Flashcards in Energy Deck (48)
What energy source is the moon the ultimate source of?
What energy sources are radioactive particles under the Earth's surface the ultimate source of?
Nuclear and geothermal
What is the energy change for fossil fuels?
(fuel) (burn it) (steam turns turbine)(generator)
What is the energy change for wind/wave power?
What is the energy change for nuclear/geothermal power?
What is the energy change for HEP?
(water stored in lake) (released downhill)
What is a renewable resource?
It is in infinite supply or it can be replaced faster than they are used
What is a non-renewable resource?
It is a finite resource and will eventually run out
What are fuels?
Concentrated sources of energy
What are fossil fuels?
Coal, oil and gas, created by processes that take millions of years
What is coal made from?
What is oil made from?
The skeletons of dead sea creatures
What is gas made from?
Gas (methane) evaporates off oil reserves and gets trapped in rocks.
What is released when we burn fossil fuels?
Heat, CO2 and SO2
What is CO2?
It is a 'greenhouse gas', thought to be responsible for global warming.
What is SO2?
It is a gas that combines with water to form acid rain.
Where are nuclear power stations built?
They are built near to a constant supply of water, usually near the coast. Due to their huge size and safety considerations, they need to be built in areas that are geologically sound.
What does 'decommissioning' mean?
Decommissioning is the process of safely shutting down a nuclear power station once it has reached the end of its productive life (after around 40-50 years). This takes years, possibly decades, to complete and costs tens of billions of pounds.
What is a reliable power station?
One that isn't dependent on the weather or other conditions in generating electricity.
Why are alternative methods of electricity generation to fossil fuels and nuclear power problematic?
The energy that they to utilise is more dilute (spread out) than in a fuel, so it takes longer and normally costs more to generate the same amount as a conventional power station.
Why are alternative forms of energy generation often unreliable?
They are affected by weather conditions and other conditions in generating electricity. For example, a wind turbine doesn't generate electricity unless the speed of wind is above a certain speed.
What does 'start up time' mean?
How long it takes to stop generating electricity from the moment they are switched on.
How long do nuclear power stations take to re-start?
They take weeks to re-start
How long do fossil fuels take to start up?
Normally in a few hours
How long do HEP stations take to start up?
In seconds, which is why they are good for supplying extra electricity at times of peak demand.
What is an example of a predictable change in demand for electricity?
When a popular TV series finishes.
What is an example of an unpredictable chance in demand for electricity?
It is a very cloudy day and people need lights for the whole day.
What energy sources is the Sun the ultimate source of?
Fossil fuels, wind power, wave, solar, HEP and biomass
Why is CO2 a 'greenhouse gas'?
Light from the Sun gets through the atmosphere and reaches the Earth. The heated Earth gives off infrared rays (heat). Some of that heat gets out of the atmosphere but some is absorbed by CO2.
Explain the advantage of using a wind turbine to produce electricity?
The wind is a renewable resource, so we will always be able to generate electricity from it. Homeowners can also produce their own energy.
Advantage of using fossil fuels
They're reliable because we can generate electricity from them with no regards to weather conditions (or any other conditions).
Advantage of using nuclear fuels
Nuclear produces so much more electricity per kg in nuclear fuel than fossil fuels.
Advantage of using renewable resources
They do not produce any damaging gases for the atmosphere.
Disadvantage if using fossil fuels
They emit harmful gases (CO2 and SO2) and they cause global warming and acid rain.
Disadvantage of using nuclear fuels
They're incredibly dangerous: mining for uranium produces radioactive waste and this stays with us for 200,000 years.
Disadvantage of using renewable sources
They often aren't very predictable because we can't predict what nature is going to do.
What is the equation for GPE?
GPE = mass x gravity x height
What is the equation for change in GPE?
Change in GPE = mass x gravity x change in height
What is the equation for kinetic energy?
KE = 0.5 x mass x velocity2
What is efficiency defined as?
Efficiency is the fraction of total energy transferred that is useful energy.
What is the equation to work out efficiency?
Efficiency = Useful Energy/Power Output
Total Energy/Power In
What is the energy transfer for a lightbulb?
electrical ------> light + heat
What is the energy transfer for an electric motor?
electrical ---> kinetic + heat + sound
What does 'doing work' mean?
When we apply a force to an object and make it move, we are said to have 'done work' on the object.
What is the equation to work out work done?
work done = force x distance moved in direction of force
What is power?
Power is the quantity that tells us how much energy is changed/used by a person/machine/processed by a person/machine/process per second.
What is the equation that can be used to work out power?
power = energy changed