EngPhys. 160, 51707

1
Eng/Phys. 160, 5/17/07

• Photovoltaics more basics
• ? Insulators, metals, conductors
• ? Photovoltaic effect
• ? Need for an np junction (conventional)
• ? Efficiency
• ? Alternatives to silicon - organic PVs,
  Gratzel cells
• ? New ideas - carrier multiplication hot
  electrons
• Photovoltaics growth of usage
• Wind Power
• --gt Basics theoretical efficiency max, wind
  energy density, places of high density
• --gt Growth of usage
• --gt Cost
• --gt Drawbacks (visual, noise pollution,
  longevity, raptor deaths)
• Hydroelectric
• --gt Basics
• --gt Limits to large scale hydro
• --gt Problems with large scale hydro
  (earthquakes, displacement, increased
  greenhouse effect, risks of catastrophic
  flooding, silting out of dams..)

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Gratzel dye and chlorophyll
3
Gratzel Cell mimic photosynthesis
4
Beat the limit with nanostructures

• Nanostructures have intrinsically multiple bands
  from quantum confinement
• Can increase the open circuit voltage by
  inhibiting carrier relaxation (emission of
  phonons)
• Can increase the current by increasing number of
  particle hole pairs induced per photon (Klimov,
  Los Alamos)

5
Typical efficiencies of current photovoltaics
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Photovoltaic growth

• Upper left world growth of sales
• Lower left Growth of installed capacity in Japan
• Lower right growth of installed capacity
  worldwide

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Photovoltaic Costs
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Wind energy
9
Maximum wind efficiency--on blackboard. Neat
result.
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Wind-where is it?
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Wind energy growth
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Wind energy costs
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Dams Hoover, Grand Coulee, Three Gorges
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Where's left for dams?
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Image credits

• Data from Japan www.poweringtherim.org/casestudie
  s/egill.html
• PV Growth, MW www.votesolar.org/whysolar.html
• PV Growth, Sales www.heliovolt.com/market.php
• PV Costs, efficiency charts www.eere.energy.gov/.
  ../solar_power_from_pv.html
• Wind energy growth www.ecotopia.com
• Wind energy development blackhawkfund.com
• Wind cost http//www.eere.energy.gov/tribalenergy
  /guide/images/chart2_wind.gif
• Where there's wind map www.nrel.gov/wind/wind_map
  .html
• Hoover Dam http//www.nuc.berkeley.edu/courses/cl
  asses/E-124/hoover20dam_1.jpg
• Grand Coulee Damwww.nwcouncil.org,
  www.grandcouleedam.com
• Three Gorges Dam http//www.tourroundchina.com/ne
  ws/three_gorges_dam_to_open_to_visitors.htm
• Hydro potential nationalatlas.gov/articles/people
  /a_energy.html

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Image credits

• Working Gratzel Cell http//www.bath.ac.uk/physic
  s/news/gratzel.jpg
• Gratzel schematic (liquid electrolyte)
  http//www.bath.ac.uk/chemistry/electrochemistry/i
  mages/mechanism_small.jpg
• Gratzel schematic (polymer electrolyte)
• http//www.rsc.org/ejga/CC/2005/b416461j-ga.gif
• Polymer photovoltaic photo http//www.polymercent
  re.org.uk/industry/pics/03photovoltaic.jpg
• Alan Heeger http//www.konarkatech.com/images/hee
  ger.jpg
• Konarka Power plastic http//energypriorities.com
  /graphs/konarka-power-plastic.jpg
• Chlorophyl http//amanda.berkeley.edu/bramall/wo
  rk/astrobiology/images/chlorophyll.jpg
• PV schematic http//www.speedace.info/speedace_im
  ages/solar_cell_schematic.jpg
• Met/ins/semic schematic http//www.physics.udel.e
  du/watson/scen103/semi1.gif