logging in or signing up 09 solar1 Michelino Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINTLite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 135 Category: Education License: All Rights Reserved Like it (0) Dislike it (0) Added: January 23, 2008 This Presentation is Public Favorites: 1 Presentation Description No description available. Comments Posting comment... By: VRUSHABH77 (17 month(s) ago) Hello, You have done a wonderfull presentation, can I have the down load of this for my school project. Thanking you in anticipation Yours sincerely Vrushabh Saving..... Post Reply Close Saving..... Edit Comment Close Premium member Presentation Transcript Solar Energy: Solar Energy Introduction to renewable energy Energy from the sunRenewable Energy Consumption: Renewable Energy Consumption much room for improvement/growth, but going backwards!The Solar Spectrum: The Solar Spectrum O2 H2O H2O H2O,CO2 H2O, CO2 Atmospheric absorption above the atmosphere at ground levelHow much energy is available?: How much energy is available? Above the atmosphere, we get 1368 W/m2 of radiated power from the sun, across all wavelengths This number varies by ±3% as our distance to the sun increases or decreases (elliptical orbit) The book uses 2 calories per minute per cm2 (weird units!!) At the ground, this number is smaller due to scattering and absorption in the atmosphere about 63%, or ~850 W/m2 with no clouds, perpendicular surface probably higher in dry desert airInput flux (average properties): Input flux (average properties)Making sense of the data: Making sense of the data We can infer a number of things from the previous figure: 52% of the incoming light hits clouds, 48% does not in cloudless conditions, half (24/48) is direct, 63% (30/48) reaches the ground in cloudy conditions, 17/52 = 33% reaches the ground: about half of the light of a cloudless day averaging all conditions, about half of the sunlight incident on the earth reaches the ground the above analysis is simplified: assumes atmospheric scattering/absorption is not relevant when cloudyA naturally balanced budget: A naturally balanced budgetComparable numbers: Comparable numbers Both versions indicate about half the light reaching (being absorbed by) the ground 47% vs. 51% Both versions have about 1/3 reflected back to space 34% vs. 30% Both versions have about 1/5 absorbed in the atmosphere/clouds 19% vs. 19%Energy Balance: Energy Balance Note that every bit of the energy received by the sun is reflected or radiated back to space If this were not true, earth’s temperature would change until the radiation out balanced the radiation in In this way, we can compute surface temperatures of other planets (and they compare well with measurements)Average Insolation: Average Insolation The amount of light received by a horizontal surface (in W/m2) averaged over the year (day & night) is called the insolation We can make a guess based on the facts that on average: half the incident light reaches the ground half the time it is day the sun isn’t always overhead, so that the effective area of a horizontal surface is half it’s actual area half the sphere (2R2) projects into just R2 for the sun twice as much area as the sun “sees” So 1/8 of the incident sunlight is typically available at the ground 171 W/m2 on averageInsolation variation: Insolation variation While the average insolation is 171 W/m2, variations in cloud cover and latitude can produce a large variation in this number A spot in the Sahara (always sunny, near the equator) may have 270 W/m2 on average Alaska, often covered in clouds and at high latitude may get only 75 W/m2 on average Is it any wonder that one is cold while one is hot?Average daily radiation received: Average daily radiation received divide by 24 hr to get average kW/m2 ranges in W/m2: < 138 138–162 162–185 185–208 208–231 > 231 Higher Resolution Insolation Map: Higher Resolution Insolation MapTilted Surfaces: Tilted Surfaces Can effectively remove the latitude effect by tilting panels raises incident power on the panel, but doesn’t let you get more power per unit area of (flat) real estate flat arrangement tilted arrangementWhich is best?: Which is best? To tilt, or not to tilt? If the materials for solar panels were cheap, then it would make little difference (on flat land) If you have a limited number of panels (rather than limited flat space) then tilting is better If you have a slope (hillside or roof), then you have a built-in gain Best solution of all (though complex) is to steer and track the sunOrientation Comparison: Orientation ComparisonNumerical Comparison: winter at 40º latitude: Numerical Comparison: winter at 40º latitude overall winner better in summer good in winter 2nd place based on clear, sunny daysTotal available solar energy: Total available solar energy Looking at average insolation map (which includes day/night, weather, etc.), I estimate average of 4.25 kWh/day = 177 W/m2 The area of the U.S. is 3.615106 square miles this is 9.361012 m2 Multiplying gives 1.661015 Watts average available power Multiply by 3.1557107 seconds/year gives 5.231022 Joules every year This is 501018 Btu, or 50,000 QBtu Compare to annual budget of about 100 QBtu 500 times more sun than current energy budgetSo why don’t we go solar?: So why don’t we go solar? What would it take? To convert 1/500th of available energy to useful forms, would need 1/500th of land at 100% efficiency about the size of New Jersey But 100% efficiency is unrealistic: try 15% now need 1/75th of land Pennsylvania-sized (100% covered) Can reduce area somewhat by placing in S.W.Making sense of these big numbers: Making sense of these big numbers How much area is this per person? U.S. is 9.361012 m2 1/75th of this is 1.251011 m2 300 million people in the U.S. 416 m2 per person 4,500 square feet this is a square 20.4 meters (67 ft) on a side one football field serves only about 10 people! much larger than a typical person’s house area rooftops can’t be the whole answer, especially in citiesWays of using solar energy: Ways of using solar energy Direct heating of flat panel (fluids, space heating) Passive heating of well-designed buildings Thermal power generation (heat engine) via concentration of sunlight Direct conversion to electrical energyAssignments: Assignments Read Chapter 4 if you haven’t already Midterm next Thursday, 05/03 covering material up through this lecture (#9); Book material through Section 4.2 Review session TBA Study guide on web You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.
09 solar1 Michelino Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINTLite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 135 Category: Education License: All Rights Reserved Like it (0) Dislike it (0) Added: January 23, 2008 This Presentation is Public Favorites: 1 Presentation Description No description available. Comments Posting comment... By: VRUSHABH77 (17 month(s) ago) Hello, You have done a wonderfull presentation, can I have the down load of this for my school project. Thanking you in anticipation Yours sincerely Vrushabh Saving..... Post Reply Close Saving..... Edit Comment Close Premium member Presentation Transcript Solar Energy: Solar Energy Introduction to renewable energy Energy from the sunRenewable Energy Consumption: Renewable Energy Consumption much room for improvement/growth, but going backwards!The Solar Spectrum: The Solar Spectrum O2 H2O H2O H2O,CO2 H2O, CO2 Atmospheric absorption above the atmosphere at ground levelHow much energy is available?: How much energy is available? Above the atmosphere, we get 1368 W/m2 of radiated power from the sun, across all wavelengths This number varies by ±3% as our distance to the sun increases or decreases (elliptical orbit) The book uses 2 calories per minute per cm2 (weird units!!) At the ground, this number is smaller due to scattering and absorption in the atmosphere about 63%, or ~850 W/m2 with no clouds, perpendicular surface probably higher in dry desert airInput flux (average properties): Input flux (average properties)Making sense of the data: Making sense of the data We can infer a number of things from the previous figure: 52% of the incoming light hits clouds, 48% does not in cloudless conditions, half (24/48) is direct, 63% (30/48) reaches the ground in cloudy conditions, 17/52 = 33% reaches the ground: about half of the light of a cloudless day averaging all conditions, about half of the sunlight incident on the earth reaches the ground the above analysis is simplified: assumes atmospheric scattering/absorption is not relevant when cloudyA naturally balanced budget: A naturally balanced budgetComparable numbers: Comparable numbers Both versions indicate about half the light reaching (being absorbed by) the ground 47% vs. 51% Both versions have about 1/3 reflected back to space 34% vs. 30% Both versions have about 1/5 absorbed in the atmosphere/clouds 19% vs. 19%Energy Balance: Energy Balance Note that every bit of the energy received by the sun is reflected or radiated back to space If this were not true, earth’s temperature would change until the radiation out balanced the radiation in In this way, we can compute surface temperatures of other planets (and they compare well with measurements)Average Insolation: Average Insolation The amount of light received by a horizontal surface (in W/m2) averaged over the year (day & night) is called the insolation We can make a guess based on the facts that on average: half the incident light reaches the ground half the time it is day the sun isn’t always overhead, so that the effective area of a horizontal surface is half it’s actual area half the sphere (2R2) projects into just R2 for the sun twice as much area as the sun “sees” So 1/8 of the incident sunlight is typically available at the ground 171 W/m2 on averageInsolation variation: Insolation variation While the average insolation is 171 W/m2, variations in cloud cover and latitude can produce a large variation in this number A spot in the Sahara (always sunny, near the equator) may have 270 W/m2 on average Alaska, often covered in clouds and at high latitude may get only 75 W/m2 on average Is it any wonder that one is cold while one is hot?Average daily radiation received: Average daily radiation received divide by 24 hr to get average kW/m2 ranges in W/m2: < 138 138–162 162–185 185–208 208–231 > 231 Higher Resolution Insolation Map: Higher Resolution Insolation MapTilted Surfaces: Tilted Surfaces Can effectively remove the latitude effect by tilting panels raises incident power on the panel, but doesn’t let you get more power per unit area of (flat) real estate flat arrangement tilted arrangementWhich is best?: Which is best? To tilt, or not to tilt? If the materials for solar panels were cheap, then it would make little difference (on flat land) If you have a limited number of panels (rather than limited flat space) then tilting is better If you have a slope (hillside or roof), then you have a built-in gain Best solution of all (though complex) is to steer and track the sunOrientation Comparison: Orientation ComparisonNumerical Comparison: winter at 40º latitude: Numerical Comparison: winter at 40º latitude overall winner better in summer good in winter 2nd place based on clear, sunny daysTotal available solar energy: Total available solar energy Looking at average insolation map (which includes day/night, weather, etc.), I estimate average of 4.25 kWh/day = 177 W/m2 The area of the U.S. is 3.615106 square miles this is 9.361012 m2 Multiplying gives 1.661015 Watts average available power Multiply by 3.1557107 seconds/year gives 5.231022 Joules every year This is 501018 Btu, or 50,000 QBtu Compare to annual budget of about 100 QBtu 500 times more sun than current energy budgetSo why don’t we go solar?: So why don’t we go solar? What would it take? To convert 1/500th of available energy to useful forms, would need 1/500th of land at 100% efficiency about the size of New Jersey But 100% efficiency is unrealistic: try 15% now need 1/75th of land Pennsylvania-sized (100% covered) Can reduce area somewhat by placing in S.W.Making sense of these big numbers: Making sense of these big numbers How much area is this per person? U.S. is 9.361012 m2 1/75th of this is 1.251011 m2 300 million people in the U.S. 416 m2 per person 4,500 square feet this is a square 20.4 meters (67 ft) on a side one football field serves only about 10 people! much larger than a typical person’s house area rooftops can’t be the whole answer, especially in citiesWays of using solar energy: Ways of using solar energy Direct heating of flat panel (fluids, space heating) Passive heating of well-designed buildings Thermal power generation (heat engine) via concentration of sunlight Direct conversion to electrical energyAssignments: Assignments Read Chapter 4 if you haven’t already Midterm next Thursday, 05/03 covering material up through this lecture (#9); Book material through Section 4.2 Review session TBA Study guide on web