Comparing Power Stations

Section 1 of 6Criteria for comparison

Comparing power stations

Costs

• Costs Commissioning costs cover land, planning and legal fees, materials and construction labour.
• Running costs include staff, fuel, waste disposal and maintenance.
• Decommissioning costs cover demolition, clean-up and, for nuclear plants, removing the fuel.

Reliability

• Reliability How quickly it can be switched on and off, how consistently it produces electricity, how well it follows changes in demand and how fast it recovers from faults.

Carbon footprint

• Carbon footprint Carbon released during operation, in manufacturing the components, and in transporting fuel and materials.

Efficiency and output

• Efficiency and output Efficiency is the fraction of input energy turned into useful electricity, and output is the power the station can supply.

Section 2 of 6Data for five types of station

Feature	Coal	Wind farm	Nuclear	Solar farm	Tidal barrage
Commissioning cost	High	Low	Very high	Very low	Low
Running cost	High	Very low	High	Very low	Very low
Decommissioning cost	High	Low	Very high	Very low	Very low
Typical construction time	5 years	6 years	7 years	Months	10 years
Typical efficiency	32%	50%	35%	20%	80%
Reliability	Very high	Low	Very high	Low	High
Carbon footprint	Very high	Low	Low	Very low	Low
Average output	500 MW	3 MW	1 GW	5 MW	16 kW

Section 3 of 6Reading the table

Fossil and nuclear

• Fossil and nuclear Coal and nuclear stations are very reliable and have large outputs, but they cost a lot to run and decommission.
• Coal has a very high carbon footprint, while nuclear has a low one but leaves radioactive waste.

Wind and solar

• Wind and solar These are cheap to run and have small carbon footprints, but depend on the weather, so reliability is low.
• Each unit gives a small output, so many are needed to match one large station.

Tidal barrage

• Tidal barrage Very efficient and cheap to run, but slow to build, with a small output in this data and a big impact on estuaries.

Section 4 of 6Making a justified choice

1

Decide which criteria matter most for the situation, for example reliability for a city or low cost for a remote village.

2

Pick the data from the table that relates to those criteria, quoting actual values.

3

Compare at least two types of station, giving a strength and a weakness for each.

4

Link the choice to a mixture of sources: reliable stations cover the base demand while renewables cut emissions.

5

Finish with a clear conclusion supported by the evidence.

Section 5 of 6Key terms

Term	Meaning
Commissioning	Everything needed to plan, build and bring a power station into operation.
Decommissioning	Shutting down and safely removing or cleaning up a power station at the end of its life.
Reliability	How consistently a station can supply electricity when it is needed.
Carbon footprint	The total carbon dioxide released through building, running and fuelling a station.
Power output	The electrical power a station can supply, measured in watts, kilowatts, megawatts or gigawatts.

Section 6 of 6Exam technique

1

Judging a station on one criterion only; the question usually wants several to be weighed.

2

Ignoring construction and decommissioning when stating the carbon footprint or cost.

3

Mixing up units1 GW = 1000 MW = 1 000 000 kW.

4

Quoting words like 'high' without using the numbers from the data when asked to use the table.