1  

•  Hydrogen  gas  does  not  exist  freely  on  earth  •  but  is  bound  to  other  molecules  

•  Spli9ng  hydrogen  from  other  molecules  requires  energy  •  Electrolysis  

•  electricity  splits  hydrogen  atoms  from  oxygen  atoms  in  water  molecules:    

•  2H2O  ⇒  2H2  +  O2    

•  Produces  pure  hydrogen  •  The  polluBon  produced  depends  on  the  source  of  electricity  

2  

•  Hydrogen  can  also  be  obtained  from  biomass  and  fossil  fuels:  

CH4  +  2H2O  ⇒  4H2  +  CO2  

 

•  Results  in  emissions  of  carbon-­‐based  polluBon  

•  Whether  a  hydrogen-­‐based  energy  system  

•   is  environmentally  cleaner  than  a  fossil  fuel  system    

•  depends  on  how  the  hydrogen  is  extracted  

•  Once  isolated,  hydrogen  gas  can  be  used  as  a  fuel  to  produce  electricity  within  fuel  cells  

•  The  chemical  reacBon  involved  in  that  fuel  cell  is  the  reverse  of  electrolysis:  

2H2  +  O2  ⇒  2H2O  

•  The  movement  of  the  hydrogen’s  electrons  from  one  electrode  to  the  other    

•  creates  electricity  

•  Drawbacks  include  

•  a  lack  of  infrastructure  and  faciliBes  

•  enormous  expense  

•  hydrogen  leakage  could  deplete  stratospheric  ozone  

•  Benefits  include:  

•  An  unlimited  supply  that  is  clean  and  nontoxic  to  use  

•  Few  greenhouse  gases  and  other  pollutants  are  made  

•  Is  no  more  dangerous  than  gasoline  in  tanks  

•  Cells  are  energy  efficient,  silent,  non-­‐polluBng,  and  won’t  need  to  be  recharged  

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•  More  people  are  becoming  convinced  that  we  need  to  shiU  to  renewable  energy  sources.  

•  Biomass  and  hydropower  already  play  important  roles.  

•  Renewable  sources  include  solar,  wind,  geothermal,  and  ocean  energies.  

•  Hydrogen  fuel  may  produce  electricity.  

•  Most  renewable  sources  have  been  hampered  by  inadequate  funding  for  research  and  by  arBficially  cheap  fossil  fuels.  

•  But  there  is  hope  that  we  can  shiU  to  renewables  with  minimal  disrupBon.  

In  the  United  States,  where  does  most  renewable  energy  come  from?    

a)  Hydropower  and  geothermal  energy  b)  Wind  power  and  solar  power  c)  Geothermal  energy  and  biomass  

d)  Biomass  and  hydropower  e)  Nuclear  and  coal  

 Ethanol  in  the  U.S.  is  made  mainly  from  ______,  and  is  used  to  ______.  

 a)  Soybeans,  heat  homes  b)  Sugar  cane,  drive  cars  c)  Corn,  drive  cars  d)  Willow  trees,  make  electricity  e)  Wood,  heat  homes  

4  

 Which  of  the  following  is  NOT  a  benefit  of  hydropower?  

 a)  It  produces  carbon  dioxide.  b)  It  is  a  clean  source  of  energy.  c)  It  is  renewable.  

d)  It  will  last  as  long  as  rivers  do.  e)  All  of  these  are  benefits  of  hydropower.  

Which  of  these  is  NOT  a  passive  solar  technique?  

a)  The  use  of  thermal  mass  b)  Using  flat-­‐plate  solar  collectors  c)  Installing  low,  south-­‐facing  windows  that  will  maximize  sunlight  

capture  in  the  winter  d)  Using  strategically  planted  vegetaBon  

e)  All  of  these  are  passive  solar  techniques.  

We  can  harness  power  from  wind  by  using  devices  called:    

a)  Wind  turbines  b)  Wind  parks  c)  Wind  farms  

d)  Solar  cells  e)  Nacelles            

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Wind  turbines  can  be  erected  singly,  but  they  are  most  oUen  erected  in  groups  called:  

a)  Wind  turbines  b)  Wind  farms  

c)  Wind  mills  d)  Solar  cells  e)  Farms            

Which  energy  source  may  not  be  renewable,  and  is  laced  with  minerals  that  corrode  equipment?  

a)  Solar  panels  b)  Wind  energy  

c)  Geothermal  energy    d)  Hydrogen  fuel  cells  e)  Wave  energy  

KineBc  energy  from  waves  and  Bdes  can  be  converted  into:  a)  Electricity  

b)  Wind  energy  c)  Heat  for  homes    d)  Hydrogen  fuel  cells  

e)  Hot  water  for  homes  

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ProducBon  of  hydrogen  fuel  can  come  from  all  of  these  sources  EXCEPT:  a)  Biomass  

b)  Water  c)  Coal    d)  Oil  

e)  It  can  come  from  all  of  these  sources.  

 Given  the  choice  of  living  next  to  a  coal-­‐burning  power  plant  or  nuclear  plant,  which  would  you  choose?  

a)  The  nuclear  plant,  because  it’s  cleaner  b)  The  coal  plant,  because  it  won’t  emit  radioacBve  materials  c)  Neither  one;  I’d  move  to  another  place  d)  Either  one;  I  don’t  care  

Would  you  support  wind  turbines  being  put  in  your  neighborhood?    

a)  Yes,  because  it  is  healthier  for  the  environment.  b)  Yes,  because  I  don’t  care  if  I  see  turbines  when  I  look  out  the  

window.  c)  No,  because  I  don't  care  about  the  environment.  d)  No,  because  I  don’t  want  to  see  turbines  when  I  look  out  my  

window.      

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_____ is the best state for producing solar energy, while _____ is best for wind energy.

a)  Maine,  Florida  b)  Texas,  Kentucky  c)  Arizona,  Idaho  d)  North  Dakota,  Ohio  e)  Louisiana,  Oklahoma  

Solar

Wind

If  ethanol  in  the  U.S.  is  produced  from  corn,  a  drawback  suggested  from  this  graph  could  be:  

a) More corn would become available

b) More competition between food and fuel

c)  Less land planted in corn d)  Corn would cost less d) None of these