Solar Energy: The Ultimate Source Of Energy

Efforts By: Efforts By: GaurangGaurang (X-D 20)(X-D 20)

The SunThe Sun

yellow dwarf star in the center yellow dwarf star in the center

of the solar systemof the solar system

diameter = 1,392,000 kmdiameter = 1,392,000 km

mass = 2×10mass = 2×103030kg, kg,

99.86% of the solar system’s total mass99.86% of the solar system’s total mass

¾ hydrogen, the rest is mostly helium¾ hydrogen, the rest is mostly helium

primary source of energy in the earth primary source of energy in the earth

What is Solar Energy?What is Solar Energy? Originates with the Originates with the

thermonuclear thermonuclear fusion reactions fusion reactions occurring in the occurring in the sun.sun.

Represents the Represents the entire entire electromagnetic electromagnetic radiation (visible radiation (visible light, infrared, light, infrared, ultraviolet, x-rays, ultraviolet, x-rays, and radio waves).and radio waves).

Advantages and Advantages and DisadvantagesDisadvantages AdvantagesAdvantages

All chemical and radioactive polluting All chemical and radioactive polluting byproducts of the thermonuclear reactions byproducts of the thermonuclear reactions remain behind on the sun, while only pure remain behind on the sun, while only pure radiant energy reaches the Earth.radiant energy reaches the Earth.

Energy reaching the earth is incredible. By Energy reaching the earth is incredible. By one calculation, 30 days of sunshine striking one calculation, 30 days of sunshine striking the Earth have the energy equivalent of the the Earth have the energy equivalent of the total of all the planet’s fossil fuels, both used total of all the planet’s fossil fuels, both used and unused!and unused!

DisadvantagesDisadvantages Sun does not shine consistently.Sun does not shine consistently. Solar energy is a diffuse source. To harness Solar energy is a diffuse source. To harness

it, we must concentrate it into an amount and it, we must concentrate it into an amount and form that we can use, such as heat and form that we can use, such as heat and electricity. electricity.

Addressed by approaching the problem Addressed by approaching the problem through: through:

1) collection, 2) conversion, 3) storage.1) collection, 2) conversion, 3) storage.

How much solar energy?How much solar energy?

The surface receives about 47% of the total solar energy that reaches the Earth. Only this amount is usable.

Power TowersPower Towers“Solar One”, Barstow, California ,1,800 sun-tracking mirrors reflect heat to a central collector

Solar Panels in UseSolar Panels in Use Because of their current costs, Because of their current costs,

only rural and other customers only rural and other customers far away from power lines use far away from power lines use solar panels because it is more solar panels because it is more cost effective than extending cost effective than extending power lines.power lines.

Note that utility companies are Note that utility companies are already purchasing, installing, already purchasing, installing, and maintaining PV-home and maintaining PV-home systems (Idaho Power Co.).systems (Idaho Power Co.).

Largest solar plant in US, Largest solar plant in US, sponsored by the DOE, served sponsored by the DOE, served the Sacramento area, the Sacramento area, producing 2195 MWh of producing 2195 MWh of electric energy, making it cost electric energy, making it cost competitive with fossil fuel competitive with fossil fuel plants. plants.

Efficiency and Efficiency and DisadvantagesDisadvantages

Efficiency is far lass Efficiency is far lass than the 77% of solar than the 77% of solar spectrum with usable spectrum with usable wavelengths.wavelengths.

43% of photon energy is 43% of photon energy is used to warm the used to warm the crystal.crystal.

Efficiency drops as Efficiency drops as temperature increases temperature increases (from 24% at 0°C to 14% (from 24% at 0°C to 14% at 100°C.)at 100°C.)

Light is reflected off the Light is reflected off the front face and internal front face and internal electrical resistance are electrical resistance are other factors.other factors.

Overall, the efficiency is Overall, the efficiency is about 10-14%.about 10-14%.

Cost of electricity from coal-Cost of electricity from coal-burning plants is anywhere burning plants is anywhere b/w 8-20 cents/kWh, b/w 8-20 cents/kWh, while photovoltaic power while photovoltaic power generation is anywhere b/w generation is anywhere b/w $0.50-1/kWh.$0.50-1/kWh.

Does not reflect the true Does not reflect the true costs of burning coal and its costs of burning coal and its emissions to the emissions to the nonpolluting method of the nonpolluting method of the latter.latter.

Underlying problem is Underlying problem is weighing efficiency against weighing efficiency against cost.cost. Crystalline silicon-more Crystalline silicon-more

efficient, more expensive efficient, more expensive to manufactureto manufacture

Amorphous silicon-half as Amorphous silicon-half as efficient, less expensive efficient, less expensive to produce.to produce.

Uses Of Solar Uses Of Solar EnergyEnergy 1. 1. Architecture and PlanningArchitecture and Planning: :

Sunlight has influenced building design since the Sunlight has influenced building design since the beginning of architectural historybeginning of architectural history. Advanced solar . Advanced solar architecture and urban planning methods were first architecture and urban planning methods were first employed by the employed by the Greeks and  and Chinese, who oriented their , who oriented their buildings toward the south to provide light and warmthbuildings toward the south to provide light and warmth. . Urban heat islands (UHI) are metropolitan areas with Urban heat islands (UHI) are metropolitan areas with higher temperatures than that of the surrounding higher temperatures than that of the surrounding environmentenvironment. A straightforward method of counteracting . A straightforward method of counteracting the UHI effect is to paint buildings and roads white and the UHI effect is to paint buildings and roads white and plant trees. Using these methods, plant trees. Using these methods, a hypothetical "cool a hypothetical "cool communities" program in communities" program in Los Angeles has projected that  has projected that urban temperatures could be reduced by approximately urban temperatures could be reduced by approximately 3 °C at an estimated cost of US$1 billion, giving 3 °C at an estimated cost of US$1 billion, giving estimated total annual benefits of US$530 million from estimated total annual benefits of US$530 million from reduced air-conditioning costs and healthcare savings.reduced air-conditioning costs and healthcare savings.

2. 2. Agriculture and Horticulture: Agriculture and Horticulture: Agriculture and  and horticulture seek to optimize the capture of  seek to optimize the capture of solar energy in order to optimize the productivity solar energy in order to optimize the productivity of plants. of plants.  Greenhouses convert solar light to  convert solar light to heatheat, enabling year-round production and the , enabling year-round production and the growth (in enclosed environments) of specialty growth (in enclosed environments) of specialty crops and other plants not naturally suited to the crops and other plants not naturally suited to the local climate. local climate. Primitive greenhouses were first Primitive greenhouses were first used during Roman times to produce used during Roman times to produce cucumbers year-round for the Roman emperor  year-round for the Roman emperor Tiberius.. The  The first modern greenhouses were built in Europe in first modern greenhouses were built in Europe in the 16th century to keep exotic plants brought the 16th century to keep exotic plants brought back from explorations abroad.back from explorations abroad.[34] Greenhouses  Greenhouses remain an important part of horticulture today, remain an important part of horticulture today, and plastic transparent materials have also been and plastic transparent materials have also been used to similar effect in used to similar effect in polytunnels and  and row covers..

3. Water Treatment: 3. Water Treatment: Solar distillation can be used to make Solar distillation can be used to make saline or  saline or  brackish water potable. The  potable. The first recorded instance of this was by first recorded instance of this was by 16th-century Arab alchemists. A large-16th-century Arab alchemists. A large-scale solar distillation project was first scale solar distillation project was first constructed in 1872 in the constructed in 1872 in the Chilean mining town of Las Salinas. The plant,  mining town of Las Salinas. The plant, which had solar collection area of which had solar collection area of 4,700 m4,700 m22, could produce up to , could produce up to 22,700 L per day and operated for 22,700 L per day and operated for 40 years.40 years.

Darmstadt University of Technologyin Germany won the 2007 Solar Decathlon in Washington, D.C. with thispassive house designed specifically for the humid and hot subtropical climate.[22]Greenhouses like these in the Westland municipality of the Netherlands grow vegetables, fruits and flowers.

Solar Water Disinfection in IndonesiaSolar Water Disinfection in Indonesia

Final ThoughtFinal Thought Argument that sun provides power only during Argument that sun provides power only during

the day is countered by the fact that 70% of the day is countered by the fact that 70% of energy demand is during daytime hours. At energy demand is during daytime hours. At night, traditional methods can be used to night, traditional methods can be used to generate the electricity.generate the electricity.

Goal is to decrease our dependence on fossil Goal is to decrease our dependence on fossil fuels. fuels.

Currently, 75% of our electrical power is Currently, 75% of our electrical power is generated by coal-burning and nuclear power generated by coal-burning and nuclear power plants.plants.

Mitigates the effects of acid rain, carbon Mitigates the effects of acid rain, carbon dioxide, and other impacts of burning coal and dioxide, and other impacts of burning coal and counters risks associated with nuclear energy.counters risks associated with nuclear energy.

pollution free, indefinitely sustainable.pollution free, indefinitely sustainable.

SourcesSources

http://www.solarenergy-http://www.solarenergy-solarpower.comsolarpower.com

http://www.wikipedia.orghttp://www.wikipedia.org http://www.google.comhttp://www.google.com Google ImagesGoogle Images the world of science, vol 10, the world of science, vol 10,

technology of changetechnology of change Tell Me Why ??Tell Me Why ??