operation.

Conclusions
The total production cost of desalinating brackish groundwater ranged from US $ 0.29 to US $ 0.66 per m 3 , Arroyo and Shirazi [15]. In SWRO (Seawater Reverse Osmosis) projects, this cost has been has flattened since 2005 in a wide the range of US $ 0.79 to US $ 2.38 per m 3 , Kim, et al. [16,17] and Ghaffour, et al. [18].
The expected results of this studies are: 1) Providing 1.48 $/m 3 for LCOW with Integrated CSP-Tower Solar Thermal Desalination Plant and most likely less, 2) Distributing the distillate water which meets standards to water grid system for public utilization; and 3) Adding value to existing conventional power generating equipments. According to the market conditions, using lower or zero interest rates, the values of LCOW or MLCOW will be lower; and the payback period will be shorter. After CAPEX payback, there will be no fuel and energy cost that is the cost of production of water for m 3 will be far under one US dollar, MLCOW is the apparent and definite metric for these calculations.