Energy Technologies

1
Energy Technologies

• Fossil Fuels, Nuclear Power, Batteries, and
  Hydroelectric Power

2
Energy Uses and Sources
Uses 30 generating electricity, 25
transport-ation, rest for heat for industry and
homes
http//www.cbsnews.com/sections/indepth/main500142
.shtml
3
Types of Energy Sources

• Non-renewable source is consumed at a rate that
  is much faster than it is naturally replaced -
  fossil fuels require over a million years for
  replacement
• Renewable source is essentially replaced
  naturally as it is consumed - hydroelectric power
• Need to maximize use of renewable energy sources

4
Fossil Fuels

• Natural gas, coal, and petroleum are called
  fossil fuels since they are formed in the carbon
  cycle over long time periods by the decay of
  living matter
• Major components of the fossil fuels are CH4 for
  natural gas, C for coal, and a mixture of
  saturated hydrocarbons that can be represented as
  CnH2n2 for petroleum

5
Fuels from Crude Oil
Separated by differences in London Dispersion
Force
http//www.wpbschoolhouse.btinternet.co.uk/page04/
OilProducts.htm
6
Combustion Reaction

• Chemical energy of fossil fuel is converted to
  thermal energy by combustion (burning with O2)
• When reacted with O2, all C in a fossil fuel is
  converted to CO2 (CO bond energy 187
  kcal/mole), and all H is converted to H2O (H-O
  bond energy 110 kcal/mole), making reaction
  exothermic

7
Heat can be used to power an internal com-bustion
engine, to produce electricity, etc.
Tro, 220
8
Internal Combustion Engine
Mixture of gasoline and air is ignited by a spark
from spark plug. Explosion forces piston
downward and causes crankshaft to rotate
http//www.howstuffworks.com/engine.htm
9
3
auto-ignition
Heptane
http//www.uwcsea.edu.sg/chem/IBfolder/IBH/ORGANIC
/Petrol/IsoOctane.html
10
Technology for the Production of Electricity
Hill/Kolb, Chemistry for Changing Times,
7th,Prentiuce Hall, NJ, 1995, 426
11
Conversion of Mechanical Energy to Electrical
Energy
Rotating a coil of wire in a magnetic field
induces a flow of electricity in the wire
Stanitski at al, Chemistry in Context, 3rd,
McGraw Hill, MA, 2000, 311
12
Converting Mechanical Energy to Electrical Energy
Alternating Current
Hinrich, Energy, 2nd, Saunders, NY, 1996, 359
13
Nuclear Reactions

• Reactions that convert unstable nuclei to more
  stable nuclei are spontaneous
• Fusion involves small nuclei combining to form a
  larger more stable nucleus
• Fission involves a large nucleus breaking up into
  two smaller more stable nuclei plus some free
  neutrons

14
Exothermic Nuclear Reactions
Olmstead/Wms, Chemistry, 3rd, Wiley, NY, 2002,
1005
15
Fission Reaction
Tro, 189
16
Chain Reaction

• Chain reaction - reactant in one step is formed
  as a product in a later step
• A chain reaction occurs when the neutrons set
  free in the fission reaction all react with other
  U-235 nuclei
• Critical mass is the mass of active nuclei
  required so that nearly all the neutrons set free
  are able to react with a U-235 atom

17
Multiplying Chain Reaction in Atomic Bomb
U-235 neutron Sr-90
Xe-144 2 neutrons
U-236
Chain
Tro, 190
18
Nuclear Power Technology

• Ratio of neutrons to U-235 atoms in a fission
  reaction is adjusted to 11 by reacting excess
  neutrons with non-fissionable atoms in control
  rods
• Sustains chain but prevents its multiply-ing so
  heat is released more slowly
• Major system failure can produce a meltdown,
  but not nuclear explosion (critical mass not
  present in fuel rods)

19
Nuclear Power Plant
Tro, 193
20
Nuclear Power Plant Including Cooling Cycle
Birk, Chemistry, Houghton Mifflin, MA, 1994, 876
21
Reduction - Oxidation Reactions (Redox)

• Involve the transfer of electrons from one
  particle to another - one particle loses
  electrons (oxidation) and the other gains
  electrons (reduction)
• Zn Cu2 gt Zn2 Cu
• Zn is oxidized since it loses electrons
• Cu2 is reduced since it gains electrons

22
Direct Transfer of Electrons The reaction, Zn
Cu2 gt Zn2 Cu, takes place on the surface of
the Zn if the Cu2 and Zn are placed in direct
contact with each other
Fay/McMurray, Chemistry, 2nd, Prentice Hall,
NJ1998, 728
23
Battery

• Converts the chemical energy of a redox reaction
  to electrical energy by requiring the transfer of
  electrons between two particles to occur
  indirectly through a wire
• Motion of electrons through the wire is
  electrical energy

24
Indirect Transfer of Electrons - Battery
Fay/McMurray, Chemistry, Prentice Hall, NJ, 1995,
706
25
At the lead electrode Pb
SO42- ltgt PbSO4 2e At the lead dioxide
electrode PbO2 4 H SO42- 2e ltgt PbSO4
2 H2O Overall Reaction Pb PbO2 4H
2SO42- ltgt2 PbSO4 2 H2O Forward reaction is
discharge, reverse reaction is charge
Closed system - can exchange energy but not
matter with surroundings
Odom et al, Chemistry, Heath, MA, 1992, 616
26
Fuel Cell

• Battery in which the reactants are continuously
  supplied from external sources
• Fuel cell is an open system, i.e., the system can
  exchange both energy and matter with its
  surroundings

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28
Hydrogen Fuel Cell
http//www.fuelcells.org/whatis.htm
29
(O2)
(H2)
http//science.howstuffworks.com/fuel-cell2.htm
30
Stanitski at al, Chemistry in Context, 3rd,
McGraw Hill, MA, 2000, 311
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FOCUS by Ford Motors
Powered by hydrogen fuel cells
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DaimlerChrysler introduces car powered by fuel
cells March 17, 1999
http//www.cnn.com/NATURE/9903/17/fuel.cell.car/
34
Hydroelectric Power

• Solar Energy drives the Water Cycle
• Rain water is stored in a reservoir behind a dam
  (potential energy)
• Potential energy is converted to kinetic energy
  when water flows downward
• Kinetic energy of flowing water is converted to
  mechanical energy by a turbine which drives
  electric generator

35
Hydroelectric Power
Nebel/Wright, Environmental Science, 7th,
Prentice Hall, NJ, 2000, 370
36
Hydroelectric Power Generation
http//www.cbsnews.com/sections/indepth/main500142
.shtml
37
http//www.howstuffworks.com/hydropower-plant.htm