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In the current modern society, the increase in industrial activity has caused a lot of pollution of the natural water sources. As a result, water available for use either for drinking or for domestic purposes has decreased greatly. This is evident in many of the developed nations like Australia while countries in the Middle East which had minimal water sources experience a crisis.
This has prompted the need to practice desalination a process where engineering technology is used to remove minerals and salts from seawaters. This process ensures effective production of fresh water that is suitable for consumption by human beings and for agricultural needs. The following dissertation focuses on the developments made in the desalination technologies as numerous governments consider them as solutions for the fresh water crisis. One major development noted is the use of alternative clean energy such as solar and wind to effectively reduce energy costs. This technological advancement has been applied in numerous countries around in the desalination plants whereby reduction in operational costs results in maximization of supply of fresh water.
1. Specific Clean Technology
When desalination process was first established, it was noted that process required quite a lot of energy to ensure effective production of safe drinking water. For instance, In Israel Mekorot served as the first desalination plant 1965 providing fresh water to the city residents of Eilat. The facility utilized vaporization technology that required high levels of energy to enable production of fresh water in the area. As such, alternative energy-saving processes were sought to fully enable the fresh water production while minimizing the costs incurred in the operations of the plant. Numerous countries across the world did the same including the US, Australia and some of the Middle Eastern countries where water crisis is a major concern. Extensive research ensures improved technologies that enabled clean energy that would help conserve the capital invested into the projects for alternative use. California is yet another region to join the long list of areas with water crisis for domestic use. A solar thermal desalination plant is now underway that will apply the high pressure reverse osmosis to provide 50 million gallons of water per day.
The need for highly technological plants such as these demonstrates the water crisis present in the world. It is estimated that one in every eight people lack safe drinking water in the world. At the moment, this is evident in countries in the Middle East who are struggling to produce high amounts of fresh water for their citizens. Through the focus on solar photovoltaic power system, these engineering innovations will manage to reduce costs spent on energy used in production and maintenance fees making the water produced cheaply available to the numerous residents around. Solar panels are utilized in converting the sunlight rays into electricity. Reports by economic analysts indicate growing size of the desalination industry through clean technology as it is estimated to enter the $2 trillion threshold as of 2030. As the world seeks to improve on the co2 emissions, the need for clean technology is increased.
2. How it Works
The majority of clean technology desalination plants apply the reverse osmosis (RO) in the process of producing fresh water. This is a process that uses membrane technologies in the operations. This process was introduced in the 1970s as an alternative to the distillation, ion exchange and other processes that require a high amount of energy. Pressure is a major factor in the reverse osmosis as it forces the saline water through a semi-permeable membrane. The pores in the membrane is noted to be 1/100,000th diameter of human hair. It is effective as the pressure only allows the water to flow through leaving the minerals of Sodium and Chloride behind. There are four major processes that are implemented in this system including: Pretreatment system, high-pressure pumps, membrane systems and post treatment.
As a measure of keeping the membrane clean at all times, the pretreatment process is necessary. This is where all solids that are suspended in the water are removed to ensure microbial growth does not take place on the membranes. This may involve chemical feed or sedimentation and filtering of the sand particles. Alternatively, the pretreatment may involve microfiltration or ultra-filtration processes. Numerous factors influence the choice of pretreatment selected including available space, RO membrane requirements or the quality of the water feed.
The next step is the high pressure pumps that provide the required pressure to separate the minerals with fresh water through the semi-permeable membrane. The conventional 8 inch tubes are used in majority of the clean technology plants however, there are cases where larger tubes have been used up to 16 inches in diameter. As a result, the plant requires fewer pressure pipes reducing the costs for hardware. In the case of briny water, the pressure is lower at 150 psi as opposed to seawater that requires 800-1000 psi. The membrane systems are included in the pressure vessels where two possible semi-permeable membranes may be used: hollow fiber or spiral wound. The pressurized water is allowed to flow through a spiral path that is enclosed by the membrane and the fresh water is collected in a central tube.
Some of the feed water is allowed to flow through without passing through the membrane to avoid a case where the feed water becomes super saturated with the minerals. The discharged water is usually either 20% or 50% of the feed water in briny water and seawaters respectively. However, in the case of the upcoming project in California, only 7 gallons out of 100 gallons will be discharged of concentrated seawater. The following step is the post-treatment of the collected fresh water where it is stabilized before it is distributed for use by consumers. In this stage, the pH of the water is adjusted while it is disinfected for direct consumption. Moreover, it is important that the desalinated water is checked for compatibility with other stored in sources of supply. This will ensure the water remains safe for consumption.
Construction of these desalination plants is seen to be quite expensive as many have been noted to be upwards of $200 million with the ongoing project in California amassing to $1 billion. Not many organizations are able to pay up such huge sums of money to erect these plants that are necessary for production of fresh water. This is most evident is poor countries particularly in the MENA region where there is a high need for water for domestic and agricultural purposes. The high amount of energy that is required for running the processes of desalination along with the increase in cost of fossil fuel have led to the use of concentrated solar power. Hereby, solar energy is used either directly or stored for later use during the night. As these are usually desert regions, heat from the sun is available throughout the year and enables for effective use in the production of fresh water.
In addition, the use of concentrated solar power enables the global practice of reduced greenhouse gas emissions from fossil fuels. In countries like Morocco where the Noor-Ouarzazate Concentrated Solar Power (CSP) project is being established, high sums of funding is required to ensure its completion. The African Development Bank has approved approximately $250 million to fund the second phase of the project to enable 350 MW of electricity for the plant. The WaterFX Hydro I, Inc., responsible for a similar project in California is issuing up to $10 million worth of stock to raise funds for its completion. This will serve as the first commercial-scale plant in the state that has suffered high levels of drought.
The use of concentrated solar power and solar PV power systems is identified to be the future of desalination of seawaters. The Sorek desalination plant has been seen as the benchmark for using solar power in the production of fresh water for consumption and irrigation purposes. The plant has enabled the use of minimal space for the production of large scale fresh water. The plant sits on 10 hectares of land and is able to provide 20% of the total supply of desalinated water in Israel. This is unlike other plants in the world like the Point Paterson plant that was built on a 50,000 hectare site. A Victorian company erected the large scale plant near Port Augusta in South Australia that would be worth an estimated $370 million. It would be the first solar powered plant in Australia. The plant was believed to produce 5.5 gigalitres of water per year that will be enough for 34,000 people. This is far less that the amount produced by the Sorek project. Nonetheless, its usefulness is greatly acknowledged in this dry region.
The use of this engineering advancement is identified as a major prospect of reducing water crisis in world where nearly 884 million people across the world lack safe drinking water. The number is set to more than double before 2016 increasing the need for desalinated water. The benchmark created by the Sorek plant demonstrates that fresh water can be produced and sold at low prices where 1000 liters are sold at 58 US cents. As aforementioned, this water crisis will result in a trillion dollar industry by 2030 where continued pollution of the environment will ensure enormous increase in thirsty people.
5. What the factors favoring its use:
Through the use of solar concentrated and solar PV power systems, a huge amount of energy costs is reduced. Research indicates that the fossil fuels which have been used for quite some time are slowly being depleted and may become extinct in the near future. As such, the current prices of these fuels have sky rocketed and establishing these large plants that depend on electricity for effective functioning would be cost restrictive. Therefore, the importance of renewable energies has been considered in the development of Reverse Osmosis desalination plants as a means of reducing costs.
It is also noted that desalination plants are required on a large scale as a means of serving a larger population. In order for such a case to occur it is necessary that the plant reduces its costs of operation. As such, the creation of solar powered plants has been a major step towards reducing these operational costs. This is evident at the Point Paterson plant that has significantly reduced the costs for the operation such that it was able to provide a 2 year free supply of water for the neighboring residents.
The water crisis has been caused almost in its entirety by the increased industrial activities in the world. These industries have polluted the available fresh water sources while emitting greenhouse gases that result in global warming. Therefore, through the solar concentrated plants GHG emissions are greatly reduced. The solar power is renewable and can be stored for later use without negative effects on the environments like emission of carbon.
With increased consideration of the environment, desalination technologies have greatly considered the waste product of the process which is brine. The reverse osmosis technology has resulted in the production of minimal waste where the discharged feed water is treated before being poured into the seas or river systems. Through this process the plant is able to control the amount of waste deposited to the seas obviating a case of super-saturation of salts in the concentrate.
6. Barriers for its Use
There are numerous factors associated with the Renewable Energy Desalination that may cause investors from investing in similar projects. Some of these factors are technological where the available technology is only effective for application on a large scale plant. As identified in the above discussion, the plants that utilize renewable energy have cost millions of dollars especially in its construction. The use of these technologies on a small scale will result in significant loss for the investors. Moreover, as the famous blogger from an essay writing company states, the technologies used by RE-D plants will require constant supply of the energy source. For instance, solar concentrated power systems will require availability of sun rays on a daily basis to ensure the plant continues its effective production of fresh water. As such, areas where hot conditions are not present, the plant cannot be erected as it will not effective. Such a case results in increased capital from investors to ensure variable energy supply and cost of maintenance increases significantly.
Numerous technologies have been developed as such provide high competition for the use of RE-D plants. For instance, the Multi Effect Distillation with Thermal Vapor Consideration (MED-TVC) only requires temperatures up to 70̊ C. As such they can be as closely efficient as the membrane processes. The technologies used in majority of the RE-D plants are developed independently and not as a single system. Hereby, the use of a particular component of the entire system could work poorly reducing the efficiency of the entire plant. The RE-D technologies could showcase poor reliability and an increase in the cost of desalinated water. This is evident where the energy supply and its demand are mismatched. The poor operation may cause a high need for maintenance resulting in increased costs for the investors. The high use of energy may result in the replacement of the membranes are they are worn out.
In the RE-D industry, there is lack of a comprehensive analysis of the market as the size is unknown, the locations of high need and its numerous segments. As a result, the investors are unable to effectively calculate the risk associated with entry to this market. Many of willing investors are coy on joining an industry that cannot be effectively assessed. Furthermore, it is evident that some of the niche markets are inaccessible. This is where some of the areas that require high levels of fresh water production like North African countries may lack the resources to establish such plants. Lack of knowledge on the industry may prove to be a barrier in entering the market. This may be associated with cases of structures of pricing and subsidies of water supply that may create unfair competition.
In a bid to improve the barriers associated with technology, it is necessary that innovation in technology is closely linked with the industry whereby machinery is made available for use on small scale purposes. The current RE-D technologies are noted to serve the large scale production and hence the small scale niche markets remained untapped. Development of small scale technologies will result in an increased investment and consequent production of fresh water.
It is also evident that politicians and locals are opposed to the development of RE-D plants that may be effective in solving the world water crisis. Previous failures by prototype plants have resulted in a negative perception of the technologies. However, private corporations have demonstrated their ability to fully invest and develop technologies that will enable a sufficient supply of water. As a result, it is necessary to introduce policies that serve to eliminate the heavy influence of politicians and allow for the privatization of the industry. Furthermore, national policies related to innovation in science and technology where stakeholders will help in developing plans as they will apply in this critical issue.