+ All Categories
Home > Documents > Solar System - EVS Project

Solar System - EVS Project

Date post: 08-Apr-2015
Category:
Upload: pranav
View: 1,634 times
Download: 8 times
Share this document with a friend
18
Solar System: Sun and The Solar Energy Introduction: Our Sun in Solar System. The Sun is the most prominent feature in our solar system. It is the largest object and contains approximately 98% of the total solar system mass. One hundred and nine Earths would be required to fit across the Sun's disk, and its interior could hold over 1.3 million Earths. The Sun's outer visible layer is called the photosphere and has a temperature of 6,000°C (11,000°F). This layer has a mottled appearance due to the turbulent eruptions of energy at the surface. Solar energy is created deep within the core of the Sun. It is here that the temperature (15,000,000° C; 27,000,000° F) and pressure (340 billion times Earth's air pressure at sea level) is so intense that nuclear Pranav H. Vashi 1
Transcript
Page 1: Solar System - EVS Project

Solar System:Sun and The Solar Energy

Introduction:

Our Sun in Solar System.

The Sun is the most prominent feature in our solar system. It is the largest object and contains approximately 98% of the total solar system mass. One hundred and nine Earths would be required to fit across the Sun's disk, and its interior could hold over 1.3 million Earths. The Sun's outer visible layer is called the photosphere and has a temperature of 6,000°C (11,000°F). This layer has a mottled appearance due to the turbulent eruptions of energy at the surface.

Solar energy is created deep within the core of the Sun. It is here that the temperature (15,000,000° C; 27,000,000° F) and pressure (340 billion times Earth's air pressure at sea level) is so intense that nuclear reactions take place. This reaction causes four protons or hydrogen nuclei to fuse together to form one alpha particle or helium nucleus. The alpha particle is about .7 percent less massive than the four protons. The difference in mass is expelled as energy and is carried to the surface of the Sun, through a process known as convection, where it is released as light and heat. Energy generated in the Sun's core takes a million years to reach its surface. Every second 700 million tons of hydrogen are converted into helium ashes. In the process 5 million tons of pure energy is released; therefore, as time goes on the Sun is becoming lighter.

1

Page 2: Solar System - EVS Project

Solar System:Sun and The Solar Energy

Different layers in the Sun.

The chromosphere is above the photosphere. Solar energy passes through this region on its way out from the center of the Sun. Faculae and flares arise in the chromosphere. Faculae are bright luminous hydrogen clouds which form above regions where sunspots are about to form. Flares are bright filaments of hot gas emerging from sunspot regions. Sunspots are dark depressions on the photosphere with a typical temperature of 4,000°C (7,000°F).

The corona is the outer part of the Sun's atmosphere. It is in this region that prominences appear. Prominences are immense clouds of glowing gas that erupt from the upper chromosphere. The outer region of the corona stretches far into space and consists of particles traveling slowly away from the Sun. The corona can only be seen during total solar eclipses.

2

Page 3: Solar System - EVS Project

Solar System:Sun and The Solar Energy

The Sun appears to have been active for 4.6 billion years and has enough fuel to go on for another five billion years or so. At the end of its life, the Sun will start to fuse helium into heavier elements and begin to swell up; ultimately growing so large that it will swallow the Earth. After a billion years as a red giant, it will suddenly collapse into a white dwarf -- the final end product of a star like ours. It may take a trillion years to cool off completely.

Sun Statistics:

Mass (kg) 1.989e+30Mass (Earth = 1) 332,830Equatorial radius (km) 695,000Equatorial radius (Earth = 1) 108.97Mean density (gm/cm^3) 1.410Rotational period (days) 25-36*Escape velocity (km/sec) 618.02Luminosity (ergs/sec) 3.827e33Magnitude (Vo) -26.8Mean surface temperature 6,000°CAge (billion years) 4.5

Principal chemistry:

HydrogenHeliumOxygen CarbonNitrogenNeonIronSiliconMagnesiumSulfurAll others

92.1%7.8%0.061%0.030%0.0084%0.0076%0.0037%0.0031%0.0024%0.0015%0.0015%

3

Page 4: Solar System - EVS Project

Solar System:Sun and The Solar Energy

Solar Energy:

Solar energy is the radiant light and heat from the Sun that has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar radiation along with secondary solar resources such as wind and wave power, hydroelectricity and biomass account for most of the available renewable energy on Earth. Only a minuscule fraction of the available solar energy is used. Solar power provides electrical generation by means of heat engines or photovoltaics.

Six dish Stirling Systems developed by Schlaich Bergermann und Partner of Stuttgart, Germany, in operation at the Plataforma Solar de Almeria in Spain. The three dishes in the foreground are second-generation systems. The systems produce 10 kW of power from a Solo Kleinmotoren engine.

Solar technologies are broadly characterized as passive solar and active solar techniques. Active solar techniques include the use of photovoltaic panels and solar thermal collectors to convert sunlight into useful outputs. 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.

4

Page 5: Solar System - EVS Project

Solar System:Sun and The Solar Energy

Energy from the Sun:

The Earth receives 174 petawatts (PW) of incoming solar radiation (insolation) at the upper atmosphere. Approximately 30% is reflected back to space while the rest is absorbed by clouds, oceans and land masses. The spectrum of solar light at the Earth's surface is mostly spread across the visible and near-infrared ranges with a small part in the near-ultraviolet.

Earth's land surface, oceans and atmosphere absorb solar radiation, and this raises their temperature. Warm air containing evaporated water from the oceans rises, causing atmospheric circulation or convection. When the air reaches a high altitude, where the temperature is low, water vapor condenses into clouds, which rain onto the Earth's surface, completing the water cycle. The latent heat of water condensation amplifies convection, producing atmospheric phenomena such as wind, cyclones and anti-cyclones. Sunlight absorbed by the oceans and land masses keeps the surface at an average temperature of 14 °C. By photosynthesis green plants convert solar energy into chemical energy, which produces food, wood and the biomass from which fossil fuels are derived.

About half the incoming solar energy reaches the Earth's surface.

5

Page 6: Solar System - EVS Project

Solar System:Sun and The Solar Energy

The total solar energy absorbed by Earth's atmosphere, oceans and land masses is approximately 3,850,000 exajoules (EJ) per year. In 2002, this was more energy in one hour than the world used in one year. Photosynthesis captures approximately 3,000 EJ per year in biomass. The amount of solar energy reaching the surface of the planet is so vast that in one year it is about twice as much as will ever be obtained from all of the Earth's non-renewable resources of coal, oil, natural gas, and mined uranium combined.

Yearly Solar fluxes & Human Energy Consumption

Solar 3,850,000 EJ

Wind 2,250 EJ

Biomass 3,000 EJ

Primary energy use (2005) 487 EJ

Electricity (2005) 56.7 EJ

From the table of resources it would appear that solar, wind or biomass would be sufficient to supply all of our energy needs, however, the increased use of biomass has had a negative effect on global warming and dramatically increased food prices by diverting forests and crops into biofuel production. As intermittent resources, solar and wind raise other issues.

6

Page 7: Solar System - EVS Project

Solar System:Sun and The Solar Energy

Applications of Solar Technology:

Solar energy refers primarily to the use of solar radiation for practical ends. However, all renewable energies, other than geothermal and tidal, derive their energy from the sun.

Average insolation showing land area (small black dots) required to replace the world primary energy supply with solar electricity. 18 TW is 568 Exajoule (EJ) per year. Insolation for most people is from 150 to 300 W/m² or 3.5 to 7.0 kWh/m²/day.

Solar technologies are broadly characterized as either passive or active depending on the way they capture, convert and distribute sunlight. Active solar techniques use photovoltaic panels, pumps, and fans to convert sunlight into useful outputs. Passive solar techniques include selecting materials with favorable thermal properties, designing spaces that naturally circulate air, and referencing the position of a building to the Sun. Active solar technologies increase the supply of energy and are considered supply side technologies, while passive solar technologies reduce the need for alternate resources and are generally considered demand side technologies.

7

Page 8: Solar System - EVS Project

Solar System:Sun and The Solar Energy

Architecture and urban planning:

The common features of passive solar architecture are orientation relative to the Sun, compact proportion, selective shading and thermal mass. When these features are tailored to the local climate and environment they can produce well-lit spaces that stay in a comfortable temperature range. The most recent approaches to solar design use computer modeling tying together solar lighting, heating and ventilation systems in an integrated solar design package. Active solar equipment such as pumps, fans and switchable windows can complement passive design and improve system performance.

Darmstadt University of Technology in Germany won the 2007 Solar Decathlon in Washington, D.C. with this passive house designed specifically for the humid and hot subtropical climate.

Urban heat islands (UHI) are metropolitan areas with higher temperatures than that of the surrounding environment. The higher temperatures are a result of increased absorption of the Solar light by urban materials such as asphalt and concrete, which have lower albedos and higher heat capacities than those in the natural environment. A straightforward method of counteracting the UHI effect is to paint buildings and roads white and plant trees.

8

Page 9: Solar System - EVS Project

Solar System:Sun and The Solar Energy

Agriculture and horticulture:

Agriculture seeks to optimize the capture of solar energy in order to optimize the productivity of plants. Techniques such as timed planting cycles, tailored row orientation, staggered heights between rows and the mixing of plant varieties can improve crop yields. While sunlight is generally considered a plentiful resource, the exceptions highlight the importance of solar energy to agriculture. During the short growing seasons of the Little Ice Age, French and English farmers employed fruit walls to maximize the collection of solar energy. These walls acted as thermal masses and accelerated ripening by keeping plants warm. Early fruit walls were built perpendicular to the ground and facing south, but over time, sloping walls were developed to make better use of sunlight. In 1699, Nicolas Fatio de Duillier even suggested using a tracking mechanism which could pivot to follow the Sun. Applications of solar energy in agriculture aside from growing crops include pumping water, drying crops, brooding chicks and drying chicken manure. More recently the technology has been embraced by vinters, who use the energy generated by solar panels to power grape presses.

Greenhouses like these in the Westland municipality of the Netherlands grow vegetables, fruits and flowers.

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

9

Page 10: Solar System - EVS Project

Solar System:Sun and The Solar Energy

Solar Lighting:

Daylighting systems collect and distribute sunlight to provide interior illumination. Although difficult to quantify, the use of natural lighting also offers physiological and psychological benefits compared to artificial lighting. Daylighting design implies careful selection of window types, sizes and orientation; exterior shading devices may be considered as well. Individual features include sawtooth roofs, clerestory windows, light shelves, skylights and light tubes. When daylighting features are properly implemented they can reduce lighting-related energy requirements by 25%.

Daylighting features such as this oculus at the top of the Pantheon, in Rome, Italy have been in use since antiquity.

Although daylight saving time is promoted as a way to use sunlight to save energy, recent research has been limited and reports contradictory results: several studies report savings, but just as many suggest no effect or even a net loss, particularly when gasoline consumption is taken into account.

10

Page 11: Solar System - EVS Project

Solar System:Sun and The Solar Energy

Solar Thermal:

Solar thermal technologies can be used for water heating, space heating, space cooling and process heat generation.

Solar House #1 of Massachusetts Institute of Technology in the United States, built in 1939, used seasonal thermal storage for year-round heating.

Solar water heaters facing the Sun to maximize gain.

11

Page 12: Solar System - EVS Project

Solar System:Sun and The Solar Energy

Application of SODIS technology in Indonesia to water disinfection.

Advantages of Solar Energy:

After the initial investment has been recovered, the energy from the sun is practically free

It's not affected by the supply and demand of fuel and is therefore not subjected to the ever-increasing price of gasoline.

Solar Energy is clean, renewable (unlike gas, oil and coal) and sustainable, helping to protect our environment.

It does not pollute our air by releasing carbon dioxide, nitrogen oxide, sulphur dioxide or mercury into the atmosphere like many traditional forms of electrical generation does.

Therefore Solar Energy does not contribute to global warming, acid rain or smog.

By not using any fuel, Solar Energy does not contribute to the cost and problems of the recovery and transportation of fuel or the storage of radioactive waste.

Disadvantages of Solar Energy:

12

Page 13: Solar System - EVS Project

Solar System:Sun and The Solar Energy

The initial cost is the main disadvantage of installing a solar energy system, largely because of the high cost of the semi-conducting materials used in building one.

The cost of solar energy is also high compared to non-renewable utility-supplied electricity. As energy shortages are becoming more common, solar energy is becoming more price-competitive.

Solar panels require quite a large area for installation to achieve a good level of efficiency.

The efficiency of the system also relies on the location of the sun, although this problem can be overcome with the installation of certain components.

The production of solar energy is influenced by the presence of clouds or pollution in the air and no solar energy produced during night time.

As we can see there are many solar energy advantages compared to its disadvantages. Disadvantages can be found in any product or system, but it is important to know that they can be managed in this case. Therefore our solar system which consists of abundant energy has lot of hopes to provide renewable energy and save scarce resources of energy. The only need is for channelizing maximum energy to its proper use which we can manage using modern technologies available to us.

13


Recommended