Environmental Technology ( ET ) refers to the cognition and accomplishments that are necessary to pull off, work with, and control risky stuffs and pollutants. These accomplishments, based on applied scientific discipline rules, and designed to cut down human wellness and ecological hazards while being to the full in conformity with governmental ordinances. The general populace has shown interested and political influence in the last 3 decennaries in countries associating to public wellness and the environment. Greater public engagement led the authorities to ordain more Torahs related to protection of public wellness and the saving of the environment. This alteration in the way of public policy has resulted in the 1990s being heralded as the “ decennary of the environment ” .
First, recyclingA is the procedure of wastedA stuffs into new merchandises to forestall waste of potentially utile stuffs, reduces the ingestion of fresh natural stuffs, A energyA use, air pollution ( fromA incineration ) and H2O pollution ( fromA landfilling ) by cut downing the demand for “ conventional ” waste disposal, and lower the nursery gasA emanations as compared to virgin production.A Next, renewable energyA isA that energy which is A generated by biofuel, biomass, geothermic, hydroelectricity, solar energy, tidal power, wave power and air current power which come fromA renewable natural resources.
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Second, H2O purificationA is the procedure of taking unwanted chemicals, biological contaminations, suspended solids and gases from contaminated H2O by methods used such asA filtration, A deposit, distillment, A slow sand filtersA orA biologically active C, flocculation, A chlorinationA and the usage of electromagnetic radiation such asA UV visible radiation. Then, air purification is the maintaining of air freshness and it can be done by green workss because all workss have the ability of convert Carbon Dioxide intoA Oxygen.
Third, sewerage treatmentA is the procedure of taking taint from wastewaterand householdA sewerage, bothA runoffA ( wastewaters ) and domestic.A Its aim is to bring forth an environmentally safe fluid waste watercourse ( or treatedA wastewater ) for imbibing H2O intent as Singapore and a solid waste ( or treatedA sludge ) that suited for disposal or reuse as farm fertiliser. After that, environmental redress trades with the remotion of pollutants or contaminantsA from environmentalA media likeA dirt, A groundwater, A deposit, orA surface waterA for the general protection of human wellness, the environment or from brownfield siteA forA renovation intent by digging or dredging, SEAR ( surfactant enhanced aquifer redress ) , pump and dainty, hardening and stabilisation, in situ oxidization, dirt vapour extraction, phytoremediation, dual-phase extraction, mycoremediation and mycofiltration
1.2 Aims of the Study
One of the aims is to do better apprehension for the people on solar cells. This is to make more consciousness among the people of Malaysia on the importance of solar engineering.
Another intent is to present information for illustration history on how solar engineering is used in the past and in the present.
Next, it is to present the current development of solar cell engineering to the people.
Besides that, our purpose is to demo how good the solar cell engineering towards us Malaysians for current and future usage.
2.0 Literature Review:
2.1 History of Solar Technology:
In the second century B.C a Grecian scientist, Archimedes used light contemplation phenomenon utilizing a bronze shield to concentrate sunlight and bring forthing heat/fire to wooden ships of the Roman Empire which were blockade Syracuse. ( Although this is some type of myth, Greek naval forces had done an experiment to put fire in the wooden boat at a distance 50m and it was success in the twelvemonth 1973.
In 1839, the find of the effects of photovoltaic cell, an experiment was conducted by a Gallic scientist, Edmond Becquerel on a two electrodes that immersed in electricity-conducting solution, the consequences shows the coevals of electricity increased when exposed to the sunshine and in 1876 a new find had been done about Se that can make an electric energy when it is exposed to the sunshine by Richard Evans Day and William Grylls Adams.
Gerald Pearson, Calvin Fuller and Daryl Chapin had besides developed the Si photovoltaic cell in Bell Labs in United States and this is the get downing point of the being of Photovoltaic Technology in 1954. The 1st solar cell was capable to prolong sufficient sum of Sun ‘s energy and change over it into electricity that can run any electrical equipment. Bells Laboratory make a solar cell with efficiency 4 % and subsequently reached 11 % . Subsequently in 1982, the U.S. Department of Energy, along with an industry pool, begins runing Solar One, a 10-megawatt central-receiver presentation undertaking. The undertaking established the feasibleness of power-tower systems, a solar-thermal electric or concentrating solar power engineering. In 1988, the concluding twelvemonth of operation, the system could be dispatched 96 % of the clip.
Then in 1986, World largest solar thermic installation was been commissioned in Kramer Junction on California. The solar energy was being concentrated onto a system of pipes go arounding a heat transportation fluid utilizing row of mirror at the solar field. A steam is produced by the heat transportation fluid used to powered a conventional turbine to bring forth an electric energy and, U.S. Department of Energy ‘s Solar Energy Research Institute had been redesignated as the National Renewable Energy Laboratory by President George Bush in 1991.
A solar cell that was made from Ga In phosphide and Ga arsenide had become the first solar cell that success to transcend 30 % transition efficiency and it was developed by The National Renewable Energy Laboratory in 1994. Then subsequently in 1999, a photovoltaic solar cell that is able to change over 32.3 % of sunshine which hits the solar panel to electricity was developed by Spectrolab, Inc. and the National Renewable Energy Laboratory. The ground of this higher accomplishment is because they combine three beds of photovoltaic stuffs into a individual solar cell. By uniting the stuffs, it is able to have sunshine concentrated much expeditiously and can make 50 times normal. To utilize such cells in practical applications, the cell is mounted in a device that uses lenses or mirrors to concentrate sunshine onto the cell. Such “ concentrator ” systems are mounted on tracking systems that keep them pointed toward the Sun.
2.1.1 Facts of Solar cell:
In the early 1950s, R.S Ohl discovered that sunlight striking a wafer of Si will bring forth a big figure of free negatrons. In 1994, G.L Pearson, C.S Fuller, and D.M Chapin created an array of several strips of Si, placed them in sunshine, captured the free negatrons change overing them into electric current. It could merely change over 6 % of sunshine into utile energy.
Semiconductor stuffs such as Si, Ga arsenide, Cd telluride or Cu In diselenide are used in these solar cells. A solar cell or photovoltaic cell converts sunlight to electricity through photovoltaic consequence. Photovoltaic is the country of engineering and research related to the usage of solar cells as solar energy. Cell assemblies are used to do solar faculties or photovoltaic arrays. Photovoltaic cells generate energy utile where electric from the power grid is unavailable such as the usage in orbiters. The bed confronting the Sun ‘s visible radiation is negatively doped with P. The bed below it isA positivelyA dopedA withA B. At the boundary bed, an electrical field is produced that leads to the separation of the charges ( negatrons and holes ) released by the sunshine. In order to be able to take power from the solar cell, metallic contacts need to be fitted on the forepart and dorsum of the cell. Screen printing is usually used for this intent. On the buttocks of the solar cell it is possible to use a contact bed over the whole surface utilizing aluminum or Ag paste.
A all right metal grid is used on the side confronting the Sun to maintain the shaded country every bit little as possible. The front contacts are frequently applied utilizing a screen printing procedure where Ag paste is applied through a screen onto the Si wafer.
Losingss happen at the solar cell because of recombination, contemplation and shading caused by the front contacts.
Silicon is non present in pure signifier, but in chemical compounds, with O on the signifier of vitreous silica or sand. The unwanted O foremost has to be separated out of the Si dioxide. To make this, the Si is heated together with coke, C pulverization, wood coal in an electrical discharge furnace to a temperature of 1800C to 1900 Celsius.
Monocrystalline Si cells
Polysilicon is melted in a vitreous silica melting pot at around 1410 Celsius. A seed crystal with a defined orientation is dipped into the Si thaw and easy drawn upwards out of t6he thaw. In this procedure, the crystal grows into a cylindrical mono-crystal up to 30cm in diameter and several metres in length. The cylindrical mono-crystals are cut to bring forth semi-round or square bars, which are so cut with wire proverb into wafers with a thickness at about 0.3mm. During the film editing and sawing of the mono-crystals and wafers, a big sum of Si is lost as sawdust and needs to be re-melted, every bit good as the conelike terminals of the rods. The wafers are chemically wet cleaned in etching and rinsing baths to take sawing residues and Markss. The efficient rate of this cell is 14-18 % .
Polycrystalline Si cells
The silicon natural stuff is melted in a vitreous silica crucible and moulded into a cubelike form. The ground of this directed hardening is to do large Numberss of the biggest possible homogeneous Si crystals, with grain size from a few millimetres to a few centimetres. The grain boundaries make up crystal defects with an increased recombination hazard and have a negative consequence on the efficiency of polycrystalline solar cells, which is lower than mono-crystalline cells. Using this method, big Si blocks are made. The efficiency of this cell is 13 to 17 % .
Ribbon pulled Si cells
To deter high stuff losingss and promote material use, assorted ribbon-pulling ways have been created. The Si threads have already possess the thickness of future wafers, so the level surfaces are cut into pieces with optical masers.
They have been developed to follow with demands and the fabrication costs of solar cells. Alternate production ways such as vapour deposition, electroplating, and usage of Supersonic Nozzles are good because they decrease high temperature treating significantly. The most moneymaking 2nd coevals stuffs are cadmium telluride, Cu In Ga selenide, formless Si and micromorphous Si. These stuffs are put in a thin movie to a back uping substrate like glass or ceramics to diminishing material mass and costs.
In the early 1990s there has been increased development for bring forthing solar cells. In these photoactive semiconducting materials are used as thin beds to a low priced substrate. The ways used consists of vapour deposition, spatter procedures ( cathode sputtering ) and electrolytic baths with many beds. The thickness scope of that certain bed is large and differs from a few nanometres to 10s of microns. Assorted photovoltaic stuffs are deposited with different deposition ways with a diverseness of substrates. Thin Film Solar cells are frequently classified based on the photovoltaic stuff used. Even though the efficiency is low, the energy aggregation can under certain conditions be rather considerable. The use of diffuse and dim visible radiation is better in thin movie cells and there is a more preferable temperature coefficient. Thin movie cells have less sensitiveness to shading.
During the early 1990s research labs have been for many old ages able to make a really efficient crystalline Si cells with efficiency of up to 25 per centum. The electrical losingss are reduced. The beginning stuff used here is a truly pure polycrystalline Si rod with a mono-crystalline Si seed at its terminal. This stuff is truly expensive. Third coevals engineering was created to get the better of hapless electrical public presentation of 2nd coevals engineering at the same clip bring forthing at low fabrication costs. Research right now is taking transition efficiencies of 30 to 60 % while keeping low cost stuffs and low fabrication methods. They can transcend the theoretical solar transition efficiency bound for one energy threshold stuff, that was counted in 1961 by Shockley and Queisser as 31 % under 1 sun light and 40.8 % under maximal concentration of sunshine. Technologies includes: Silicon nanostructures, Up/Down convertors, Hot-carrier cells, Thermoelectric cells.
2.2The current usage of Solar cells:
2.2.1 Architecture and urban planning:
This type of engineerings has influenced the edifices planing since the beginning of the architectural history. The methods of this engineering were foremost employed by the Greeks and the Chinese who used this engineering for many things such as warming up their houses in the cold seasons. The common construct ( definition ) of Solar is largely related to Sun. one of the authoritative illustrations of this solar engineering design is the Socrates Megaron house, the newest solar design presents are utilizing computing machine mold.
2.2.2 Solar thermic energy:
It ‘s a really utile manner change overing the solar energy to acquire a thermic energy alternatively of it. The Solar Thermal Energy low temperature aggregators are largely a level home bases by and large used to heat swimming pools. The medium temperature aggregators are besides level home bases but are frequently used for heating the H2O and used besides for the residential and the commercial intents. The high temperature aggregators are frequently used for roll uping or making the electricity, this type of Solar cells coverts.
This type of power is a transition of sunshine into electricity. Either by utilizing exposure Gur or indirectly by utilizing concentrated solar power.CSP systems use mirrors or lenses and tracking systems to concentrate a big country of Sun visible radiation into a little beam. Photovoltaic converts visible radiation into an electric current by utilizing the Photoelectric consequence.
2.2.3 Solar Chemical:
This type of Solar Applications uses the solar energy to execute the chemical reactions. The chemical processes countervail energy that would otherwise come from a fossile fuel beginning and it can besides change over the energy of the solar into a storable and movable fuel. Solar induced chemical reaction can be divided into two classs thermo chemical or photochemical. It is besides possible to bring forth a assortment of fuels by the unreal photosynthesis.
The solar has besides many other application which being presently used in assorted things in our life such as the of the solar for salvaging or hive awaying energy. The solar is still considered as a major manner to hold the energy for our day-to-day life.
2.3Usage/Purpose of Solar Cell:
The modern solar cell is an electronic device, fabricated from semiconducting stuff. It converts a fraction of the energy contained in sunshine straight to electrical energy at a electromotive force and current degree based on the factors such as the belongingss of the semiconducting material, the solar cell design and building technique, and the incident visible radiation.
Solar cell has been used in many applications by commercial companies, occupants, and besides military section such as power beginnings for places and commercial edifices, set downing obstructor visible radiations for airdrome, H2O pumping for irrigation, margin dismay senders, electronic boundary line fencings, invasion dismaies for security, main road marks, portable back pack wirelesss, remotely located, remote-controlled electronic surveillance systems, educational Television broadcast medium, and etcetera.
Increasing oil monetary values, terrorist onslaughts on oil installings, high energy costs, inauspicious political environments, terrible conditions conditions, high capital investings, radiation from atomic power station and planetary nursery effects have compelled energy contrivers to look for alternate beginnings to cut down trust on fossil fuels and to exchange to other clean signifiers of energy needed to protect Earth. With these grounds, all industrial and Western states such as the United States, Germany, Japan, Brazil, Italy, Spain, and other European states are turning to electrical power coevals from solar cells.
2.3.1 The Cost:
Housing construction, protective screen, fabricating tolerances, quality control reviews needed, panel size and type and figure of solar cells installed on a given panel country determine the solar panel production cost. Preliminary solar panel cost estimations received from assorted panel providers and installers indicate that approximately 65 % of the cost is for solar panels or faculties, 15 % of the cost is for the inverter and staying 20 % is for the labour required for panel installing. However, the overall solar power system cost for residential installings varies from 6 to 8 dollars per W of the installed capacity. Based on this cost estimation, a 5 kilowatt solar power system will be presently anyplace from $ 30,000 to $ 40,000 before the discounts and revenue enhancement inducements. Harmonizing to panel providers, both the province and federal revenue enhancement benefits come to about $ 10,000, which can hold a pay-back clip of 10 old ages for a household with a annual electric measure of $ 2,000.
2.3.2 The Advantages:
There are many advantages worth sing when it comes to solar energy and everything that it offers.
Solar cells are non merely environmental-friendly, but they offer clean, efficient, dependable, self-contained, dependable, quiet, maintenance-free, and year-round uninterrupted and limitless operation at moderate costs and uninterrupted beginnings of electrical energy. Furthermore, it ‘s a long-run device as it can last longer up to 20-30 old ages. It besides can be constructed to any size based on energy demands. Solar energy is a wholly renewable beginning of energy.
Furthermore, really small care is required to maintain solar cells running. There are no traveling parts as machines in a solar cell. Solar panels and solar lighting may look rather expensive for the first purchase, but in the long tally it is salvaging rather a great trade of money. After all, it does non be anything to tackle the power of the Sun and therefore do the most of the world that solar power brings autonomy. Besides, people have begun utilizing it more and more non merely for personal usage, but for mainstream usage as this energy helps people become autonomous in a universe where there is scarceness of electricity. Billions of dollars can be saved as people easy get out of the immense energy crisis that they are confronting today. Next, solar powered panels and merchandises are typically highly easy to put in. Wires, cords and power beginnings are non needed at all. Tax interruptions and inducements have offered for some country for put ining solar panel systems, for illustration at California, offers such enterprises to their residents.A
Solar power engineering is bettering systematically over clip, as people begin to understand all of the benefits offered by this unbelievable engineering.
2.3.3. The Disadvantages/Limitation:
The sum of sunshine being received by solar cell depends on the clip of twenty-four hours, the season of the twelvemonth, geographic location and clime conditions. Peak power degrees are generated merely under the summer Sun and clear skies. Even if a trailing solar energy aggregation system is used, it ‘s hard to vouch the unvarying solar energy input.In add-on, proprietors of commercial solar power systems must maintain a sensible figure of trim parts for the system they own such as solar cell faculties and shunt regulators.
Temperature affects the solar array public presentation. The solar array ‘s design electromotive force of 15V will drop to 13V if the noontime temperature reaches 43oC.. The efficiency depends on the status of the mirrors or lenses and the truth of the solar trailing setup.
The presence of wet on the solar cell surface degrades the cell public presentation significantly due to losingss by soaking up and refraction, and causes the growing of organic substances. The ultraviolet beams of the Sun darken the encapsulating stuff, taking to farther decrease in the cell public presentation.
Gluey surfaces of faculties collect soil easier therefore shadowing the panels.