1. Energy (efficiency, national and global energy resources) Flashcards
What is efficiency?
Efficiency is the ratio of the useful work done by a machine, engine, device, etc, to the energy supplied to it, often expressed as a percentage
What is the equation for efficiency?
useful power output
____________________________
total power input
How can the efficiency of a system be increased?
- Reducing waste output (lubrication, thermal insulation)
- Recycling waste output
What is an example of recycling waste output?
Absorbing thermal waste and recycling as input energy
What are the main energy resources for use on earth? (9)
- Fossil fuels (coal, oil, gas)
- Nuclear fuel
- Biofuel
- Wind
- Hydro-electricity
- Geothermal
- Tidal
- Solar
- Water waves
What are examples of non-renewable energy resources?
- Coal
- Oil
- Gas
- Nuclear fuel
What are examples of renewable energy resources? (7)
- Biofuel
- Wind
- Hydro-electricity
- Geothermal
- Tidal
- Solar
- Water waves
What are renewable energy resources?
Energy resources that are being replenished as it is used
What are non-renewable energy resources?
Energy resources that are finite
What are energy resources used for?
- Transport
- Electricity generation
- Heating
What are the advantages of renewable energy?
- It is being replenished as it is being used, so it will never run out
- It does not contribute to global warming
- They can do damage to the environment, but a lot less than non-renewable resources do
What are the disadvantages of renewable energy resources?
- They are very expensive
- They don’t provide much energy
- Some of them are unreliable because they are dependent on the weather
What are the disadvantages of fossil fuels?
- They will run out one day
- They release greenhouse gases: carbon dioxide and sulfur dioxide
What are the advantages of fossil fuels?
- They provide a large amount of energy, so can be used for more large-scale energy supplies
- They are reliable
- they are abundant
- they are relatively cheap
What are fossil fuels and how are they formed?
They are natural resources that form underground over millions of years
How is nuclear energy generated?
- Nuclear fuels are reacted to heat water to produce steam
- the steam turns turbines to generate electricity
How is energy from biofuels generated?
fromthe burning of plant-matter, methane or ethanol
How is energy from hydroelectricity generated?
Water is stored at a height, and when released, rushing water turns turbines directly to generate electricity
How is tidal energy generated?
The movement of water due to tides turn turbines directly to generate electricity
How is geothermal energy generated?
- Hot rocks underground are used to heat water to produce steam
- the steam is used to turn turbines which generate electricity
How are water waves used to generate electricity?
Moving water due to waves turn turbines directly to generate electricity
How do solar cells generate electricity?
They generate electric currents directly from sunlight
What energy resources are used for transport fuel for vehicles?
- Fossil fuels (coal and oil)
- Biofuels
- Renewable energy resources (electric cars)
What can renewable and non-renewable energy stations involve destroying?
Landscapes and habitats
