How can electricity be generated? Flashcards
Why is energy used or important?
everything requires energy and a way to use energy is to transfer it from one energy store to another.
What are energy resources?
systems that can store large amounts of energy
What are the important energy resources to produce electricity?
fossil fuels, nuclear fuel, bio-fuel, wind, hydroelectricity, geothermal, tidal, water waves and the Sun
Where does all energy on Earth come from?
the sun but has been stored as different energy sources
What is energy needed in?
homes - for cooking, heating, etc.
public services e.g. schools and hospitals for running warm rooms and machinery
factories and farms - operating heavy duty machines
transport - cars, buses, trains all need a fuel source
What can cause damage to the enviroment?
producing and distributing electricity
releasing energy from some stores causes pollution and harmful waste products
What are some trends in using energy resources?
in 20th century, electricity became a way of distributing energy that can be used for many devices such as computing technologies, lighting, heating, etc.
during early evenings, a lot of energy is needed for heating, lighting and cooking but overnight little is needed while people sleep
Why is most of the electricity generated still produced by fossil fuels?
the high power output fossil fuels give compared to other resources like wind and water
the existing infrastructure for transporting, extracting and processing fossil fuels which makes them cheaper
What do most countries agree?
the use of fossil fuels should be reduced to limit the emission of the greenhouse gases that cause climate change
the cause of burning fossil fuels has causes society to develop the use of renewable energy resources
What are nuclear power stations?
a growing form of electricity generation
nuclear fuel can release large amounts of energy and does not emit carbon dioxide
How can renewable resources be replenished?
by human action or natural processes
human action - e.g. cutting trees down
natural processes - e.g. let water through a dam for hydroelectricity which is replaced through the water cycle
What are different energy resources?
fossil fuels - high power output
nuclear fuels - very high power output
biofuels - medium power output -
wind - very low output -
hydroelectricity - medium power output
geothermal - medium power output
tides - very high power output
sun - dependent on weather power output
water waves - low power output
What are the power stations that use fossil fuels or nuclear fuel?
they are very reliable sources of energy
two types of stations - gas power stations or hydroelectric power stations - they come on very quickly and start generating electricity quickly
the fuel for nuclear power stations is cheap but xpensive to build
Why is water power reliable?
e.g. tidal and hydroelectricity
because the moon causes the tides and rainfall filling reservoirs
they can be used to supply demand for energy
has no cost but expensive to build
How is electricity generated?
generators in a power station produces electricity when a coil of wire is in a changing magnetic field - which is caused by spinning a magnet inside the coil
fossil fuel and nuclear power stations use the energy store to heat water and produce steam to turn a turbine which is connected to magnet to make it spin
What is the national grid?
electricity is generated in power stations and transported across the UK
it is very efficient
How do you move power around the national grid?
before electrical power leaves a power station - it is transferred at high voltages by using step up transformers to increase the voltage to 275k V or 400k V
before electrical power enters homes and factories the voltages are decreased by ‘step-down’ transformers to 33,000 V (large factories), 11,000 V (medium factories), 230 V (homes, shops, small factories and offices)
What is a set-up transformer?
can change the voltage of an alternating current (ac). A basic transformer is made from two coils of wire ‐ a primary coil from the ac input and a secondary coil leading to the ac output. The coils are not electrically connected. Instead, they are wound around an iron core. This is easily magnetised and can carry magnetic fields from the primary coil to the secondary coil.
What are step down transformers?
Step-down transformers are used to decrease or ‘step-down’ voltages. These are used when voltages need to be lowered for use in homes and factories. A step-down transformer has fewer turns of wire on the secondary coil than on the primary coil. This transformer steps down the voltage by increasing the current.
What is mains electricity?
energy brought into peoples home
The UK mains supply is connected to appliances in the home by using a plug. The plug contains three wires ‐ the live, neutral and earth wires.
What is the live wire and neutral wire?
the two wires that form the complete circuit with a household appliance.
What is the earth wire?
not part of the circuit and is a safety wire
it is connected to earth which is a large metal spike buried under a house
What are the three safety features found in plugs and appliances?
the fuse, double insulation and the earth wire
What is the fuse?
to melt if a current flows through it that is too large
if the current gets too high, too much heat can be produced which can cause a fire to the appliance
What is double insulation?
contains metal parts surrounded with a casing made from a plastic insulation
stops the user from coming into contact with any metal parts that conduct current
coming into contact with these areas can cause electrocution
What is the earth wire?
allows large current to pass through the fuse when a live wire loosens and touches a metal part of the appliance
if there is no earth wire, and a live wire was loose, touching the appliance would cause the person to be electrocuted as a high current would pass through the body to the ground
