
fossil fuels, we have released 400 billion tonnes of carbon, and burning the
entire reserves could eventually raise world temperatures by 13°C. Among other horrors,
this would result in the destruction of all rainforests and the
melting of all Arctic ice. London
would be as hot as Cairo, but would also be engulfed by seawater.
(See our Special Report on Climate Change for
Natural gas reserves could plug some of the gap
from oil, but reserves of that - some of which are in Russia, the Middle East
and the Wadden Sea - will not
last into the 22nd century either. We currently use it
for around one-third of world electricity generation.
Natural gas, which is
mostly methane, is the cleanest fossil fuel by
weight, emitting just 40% the greenhouse gases of coal and 25% of oil. As a
less-polluting alternative to petrol, its use is increasing in automobiles -
either as compressed natural gas
or for powering hydrogen fuel cells.
When reserves do run low, we may be able to access vast frozen methane hydrate
reserves beneath the seabed.
In the next few decades,
one way for the UK and others to
meet greenhouse gas reduction commitments, could be increased nuclear power
generation. Currently, about 440 reactors in 32 countries generate 16% of world
electricity. (See our Special Report on The Nuclear Age for
Despite a slow decline of
support for nuclear power in the
west following the Chernobyl disaster in
1986, many countries, such as the US, Japan and India are now embracing
the technology again. But using nuclear power to mitigate environmental damage
is a double-edged sword,
because disposing of nuclear waste is itself
an intractable problem. Expense, safety in usual
operation and terrorism are major concerns too, not
to mention the fact that building new facilities can take decades.
energy sources offer a more practical long-term energy solution. They may benefit the world's poor
too. "Renewable" refers to the fact these resources are not used
faster than they can be replaced.
The Chinese and Romans used
watermills over 2000 years ago.
But the first hydroelectric dam was
built in England in 1870. Hydroelectric power is now the most common
form of renewable energy, supplying around 20% of world electricity.
China's Three Gorges Dam, which
has just been completed, is the largest ever. At five
times the size of the US's Hoover Dam, its 26 turbines will generate the
equivalent energy of 18 coal-fired power stations. It will satisfy 3% of
China's entire electricity demand. Surprisingly, some argue that hydroelectric
dams significantly contribute greenhouse
In 2003, the first commercial power station
to harness tidal currents in the
open sea opened in Norway. It is designed like windmill, but others take the
form of turbines, oscillating hydroplanes,
flexible eel-like generators, or
are made of floating pontoons that rise up and down with the waves and tide.
As prices fall, wind
power has become the fastest growing type of
electricity generation - quadrupling worldwide between 1999 and 2005. Modern
wind farms consist of turbines that generate
electricity. Though it will be more expensive, there is more than enough wind
to provide the world's entire energy needs.
Wind farms come in onshore
and offshore forms. They
can often end up at spots of natural beauty, and are
often unpopular with
residents. And turbines are not totally benign - they can interfere with radar
and leave a significant ecological footprint; altering climate,
sending wildlife diving for cover and
killing sea birds. Migrating
birds may have more luck avoiding
Scotland is building Europe's largest wind farm,
which will power 200,000 homes. The UK's goal is to generate one-fifth of power
from renewable sources, mainly wind, by 2020. But this may cause problems, because wind
Future buildings with integrated turbines
could generate 20% of their own power. Other visions see wind-power revived for
shipping, floating wind farms, or
28-kilometre-wide flying behemoths
powered by high speed winds in the upper atmosphere. There are also plans to
construct a 1-kilometre-tall tower
t