The World in 2030

132 The World in 2030
the upturned ends of wings – increases fuel economy by up
to 6 per cent. 264 )
Of the semi-plastic Boeing 787, The Economist reported
in June 2007 under the headline ‘Travelling green tonight’:
With half its primary structure, including the fuselage
and wings, made from composites, the 787 is much
lighter than any metal aircraft of similar size. That
not only saves fuel but allows other improvements.
For example, the air is nicer to breathe. Airliners have
to be pressurised when flying above 10,000 feet because
oxygen levels drop dangerously low. At cruising
height, usually around 35,000 feet, cabin pressure in
most aircraft is kept at the equivalent of around 8,200
feet (about the same as Mexico City) because maintaining
a higher pressure in a conventional aircraft
might accelerate metal fatigue. To add to passengers’
discomfort, the air is kept as dry as possible because
moisture causes metal to corrode. But the 787 is pressurised
at the equivalent of 6,000 feet and the air can
be kept less dry because the composites are stronger
than metal and unaffected by moisture. 265
Producing biofuel for jet engines would not have the vast and
potentially disastrous environmental impact that switching to
biofuels such as ethanol for road transport would have (see
my later section ‘The Future of Energy’). Even the enlarged
jet fleets of the future would use only a tiny fraction of the
fuel consumed by the world’s millions of road vehicles and
aviation’s potential for harmful carbon emissions is so great
that a good case for switching to biofuels can be made easily.