The Multiple Stage Flash (MSF) Process evaporator consists of three consecutive chambers with decreasing pressures and temperatures ordered from hot to cold. Seawater flows through the heat exchanger tubes, which is then warmed by the condensation of the vapor produced. The temperature then increases from sea temperature to inlet temperature. The seawater flows through the brine heater, which is where it receives enough heat for the MSF process to occur. The seawater is thus overheated compared to the temperature and pressure of stage 1 and will immediately flash, which is when released heat and vapor comes to an equilibrium with the stage conditions. This vapor is thus condensed into fresh water and captured in the tubular exchanger at the top of the cell. The process then repeats itself when the water flows into the next stage. The produced distillate fresh water is extracted from the last stage. 
Engineers are exploring new possibilities to reduce the overall cost of seawater desalination. Changes in plant capacity, materials used, system design, energy use and the implementation of hybrid systems have demonstrated the ability to help reduce cost and make water more affordable to consumers. These changes are expected to grow in the next ten to twenty years as technology advances. Desalination costs in general have been decreasing as new advancements are discovered. The MED method and the SWRO methods have now become affordable options for today’s desalination necessity, with the cost of both reduced in the last decade.  However, desalination experts do not expect the cost to decrease further in the future. There are a few reasons for this hypothesis. 1) The price of crude oil will likely increase in the future as depletion continues, which will increase the cost of energy necessary for a desalination plant. 2) Inflation and fluctuations in currency. 3) Membrane, chemical and equipment prices are expected to rise in the future due to technological advancement and competition among manufacturers which can significantly affect operating costs.   4) Increased shipping costs. 5) Increased environmental regulations will rise the cost of obtainable permits. 
While improvements are allowing desalination methods to become more sustainable, advancements and renewable technologies are not expected to significantly decrease cost in the near future. New hybrid and renewable methods will eventually bring production cost down in the future, but these methods will struggle to compete with common and well-known processes like MED and SWRO in the near future.  However, choosing an MED method over an SWRO method for our desalination project may help to minimize some of these expected future capital and operating costs, minimize future water costs, and shows promising performance potential for future security.  The use of solar methods will reduce required energy costs for this plant by capturing and storing free energy. Also, there will be no need to purchase membrane equipment, minimizing replacement and maintenance costs. New MED technologies and lower production costs have allowed the process to become more reliable and productive than other distillation methods like MSF , and can help us to combat Arizona’s water crisis for a better, and healthier future.
Social & Cultural Benefits of this Distillation Plan
1) Jobs will be created for Arizonans.
2) Lost groundwater will be constantly replaced.
3) Agricultural jobs can continue and ensure economic growth for Arizona.
4) Arizona will be the forefront example for distillation technology in the United States.
5) Arizona will not need to depend on California and Colorado for water like we currently are in the Colorado River Contract.
6) Arizona is not dense like New York. We have the available land for the distillation technologies, while using the sun as a renewable resource.
7) Arizona is mostly basically tectonically sound.
Ultrafiltration is a highly efficient filtering system that uses a cross-flow separation process to remove contaminants such as colloidal materials along with inorganic and organic polymeric molecules, and anything else with a high molecular weight. The membrane used for UF has pores ranging from 0.1 to 0.001 microns. 
Ultrafiltration system operation and maintenance should include daily records of feed and permeate flow, feed pressure and temperature, and pressure drop across the system. Feed flow is critical to the operation of ultrafiltration systems. Membranes should be cleaned when the system permeate rate drops by 10% or more. The recovery of an ultrafiltration system is defined as the percentage of the feed water that is converted into the permeate, or: R= P F × 100 Where: R is Recovery, P is Volume of permeate, F is Volume of Feed. 
Why Evaporation Ponds?
Why Wind and Solar?
Wind and Solar are both site specific and require a great deal of land, which limits where they can be installed, and they both work intermittently. Wind technology has an advantage over solar because it can function at night. The turbines are large and their efficiency goes up with size . At the same time, many people dislike them due to their appearance, noise, and other aspects.
Solar technology is diverse and each type has important advantages and disadvantages to consider. Photovoltaic panels (PV), Solar Power Towers (SPT), and Parabolic Troughs (PT) were all researched and considered for this project. Solar energy is appealing because it is both abundant and ubiquitous, but it is not consistent everywhere. Arizona is an ideal location for it due to the high concentration of solar irradiation we receive almost every day of the year (Solar Energy Development Programmatic 2014).
Photovoltaic panels’ primary advantages over the other methods of solar energy generation is that they do not require water to cool the system as they work nor do they require as much land as Concentrated Solar Power (CSP) systems such as SPT or PT . Otherwise, they make far less energy at a slower rate, emit quite a bit of waste heat, and have a poor conversion efficiency. Also, they are built on a single axis, which means their ability to gather solar energy is limited by their permanent angle once installed . Concentrated Solar Power specializes in large-scale energy production. Both PT and SPT have the ability to achieve much higher temps than PV and are built on a dual axis allowing them to track the sun, which maximizes their daily intake . PT has been the CSP technology of choice for years but it has come to a point where little more progress can be made. The system itself does not achieve very high temperatures therefore suffering quite a bit of energy loss during transport, which makes it quite inefficient. Out of all forms of CSP, PT requires the most water for cooling and land for operation .
Why did we chose Solar Power Towers?
Concentrated Solar Power (CSP) technology is rapidly becoming a top competitor with PV. It is predicted to become highly competitive for bulk load in 2020 and base load in 2025 . CSP stands out from PV because some technologies are capable of storing a backup supply.
Solar Power Towers (SPT) are highly appealing due to their ability to store large amounts of energy, diversity in form, and potential for growth . The general set up of an SPT consists of a central tower surrounded by heliostats equipped with dual axis providing them with the ability to track the sun more efficiently. This gives SPTs an advantage because they are able to achieve higher temperatures, which means greater efficiency . A key component of this function is the number of heliostats surrounding the SPT. It is projected that by the year 2020, SPT will be the most affordable of all CSP technologies and require the least amount of land. 
The efficiency of SPT is based on many components that are all linked together. The Heating Transfer Fluid (HTF) becomes more efficient at higher temperatures. Higher temperatures decrease storage costs for excess energy. The piping is centralized in the center of the plant minimizing energy loss and materials needed for construction. The SPT maintains the highest efficiency out of all CSP systems; this minimizes the amount of water needed for cooling. It currently requires 1,500 L/MWh of water for cooling, in comparison to other CSP systems that need 2,500+ L/MWh of water for cooling. Thermal Energy Storage (TES) currently has a 99% efficiency rate, which is a key part of our process . There are downsides to SPTs equipped with TES, if not maintained properly. The most successful TES currently in use is molten salt. Depending on the mix of salts, once the temperature of the storage system drops to a certain point the salt will begin to crystallize. If the temp continues to decrease it will solidify. Its optimal operation range is between 260 ˚C and 621 ˚C . Also, as stated before, SPTs require water for cooling the system to prevent overheating, and plants built with TES require more land for extra heliostats in order to collect enough heat for night time energy generation .
RO Average Energy Demand 30,000 MWh/day
Distillation Average Energy Demand 15,000 MWh/day
As shown in the table, Wind and Natural Gas are the lowest costs annually, for the upfront costs, but the land availability for Wind power generation is difficult to meet, and Natural Gas doesn’t meet the team’s requirement for Green energy for a project of this size. Solar is the energy source of choice, even though the annual costs are higher. The challenge will be to reduce the energy demand with innovative technologies. Concentrated Solar Power is an up and coming technology that should be considered for production of this magnitude. CSP has the added benefit of storing energy for up to 10 hours after the sun goes down.
Why use Open Intake?
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