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Solar energy
- 1. ALTERNATIVE ENERGIES DONE BY AMEENAH KHAN 09/0509/1391
- 5. SOLAR ENERGY
- 13. SOLAR CELL Solar modules/panels A basic structure of a typical solar cell
- 34. THANK YOU
Notes de l'éditeur
- The spectrum of electromagnetic radiation striking the Earth's atmosphere spans a range of 100 nm to about 1 mm . This can be divided into five regions in increasing order of wavelengths : Ultraviolet C or (UVC) range, which spans a range of 100 to 280 nm. The term ultraviolet refers to the fact that the radiation is at higher frequency than violet light (and, hence also invisible to the human eye ) Ultraviolet B or (UVB) range spans 280 to 315 nm. It is also greatly absorbed by the atmosphere, and along with UVC is responsible for the photochemical reaction leading to the production of the ozone layer Ultraviolet A or (UVA) spans 315 to 400 nm. It has been traditionally held as less damaging to the DNA , and hence used in tanning and PUVA therapy for psoriasis . Visible range or light spans 380 to 780 nm. As the name suggests, it is this range that is visible to the naked eye. Infrared range that spans 700 nm to 106 nm (1 mm ). It is responsible for an important part of the electromagnetic radiation that reaches the Earth
- Concentrated solar power systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam.
- Solar cells are often electrically connected and encapsulated as a module . Photovoltaic modules often have a sheet of glass on the front (sun up) side, allowing light to pass while protecting the semiconductor wafers from abrasion and impact due to wind-driven debris, rain , hail , et cetera. Solar cells are also usually connected in series in modules, creating an additive voltage . Connecting cells in parallel will yield a higher current. Modules are then interconnected, in series or parallel, or both, to create an array with the desired peak DC voltage and current.
- The solar cell works in three steps: Photons in sunlight hit the solar panel and are absorbed by semiconducting materials, such as silicon. Electrons (negatively charged) are knocked loose from their atoms, allowing them to flow through the material to produce electricity. Due to the special composition of solar cells, the electrons are only allowed to move in a single direction. An array of solar cells converts solar energy into a usable amount of direct current (DC) electricity. Most commercially available solar cells are capable of producing electricity for at least twenty years without a significant decrease in efficiency.
- Slide 14- after 1st pt Techniques such as timed planting cycles, tailored row orientation, staggered heights between rows and the mixing of plant varieties can improve crop yields.
- Slide 15- after 1st pt This passive technology directly offsets energy use by replacing artificial lighting, and indirectly offsets non-solar energy use by reducing the need for air-conditioning
- After 2nd pt- HSL systems collect sunlight using focusing mirrors that track the Sun and use optical fibers to transmit it inside the building to supplement conventional lighting.
- Slide 19-after 2nd pt The use of evaporation ponds to obtain salt from sea water is one of the oldest applications of solar energy. Modern uses include concentrating brine solutions used in leach mining and removing dissolved solids from waste streams
- Slide 22-after 2nd pt Aside from electrolysis driven by photovoltaic or photochemical cells, several thermochemical processes have also been explored. One such route uses concentrators to split water into oxygen and hydrogen at high temperatures (2300-2600 °C).
- Slide 23- after 2nd pt As sunlight shines on the balloon, the air inside is heated and expands causing an upward buoyancy force, much like an artificially heated hot air balloon. Last pt Unlike rockets, solar sails require no fuel. Although the thrust is small compared to rockets, it continues as long as the Sun shines onto the deployed sail and in the vacuum of space significant speeds can eventually be achieved
- Slide 24-after 3rd pt A prime example of this is in space, where satellites are powered by high efficiency solar cells. After 6th pt Eliminates the problem of finding the required space for solar panel placement. After 7th pt Although the initial investment of solar cells may be high, once installed, they provide a free source of electricity, which will pay off over the coming years.
- slide 26- Environmental Effects of Solar Energy carbon emissions The best thing about solar energy in terms of its environmental effects is that it produces almost no carbon emissions or greenhouse gases. It doesn't burn oil, it doesn't produce toxic waste, and its lack of moving parts reduces the chances of an environmentally devastating accident to nil. Indeed, the only pollutants which factor into solar power are those involved in the construction and transportation of its parts; that ranks it among the cleanest forms of energy on Earth. Implementing solar energy on a large scale would reduce its environmental footprint to a tiny fraction of its current levels. Renewable energy Solar power is also environmentally advantageous because its energy supply never runs out. Sunlight will always shine upon the Earth and, as long as it does, hold energy which solar technology can exploit. Contrast this with fossil fuels such as coal or oil, which need to be mined or drilled and thus have a tremendous environmental impact, even in comparatively safe circumstances. Abundant Components The photovoltaic cells which constitute most solar energy systems are usually made of silicon, one of the most common minerals found on Earth. That means that creating the components is extremely easy, doesn't require mining or drilling in a dangerous locale to produce, and can be acquired without involvement in politically unstable areas such as the Middle East. The environmental effects of this are subtle but, because fewer resources are expended in the acquisition of silicon, its overall effect on the ecosystem is reduced. Cadmium Cadmium is used in cadmium telluride solar cells as a semiconductor to convert solar energy into electricity. Though used in very small amounts, it is extremely toxic and can build up in a given ecosystem if it isn't monitored. Firms which make this kind of solar cell often instigate recycling programs so that damaged or unusable cells don't inadvertently damage the surrounding environment. Space Considerations Solar panels are not as efficient as they could be -- one of the reasons why they have not been widely implemented yet. To capture appreciable amounts of energy, they require a large number of cells, which can take up a considerable amount of space. One practical solution is to mount the cells on a rooftop, which saves a lot of space while still allowing them maximum exposure to the sun. Large-scale solar farms still require a lot of room, however, and trees and bushes can't coexist with them lest they block sunlight from the receivers.
- Slide 27-after 2nd pt-- MEDICAL USES OF SOLAR ENERGY It deactivates the DNA from pathogens and makes it impossible for them to multiply. Ultraviolet light damages the nucleic acid of microorganisms which keeps the organism from reproducing. After 4th pt- Dr. Stallone at Arizona Integrative Medical Center uses ozone or hydrogen peroxide combined with light therapy to restore oxidative metabolism. This treats chronic diseases. After last pt This is called phototherapy. UVA phototherapy is generally used along with psoralen which is a light sensitizing tablet. UVB uses one wavelength to treat skin diseases and is very beneficial for psoriasis. It is also used to treat pruritus, vitiligo and lichen planus. These treatments help heal inflamed tissues, damaged cells and wounds. Ultraviolet germicidal or bactericidal lamps are often used in the medical field to help keep disease under control so it doesn't spread. Common Microorganisms Destroyed by UV Light: Bacillus anthracis Corynebacterium diphtheriae Dysentary bacilli (diarrhea) Escherichia coli (diarrhea) Legionella pneumophilia Mycobacterium tuberculosis Pseudomonas aeruginosa Salmonella (food poisoning) Salmonella paratyphi (enteric fever) Salmonella typhosa (typhoid fever) Shigella dysentariae (dysentery) Shigella flexneri (dysentery) Staphylococcus epidermidis Streptococcus faecaelis Vibro commo (cholera) Bacteriophage (E. Coli) Hepatitis Influenza Poliovirus (poliomyelitis) Baker's yeast What are the Advantages of UV Disinfection? Environmentally friendly, no dangerous chemicals to handle or store, no problems of overdosing. Universally accepted disinfection system for potable and non-potable water systems. Low initial capital cost as well as reduced operating expenses when compared with similar technologies such as ozone, chlorine, etc. Immediate treatment process, no need for holding tanks, long retention times, etc. Extremely economical, hundreds of gallons may be treated for each penny of operating cost. Low power consumption. No chemicals added to the water supply - no by-products (i.e. chlorine + organics = trihalomethanes). Safe to use. No removal of beneficial minerals. No change in taste, odor, pH or conductivity nor the general chemistry of the water. Automatic operation without special attention or measurement, operator friendly. Simplicity and ease of maintenance, TWT Deposit Control System prevents scale formation of quartz sleeve, annual lamp replacement, no moving parts to wear out. No handling of toxic chemicals, no need for specialized storage requirements, no OHSA requirements. Easy installation, only two water connections and a power connection. More effective against viruses than chlorine. Compatible with all other water processes (i.e., RO, filtration, ion exchange, etc.)
- Solar Energy Health Effects on Humans Slide 28- after 1st pt Electromagnetic Radiation From Solar Panels Modern solar systems use components that radiate high levels of radio frequency electromagnetic radiation, which poses health risks to those with electromagnetic hypersensitivity (EHS). The primary health hazard involved with solar energy generation is that people with EHS get sick from electromagnetic radiation in even very small amounts. Such a health problem may be triggered by small frequencies from cell phones, computers and other electronic appliances. The production of solar energy can further aggravate the situation. Since some of the symptoms of this health risk are common and non-specific, such as headaches and restlessness, a person inside a solar-powered home or building may not even realize what's going on. Silicon Dust from Solar Panels A solar panel's basic component contains pure silicon. Silicon dust is a harmful substance when inhaled, especially over long periods of time. Exposure to this dust can result in a lung disease called silicosis, which causes scar tissue to form in the lungs. This scar tissue reduces the lungs' capacity to process oxygen. Solar cells are also made of non-recyclable materials. Therefore, the absence of an environment-friendly way to dispose of non-functioning solar cells could pose a threat to the environment as well. Exposure to Electrical and Chemical Components of Solar Heat Systems A solar hot water system takes the heat of the sun to warm up bath water. Some solar heat systems can heat up an entire house. These technologies usually have a solar collector that processes the energy to generate heat. These methods pose health risks to chemically or electrically sensitive people, especially if they are constantly exposed to these systems. The Future of Solar Energy With more research and development projects, the health risks related to the acquisition and utilization of solar energy can be better managed and addressed. Hopefully, new solar energy technology will be free from these negative health effects.
- Solar energy project in Guyana Summary- A solar energy system will provide 1st ever electricity & HF radio communication for isolated village of 100 Amerindians; students/adults will benefit from DVD/TV educational & entertainment programs Potential Long Term Impact Solar energy/HF radio will improve quality of life for 100 persons in rainforest environment thru immediate radio contact for medical emergencies, community meetings & better educational systems. It will bring smiles to faces via DVD entertainment.