Technical report

product

Solar Desalination Plant

application of

Utilizing Solar Radiation in Water Desalination

by

Desert Fish

Executive Summary

Our product is a power plant that harvests energy from Solar radiation to

utilize it in a much needed application: water desalination. It is a large scaled project

that we designed to provide fresh water for countries that have sea coasts, but lack in

natural fresh water resources.

Unlike most of the current water desalination methods, our method is eco-

friendly and emission free. Except for a slight need of electrical power, the system

fully operates on solar energy.

Our Water desalination process is similar to that of the nature, which happens

in the water cycle; saline water is heated by sun, water evaporates free of salt, clouds

condense, and finally, fresh water fall as rain. To speed up this process, we must

intensify the amount of sun rays affecting the saline water. To achieve that, we spread

a considerable amount of mirrors that focus Solar rays at a set point about 10 meters

high. At that point, a concave mirror is places to reflect and direct all sunrays

downward on a water container. Within the container, a black metal plate with

branches of wire is fixed. The plate's role is to transform most sunlight into heat, and

distribute that heat in the container. The minor need of electricity is operational,

where the mirrors are placed on electronic directors to keep in alignment with the

sun's position in the sky.

After the first phase water goes through, its vapor enter the second phase. That

is when water vapor is naturally directed to a higher chamber. The chamber is

thermally insulated. In addition, tubes of cool water in the walls of the chamber cools

it down. Thus, when the water vapor come into contact with the interior of the

chamber, it condenses to stream down as liquid water. Free of excessive unwanted

minerals, seawater is good for drinking now!

This simple process provides numerous natural and financial advantages.

Since our product doesn't burn fossil fuel, it is totally emission free. Hence, it is

environmentally friendly. Furthermore, present-day water desalination plants use huge

amounts of valuable natural gas, requiring a lot of money. With our product, that

money will no longer be necessary.

Need Statement

People try to prevent a hazardous an expected Mother Nature event that is just

starting, which is known as global warming. Global warming can be prevented in

many ways, and the main key to prevent it is to use clean energy. Nowadays, most

people depend on polluting energy sources (which comes from the burning of fossil

fuels; emitting carbon dioxide) in operating almost everything ranging from cars,

factories, houses, and other buildings. This resulted in the increase of carbon dioxide

emissions by 5.9% in 2010. This increase can be effective in many negative ways, and

people can predict how much will it increase in the coming years. That’s why

planning the future is a vital factor. The world should decrease the use of polluting

energy, and increase the use of clean energy in order to put a stop to global warming.

Water is the most vital element for life. Without water, it is impossible to

survive. Saline oceans make up to 71% of the earth’s surface1. People obtain fresh

water directly from lakes and rivers. Whereas ocean (saline) water must undergo a

process called desalination in order to be good for human consumption or crop

irrigation. Studies show that 14,451 water desalination plants around the world

produce 15.8 billion gallons of water every day. These plants require massive

amounts of energy to function, which can contaminate Earth’s atmosphere. But how

valuable would it be if water desalination plants were to function on clean energy?

What a great advantage to the environment and atmosphere that would be!

Saudi Arabia is the largest producer of desalinated water in the world. The

government pays annual subsidies at a cost of 3.2 million US dollars for water

desalination. There are 30 governmental desalination plants that are spread around the

country. These 30 plants produce over 2.98 million m3 of desalinated water per day.

About three million barrels of oil are used to power these plants every day; it is

expected that this number is going to triple in the next five years.

Another example is the Jebel Ali desalination plant located in the United Arab

Emirates, and it’s the world’s largest desalination plant. Jebel Ali plant is capable of

producing 300 million m3 of water per year. Such enormous amounts of desalinated

water require tremendous amounts of energy. Using pure, clean energy is just what

countries like Saudi Arabia, United Arab Emirates and many others need, looking at

the massive quantities of desalinated water they produce per day using energy that can

cause great harm to the environment.

25,000 people die from starvation every day. Somalia is a suitable example for

that. Due to poverty and land dryness, Somalia loses a large number of people

because of hunger, thirst, and diseases. Although Somalia is bordered with the Indian

Ocean from the east, it doesn’t have the financial abilities nor the facilities to exploit

the ocean in the right way. A large number of countries participated in donating

generous sums of money and provisions to Somalia. But the question is: why can't

Somalia consistently provide its own provisions? Should people keep on donating or

should they put a plan that will satisfy the needs of the people in Somalia? This is one

of the major problems our world faces today, and such misfortunes require immediate

solutions. As you know water is an essential component that can save the lives of

many in Somalia. Water is not only used as a hydrant for the human body but it is also

used to grow crops and create a land full of vegetation for people and animals. In such

problems, easy fresh water sources are the solution.

Looking at these problems happening in our world today, desert fish came up

with an innovative idea that can solve these problems with suitable and appropriate

solutions. We developed a water desalination plant that requires almost nothing but

sunlight to fully function. This plant is capable of supplying fresh water in an

economical and ecological friendly method. Our plan may solve present problems that

are happening in the world today but it can also solve problems in the future. Many

people talk about global warming and how effective and destructive it is, but the only

solution for that is to use clean energy that doesn't have a negative effect on Earth's

atmosphere. Sunlight is a main source of energy that hasn't been utilized completely,

but why do people tend to use other sources of energy that can negatively affect the

atmosphere for many important applications rather than using sunlight, which is

dramatically better source of energy?

Clean energy is the right path to take in order to prevent global warming. Our

innovative product can make the desalination of water a really simple, inexpensive

process, and on top of that, it functions on clean energy. Not only the desalination of

water should undergo a clean energy process but also everything we use in our daily

life.

Background Technology

Our product aims to determine how to harness solar rays as a substitute in

water desalination, and the creation of the quantities involved; such as the amount of

water, the amount of rays necessary to vaporize the water, and the total time for the

process. The Desert Fish team was unique because they gathered different technology

methods, used the methods of other well-known products, and researched in the laws

of physical science, then came up with a new, special, and innovative product that is a

solution for a worldwide problem.

First of all, with the rapid spreading of news channels and forecasts on

weather changes, it is not obscure to the world anymore that the vicinity of the

Middle-East and North of Africa are areas that receive the highest amount of solar

radiation reaching up to 2400 KW/m2(Kilowatts per Meter squared). Having this

amount of solar natural radiation is one advantage that must be exhausted properly. A

method had been functioned by constructing huge water containers in the vast deserts,

which are isolated from their surroundings using glass. This allows the sunrays to

penetrate them to heat the salty water in the containers. The water evaporates; but

over a long period of time, similar to the natural processes that form clouds. We used

the same method, but we adjusted and added enormous things on the original method

in order to intensify the sun radiation and thrive the speed of boiling the water and

evaporating in a much quicker passage of time.

To intensify the solar radiation, we install mirrors in large quantities around

the containers. These mirrors are spread along 50 to 100 meters encircling the glass

tanks, we'd like to name these: primary mirrors. Primary mirrors are set on electronic

directors that detect Sun’s position and focus its rays to another concaved mirror

placed on poles exactly above and facing the container. The Concave mirror is to

intensify the primary mirrors' rays towards the container. Inside the containers, a

black metal plate, which doesn’t reflect light, is placed in order to heat the water to its

boiling point; hence, speeding up its evaporation.

The Primary mirrors are set on electronic directors which helps them to shift

angles in order to absorb the most of the sun’s radiation in all times. We have

researched and came up with results. An example of one of our studies is: Using 150

mirrors with the size of 10m2, and the sun radiation is perpendicular on the mirrors

the estimated time of reaching the boiling point is 14-16 minutes. With our research

we also found a technological mirror that is qualified for our product and it can be

used as the Primary Mirrors, which are called Fresnel Reflectors. Fresnel reflectors

are made of many thin, flat mirror strips to concentrate sunlight onto tubes through

which working fluid is pumped. Flat mirrors allow more reflective surface in the same

amount of space as a parabolic reflector, thus capturing more of the available sunlight,

and they are much cheaper than parabolic reflectors. Fresnel reflectors can be used in

various sizes.

Why a Concave mirror? This question might wander around your mind. The

answer is simple; it is well known that concave mirrors have the shape of an umbrella.

If the sunlight that is reflected from the primary mirrors hits any spot in the mirror it

will be directly reflected to one median point in order to have extensive sun radiation.

Some criticizers may say that our product is too imaginative to be applied in

reality in addition to other alternatives which aim to the exact purpose that could be

more efficient. Well, I clearly stress my words on rejecting the criticizer's thought and

say that "Our product is the best alternative to solve this endemic problem, for many

reasons: First, our product could be applied in reality because of the existence of

products with same core idea of utilizing solar rays naturally which is applied is

Spain. Second, other products may have more efficiency than ours, but I assure you

that our product is part of the high level efficiency while using less amount of energy

and money, and that what makes our product really beneficial to the environment and

also makes it a part of the clean energy field."

Concept Details

The function of our product, Solar Desalination Plant, is to desalinate saline

water in order to produce fresh water. The structure of the plant is simple, flexible,

and expandable. That allows the technology that we innovated, Utilizing Solar

Radiation in Water Desalination, to efficiently work with ease and with clear

mechanics. All these factors benefits the facility by giving it the capability to adjust to

various water supply needs.

The design of the facility is similar to that of an auditorium. A cylinder water

container is located at the center, and arc-shaped rows of mirrors surround it. Above

the water container at the center, a sector of a big concave mirror hangs on a pole,

facing downwards at the container. However, the container and the mirrors around it

are not on the same altitude. The mirrors are raised above the surface of the container

by several meters. That allows some space to be available for building steam

chambers under the mirrors, but still higher than the container's surface. Furthermore,

both the steam chamber and the water container must be under the sea-level.

The technology by which our product operates emphasizes the efficiency of

solar radiation in producing thermal energy. It provides an effective way to harness

solar energy, convert it into thermal energy, and use that heat in an indispensable

application: water desalination.

Solar rays are collected through reflecting mirrors that are widely spread in a

sunny area. These mirrors are known as "heliostats". Heliostats have the ability to

keep reflecting sunlight toward a predetermined target. They are controlled by

computers which calculate Sun's position. Also given the heliostat's position, the

computer operate motors that rotate the heliostat to keep it in correct alignment with

the sun and the target. The target however, is not the final destination of the collected

light. Around 15-30 meters high hangs the target of the heliostats: a concave mirror

whose role is to reflect a concentrated light beam at the water container under it.

Concave mirrors focus defused light at a certain focus point due to the shape of its

curve and the angles of incoming light. Our concave mirror must be designed and

positioned so that its focus point is inside the water container. Its placement at that

height can be achieved by simply attaching it to a pole from its side. Preferably, the

height of the mirror should be adjustable; it should be attached to a slider on the pole

so that it can slide up and down.

At the focus point in the container, a sufficient amount of energy is available,

but it is in the form of light, and we need to convert it into thermal energy. As light

hits any object, part of that light goes through (as in invisible bodies), another part is

reflected back (as in visible bodies), and the remaining light transforms into heat (as

in black bodies). To transform as much heat from the light as possible, a black metal

plate is placed inside the water container. The metal plate serves for another purpose:

the distribution of heat in the container. Therefore, it must be a good heat conductor.

Copper or copper alloys (e.g., bronze, brass) are good materials to build the plate.

They are highly conductive, affordable, and less corrosive than many other metals.

Since our product is a large scaled facility with multiple operations, its

features are better expressed and understood by describing work process phases rather

than describing its physical parts. After the energy is collected, saline water goes

through two main phases in order to desalinate completely: vaporization and

condensation. In chemistry, the process of purifying liquids by vaporization and

condensation is known as distillation.

The water comes directly from the ocean through pipes. Because the container

is under the sea-level, the water naturally flows to it from the ocean without any need

of pumps. 5 tons of water fill the container, and come into contact with the metal plate

inside. The metal plate gets heated up pretty fast by the effect of the concentrated

sunlight beam on its surface. By the laws of thermodynamics, when two bodies come

into physical contact, heat transfers from the hotter (higher temperature) body to the

cooler (lower temperature) body until they reach thermal equilibrium (equal

temperatures). Therefore, heat will transfer from the hot plate to the water until they

reach thermal equilibrium. As the beam keeps on heating the plate, the water's

temperature will keep on rising. When the water reaches its boiling point (i.e. 100°C),

the continuous thermal energy will start to evaporate the saline water. Water

evaporates free of harmful minerals.

For this process to work properly, the container must be thermally insulated.

In addition, the top cover of the container must have special features to perform its job

correctly. It must be transparent (e.g., glass) so that the beam of light coming from

above goes through to reach the metal plate. It also must have a special shape so that

its center is low to be in the water close to the plate, and its edges on the edges of the

container. That prevents water vapor from blocking the light beam as it might get

between the cover of the container and the metal plate.

Note that the waste when evaporating saline water (i.e. salt) remain as residue

in the bottom of the container. Therefore, the container must have a door for daily

cleaning. Cleaning is necessary to keep the plant functioning properly.

After the water becomes mostly vaporized, valves at the top the container

electronically open. The valves lead to the steam chamber placed under the heliostats.

Because it is higher than the container, as soon as the valves open, water vapor

naturally flows into the chamber. The chamber's walls are made of thin sheets of

copper or copper alloys because it's highly conductive and less corrosive than other

metals. When water vapor comes into contact with the cooler walls, it condenses and

transforms back to liquid water. Water leak on the walls to collect at the bottom of the

chamber. The chamber's floor incline downwards to its edge, and that's where a set of

valves takes the fresh water outside. This is the end of the desalination process.

According to the laws of thermodynamics, the steam chamber will eventually

become hot. To keep the desalination process working, we have developed a cooling

system that needs no energy at all. The chamber is in the shade of the heliostats which

helps keep it cooler. To prevent the chamber from absorbing heat from its

surroundings, we must thermally insulated it. In addition, the insulation material

would be white so that it reflects as much sunlight of itself as possible. The insulation

material must also be a couple millimeters apart from the metal sheets. That allows

the most important element of the cooling system to exist. In the apace between, we

engrave and define boundaries for water paths. These paths incline downwards from

one edge to another. Cool water from the ocean go through these paths to cool down

the chamber. Eventually, this water becomes warmer, hence, easier to heat up.

Through a set of valves, this water goes to the water container for its desalination.

This is the water source which fills the container.

All valves streaming in/out water or steam is operated electronically by a main

computer. The computer also calculates temperatures and pressures of different areas

of the facility from feedback signaled from electronic sensors. According to these

information, the computer opens and closes valves to initiate different phases of the

process.

It is obvious that this desalination plant has special location requirements. It

must be close to a sea or any water source. Furthermore, it must be its altitude must be

lower than sea-level. That would probably require excavation works. More important

location relating issue is the project's latitude. Sunny places closer to the equator are

more convenient for our project. Actually, major parts of the design changes its shape

depending on the area of construction, e.g., the width of the heliostat row arc and,

accordingly, that of the concave mirror sector.

Further R&D is necessary for this technology to thrive. Many aspects of the

product need to be developed, especially building materials. Some information and

calculations are hard for high school students to acquire such as optical

measurements.

Sources:

1. http://www.universetoday.com/65588/what-percent-of-earth-is-water/

2. Lisa Henthorne (November 2009). "The Current State of Desalination".

International Desalination Association. Retrieved 2011-09-05.

3. http://sourcing.indiamart.com/engineering/articles/sea-water-desalination-

giving-new-lease-life-middle-east/

4. Applause, At Last, For Desalination Plant, The Tampa Tribune, December 22,

2007.

5. a b International Traffic Network, The world trade in sharks: a compendium of

Traffic's regional studies, (Traffic International: 1996), p.25

6. New York Times: Global Warming & Climate Change (2011 Durban

Conference), updated 21 dec, 2011.