Has flying been unfairly demonised?
- 25 May 07, 07:14 PM
Let me come clean: I love flying and I have done ever since I was a boy.
Indeed, I still remember the day a friend of mine brought an impossibly exotic treasure into our primary school classroom. It was one of those plastic packets of miniature “travel essentials” from some now defunct airline – Pan American or BOAC.
I can’t remember exactly what it contained – nylon socks, an eye-shade and a perfumed face wipe in a foil wrap perhaps. That wasn’t the point. What made my friend’s little plastic package so fabulous was that it was proof that my friend had actually flown in a plane.
It was three years before I flew for the first time – a family holiday to Morocco when I was about 10. Of course I’ve flown hundreds of times since then – most recently on my Mission to Mumbai – but I still enjoy every flight.
My problem is that a year of carbon-counting as Ethical Man brought home just what an environmental disaster flying is – my family’s one trip to the Canaries last year created as much carbon as a year of driving our car.
That’s why I’ve posed my deliberately provocative question. I want to know if it is possible to fly with a clear conscience.
So here’s the good news: when you look at the numbers, modern jet aeroplanes are actually a very efficient form of transport.
Indeed, the jet engine is one of the most effective ways to convert the energy from fuel into thrust. The best jets are 37 per cent efficient. By contrast it seems modern petrol engines are around 25 per cent efficient while a finely tuned diesel will achieve, at best, 32 per cent efficiency.
How does that translate into actual fuel consumption? Take a look at some figures: my old car - a two litre petrol Saab 9-5 estate - uses 8.6 litres per 100km. The most efficient cars do better than that. The Toyota Prius, for example, is much more frugal. It uses 4.3 l/100km.
So what about aircraft? The average jet plane now uses around 4.8 l/100 km per passenger – just a little worse than a Prius with no passengers. But the manufacturers say that modern jets are much more efficient.
Airbus claims it makes the most efficient aeroplane currently flying, the A380. It says this behemoth uses just 2.9 l/ 100km per passenger. (Here’s the dull bit: that’s the fuel consumption when you assume a three class configuration operating at capacity with 525 passengers).
As far as I can tell the latest jumbos are similarly efficient – it is hard to be certain because the manufacturers do not publish comparable figures – but Boeing’s 747-8 uses 3.7 l/100kms per passenger when operating at 70 per cent of capacity. (Assuming it is configured to hold 470 passengers in three classes).
So if jet engines are more efficient than car engines why do they get such a bad rap?
One reason is pretty obvious - we use planes to travel extremely long distances. I covered 14,000 kilometres on my trip to Mumbai and that weekend in Jamaica racked up just over 15,000 kms. Each trip covered pretty much the same distance as the average British car driver travels in a year.
The other big problem is that planes release their pollutants high up in the atmosphere where they have an even stronger greenhouse effect. The process is known as radiative forcing. What radiative forcing means is that aircraft emissions are reckoned to be almost twice as damaging as emissions at ground level.
So, combine the distance you fly with the effect of radiative forcing you can see why environmentally conscious people get so worried by our appetite for air travel. You can do as I did - get rid of your car, switch to energy efficient bulbs, eat locally grown food - but take one holiday flight and you will wipe out all your careful carbon cuts.
So here’s the important question: is there anything that can make flying less environmentally damaging? The received wisdom is that there is no simple fix but I’m not so sure. Here are some thoughts – please tell me what you think.
My friend Omar - who featured in our original flying film – speculates that turboprop planes – a kind of hybrid between a propeller and a jet plane could be as much as a third more efficient on short journeys.
That huge saving isn’t because turboprops are inherently more efficient than jets. The reason is that much of the fuel used by jets on short journeys is to get them to the high altitudes where they are most efficient. Turboprops fly at lower altitudes which saves fuel and also reduces radiative forcing.
What I want to know is this: if Omar is right why don’t more airlines use turboprops?
And Omar reckons turboprops would be less efficient than jets on long-haul flights. But there is some good news here too. The aeroplane manufacturers say they are doing their very best to improve fuel efficiency. They say today’s aircraft are 70 per cent more efficient than those of 40 years ago and that more efficient planes are in development.
Boeing boasts that its new 787 will better the fuel efficiency of even the A380. It claims that fuel consumption (assuming a two class configuration and 90 per cent occupancy) could be as low as 2.4 litres per 100 km.
There are other ways to cut emissions. IATA, the International Air Transport Association, estimates that improving air traffic control could cut emissions by as much as 12 per cent. It claims that by straightening out air lanes it has already cut millions of tonnes of CO2.
And I’ve got a last suggestion that would massively increase aircraft efficiency in a stroke. It would be straightforward and cheap to implement and doesn’t rely on some untested new technology.
What is my innovation? Just get rid of first and business class.
Think about it. If you packed the A380 with economy seats it could hold 853 passengers. A back of the envelope calculation suggests this “economy” Airbus (operating at capacity) would use 1.9 litres per passenger per 100km. That’s pretty much half the fuel consumption of most current aircraft.
Of course flying in such an aircraft would still be a carbon intensive activity but considerably less so than current planes. That’s because the effect of radiative forcing means each tonne of carbon you don’t emit is the environmental equivalent of saving two tonnes.
In fact – here’s a thought – now that I’m not Ethical Man maybe that’s what I should do. An economy-only eco-airline, the green alternative!
What’s the telephone number of Airbus again?