Tag Archives: wind energy

Fact Check: Comparing wind and nuclear power

Climate Scientist Kevin Anderson has criticised claims made by Sue Ion, a former technical director of British Nuclear Fuels, made on the BBC. Anderson makes the following quite strongly worded criticism of Ion:

Early on in the programme Sue emphasised how she is committed “to try and do more to help get facts across as opposed to just let the media run with whatever they thought … sometimes stories run when they actually do have no foundation in fact”.

Certainly the world of energy and climate change is awash with educated eloquence trumping quantitative analysis – and any attempt to rescue the latter from the former has to be welcomed.

However, despite Sue Ion’s concern about energy stories often having “no foundation in fact”,when it came to drawing comparisons between electricity generation from nuclear and wind power her comments only added to the misinformation that pervades energy debates.

Sue Ion suggests 1500 offshore wind turbines generate the same electricity as one nuclear power station; the real number is much lower – somewhere between 250 and 600.

So, Ion apparently had a figure that is three times higher than it should be. The comments by Ion can be heard about 20 minutes in. [Update:  in the comments section David has pointed out that Anderson has misunderstood what Ion was referring to. The question asked to her was in relation to a "nuclear power station," not an individual reactor. Historically nuclear power stations in the UK have had two reactors, in France they often have four. The new nuclear power stations planned for the UK have more than 1 reactor, so this presumably is what Ion has in mind. So, Anderson should really be multiply his nuclear GW by 2.]

Below is the argument Anderson uses to counter Ion’s claim:

Calculations and Assumptions

The following calculations are premised on proposals for new-nuclear build,
assuming full operation by 2020 and assuming the load factor is significantly
improved from the UK’s experience of operating nuclear stations. The figures for
wind turbines similarly are premised on appropriately sited designs, with a good
capacity factor and assuming turbines at sizes equivalent to the larger models
now being installed and those likely to be installed before 2020.

NUCLEAR

Three reactor designs are now being considered for UK new-build.
§ Areva’s EPR – with a capacity of 1.6GW
§ Westinghouse’s AP1000 – with a capacity of 1.15GW
§ Hitachi-GE’s Advanced Boiling Water Reactor – with a capacity of 1.3GW
Assume an 85% load factor for all the nuclear designs
Note: this is 5% higher than is sometimes suggested should be the starting value
for nuclear load factors, and is 25 percentage points above the mean UK load
factor for nuclear power between 2007 ad 2011 (i.e. 60.1%).

WIND

Currently, installation of 6MW turbines is proceeding, with 8MW designs planned for
installation by ~2014, heading towards 10MW within a few more years. Some
companies are already proposing designs of up to 15MW per turbine. For comparing
with the nuclear designs operational by 2020, these calculations assume 6 to 10MW
turbine designs.
Assume a conservative capacity factor of 40% for offshore wind turbines.
For a well-sited large and offshore turbine, a 40% capacity factor is not
unreasonable figure to assume. It is worth noting, asthe capacity (MW per turbine)
increases, so does the hub height and hence the typical capacity factor. Moreover,
if sited off the West coast of the UK the capacity factor is likely to be higher still.

COMPARISON

The three nuclear designs with a 85% load factor would generate between 8.6TWh and
11.9TWh each year
A 6MW and 10MW wind turbine with a 40% capacity factor would generate 21GWh
and 35GWh/year respectively.
Consequently, between 244 and 567 turbines are required to generate the same
quantity of electricity in a year as the three proposed new-nuclear designs

Who is correct?

Sadly, it appears that while Anderson is probably correct that Ion is making an inaccurate claim, he is also doing exactly what he has criticized Ion for doing, by correcting misleading information with misleading information.

First, consider that he uses turbine capacity of at least 6 MW. A quick look at Wikipedia will tell you that the average for existing UK offshore wind farms is slightly below 3.6 MW, with most wind farms using a 3.6 MW turbine. You can also see that 3.6 MW turbines predominate in the offshore wind farms that are currently being constructed. Ion’s remarks appear to clearly relate to existing wind farms, so exactly why Anderson is using a turbine capacity this large is unclear.

Anderson also claims that a 40% capacity factor for offshore wind farms is conservative. This may or may not be true for new offshore wind farms with 6 or 10 MW turbines, however for existing offshore wind farms it appears to be too high. Historic offshore wind farm capacity factors can be found from the UK government’s Department for Energy and Climate Change. These have been around 33-35% over the last few years.

So, let’s rephrase Ion’s claim and ask how many 3.6 MW turbines, at the UK average capacity factor of 35%, would provide as much electricity as a modern nuclear power plant. To get the same power as the 1.6 GW would take about 1,100 turbines. Matching Hitachi’s 1.3 GW reactor would take about 880 turbines.

What we are looking at is one of those rare occasions where the truth lies somewhere in between, and another example of people using numbers to make a point, and not to inform. [though I'll now take back my comment about the truth lying somewhere in between, as Ion seems to have produced very reasonable numbers given that she was actually referring to a nuclear power station.]