.edu /~ Page metin 1 Resources – Renewables - Solar utdallas Outline Astrophysics: Source of solar power Area Requirements Harvesting Solar Power Thermal Photovoltaic Solar power economics and policies Based on - R.L. Nersesian. 2007. Sustainable Energy Chapter 9 of Energy for the 21st Centrury: A Comprehensive Guide to Conventional and Alternative Resources. - U.C.V. Haley and D.A. Schuler. 2011. Government Policy and Firm Strategy in the Solar Photovoltaic Industry. California Management Review, Vol. 54, No. 1: 17-38. .edu /~ Page metin Feasibility of Solar Energy 2 Then and Now utdallas Parigi Gieulio • Solar energy in the siege of Syracuse, Sicily 214-212 BC. Syracuse was a Hellenistic city and was attacked by Romans. • According≈ to a legend, during the siege, Archimedes-designed mirrors burned Roman ships. At the end, Rome conquered the city and 75+ year old Archimedes was killed by Roman soldiers. century, Uffizicentury, Museum www.uffizi.org Siege of Syracuse, bySyracuse, ofSiege th 17 .edu /~ Page metin Nuclear energy Electromagnetic Energy 3 Solar Energy utdallas Helium fusion reactions take place in the sun’s core and mass (4 mega tons / second) is converted into energy. X-axis is the wavelength more of emission in 10 Sun’s temperature at the center 15,000,000 Celsius and on the heat surface 5,700 Kelvin (=273+5,423 Celsius). meters = nanometer −=nm.9 ≈ Y-axis is the power P , ≈ in 10 watts per , nm and4 sr (steradian2). A heated up metal (substance that does not burn) becomes first red Source: Figure 3.8 Carroll & and then yellow. It emits light. Ostite. 2006. Introduction to An ideal model for sun’s light emission is blackbody radiation. A Modern Astrophysics. blackbody does not reflect any light but can emit its own. A blackbody does not appear black to eye. Depending on its temperature T, a black body emits power P , at less heat different wavelengths . The total power emitted is the area under P , Planck curve. Higher temperature objects emit more power but 4G network Infrared goggles at lower wavelengths. 0.6-2.5 Giga Hz detect infrared waves Units of power is watts per squaremeter per steradian; see appendix. www.lbl.gov Source: An approximate formula for P , is offered by Planck. less energy, safe higher energy, danger .edu /~ Page metin 4 Solar Power on Atmosphere and Surface utdallas Take the blackbody radiation Planck curve at 5777 K from the previous page. Light is neither a wave nor a particle; it is both. This is known as wave-particle duality in quantum physics. Planck equation: Light has energy its frequency = 1/wavelength. From nuclear energy, 1 eV=1.6*10-19 J. The radiation that falls on the earth outside atmosphere is more than the radiation on the surface. ∝ – Atmosphere (ozone, oxygen, water, carbondioxide) absorbs particular wavelengths of emission. E.g., Ozone O3 absorbs short wavelength (high energy) emissions. Lack of ozone High energy emissions Skin cancer. ⟹ ⟹ Source: Figure 2 of JA Herron, J Kim, AA Upadhye, GW Huber & CT Maravelias. 2015. A general framework for the assessment of solar fuel technologies. Energy & Environmental Science, 8: 126-157. Remarks: 1) The unit of /( ) on the right-hand vertical axis is from the black body2 radiance theoretical model. 2) 1 electron volt Empirical ∗ ∗data are from Reference Solar Spectral Irradiance: Air Mass 1.5, http://rredc.nrel.gov/solar/spectra/am1.5/, accessed June 2014. Units for these data are in /( ). 3) Solar power reaches earth in several wavelengths ( ) not2 just one. The total power per area reaching earth is the area under ∗ the spectral irradiance curve Total Power per area of squaremetre = , = 5777 ∞ 0 O3 ∫ Instead of integral, approximate the integral by the area of the triangle above. The power that reaches the earth’s atmosphere is approximately the area of the triangle with base 1750-250 nm wavelength and height 1.75 /( ). The theoretical irradiance (area of the triangle) is 1312.5 / . 2 – The empirical irradiance is 1361 / . 2 ∗ 2 .edu /~ Page metin 5 Solar Power Accounting for Zenith Angle utdallas Solar power provides ~ 1360 W/m2 outside the earth’s atmosphere. This is also called AM0 irradiance. It provides less after passing through the atmosphere. When the sun is falling directly, air mass (AM)=1. 900 1 0 AM = 48 600 Cos cos 0 = 1; cos 48 = 0.67; cos 60 = 0.5; 푍 AM= 1 AM= 1.5 AM= 2 cos 90 = 0; AM= ∞ Half of 1360 W/m2 reaches solar panels. The rest is reflected back to space or absorbed by the atmosphere. – Solar radiation bouncing from atmospheric particles move in various directions. This called diffuse radiation, which is higher on hazy or cloudy days. When the zenith angle is wider, the light must travel longer in the atmosphere and drops more of its energy at the atmospheric particles. AM1.5 irradiance is generally about 827 W/m2. Industry rounds AM1.5 up to 1000 W/m2. Earth wide average solar power per area 650 W/m2. ≈ .edu /~ Page metin 6 Solar Power Accounting for Nights & Clouds utdallas AM1.5’s irradiance 1 kW/m2 (=1,000 W/m2) is available during the day when the sun is visible. Power/area 2 1 kW/m2 Average daily 4.7 kWh/m Average annual 1715.5 kWh/m2 Day 1 total 5.4 kWh/m2 Day 2 total 4.4 kWh/m2 based on only day 1 and 2 Night Night Night Hours 1 9 17 1 9 17 Pyranometer measures solar radiation .edu /~ Page metin 7 T/X Questions utdallas 1. Diffuse radiation outside the atmosphere is the largest. X, there is no diffuse radiation outside the atmosphere. 2. The energy generated by the sun is due to fusion reaction. T 3. Only visible light generated by the sun reaches the earth. X, light reaches in different wavelengths including infrared and ultraviolet. 4. Lower frequency electromagnetic waves carry less energy. T 5. A hot substance emits power through electromagnetic waves at different wavelengths. T 6. A hotter substance emits a higher amount of power at some but not all wavelengths. X, it emits higher amount of power at all wavelengths. 7. Depletion of ozone in the atmosphere increases the solar power reaching the panels on earth’s surface. T 8. Air Mass (AM) in solar energy refers to the mass of air in 1 cubicmetre volume at various altitudes. X, AM is the 1/cos(zenith angle) and is used to measure the air mass the light travels through in the atmosphere. 9. Zenith angle at dawn is zero degrees. X, zenith angle at dawn is 90 degrees. .edu /~ Page metin 8 Solar Power Area Requirement utdallas Overton, North Texas receives maximum irradiance of about 6 kW/m2 in August and minimum of about 2 kW/m2 in December. Texas solar irradiance database is www.me.utexas.edu/~solarlab. Southwest US receives more solar energy about 6 kW/m2. – Optimistically suppose sun is out 12 hours/day and 30% conversion efficiency, so we get 0.9 kW/m2 (=(6/2)*0.3) of radiation at every hour. How many m2 required to generate 350,000 kW (capacity of Mojave desert panels)? » 350,000/0.9 = 388,888 m2 which can be made up by a 623 metre x 623 metre square. A (American) football field is 4,500 m2. About 90 football fields are needed. – More likely scenario has sun out 8 hours/day and 20% conversion efficiency, so we get 0.4 kW/m2 of radiation at every hour. How many m2 required to generate 350,000 kW? » 350,000/0.4 = 875,000 m2 which can be made up by a 935 metre x 935 metre square. About 200 football fields are needed. – Where to find such a large deserted land? In a desert! Total US generation capacity was 1,000,000,000 kW in 2007, which requires 1,100,000,000 – 2,500,000,000 m2 or 250,000 – 560,000 football fields. Source: http://sroeco.com/solar Mojave desert 5000-6000 W/m2 Solar parabolic panels, Mojave desert .edu /~ Page metin 9 Roofs for Solar Power at UTD and around utdallas In 2013, UTD installs 220 kilo watt solar panels on the new Parking Structure, see the photo below. With this, UTD was able to participate in a Solar Program funded by Oncor and qualified to receive $203,722. UTD also qualified for another $98,371 in incentives during 2012 for efficient chiller installations and by constructing buildings that are more efficient than the code requirement. This brought the total incentive in 2013 to $302,093. UTD’s Energy Revolving Fund reinvests these incentives in energy efficiency projects on campus. Savings from the projects refill the fund. In Fall 2013, parking lot In 2015, ATT installs 677 kilo watt ground northwest of SOM building mounted solar panels. 2,000 panels provide In 2014, FedEx installs 1,400 kilo watt roof about 40% of building’s annual power need. mounted solar panels. 4,622 panels provide about 20% of building’s annual power need. ~0.3 kW/panel FedEx distribution center Hutchins, TX ATT distribution center Lancaster, TX Utility companies are required to invest in energy efficiencies in their service areas. – Oncor runs the “Take a Load off Texas” project, which funded $62 million in 2013. – CenterPoint invested $42 million in projects in 2013. Source: Merit Report: Plugging into Energy Efficiency. 2014. Z. Cologlu, D. Flom, T. Junt, S. Patel and A. Pizaňa. .edu /~ Page metin 10 Harvesting Solar Power utdallas Sun’s energy can be harvested as thermal solar power and as photovoltaic solar power.