GCSE Questions: Energy Sources

Q4. Electricity can be generated using various energy sources.

(a) Give one advantage and one disadvantage of using nuclear power stations rather than gas-fired power stations to generate electricity. [2 marks]

Advantage - any one from:

	produce no (or very little) greenhouse gases or carbon dioxide or doesn't contribute to global warming/climate change. just a reference to less atmospheric pollution or saying it produces no harmful gases is insufficient to get a mark. Be specific - not vague!
	produce no acid rain/sulphur dioxide
	high(er) energy density in fuel If you said 'one nuclear power station produces as much power as several gas power stations' you would get the mark but saying 'nuclear power stations can supply a lot of or more energy' is insufficient to get you a mark.
	saves using up reserves of fossil fuels or gas
	long(er) operating life

 

Disadvantage - any one from:

	produce (long term) radioactive waste
	accidents at nuclear power stations may have far reaching or long term consequences
	high(er) construction/decommissioning costs
	long(er) start up time

(b)

(i) A single wind turbine has a maximum power output of 2 MW. The wind turbine operated continuously at maximum power for 6 hours.

Calculate the energy output in kilowatt-hours of the wind turbine. Use the correct equation from the Physics Equations Sheet. [2 marks]

Energy (kWh) = Power (kW) x time (h)

Make sure you know the units each part of an equation must be in - then convert what you are given in the question into the correct unit before you start to calculate.

Power = 2 MW = 2,000,000 W = 2,000 kW

Energy = 2000 x 6 = 12,000 kWh

 

 

(ii) Why, on average, do wind turbines operate at maximum power output for only 30% of the time? [1 mark]

To operate at maximum power they need optimum wind speeds in the area they are located. Weather conditions do not always allow maximum output as the wind speed may be too high, causing the turbines to be locked down to protect them - or too low producing very little turing of the turbines.

(c) An on-shore wind farm is made up of many individual wind turbines. They are connected to the National Grid using underground power cables.

Give one advantage of using underground power cables rather than overhead power cables. [1 mark]

any one from:

cannot be seen
no hazard to (low flying) aircraft/helicopters
unlikely to be or not damaged/affected by (severe) weather
no/reduced shock hazard

Just saying 'unlikely to be damaged' or 'need less maintenance' is insufficient to get a mark - as is 'can be installed in urban areas'.

(Total 6 marks)