and much of it would be further than 50 km offshore. The outcome: if an
area equal to a 9 km-wide strip all round the coast were filled with tur-
bines, deep offshore wind could deliver a power of 32 kWh/d per person.
A huge amount of power, yes; but still no match for our huge consumption.
And we haven’t spoken about the issue of wind’s intermittency. We’ll
come back to that in Chapter 26.

I’ll include this potential deep offshore contribution in the production
stack, with the proviso, as I said before, that wind experts reckon deep
offshore wind is prohibitively expensive.

Some comparisons and costs

So, how’s our race between consumption and production coming along?
Adding both shallow and deep offshore wind to the production stack, the
green stack has a lead. Something I’d like you to notice about this race,
though, is this contrast: how easy it is to toss a bigger log on the consumption
fire, and how difficult it is to grow the production stack. As I write this
paragraph, I’m feeling a little cold, so I step over to my thermostat and
turn it up. It’s so simple for me to consume an extra 30 kWh per day. But
squeezing an extra 30 kWh per day per person from renewables requires
an industrialization of the environment so large it is hard to imagine.

To create 48 kWh per day of offshore wind per person in the UK would
require 60 million tons of concrete and steel – one ton per person. Annual
world steel production is about 1200 million tons, which is 0.2 tons per
person in the world. During the second world war, American shipyards
built 2751 Liberty ships, each containing 7000 tons of steel – that’s a total
of 19 million tons of steel, or 0.1 tons per American. So the building of 60
million tons of wind turbines is not off the scale of achievability; but don’t
kid yourself into thinking that it’s easy. Making this many windmills is as
big a feat as building the Liberty ships.

For comparison, to make 48 kWh per day of nuclear power per person
in the UK would require 8 million tons of steel and 0.14 million tonsE of
concrete. We can also compare the 60 million tons of offshore wind hardware
that we’re trying to imagine with the existing fossil-fuel hardware
already sitting in and around the North Sea (figure 10.4). In 1997, 200
installations and 7000 km of pipelines in the UK waters of the North Sea
contained 8 million tons of steel and concrete. The newly built Langeled
gas pipeline from Norway to Britain, which will convey gas with a power
of 25 GW (10 kWh/d/p), used another 1 million tons of steel and 1 million
tons of concrete (figure 10.5).

The UK government announced on 10th December 2007 that it would
permit the creation of 33 GW of offshore wind capacity (which would deliver
on average 10 GW to the UK, or 4.4 kWh per day per person), a plan
branded “pie in the sky” by some in the wind industry. Let’s run with
a round figure of 4 kWh per day per person. This is one quarter of my

Figure 10.3. Offshore wind.