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StudentLecture_27-28

StudentLecture_27-28 - CHM 11500 CHM/3/2010 Lecture Reading...

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1 CHM 11500 CHM 11500 Lecture 27, 12/3/2010 Lecture 27, 12/3/2010 Reading: Interchapter: The Chemistry of Modern Materials, Pages 656-669 Laboratory next week: Check out Homework Final, Wednesday 12/15, 1:00 PM Hall of Music 2 hours, 35 – 40 multiple choice questions Pencil, PUID, non-programmable calculator, seat location
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2 What do we do when the oil runs out? Energy sources in the U.S.A.
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3 Solar energy striking the U.S.A Energy used in the U.S.A.
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Solar Energy Solar energy available in U.S. in 1 year is about 10 times the energy available in ALL known oil reserves on the Earth U.S. avg. solar radiation ~125 W/m 2 ~250 W/m 2 surface area 5.10 x 10 8 km 2 (land: 1.49 x 10 8 km 2 ) 9.63 x 10 6 km 2 solar power available 6.38 x 10 16 W (land: 1.86 x 10 16 W) 2.41 x 10 15 W solar energy available (kwh) land: 1.63 x 10 17 kWh 2.11 x 10 16 kWh total energy consumption per year (2003) 1.23 x 10 14 kWh 2.65 x 10 13 kWh solar radiation hitting Earth’s surface (for overhead midday sun) = 925 W/m 2 (power = energy per time, 1 W = 1 J/s)
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5 Question It is estimated that the total world’s oil reserves are 1.2 x 10 12 barrels of oil (each barrel is 42 U.S. gallons or 159 L). Approximately much energy is contained in one barrel of oil? (hint: use information given on the previous slide) a. 5300 W b. 2.1 x 10 15 kWh c. 200 W d. 1700 kWh 2.11 x 10 16 /(10* 1.2 x 10 12 )
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6 Solar Energy Solar Energy Obviously can’t use it all How much could we use? How is solar energy captured and used? How does the cost per Watt compare (today) to oil-based energy?
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7 Using Solar Energy passive Allowing solar radiation to be captured as heat – such as heating water or bricks or other “heat sinks”. Heat is then released as needed. Does not use active mechanical systems active Uses electrical or mechanical equipment. For example, allowing solar radiation to strike a solar cell which converts it to an electric current. Store the electricity in batteries to use later or use it do work (example, powering a motor)
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8 Passive Solar Panels “Solar Thermal” panels – the original solar panels Generally used to heat water
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9 Passive Solar Home Design Heat absorbing material which will radiate heat back out at night. Example: brick or certain tiles. IR (“heat”) Sunlight
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10 Active Solar Cells (Photovoltaics) Overview of how they work…. Solar cells are composed of n and p type semiconductors.
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11 Photon in. Electron promoted to conduction band and flows through the outside circuit circuit to return to a hole. Solar Cell Photon
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12 Question #2 Which of the following is true? A. Electrons can freely conduct electricity in a solid as long as the solid has a regular crystal lattice. B. Insulators, metals and semiconductors are distinguished by their crystal lattice structure. C. Semiconductors consist of material that is p-type on one side and n-type on the other, where electrons can move across the junction.
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