P2 - Collecting energy from the sun, Generating Electricity, Fuels for power Flashcards
What does the sun emit and transfer energy to the Earth as?
Light and heat
What can energy from the sun be captured and used to produce?
Electricity and heat
Why is energy from the sun known as renewable energy?
Because it won’t run out
What do photocells do?
Capture light energy from the sun on flat silicon surfaces
What are photocells made from?
Silicon
How do photocells work?
The suns energy is absorbed by the photocell, causing electrons to be knocked loose from the silicon atoms in the crystal. These electrons flow freely within the silicon; this flow of charge is called an electric current.
What is DC (Direct Current)?
An electric current, which travels in the same direction all the time.
Which three things does the power output of a photocell depend on?
The surface area exposed to the sunlight, the intensity of the light, and the distance between the light source and the photocell
What is a solar panel?
Lots of photocells joined together
Name three disadvantages of photocells
No power at night, no power during bad weather
Name three advantages of photocells
Renewable energy from the sun, no need for fuel as the sun as the energy source, no pollution or waste is produced, little maintenance is required once installed, they have a long life, and can operate in remote locations to give access to electricity without installing power cables.
How can power output be maximized by an efficient solar collector? What is a disadvantage of this?
The solar collector needs to track (follow) the position of the sun through the sky. This requires additional technology, so the set-up cost increases
What are convection currents?
Wind, caused by the Sun’s energy
What energy does a wind turbine transform into electrical energy?
Kinetic energy
Name three advantages of wind turbines
Wind is a renewable energy source, there is no chemical pollution or waste, and it’s free after set up costs
Name three disadvantages of wind turbines
Turbines require a large amount of space to deliver a reasonable amount of electricity, they’re dependent on the wind so are unreliable, and cause visual pollution