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INTRODUCTION
Every day, the sun radiates (sends out) an enormous amount of energy—called solar energy. It radiates more energy in one second than the world has used since time gan. This energy comes from within the sun itself. Like most stars, the sun is a big gas ball made up mostly of hydrogen and helium gas. The sun makes energy in its inner core in a process called nuclear fusion. It takes the sun’s energy just a little over eight minutes to travel the 93 million miles to Earth. Solar energy travels at a speed of 86,000 miles per second, the speed of light. Only a small part of the radiant energy that the sun meets into space ever reaches the Earth, but that is more than enough to supply all our energy needs. Every day enough solar energy reaches the Earth to supply our nation’s energy needs for a year! Solar energy is considered a renewable energy source. Today, people use solar energy to heat buildings and water and to generate electricity.
Environment is a very broad concept. Everything that affects us during our lifetime is collectively known as environment. As human beings we are often concerned with surrounding conditions that affect people and other organisms. Today, all over the world there is growing concern about the deteriorating quality of environment and efforts are being made to stop the widespread abuse of environment and improve its quality. The first worldwide meeting of heads of state in response to the concerns for the environment took place at the Earth Summit, formally known as the United Nations Conference on Environment and Development (UNCED) in Rio de Janeiro in 1992. This conference reflects world-wide concern about the quality of our environment. International Environment Education Programme is the outcome of the 1992 conference and efforts are being made globally to educate people at all levels of society about the environmental concerns. The environment in which we live and work affects our thoughts, feelings, and behaviours. The relationship of man and environment is, however, bi-directional. That is, human beings are affected by the environment and they also affect the environment. The study of environmental psychology emphasises this interaction. In this lesson we will learn about various aspects of the man-environment interaction.
Electromagnetic radiation ranges from low frequency,relatively low energy, radiation such as radio and microwaves through to infra red, visible light, ultraviolet, X-rays and gamma rays. These last as well as other forms of radioactivity such as high energy subatomic particles (e.g. electrons - Beta rays) can cause intracellular ionisation and are therefore called ionising radiation. Exposure to ultraviolet (UV) radiation carries a increased risk of skin cancer such as melanoma, and of cataracts which are to an extent exposure related. Some pollutants such as chlorofluorocarbons (CFCs) used as refrigerants or in aerosol propellants or in the manufacture of certain plastics can damage the "ozone layer" in the higher atmosphere (stratosphere) and thus allow more UV light to reach us, and harm us directly. Ultraviolet light may also cause harm indirectly by contributing to an increase in ozone in the troposphere (the air we breathe) - see below under chemical hazards, or elsewhere in connection with air quality.
Solar Energy
Solar energy, radiant light and heat from the sun, has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar energy technologies include solar heating, solar photovoltaic’s, solar thermal electricity and solar architecture, which can make considerable contributions to solving some of the most urgent energy problems the world now faces.
Solar technologies are broadly characterized as either passive solar or active solar depending on the way they capture, convert and distribute solar energy. Active solar techniques include the use of photovoltaic panels and solar thermal collectors to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate air.
In 2011, the International Energy Agency said that "the development of affordable, inexhaustible and clean solar energy technologies will have huge longer-term benefits. It will increase countries’ energy security through reliance on an indigenous, inexhaustible and mostly import-independent resource, enhance sustainability, reduce pollution, lower the costs of mitigating climate change, and keep fossil fuelprices lower than otherwise. These advantages are global. Hence the additional costs of the incentives for early deployment should be considered learning investments; they must be wisely spent and need to be widely shared"
Solar Energy Devices
Solar energy refers primarily to the use of solar radiation for practical ends. A partial list of solar applications includes space heating and cooling through solar architecture, potable water via distillation and disinfection, daylighting, solar water heating, solar cooking, and high temperature process heat for industrial purposes. To harvest the solar energy, the most common way is to use solar panels.
Solar Panel
These panels are made up of solar cells, which have the property of directly converting sunlight into electricity by photovoltaic effect. The solar cells constituting these panels are made up of monocrystalline or polycrystalline silicon wafers.
Features & Specification
• Mounted with tough aluminum frame
• Sealed junction box seldom needs maintenance
• Environment friendly product.
SOLAR CHIMNEY
In its simplest form, the solar chimney consists of a black-painted chimney. During the day solar energy heats the chimney and the air within it, creating an updraft of air in the chimney. The suction created at the chimney's base can be used to ventilate and cool the building below.[1] In most parts of the world it is easier to harness wind power for such ventilation as is done with a Badgir , but on hot windless days a Solar chimney can provide ventilation where otherwise there would be none.
There are however a number of solar chimney variations. The basic design elements of a solar chimney are:
• The solar collector area: This can be located in the top part of the chimney or can include the entire shaft. The orientation, type of glazing, insulation and thermal properties of this element are crucial for harnessing, retaining and utilizing solar gains
• The main ventilation shaft: The location, height, cross section and the thermal properties of this structure are also very important.
• The inlet and outlet air apertures: The sizes, location as well as aerodynamic aspects of these elements are also significant.
This solar chimney draws air through a geothermal heat exchange to provide passive home cooling.
Air conditioning and mechanical ventilation have been for decades the standard method of environmental control in many building types, especially offices, in developed countries. Pollution and reallocating energy supplies have led to a new environmental approach in building design. Innovative technologies along with bioclimatic principles and traditional design strategies are often combined to create new and potentially successful design solutions.
The use of a solar chimney may benefit natural ventilation and passive cooling strategies of buildings thus help reduce energy use, CO2 emissions and pollution in general. Potential benefits regarding natural ventilation and use of solar chimneys are:
Potential benefits regarding passive cooling may include:
• Improved passive cooling during warm season (mostly on still, hot days)
• Improved night cooling rates
• Enhanced performance of thermal mass (cooling, cool storage)
• Improved thermal comfort (improved air flow control, reduced draughts)
CAD (TAS) Solar Chimney model
• Improved ventilation rates on still, hot days
• Reduced reliance on wind and wind driven ventilation
• Improved control of air flow though a building
• Greater choice of air intake (i.e. leeward side of building)
• Improved air quality and reduced noise levels in urban areas
• Increased night time ventilation rates
• Allow ventilation of narrow, small spaces with minimal exposure to external elements
A solar fan with externally mounted solar panels
A solar fan is a mechanical fan powered by solar panels. The solar panels are either mounted on the device or are installed independently. Solar fans mostly do not require secondary power sources other than solar power, as most of them are used for cooling purposes during day time. Some types are also used for heating purposes. It runs the fastest when it is the hottest outside providing savings on air conditioning costs.
Solar fans are mostly applied for residential cooling purposes [3] and in some cases, for industrial applications.
Solar mirror
A solar mirror in the Solar Collector Laboratory at Lewis Research Center, November 1966
A solar mirror is a reflective surface used for gathering and reflecting solar energy in a system being powered by solar energy. It comprises a substrate with a reflective layer for reflecting the solar energy, and in most cases an interference layer. This may be a planar mirror or parabolic arrays of solar mirrors used to achieve a substantially concentrated reflection factor for solar energy systems.
Solar Water Pumping System
This water pumping system consists of a pump, an electric motor, a controlling device and a solar module. It can be used to provide water for drinking purposes as well as for irrigation. Its applications also include providing water for swimming pools, remote areas, camping car etc.
Features & Specification
• Automatic operation, so no need for any manual intervention
• High efficiency and reliability
• Easy to install and requires minimum maintenance
• Longer lifespan
• Environment friendly product
Components
Unlike a normal pump (such as positive displacement pumps, ...), the solar powered pump is actually a more of a dictionary phrase than a technical one. It is only used to describe that there's a pump, being powered by another device (such as solar panels), being powered by the renewable electricity generated from the sun (solar electricity).
A solar powered pump thus consists of 4 parts :
• the actual fluid pump (that actually moves (pumps) gases or liquids under pressure)
• the controller (adjusting speed and output power according to input from solar panels)
• the engine (usually an electric motor)
• the energy source being powered by the sun (usually photovoltaic cells (solar panels))
Solar array (photovoltaic cells, solar panels) takes up 50% - 80% of the whole setup cost, which is the most expensive part.
There are two major types of solar pumps, DC (direct current) and AC (alternating current). DC solar pump:
• power output up to 3 kW
• suitable for small to medium applications like garden fountain, landscaping,livestock drinking,irrigation, etc.
• low-price (require 40% less solar panel compare to AC solar pumps)
• DC brushless pump is about 20% higher efficiency than AC pumps
• A pumps controller is required
AC solar pump: An inverter is needed for an AC solar pump setup. The inverter converts DC generated from solar array to AC to drive the pumps in the mean time (as the controller) to control output and speed.
• power output range from 150W to 55 kW
• suitable for various applications from landscaping to irrigation, especially large scale such as big farmland irrigation,tunnel water supply, etc.
• An big DC-AC inverter required
AC pumps is an inductive load, the start-up requires almost twice current than it in normal operations,thus the panel size should 1.8~2 of the motor size.
Applications
Water pumping
Solar PV water pumping systems are used for irrigation and drinking water in India. The majority of the pumps are fitted with a 200 watt - 3,000 watt motor are powered with 1,800 Wp PV array which can deliver about 140,000 liters of water/day from a total head of 10 meters. By 30 September 2006, a total of 7,068 solar PV water pumping systems have been installed.
Oil and gas
In order to combat negative publicity related to the environmental impacts of fossil fuels, including fracking, the industry is embracing solar powered pumping systems.[2] Many oil and gas wells require the accurate injection (metering) of various chemicals under pressure to sustain their operation and to improve extraction rates. Historically, these chemical injection pumps (CIP) have been driven by gas reciprocating motors utilizing the pressure of the well's gas and exhausting the raw gas into the atmosphere. Solar powered electrical pumps (solar CIP) can reduce these greenhouse gas emissions. Solar arrays (photovoltaic cells) not only provide a sustainable power source for the CIPs but can also provide an electric source to run remote SCADA type diagnostics with remote control and satellite/cell communications from very remote locations to a desktop or notebook monitoring computer.
Solar-powered refrigerator
A solar-powered refrigerator is a refrigerator which runs on electricity provided by solar energy.
Solar-powered refrigerator are able to keep perishable goods such as meat and dairy cool in hot climates, and are used to keep much needed vaccines at their appropriate temperature to avoid spoilage.
Solar-powered refrigerators may be most commonly used in the developing world to help mitigate poverty and climate change.
There is major environmental concern regarding conventional refrigeration technologies including contribution to ozone layer depletion and global warming. Refrigerators which contain ozone depleting and global warming substances such as chlorofluorocarbons (CFCs), in their insulation foam or their refrigerant cycle are the most harmful. After CFCs were banned in the 1980s they were replaced with substances such as hydrochlorofluorocarbons (HCFCs), which are ozone depleting substances and hydrofluorocarbons (HFCs). Both are environmentally destructive as potential global warming chemicals. If a conventional refrigerator is inefficient or used inefficiently, it will also contribute more to global warming than a highly efficient refrigerator. The use of solar energy to power refrigeration strives to minimize the negative impacts refrigerators have on the environment. Fishermen in the village of Maruata, which is located on the Mexican Pacific coast 18 degrees north of the equator, have no electricity. But for the past 16 years they have been able to store their fish on ice: Seven ice makers, powered by nothing but the scorching sun, churn out a half ton of ice every day.
Solar-powered watch
A solar-powered watch is a watch that is powered entirely or partly by a solar panel.
Some of the early solar watches of the 1970s had innovative and unique designs to accommodate the array of solar cells needed to power them (Synchronar, Nepro, Sicura and some models by Cristalonic, Alba, Seiko and Citizen). In the 1990s, Citizen started to sell light-powered watches under the Eco-Drive series name. Since their introduction, photovoltaic modules/solar panels, have greatly improved their efficiency and thereby their capacity. Watchmakers have developed their technology such that solar-powered watches are now a major part of their range of watches. Several other watch manufacturers offer similar watches or are developing such technology. These other watch manufacturers include (amongst others) Junghans, Casio and Seiko.
Typically, sunlight and artificial light are absorbed by a solar panel behind the crystal. The dial is either on a layer above or actually on the solar panel. This solar panel converts the light into electrical energy to power the watch. The watch will usually store energy in a rechargeable cell to power itself during the night or when covered such as by a person's sleeve. Citizen's watches use lithium-ion batteries to store sufficient energy to power the watch for several months/years of darkness. However, this (years) figure assumes that the watch enters a power-saving mode during which the seconds hand stops until the watch is re-exposed to light. Not all have a power-save mode, yet will still hold a charge for typically six months, such as fairly uncomplicated (date only) analog versions made by Citizen.