I. Solar Energy

• A. Definition Of Solar Energy
  
  • 1. This is energy received from the sun by the Earth in the last 100 years
    
    • a. Hydroelectric power
      
    • b. Wind power
      
      • 1) PG & E 83 MW by 1990
        
      • 2) SCE 43 MW by 1990
        
    • c. Wood
      
    • d. Ocean currents
      
    • e. Passive and direct solar power
      
• B. Advantages of Solar Power
  
  • 1. Solar energy received by the Earth is enormous 17.7 x 1016 watts
    
    • a. 100,000 x world electrical output
      
  • 2. Infinite supply
    
  • 3. Constant supply
    
  • 4. No pollution
    
  • 5. No boycotts
    
  • 6. Biologically compatible
    
• C. Passive Solar Power
  
  • 1. Space heating
    
  • 2. Water heating
    
• D. Direct Solar - Converts Sunlight to Electricity
  
  • 1. This is very expensive
    
  • 2. Modern 1000 MW plant would require 42 sq. km. or 16.2 sq. miles
    
    • a. 10,000 MW input
      
    • b. Surface receives 0.024 watts/cm2
      
      • 1) 1010 watts/0.024 watts/cm2) = 42 sq. km.
        
  • c. A future approach might involve satellite receivers microwaving the energy to Earth
    

II. Water Power

• A. History and Potential
  
  • 1. Large scale generation and transmission of water power started around 1900
    
  • 2. Present production is 45,000 MW
    
    • a. Ultimate maximum based on stream flow is 161,000 MW
      
    • b. It appears that some used potential may help compensate for declining fossil fuels
      
• B. The Problems of Hydroelectric Power
  
  • 1. Dams have a large impact on the environment
    
  • 2. Most acceptable hydro sites are already developed
    
  • 3. Hydroelectric power only supplies a small percent of the nations power
    

I. Solar Energy | II. Water Power | III. Tidal Power | IV. Geothermal Power | V. Atomic Fusion  | Links | top | Geol 357 Lecture Home

III. Tidal Power

• A. Same Basic Principle as Hydroelectric Power
  
• B. Tidal energy can be exploited in two ways:
  
  • 1. By building semi-permeable undersea tidal turbines across estuaries with a high tidal range.
    
  • 2. By harnessing offshore tidal streams
    
• C. How it works:
  
  • 1. Water flow as basin fills or empties drives turbines
    
  • 2. Similar to a wind turbine, but goes in both directions
    
  • 3. Requires a daily tidal range of 5-7 meters (~15-21 feet) to be practical
    
  • 4. Characterized by low capacity factors, usually in the range of 20-35%.
    
• D. Locations
  
  • 1. 240 MW facility has operated in France since 1966
    
  • 2. 20 MW in Canada since 1984
    
  • 3. A number of stations in China since 1977, totaling 5 MW
    
• E. La Rance, France - world's first tidal power plant
  
  • 1. Average tidal range 27 feet
    
  • 2. Dam encloses 8.5 sq. miles
    
  • 3. Capacity is 320,000 KW
    
• F. Low Production but also Low Environmental Impact
  
  • 1. No noxious waste
    
  • 2. No consumption of resources
    
  • 3. Minimum disturbance to scenery
    

I. Solar Energy | II. Water Power | III. Tidal Power | IV. Geothermal Power | V. Atomic Fusion  | Links | top | Geol 357 Lecture Home

IV. Geothermal Power

• A. Source of the Energy
  
  • 1. Conduction to the surface
    
  • 2. Convection by volcanoes and hot springs
    
• B. Two Methods of Recovery
  
  • 1. Dry Steam Geothermal Fields
    
    • a. Steam rises to the surface and is used directly to drive a turbine
      
    • b. Geysers, California is an example
      
      • 1) Produced 2000 MW by 1986
        
        • a) Serves 12 cities & 2 million people around Sonoma County
          
      • 2) Ultimate possible is 2500 MW
        
    • c. This type is rare
      
  • 2. Wet Steam Geothermal Power
    
    • a. Steam and water come to the surface and must be separated
      
    • b. This type is found and used in New Zealand, Japan, Mexico, Russia, & Iceland
      
    • c. Water may be used for conventional heating before disposal
      
    • d. Disposal method depends on salinity
      
      • 1) Pour it into a river
        
      • 2) Pipe it to the ocean for disposal
        
      • 3) Reinject it
        
• C. Recovery from Non-thermal Areas
  
  • 1. This is more challenging and has not yet been accomplished
    
  • 2. Drill 2 adjacent holes
    
    • a. Pump cold water into one & recover steam from the other
      

I. Solar Energy | II. Water Power | III. Tidal Power | IV. Geothermal Power | V. Atomic Fusion  | Links | top | Geol 357 Lecture Home

V. Atomic Fusion

• A. Possibility was first recognized by Hans Bethe 1939 - Nobel Prize)
  
  • 1. Concept is to harness the energy of the sun by fusing ₁D² into ₂He³ or ₂He⁴
    
  • 2. This has already been done in the form of the hydrogen bomb
    
• B. Definitions
  
  • 1. Proton - a positively charged subatomic particle
    
  • 2. Neutron - a negatively charged subatomic particle
    
  • 3. Isotope - atom that exhibits variation in its mass number
    
  • 4. Mass number - sum of the neutrons plus the protons in an atom
    
  • 5. Atomic number - # of protons found in the nucleus
    
  • 6. Atomic weight - average of the atomic masses of all the element's isotopes
    
  • 7. Fission - the act or process of splitting into parts
    
    • a. A nuclear reaction in which an atomic nucleus, especially a heavy nucleus such as an isotope of uranium, splits into fragments, usually two fragments of comparable mass, releasing from 100 million to several hundred million electron volts of energy.
      
  • 8. Fusion - a nuclear reaction in which nuclei combine to form more massive nuclei with the simultaneous release of energy
    
• C. The 3 Isotopes of Hydrogen
  Hydrogen ₁H¹
  Deuterium ₁D²
  Tritium ₁T³
  
• D. The Reactions
  
  • 1. ₁D² + ₁D² --> ₂He³ + n + 3.2 M_ev 106 electron volts)
    
    • a. This produces a stable end product
      
  • 2. ₁D² + ₁D² --> ₁T³ + H + 4.0 M_ev
    
    • a. ₁T³ is unstable and reacts with ₁D²
      ₁D² + ₁T³ --> ₂He⁴ + n + 17.6 M_ev
      
  • 3. Total energy released is 5 ₁D² --> ₂He⁴ + ₂He³ + H + 2n + 24.8 M_ev
    
• E. How Much Resource is Available?
  
  • 1. There is 1 ₁D² atom per 6,500 H atoms in sea water
    
  • 2. One cubic meter of sea water contains 34.4 grams ₁D²
    
    • a. Potential energy equals 269 metric tons of coal or 1,360 barrels of oil
      
  • 3. One cubic km of sea water equals 269 billion tons of coal or 1,360 billion bbls oil
    
    • a. Exceeds the entire world oil resource
      

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