energy resources

what fossil fuels are there?

• coal

• oil

• gas

how do fossil fuels generate electricity?

• the fossil fuel is burnt in oxygen

• this heats water

• the water boils to form steam

• this turns a turbine

• the turbine moves a generator

• this produces electric current

describe the energy transfers when generating electricity with fossil fuels

• chemical (fuel) → thermal (water) by heating

• thermal → kinetic (turbine) → kinetic (generator) mechanically

• kinetic → electrical of national grid mechanically

what are the advantages of fossil fuels?

• relatively cheap

• release lots of energy

• have lots of fossil fuel stations - no new set up costs

• reliable

what are the disadvantages of fossil fuels?

• release CO₂ which contributes to global warming

• coal and oil contain sulfur impurities which lead to acid rain

• non renewable - finite source - not much left

how does nuclear power generate electricity?

• energy is released by fission

• this energy heats water which boils into steam

• the steam turns a turbine

• the turbine turns a generator which generates electric current

describe the energy transfers when generating electricity by nuclear power

• nuclear → thermal (energy)

• thermal → thermal (of water) by heating

• thermal → kinetic (of turbine then generator) mechanically

• kinetic → electrical (mechanical)

what are the advantages of nuclear power?

• does not produce greenhouse or polluting gases

• lots of uranium available

• produces lots of energy

• cost per unit electricity produced is lowerr

what are the disadvantages of nuclear power?

• expensive to build and maintain

• take time to start up - not responsive

• processing uranium produces pollution

• risk of radioactive leaks

• decommissioning is expensive

• produces radioactive waster

what does a solar panel contain?

a solar panel contains:

• black pipes containing waterr under a glass layer (to trap air)

• on top of a thermal insulation layer topped with reflective material

what do solar panels do?

heat water

how do solar panels heat water?

• water in pipes absorbs energy from the sun and is heated

what are the energy transfers in solar panels?

• solar radiation → thermal energy of pipes by radiation

• thermal energy of pipes → thermal energy of water by heating

how do curved mirrors work?

• they focus the suns light onto a small area for cooking

• radiation → thermal energy

what are the advantages of solar heating systems?

• renewable

• don’t pollute or produce greenhouse gases

• free after set up

what are the disadvantages of solar heating systems?

• expensive to set up

• only work small scale

• mirrors are slow, bulky and unreliable

how does wind power generate electricity?

• wind turns a turbine

• as the turbine revolves it turns a generator

• this generator generates electricity which is transferred to the national grid

describe the energy transfers that take place when electricity is generated via wind power

• kinetic of air → kinetic of turbine mechanically

• kinetic → kinetic of generator mechanically

• kinetic → electrical of national grid electrically

what are the advantages of wind power?

• cheap to run

• tough

• relatively reliable

• don’t produce any pollution or greenhouse gases

• renewable

what are the disadvantages of wind power?

• take up space and some think they are unsightly

• can damage habitats

• can be noisy

• wind isn’t always strong enough - unreliable

• can’t alter supply to meet demand

• expensive to set up

how do solar cells generate electricity?

• use energy from the sun to directly generate electricity

• generate DC

• 15% efficient

• via photovoltaic effect

describe the energy transfers when solar cells are used to generate electricity?

light energy/radiation → electrical energy via radiation

what are the advantages of solar cells?

• renewable

• do not produce pollution/greenhouse gases

• low running costs, free after set up

• good for powering small devices

• can be connected to national grid

what are the disadvantages of solar cells?

• expensive to set up

• only useful if they have enough sunlight

• only really work on a small scale

what are tidal barrages?

tidal barrage are big dams across river estuaries which have turbines in them

how does tidal power generate electricity?

• an estuary contains tidal barrages

• as the tide comes in it fills up to a height of several meters

• the water can be allowed out of the turbines at a controlled speed

• the turbines are also turned on the way in

• turbines turn generators which generate electricity

describe the energy transfers when tidal power is used to generate electricity

• kinetic of the water → kinetic of the turbine mechanically

• kinetic → kinetic of generator mechanically

• kinetic → electrical energy mechanically

what are the advantages of tidal power?

• no pollution, renewable

• relatively reliable

• no fuel costs

• minimal running costs

what are the disadvantages of tidal power?

• prevents free access by boats

• can damage habitats

• can spoil view

• height of tides is variable so energy produced is variable

• initial costs are moderately high

how does hydro-electric power generate electricity?

• a valley is flooded by building a big dam

• rainwater is stored in this reservoir

• the water is let out in a controlled manner through turbines

• these turbines turn generators which generates electricity

describe the energy transfers when hydroelectric power is used to generate electricity

• GPE of water → kinetic of water as it falls mechanically

• kinetic of water → kinetic of turbine mechanically

• kinetic of turbine → kinetic of generator mechanically

• kinetic of generator → electrical energy electrically

what are the advantages of hydro-electric power?

• renewable

• no direct pollution

• pumped storage can be used so that supply meets demand consistently and immediately

• reliable

what are the disadvantages of hydro-electric power?

• flooding a valley can destroy habitats and cause vegetation to rot which releases methane and CO₂

• spoils view

what do most power stations have?

a surplus of energy as they have huge boilers which have to run overnight even when demand is low

what is pumped storage?

• a method of keeping spare energy generated by power stations for later use

• extra night-time electricity is used to pump water up (that has gone down) to a higher reservoir

• this can be released quickly at periods of peak demand

describe the energy transfers in pumped storage

surplus electrical energy produced by power stations → GPE of water mechanically

how does wave power generate electricity?

• lots of small wave converters are located around the coast

• as waves come to shore they provide an up and down motion - this forces air out of a gap into a wave converter

• this turns a turbine and in turn a generator

describe the energy transfers that take place when wave power is used to generate electricity

• kinetic of waves → kinetic of turbine mechanically

• kinetic of turbine → kinetic of generator mechanically

• kinetic of generator → electrical electrically

what are the advantages of wave power?

• no pollution, renewable

• no fuel costs

• low running costs

• useful on a small scale e.g. for small islands

what are the disadvantages of wave power?

• spoil view

• hazard to boats

• unreliable - waves die out when wind is low

• high initial costs

• ineffective on a large scale

where is geothermal power possible?

• areas where hot rocks lie close to the surface

• the source of most of the energy is the slow decay of radioactive elements including uranium

how is geothermal power used to generate electricity?

• water is pumped in pipes down to the hot rocks

• steam is forced back up due to pressure

• this turns a turbine which turns a generator

describe the energy transfers when geothermal power is used to generate electricity

• thermal of ground → thermal of water by heating

• thermal of water + steam → kinetic of turbine mechanically

• kinetic of turbine → kinetic of generator mechanically

• kinetic of generator → electrical energy electrically

what are the advantages of geothermal power?

• can also heat buildings directly

• free after set up

• renewable, no major environmental problems

what are the disadvantages of geothermal power?

• have to drill down a few km which is expensive

• cost of building a power plant is high compared to energy output