energy

• What is the definition of biofuel?


  A fuel made from recently living organisms
• Why is the distinction of "recently living" important when discussing biofuels?


  Because fossil fuels come from organisms that lived millions of years ago
• What are the primary sources of biofuels?


  Plants and algae
• How do plants and algae contribute to the production of biofuels?


  They photosynthesize and capture the sun's energy
• Can animal waste be used for biofuels?


  Yes, but usually on a smaller scale
• Why are biofuels generally considered carbon neutral?


  Because they absorb carbon dioxide while growing
• What makes biofuels a renewable resource?


  They can be grown repeatedly
• What is one advantage of biofuels regarding transportation?


  They are easy to transport
• How can biofuels be used in conjunction with fossil fuels?


  They can be mixed with fossil fuels like petrol
• What is a significant environmental concern associated with growing biofuels?


  It often requires converting natural land, which can damage the environment
• What is a consequence of cutting down forests for biofuel production?


  It releases tons of CO2 into the atmosphere
• What energy requirements are associated with biofuels?

  Harvesting, processing, and transporting biofuels require energy
• Why is it difficult to assess the overall effectiveness of biofuels?

  Because their environmental impact can vary widely
• How can biofuels be viewed in relation to fossil fuels?


  They can be a great substitute when used properly
• What are the pros and cons of biofuels?


  Pros:

  • Carbon neutral when grown
  • Renewable resource
  • Relatively cheap to produce
  • Easy to transport
  • Can be mixed with fossil fuels

  
  

  Cons:

  • Requires land that may damage the environment
  • CO2 released from deforestation
  • Energy required for harvesting and processing
  • Overall effectiveness is hard to determine
• What is the conclusion about the use of biofuels mentioned in the video?


  They should be used where it makes sense, not as an all-or-nothing solution
• What are the two systems used to generate electrical power discussed in the video?

  Hydroelectric dams and tidal barrages
• How do hydroelectric dams and tidal barrages generate electricity?


  By creating a difference in water levels to harness gravitational potential energy
• What is the main difference between a hydroelectric dam and a tidal barrage?


  A hydroelectric dam traps upstream water, while a tidal barrage uses tidal changes
• What is a reservoir in the context of hydroelectric dams?


  A reservoir is a large accumulation of water trapped behind the dam
• What causes the cyclic rise and fall of sea levels in tidal barrages?


  The effect of the moon's gravity
• How often do high tides occur?


  Twice each day
• Where are tidal barrages typically placed?


  In estuaries where rivers meet the ocean
• What type of energy is converted into electricity in hydroelectric systems?

  Gravitational potential energy
• What happens to the water after it passes through the turbines in a dam?


  It flows back into the river on the other side of the dam
• What are the pros and cons of hydroelectric dams and tidal barrages?

  Pros:

  • Generate large amounts of energy with no pollution
  • Reliable sources of electricity
  • Immediate response to increased demand
  • Low running costs
  • Can operate on large and small scales

  
  

  Cons:

  • Significant environmental impact
  • Flooding of large areas
  • Disruption of fish migrations and boat travel
  • High initial setup costs
• What is a significant environmental downside of hydroelectric dams?


  They often flood large areas, submerging habitats and villages
• How do hydroelectric dams and tidal barrages affect fish migrations?


  They can stop fish from traveling up or down the river
• What is a common characteristic of both hydroelectric dams and tidal barrages regarding energy generation?


  They generate energy with no pollution
• What is a benefit of hydroelectric dams in terms of electricity demand?


  They can provide an immediate response to increased demand
• What is a disadvantage of both hydroelectric dams and tidal barrages regarding setup costs?


  The initial setup is often expensive
• What is geothermal energy?


  Thermal energy generated and stored in the earth's crust
• Where does the heat energy in geothermal energy originate from?


  From the initial formation of the planet and ongoing radioactive decay of materials
• What type of energy heats hot springs around the world?

  Geothermal energy
• How can geothermal energy be used?


  It can be used directly for heat or to generate electricity
• What is the cheaper method of using geothermal energy?


  Using it directly for heat
• Describe the process of using geothermal energy for heating.


  Pumping water down into the ground, allowing it to warm up, and then pumping it back up
• How is electricity generated using geothermal energy?


  Water is heated underground until it turns to steam, which drives turbines
• What is required for geothermal energy generation to be feasible?


  Hot rocks near the surface in volcanic regions
• What is a disadvantage of geothermal power plants?


  They can be quite expensive to build