shallow 16 kWh per day per person. To obtain this average power requires
roughly 10 000 “3 MW” wind turbines like those in figure 10.1. (They have
a capacity of “3 MW” but on average they deliver 1 MW. I pop quotes
round “3 MW” to indicate that this is a capacity, a peak power.)

What would this “33 GW”’ of power cost to erect? Well, the “90 MW”
Kentish Flats farm cost £105 million, so “33 GW” would cost about £33
billion. One way to clarify this £33 billion cost of offshore wind delivering
4 kWh/d per person is to share it among the UK population; that comes
out to £550 per person. This is a much better deal, incidentally, than micro-
turbines. A roof-mounted microturbine currently costs about £1500 and,
even at a very optimistic windspeed of 6 m/s, delivers only 1.6 kWh/d. In
reality, in a typical urban location in England, such microturbines deliver
0.2 kWh per day.

Another bottleneck constraining the planting of wind turbines is the
special ships required. To erect 10 000 wind turbines (“33 GW”) over a
period of 10 years would require roughly 50 jack-up barges. These cost
£60 million each, so an extra capital investment of £3 billion would be
required. Not a show-stopper compared with the £33bn price tag already
quoted, but the need for jack-up barges is certainly a detail that requires
some forward planning.

Costs to birds

Do windmills kill “huge numbers” of birds? Wind farms recently got ad-
verse publicity from Norway, where the wind turbines on Smola, a set of
islands off the north-west coast, killed 9 white-tailed eagles in 10 months.
I share the concern of BirdLife International for the welfare of rare birds.
But I think, as always, it’s important to do the numbers. It’s been esti-
mated that 30 000 birds per year are killed by wind turbines in Denmark,
where windmills generate 9%E of the electricity. Horror! Ban windmills!
We also learn, moreover, that traffic kills one million birds per year in Den-
mark. Thirty-times-greater horror! Thirty-times-greater incentive to ban
cars! And in Britain, 55 million birds per year are killed by cats (figure 10.6).

Going on emotions alone, I would like to live in a country with virtually
no cars, virtually no windmills, and with plenty of cats and birds (with the
cats that prey on birds perhaps being preyed upon by Norwegian white-
tailed eagles, to even things up). But what I really hope is that decisions
about cars and windmills are made by careful rational thought, not by
emotions alone. Maybe we do need the windmills!

Figure 10.4. The Magnus platform in the northern UK sector of the North Sea contains 71 000 tons of steel. In the year 2000 this platform delivered 3.8 million tons of oil and gas – a power of 5 GW. The platform cost £1.1 billion.
Photos by Terry Cavner.
Figure 10.5. Pipes for Langeled. From Bredero–Shaw [].