L15-SolarEnergy

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Renewable Energy Sources I: Solar Energy:

Renewable Energy Sources I: Solar Energy Lecture # 15

The Energy Picture (2008) Sources & Consumption Sector:

The Energy Picture (2008) Sources & Consumption Sector 4/11/2011 3

The Energy Picture (2009) Sources & Consumption Sector:

The Energy Picture (2009) Sources & Consumption Sector 4/11/2011 4

Renewable Energy Sources 2009:

Renewable Energy Sources 2009 4/11/2011 5

Renewable Energy Sources(2009):

Renewable Energy Sources (2009) 4/11/2011 6

Renewable (8%) includes::

Renewable (8%) includes: Hydroelectric (hydro power): 35%; Biomass: 50%; Wood: 24%; Waste (garbage, etc.): 6%; Bio-fuel (biodiesel, ethanol): 20%( grows a little ); Geothermal: 5%(won’t change); Wind (wind power): 9%(growing); Solar: 1% (growing). 4/11/2011 7

Renewables in Real Numbers:

Renewables in Real Numbers Historical Renewable Energy Consumption by Energy Source, 2000-2007 (QBtu) (EIA AER data, table 10.1) Source 2000 2001 2002 2003 2004 2006 2007 2008 Total 6.158 5.328 5.835 6.082 6.117 6.922 6.830 7.316 Biomass 2.907 2.640 2.648 2.740 2.845 3.374 3.615 3.900 Geothermal 0.317 0.311 0.328 0.339 0.340 0.343 0.353 0.358 Conventional Hydroelectric 2.811 2.242 2.689 2.825 2.725 2.869 2.463 2.452 Solar/PV 0.066 0.065 0.064 0.064 0.063 0.072 0.080 0.091 Wind 0.057 0.070 0.105 0.115 0.143 0.264 0.319 0.514

Non-hydroelectric power source:

Non-hydroelectric power source 4/11/2011 9 Similar situation in 2008

Overview of Solar Energy:

4/11/2011 10 Overview of Solar Energy The sun—the ultimate energy source; Current situation of solar energy; Passive vs. active solar energy collection; Solar thermal electric power generation; Photovoltaic cell & solar panel; Reading: Chapter 4, EIA website.

The sun: the ultimate energy source:

4/11/2011 11 The sun: the ultimate energy source Except Geothermal and tidal, All Energy is from the sun; 30% reflects directly back off earth 47% is absorbed and re-radiated very quickly 23% Evaporation, rain, ice melting and freezing The solar energy reaching the earth is in the form of electromagnetic radiation (including heat); The source of energy is the thermonuclear reaction in the controlled way by means of gravitational confinement!

Solar Radiation Curve:

Solar Radiation Curve 4/11/2011 12

Solar Radiation Curve:

4/11/2011 13 Solar Radiation Curve

The Sun:

4/11/2011 14 The Sun The Sun’s surface temperature is 5800 K, close to 6000 K; So the peak power happens at 0.5 m m or 500 nm (what color?); That’s why our eye is most sensitive to that green color (evolution or creation?). The solar visible light region: Wavelength: 0.4 m m ~ 0.7 m m;

Absorption & Scattering of Solar Radiation:

4/11/2011 15 Absorption & Scattering of Solar Radiation

Solar energy :

4/11/2011 16 Solar energy ~70 % of solar electromagnetic radiation remains on earth; 47% is absorbed and re-radiated very quickly; 23% Evaporation, rain, ice melting and freezing; That 47% is the part we can utilize somehow.

Solar Energy:

Solar Energy Solar (solar radiation incident on earth): Direct sun light (direct solar); Indirect solar energy including: Wind; Water or hydropower; Ocean current & ocean thermal gradient; biomass (wood, garbage, etc.) Only direct solar will be discussed here (Ch 4); All indirect solar sources are considered as alternatives (Ch 5); 4/11/2011 17

A lot of energy if we can collect it:

4/11/2011 18 A lot of energy if we can collect it How much in term of energy units? Solar Constant: 2cal/min ·cm 2 ( 1400 J/s∙m 2 ; 1400 W/m 2 ; 0.12 Btu/s∙foot 2 ); Unevenly distributed: day vs. night; summer vs. winter; polar area vs. equator area; etc. Estimated gross energy incident on US soil per year (sophisticated calculation): 5.6×10 19 Btu/yr=56,000 QBtu/yr ; Recall US annual energy consumption? ~100QBtu; 560 times less than the solar energy received.

Slide 19:

4/11/2011 19

A lot of energy if we can collect it:

4/11/2011 20 A lot of energy if we can collect it

World solar energy map:

World solar energy map 4/11/2011 21

Current Situation of Solar Energy:

4/11/2011 22 Current Situation of Solar Energy Early 1980s: there was a brief solar energy boom due to the high fossil fuel price and with the help government tax incentives; Tax credits were removed in 1985; Fossil fuel price came down at about the same time; Solar heating equipment market shrunk very quickly.

Current Situation of Solar Energy:

4/11/2011 23 Current Situation of Solar Energy Table 5a. Historical Renewable Energy Consumption by Energy Use Sector and Energy Source, 1989-1999 (QBtu) Sector and Energy Source 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 Total 6.294 6.133 6.158 5.907 6.157 6.065 6.669 7.137 7.075 6.561 6.599 Biomass 3.062 2.662 2.702 2.847 2.804 2.939 3.068 3.127 3.006 2.835 2.885 Alcohol Fuels 0.071 0.063 0.073 0.083 0.097 0.109 0.117 0.084 0.106 0.117 0.122 Geothermal 0.317 0.336 0.346 0.349 0.364 0.338 0.294 0.316 0.325 0.328 0.331 Hydroelectric 2.837 3.046 3.016 2.617 2.892 2.683 3.205 3.590 3.640 3.297 3.268 Solar 0.055 0.060 0.063 0.064 0.066 0.069 0.070 0.071 0.070 0.070 0.069 Wind 0.022 0.029 0.031 0.030 0.031 0.036 0.033 0.033 0.034 0.031 0.046

Current Situation of Solar Energy:

4/11/2011 24 Current Situation of Solar Energy Table 5b . Historical Renewable Energy Consumption by Energy Use Sector and Energy Source, 2000-2004 (QBtu) (EIA data) Sector and Energy Source 2000 2001 2002 2003 2004 Total 6.158 5.328 5.835 6.082 6.117 Biomass 2.907 2.640 2.648 2.740 2.845 Alcohol Fuels 0.139 0.147 0.174 0.239 0.296 Geothermal 0.317 0.311 0.328 0.339 0.340 Conventional Hydroelectric 2.811 2.242 2.689 2.825 2.725 Solar 0.066 0.065 0.064 0.064 0.063 Wind 0.057 0.070 0.105 0.115 0.143

Current situation of solar energy:

4/11/2011 25 Current situation of solar energy 2009 data: Total energy consumption ~96 QBtu; Solar/total = 0.08/96 =0.00083 ≈0.08% only! There is a lot of room to grow!!! What do we need? Technology; Market; Favorable Policy;

Current situation of solar energy:

Current situation of solar energy 4/11/2011 26 Solar thermal collector shipments Photovoltaic cell & module shipments

How Can We Use Solar Energy?:

4/11/2011 27 How Can We Use Solar Energy? Passive solar; Active solar: Solar energy → heat Heating Electric power generation (Solar thermal electric) Direct conversion of solar energy to electricity

Passive vs. Active Collection:

4/11/2011 28 Passive vs. Active Collection

Passive Solar Energy Collection:

4/11/2011 29 Passive Solar Energy Collection Longest history of application; Stay under the sun to keep warm; Buildings were oriented toward the sun; All houses have some form of passive solar heating. No mechanical pumps or blowers; Usually built into design of building Examples: Large windows with extended eaves on south side of home; Small windows on north side;

Passive solar Home Design:

4/11/2011 30 Passive solar Home Design

Passive solar Home Design:

4/11/2011 31 Passive solar Home Design

Other Passive Design Features:

4/11/2011 32 Other Passive Design Features Insulated glass windows: 2 (or more) layers of glass with dead air space in between; Trombe wall: is a sun-facing wall patented in 1881 by its inventor, Edward Morse, and popularized in 1964 by French engineer Félix Trombe and architect Jacques Michel; Concrete or brick wall inside large glass window; Acts as both a heat collector and storage; Building on campus with this design, See if you can find it.

Trombe Wall:

4/11/2011 33 Trombe Wall

Trombe Wall:

4/11/2011 34 Trombe Wall Operation: Day & night

Which of the following buildings have the passive solar design known as “Trombe wall”?:

Which of the following buildings have the passive solar design known as “Trombe wall”? 4/11/2011 35 Hartline Science Center; McCormick Hall; Carver Hall; Centennial Hall; Student service center.

And more passive techniques:

4/11/2011 36 And more passive techniques Double door entry (mud room design); Seal cracks and openings in walls; Greenhouse entry way; Deciduous trees on south side; Leaves block sun in summer; Loss of leaves in winter allows heating.

Passive solar: Conclusion:

4/11/2011 37 Passive solar: Conclusion Solar energy Collection ; Large windows with extended eaves on south side of home; Small windows on north side; Solar collector panel; Energy Storage ; Large amount of thermal mass (heat storage materials), damps temperature changes in either directions; Thermal mass is partially provided by the internal parts of the building itself, best to add water tank since water has the highest specific heat capacity ( 62 Btu/ft 3 , or 1 cal/g ·C 0 ). Insulation : Heat insulator vs. Heat conductors distinguished by their heat conductivity. Good examples: fiberglass, wood,

All are passive solar design considerations except:

All are passive solar design considerations except 4/11/2011 38 Circulation Collection Storage Insulation Clicker question

Active Solar Energy Collection:

4/11/2011 39 Active Solar Energy Collection Includes flat plate collectors or concentrating collectors; Uses forced convection to transfer heat; A fluid (liquid or air) is forced to circulate using pumps or blowers; Advantages: Higher efficiency of collection; Compact components; Flexibility in placement; Easy to control; Examples: Flat Plate collector system used for water or space heating; Parabolic collector used for more advanced application such as solar thermal electric generation; Parabolic trough layout similar to parabolic dishes.

Flat Plate collector:

4/11/2011 40 Flat Plate collector

Flat Plate collector:

4/11/2011 41 Flat Plate collector

Roof-top Solar water heater:

4/11/2011 42 Roof-top Solar water heater Solar - heat

Parabolic collector:

4/11/2011 43 Parabolic collector Primary focus; Receiver at the focus: symbolic: power tower

Parabolic collector:

4/11/2011 44 Parabolic collector The current 14 solar concentrating dishes now using PV technology at White Cliffs in South Australia.

Parabolic trough systems :

4/11/2011 45 Parabolic trough systems The reflective surface of a parabolic trough concentrates sunlight onto a receiver tube located along the trough's focal line, heating the fluid (water, or oil) flowing in the tube which is then transported through pipes to a steam turbine / generator.

Parabolic trough systems :

4/11/2011 46 Parabolic trough systems IST-PT Parabolic Trough Solar Collectors (Spain)

Solar thermal el. Power generation:

4/11/2011 47 Solar thermal el. Power generation Use mirrors to focus sun (si-fi movies: 007-Die another day) Heat (boil) water and use steam to produce electricity Example: Solar Two Project Used ~2000 mirrors to produce 1065 0 F Produces 10 Mega watts (10,000,000 W) electricity; Still too costly, was shut down.

Solar two Project:

4/11/2011 48 Solar two Project Solar Two is located east of Daggett, California. On historic Route 66, in the Mojave desert; Prototype for the solar farm model of power plants. It consists of a field of 1,926 moving mirrors, called heliostats. Each heliostat is 42 m 2 , and can be pointed in any direction using a central computer control. Heliostats focused sunlight onto a central tower, heating water (or molten salt) to create steam and generate power with a turbine.

Solar two Project:

4/11/2011 49 Solar two Project The first phase, known as Solar One, was built in 1982 by DOD, Southern California Edison, the Los Angeles Department of Water & Power, and the California Energy Commission. It ran through 1988; In 1995 was upgraded to become Solar Two. A ring of larger heliostats, each 95 m 2 , was added to the perimeter of the field, temperature increased from 500 0 F to 1050 0 F. Solar Two could generate 10 MW of power, enough to power 10,000 homes, and successfully showing that its technology could be scaled up to the cost-efficient magnitude of 100 MW. Solar Two operated till 1999, and University of California research teams began converting Solar Two into an Air Cherenkov Telescope Array (CTA) in 2001.

Solar Two Site: Daggett, CA:

4/11/2011 50 Solar Two Site: Daggett, CA

Solar Two Site: Daggett, CA:

4/11/2011 51 Solar Two Site: Daggett, CA

Solar Two Site:

4/11/2011 52 Solar Two Site

Solar thermal el. power generation:

4/11/2011 53 Solar thermal el. power generation

Problem with solar thermal electric:

4/11/2011 54 Problem with solar thermal electric Although an active solar collection scheme, It’s an indirect conversion of solar energy: Inefficient of running a heat engine: (solar – heat – steam turbine –generator); Expensive and cumbersome due to sophisticated equipment;

Direct Conversion of Solar to Electricity:

4/11/2011 55 Direct Conversion of Solar to Electricity Uses two semi-conductor materials; When placed together and struck by light Electrons flow from one to the other That’s electric current! This technology is known as photovoltaic (PV) cell or solar cell or photocell; The array of such cells is called photovoltaic panel or in short: solar panel ; Mostly works on a small scale.

The theory::

4/11/2011 56 The theory: Known as Photoelectric effect that was first understood and characterized by Elbert Einstein in 1905 (awarded Nobel prize in 1921); When light (photons) strike on the surface of certain materials, electrons are released from that surface; photon energy is proportional to its frequency;

Photoelectric Effect:

4/11/2011 57 Photoelectric Effect

Photovoltaic Cells: Converting Photons to Electrons:

4/11/2011 58 Photovoltaic Cells: Converting Photons to Electrons The "photovoltaic effect" is the basic physical process that is similar to photoelectric effect; Through which a solar cell converts sunlight into electricity; Discovered in 1839 by 19-year-old Edmund Becquerel, a French experimental physicist; Becquerel found that certain materials would produce small amounts of electric current when exposed to light.

Photovoltaic Cells: Converting Photons to Electrons:

4/11/2011 59 Photovoltaic Cells: Converting Photons to Electrons When photons strike a solar cell (semiconductor), they may be reflected or absorbed, or they may pass right through; If a photon is absorbed, the energy of the photon is transferred to an electron in an atom of the cell; The electron is energized and is able to escape from its normal position associated with that atom to become a free moving electron; When electrons move, electric current is formed thanks to the voltage produced by P-N junction.

How does a PV cell (solar cell) work?:

4/11/2011 60 How does a PV cell (solar cell) work? Semiconductors; P-type and N-type; P-N junction which forms a diode;

P-type & N-type semiconductors:

4/11/2011 61 P- type & N -type semiconductors Semiconductor such as silicon is doped with impurities (phosphor for N-type & boron for P-type, P: positive, N: negative),

P-N junction & diode:

4/11/2011 62 P-N junction & diode At the junction, free electrons from the N-type material fill holes from the P-type material. This creates an insulating layer in the middle of the diode called the depletion zone, preventing any further move of the holes and electrons

How does a PV cell (solar cell) work?:

4/11/2011 63 How does a PV cell (solar cell) work? When light, in the form of photons, hits our solar cell, its energy frees electron-hole pairs

Structure of a Solar Cell:

4/11/2011 64 Structure of a Solar Cell

Solar Cells - Applications:

4/11/2011 65 Solar Cells - Applications Currently due to the limited scale of solar cells, it is used mostly: In remote locations; For small power needs (household, portable); In difficult areas to run power lines to; In outer space;

Remote Solar Panel:

4/11/2011 66 Remote Solar Panel

Small power needs: Solar Powered Attic Fan:

4/11/2011 67 Small power needs: Solar Powered Attic Fan

Small power needs: Portable solar panel:

4/11/2011 68 Small power needs: Portable solar panel

Difficult areas to run power lines to:

Difficult areas to run power lines to 4/11/2011 69

Solar Cells on Space Station:

4/11/2011 70 Solar Cells on Space Station

Solar Yard Light (landscaping light):

4/11/2011 71 Solar Yard Light (landscaping light)

Solar Yard Light (landscaping light):

4/11/2011 72 Solar Yard Light (landscaping light) Solar light - electricity - light

Household PV System:

4/11/2011 73 Household PV System

Solar Panel As Roof Shingles:

4/11/2011 74 Solar Panel As Roof Shingles

PV System Inside The House:

4/11/2011 75 PV System Inside The House

PV System Inside House: Batteries:

4/11/2011 76 PV System Inside House: Batteries

PV System With Net Metering:

PV System With Net Metering Instead of the battery system; A better way is to connect to the power grid known as “net metering”; Government energy policy supports it; Make money by selling extra electric energy; Less maintenance (because there is no battery) to reduce cost. 4/11/2011 77

PV System With Net Metering:

PV System With Net Metering 4/11/2011 78

Want to know more?:

4/11/2011 79 Want to know more? Check this website out: http://www.ka9q.net/pv/ ; http://www.facts-about-solar-energy.com/index.html ;

Photovoltaic Cell & Module Average Prices, 2003-2007:

Photovoltaic Cell & Module Average Prices, 2003-2007 Peak watt: The maximum rated output of a photovoltaic device (solar cell or array), under standardized test conditions, usually 1000 watts per square meter (0.645 watts per square inch) of sunlight with other conditions, such as temperature specified. Typical rating conditions are 68°F (20°C), ambient air temperature, and 1 m/s (6.2 x 10 -3 miles/sec.) wind speed 4/11/2011 80

Photovoltaic Cell & Module Shipments, 1998-2007:

Photovoltaic Cell & Module Shipments, 1998-2007 4/11/2011 81

Cost of Solar Energy:

4/11/2011 82 Cost of Solar Energy A flawed concept of solar energy: Sunlight is free, electricity generated by PV systems is not; A household PV system: quite a bit of hardware is needed; Currently, an installed PV system will cost somewhere around $8 per peak Watt . A solar hot water system cost $2,000~$4,000; A photovoltaic system cost $8,000~$10,000 for a 1kW system. (or $8 - $10 /Watt); An average American family, living in a 3-bedroom home requires a 1.5~3kW system, which will cost between US $13,000 and US $27,000, before rebates; With tax incentives and rebates, it could be cheaper.

Cost of Solar Energy:

4/11/2011 83 Cost of Solar Energy Example of Solar House Cost: A model residential home in Raleigh, North Carolina, with a PV system set up by the North Carolina Solar Center to demonstrate the technology. Estimated that its 3.6-peak-kW PV system covers about half of the total electricity needs (this system doesn't use batteries -- it's connected to the grid). Even so, at $9 per Watt, this installed system would cost you around $32,000, a big budget for an average family; Right now, it simply can't compete with the exist utilities. Researchers are confident that PV will one day be cost effective in urban areas as well as remote ones; http://greeninc.blogs.nytimes.com/2009/02/24/first-solar-claims-1-a-watt-industry-milestone/

Advantages of Solar Energy:

4/11/2011 84 Advantages of Solar Energy Clean: means environmental friendly: No Greenhouse gases; Renewable: Never be used up as long as the sun shines. Can be used in passive designs for buildings: Minimal cost of operation. Can be used for special locations and needs: (space, remote area, difficult areas to run power lines;); Can be used on small scale – individual homes for example.

Problems With Solar Energy:

4/11/2011 85 Problems With Solar Energy What if the sun isn’t shining – must have backup power source: At night, raining & overcast days; (in reality, the sun is expected to shine for another dozen billion years); Collection systems are still inefficient; Active solar systems still cost too much; More suitable for small scale application.

Current Situation:

Current Situation Requires large scale production to reduce cost; Market demand is still low; Public Awareness of the environmental issue; New technologies are coming on-line very quickly; The Obama administration comprehensive New Energy for America plan; Expect a bright future! 4/11/2011 86

What’s going on in Pennsylvania:

What’s going on in Pennsylvania General information (Commission on Economic Opportunity): http://www.pasolar.org/ Pennsylvania State Solar Power Rebates, Tax Credits, and Incentives: http://www.solarpowerrocks.com/pennsylvania/ ; Typical PA solar company: http://www.solartechofpa.com/index.htm ; 4/11/2011 87

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Attendance check: Please click 4/11/2011 88 I am still here in class  I have left for the day. 0 5