UK energy policy is “collapsing”,
says
Christopher Booker, just like the cooling towers of
closed coal-fired power station Didcot A in Oxfordshire. It’s an
arresting image, but is it right?

Booker thinks we should be sticking with cheap
coal-fired electricity instead of investing in wind power, despite
the large carbon emissions and health impacts from coal-generated
air pollution.

Wind versus Didcot A

Booker’s recurring theme is that wind power is a poor
way to generate electricity, when compared to coal.

In order to rubbish it he presents a comparison with
coal power. But it’s not easy to understand, and more importantly
it may obscure more than it reveals about what’s actually going on
with power generation in the UK.

Booker says:

“At the time when the
plant’s German owners closed down Didcot A last year… the 2,000
megawatts of electricity it was capable of supplying to the
National Grid were only slightly less than the average total of
2,200 megawatts then being unreliably generated by all of Britain’s
thousands of subsidised wind turbines put together.”

It should be immediately clear that this
argument uses a more favourable theoretical maximum for coal
(“capable of supplying”) against a tougher, “in practice” amount
for wind. But let’s pass over that for the moment, and treat the
argument on its own merits.

The BBC reports that Didcot A
closed down
on 22 March 2013. That day, the
average output from wind was 5,206 megawatts. That’s according to
data from the UK National Grid Status website
.

So on the day Didcot A closed down, wind
generated more than twice as much electricity as the Oxfordshire
coal plant could have done, if it had stayed open.

But that’s just for a day. What about over a
longer time period? Looking at the whole month of March 2013, wind
had an an average output of 2,150 megawatts a day. The theoretical
maximum output from Didcot A operating 24 hours a day was 2,000
megawatts. So again, wind comes out on top – albeit not by
much.

Capacity facts

Where then does the 2,200 figure come from? One
final possibility seems the most plausible.

By the end of March 2013 the installed capacity
of windfarms around the UK was 8,865 megawatts according to
industry group Renewable UK.

On average, the UK’s windfarms generate around a
third of their full capacity over the course of a year – because
some days are windier than others. Onshore windfarms have a
slightly lower capacity factor (29 per cent in 2013) and offshore
slightly higher (39 per cent in 2013).

Applying a relatively ungenerous 25 per cent
capacity factor to the combined total of onshore and offshore
windfarms – the 8,865 megawatts – gives you a rounded down figure
of 2,200 megawatts.

Which method is likely to produce a more
informative view of the UK energy system? We’ll leave that up to
the reader. Nevertheless, on the (presumably quite windy) day
Didcot A was closed, UK wind was cranking out about twice as much
electricity as the power station had ever managed.

Wind versus coal

Of course none of this changes that fact that
coal currently generates much more electricity than wind in the UK.
In 2013 coal
generated
36 per cent of our power, compared
with 8 per cent for wind.

It’s also the case that large, centralised power
stations like coal, gas and nuclear plants generate relatively
predictable ‘baseload’ power that – to a greater or lesser extent –
can be switched on or off to match demand.

Nevertheless, the government clearly believe
that wind power has a place in the UK’s electricity system – to say
nothing of other European countries. Wind already generates nearly
a fifth of electricity in Denmark and Spain, for
instance.

And it is equally true that coal power
comes with
a range of environmental and health impacts

that other, cleaner sources of power do
not.

Via: http://www.carbonbrief.org/blog/2014/08/unpacking-christopher-bookers-wind-vs-coal-comparison/