Title: Recap: Renewable Energy Sources

Recap: Renewable Energy Sources - Identification and the major source

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Q: Renewable Energy Sources are considered an infinite source of energy on a [...]. The most important source of energy to humans is [...]. [...] and [...] protect the earth's surface from excessive impact from [...]. [...] energy is an indirect form of [...].
A: societal time scale/societal time-scale; solar energy/solar radiation; Scattering/Absorption; scattering/absorption; solar energy/solar radiation; Wind/Wave; solar energy/solar radiation
  Hint: Hint: It has to do with time
  Hint: Hint: It is not geothermal energy
  Hint: Effects caused, amongst others, by the atmosphere
  Hint: Effects caused, amongst others, by the atmosphere
  Hint: The major energy source for our planet
  Hint: The major energy source for our planet

Recap - On wind and water

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Q: Wind turbines extract [...] energy from winds. For wind turbine placement, one has to consider the [...] of wind, as well as its [...]. A [...] is one of the tools facilitating the evaluation of the energy potential of a site candidate for such turbine. The attractiveness of a site depends also on the terrain - the wind speed depends on its [...].
A: kinetic; speed/direction; speed/direction; wind rose/wind rose diagram; roughness
  Hint: Think movement
  Hint: Again, think movement
  Hint: Again, think movement
  Hint: Hint: Non-smootheness
Q: Hydropower harvests the [...] energy of water as a result from its elevation. There is a large contrast between the theoretical potential and the true potential of hydropower, due to social, economical and [...] reasons, as well as questions of mere technical feasibility.

Waves are oscillatory motions of the water surface caused by [...] and thus indirectly by [...]. Tidal currents are caused by gravitational attractions exerted by the [...], the [...] and the rotation of the [...].
A: potential; environmental; wind/winds; solar energy/solar radiation; Moon/Sun; Moon/Sun; Earth
  Hint: Think in relation to kinetic energy
  Hint: Our natural surroundings
  Hint: Movements of air
  Hint: The major energy source on for our planet
  Hint: Planets in relevant circumfence to earth
  Hint: Planets in relevant circumfence to earth
  Hint: Our planet

Recap: Other Renewable Energy Sources

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Q: [...] energy stems from radioactive processes beneath the earth's crust and mantle. In [...] areas the harvesting of this form of energy is facilitated - Iceland is a well-known example.
A: Geothermal; volcanic
Q: Prior to the industrial revolution, [...] was the most important source of energy for heating and cooking. There are two categories one may consider regarding this type of energy: [...] which is readily available and [...] which are more expensive than the former but can be harvested in larger quantities. This form of energy can be considered carbon neutral if handled properly.
A: biomass; Biomass waste/biomass waste/waste; energy crops/crops