Planes, Trains & Automobiles?
Whether it’s Birmingham to Barcelona, or London to Los Angeles, most people’s transport choice will be based on cost and journey time. But the environment is another crucial factor. Cars, planes and trains all have an impact, but how do they compare?
DRIVING FORCE
Greenhouse gases, such as carbon dioxide (CO2), nitrous oxides (NOx) and methane (CH4), are linked with global warming. Around 25% of global CO2 emissions are from transport, with the rest coming from power stations, factories, and home users. Cars and trucks account for around 75% of global transport CO2 emissions. Currently, aircraft only account for 12% of transport emissions, but predicted growth in demand is substantial. That actually equates to less than 5% of all CO2 emissions today! The problem lies in more and more people wanting to travel by air in the future.
A useful way to compare transport modes is to calculate emissions per passenger travelling one kilometre. For cars this is easy to see; just look at the small print on any car advert to see the fuel consumption and CO2 figures. What’s interesting is the wide range in performance. A hybrid electric-petrol car may produce 80 grams of CO2 per kilometre, whereas a 4x4 might emit four times that. It’s a similar story for aircraft, with figures typically less than 100 grams per passenger kilometre, depending on journey length.
ON THE RAILS
Electric rail can be around five times less polluting than cars or planes. But this depends on where the electricity comes from – a coal-fired power station or a wind farm. On the Continent and in Japan there are extensive electric rail networks, but in the UK a significant proportion of trains are diesels, with relatively poor environmental performance.
Direct comparison of the environmental impact of different modes of transport is tricky, and susceptible to considerable bias. The key is to ask how many passengers are being carried. A 4x4 carrying four people is probably better than a Mini with one person in. Similarly, empty trains are worse than full airliners.
One thing is certain, without advanced engineering we would be in a much dirtier situation. Aircraft emissions have been halved in the last 30 years through advances in aerodynamics and engine technology. The heads of European aerospace have made a commitment called ACARE 2020. It promises a 50% reduction CO2 emissions, an 80% reduction in NOx and a 50% reduction in 
noise by 2020. The car industry has a target of a 25% reduction in emissions by 2008, with more to come. Weaning ourselves off fossil fuels is the long-term engineering challenge.
Download the ready-to-use Aviation & the Environment PowerPoint lesson plan here.
Read about how the aviation industry is facing up to the environmental challenge..
Airbus are committed to environmental leadership, at all stages of airliner manufacture and operation. See more here.
The Royal Aeronautical Society Greener by Design group has more information here...
