Reducing the carbon emissions of long distance travel
The aviation sector is the fastest growing source of GHG emissions and plans to incorporate it within the
European carbon-trading emissions scheme have only been recently introduced. The problem with aviation is
particularly acute since all practical aircraft fuels are carbon based and many biofuels have poor low
temperature properties at altitude. Moreover, aircraft engines also emit oxides of nitrogen emissions which
generates ozone, and the water emitted can remain suspended in the stratosphere as vapour, contrails or cirrus
cloud when flying at high altitudes, both of which enhance global warming. It is estimated that the combined
effect of all aircraft emissions has a global warming effect 2 to 4 times that of their CO2 alone.
Technical improvements to aircraft
Technological approaches that could reduce the fuel consumed by the aviation sector include the use of larger
bulkier aircraft, and using more efficient turboprop engines instead of jet engines, this would be most
advantageous for slower short haul flights.
Since turboprops operate most efficiently at lower altitudes below
the stratosphere, this also substantially reduces the greenhouse effect of the non-CO2 components of their
Direct technological methods of reducing greenhouse gases from long haul flights are even more limited than
for shorter flights, since jet engines are faster and therefore more desirable than turboprops, and operate most
efficiently at high altitudes were the air is less dense. However, despite these initiatives and other technological
advances, these are unlikely to stem the increase in greenhouse gas emissions from aircraft due to the forecasted
massive expansion of air travel.
One potentially zero carbon transport alternative to short haul aviation over land connected routes is MAGLEV
high-speed rail, which uses magnetic levitation for lift and propulsion. This method has the potential to be
faster, quieter and smoother than wheeled mass transit systems and can reach speeds of almost 600 km/h.
MAGLEV would also nicely complement the INITIATE concept by introducing separate lines and freeing up
the rail infrastructure for slow and medium speed traffic.
The scope for reductions in both air and land based travel are probably greatest in the business sector since there
are few activities that cannot be conducted by teleconferencing and teleworking, yet there is little evidence that
this simple solution is being taken seriously. Many corporations enthusiastically embrace high profile projects
which present an environmentally concerned image whilst they are content to let their employees spend valuable
time travelling to meetings and conferences which could be easily served by teleconferencing. Perhaps they
perceive a marketing advantage using direct interpersonal communication, or more simply, the allure of the free
foreign trip is overwhelming and is used most by those in executive positions who dictate corporate policy.
One solution would be to require all companies to calculate and prominently display their carbon footprint per
employee so their true commitment and environmental credentials can be fairly judged with respect to similar
organisations. Suitable communication technologies are extensively covered in other literature,
details are not repeated here.
66 Note whilst aircraft efficiency (in terms of fuel per km) is theoretically independent of optimum speed, short haul aircraft rarely operate
at optimum speed, for example For a trip of less than 600 nautical miles, or about 90 minutes flying time, a turboprop may use as much as
70 per cent less fuel than a similar-sized jet Times on line 21stApril 2008
67 Maglev Train