SOLAR POWER Solar Power Video 1 © Daniel L. Wilson, Dr. Michael A. De Miranda, Dr. Thomas J. Siller, & Dr. Todd D. Fantz

Review 2

Important Equations  Ohm’s Law, Georg Ohm, 1827 V=I*R I=V/R R=V/I P=V*I or P=V 2 /R or P=I 2 R 3

Let’s be Smart Smarts  Let’s review some things we have talked about:  Examples of Clean Energy include? What are some dirty or medium energy systems?  A force used to create motion is doing?  Energy vs. power? Can energy be created?  What turns on our lights: work, energy, or power?  Generators, solar cells, and fuel cells generate what?  Turbines use the energy of what?  The act of reducing our energy use is called what? 4

Power Generation 5

Simple Generator Diagram Figure 1 6

Power Generation  Almost EVERY mode of power generation on earth simply relies on trying to make something spin in a circle  Wind  Water  Coal  Nuclear All you need to make power is a magnet, a coil of wire, and some way to move the magnet across the coil. Nothing is free…EVER! It takes force to move the magnet by the coil. Continued application of force takes power The exception to this pattern is solar power 7

Solar Energy 8

Solar Energy Systems  Uses the electromagnetic radiation of the sun to generate electricity Figure 2 From: Laboratory for Computational Science and Engineering, Univ. of Minnesota URL: mages/spectrum.gif mages/spectrum.gif 9

Solar Radiation in the USA Figure 3 From: Virginia Department of Mines, Minerals and Energy URL:

How Much PV to Power the USA? 11 30*10^15 W-hr/year of energy needed How much energy falls per square meter per year in the place we are talking about? 5000 W-hr/m 2 /day * 365 day/year = 1.825*10^6 W-hr/m 2 /year How much of this energy can we actually obtain with 30% efficient panels? Gathered Energy = Available Energy * efficiency = 1.825*10^6 W-hr/m 2 /year * 0.30 Gathered Energy = 5.475*10^5 W-hr/m 2 /year How much area do we need to serve the entire country’s needs? Required Land = Energy Needed/Energy Gathered per square meter Required Land = 30*10^15 / 5.475*10^5 W-hr/m 2 /year = 5.48*10^10 m 2 Note: since PV panels are about 1m 2 in area, we would need roughly 50 billion panels Required Land = km 2 How big is this really? Required Land = km 2 = about 235km X 235km square or about 150mi x 150mi The red square represents roughly the area of the USA needed to fulfill our current power needs using 30% efficient solar PV.

Parabolic Mirrors Image 1 From: Blog for newenergydirection.com URL: power/ power/ F - principal focus of the parabolic mirror, FO - axis of revolution of the parabolic mirror Figure 4 From: Oracle Thinkquest Education Foundation URL: 12

Solar Tower/Stirling Stirling Engine Image 3 From: Eco-Thinker URL: parabolic-mirror-dish/ parabolic-mirror-dish/ Image 2 From: TreeHugger.com URL: spain.phphttp:// spain.php 13

Solar Updraft Tower  Updraft tower utilizes greenhouse effect  Energy generated from the energy of:  Solar radiation  Wind Image 4 From: Roy Spencer, Ph. D. URL: tower/ tower/ 14

Solar Updraft Tower Figure 5 From: TerritorioScuola.com URL: 15

Photovoltaic Cells p n Silicon with a little Boron Silicon with a little Phosphorus

Optimization 17

Activities  You will be optimizing your solar cell to generate as much power as possible  Optimization is one of the key factors in any engineering design process It is not just important that something works. It is important that it works well. 18

Let’s Go!  Please make sure to share our limited space with one another  Take your time and enjoy the sunshine 19