Travel

We hear so many stories about how air travel is bad for the environment. So let's take a journey from Southampton to Edinburgh by trains, planes and automobiles, comparing CO2 emissions and the cost of the journey.

Single traveller

First the train, because it is usually claimed to be the greenest form of powered land transport. That means catching a diesel-powered Arriva CrossCountry service from Southampton, which puts out 74 grams of CO2 per passenger for each kilometre travelled.

Flying emits 81 g/passenger km - using a brand new Bombardier Dash 8 Q400 turboprop plane operated by Flybe.

How much CO2 to get to Edinburgh?

And now one of the greenest cars on the road: a Toyota Prius hybrid emits 104 g/passenger km.

And just for fun, try a big Range Rover TDV8 HSE auto: 299 g/passenger km - broadly three times the emissions of the others.

So for one person travelling from the south coast to Scotland, this research claims going by plane is considerably greener than going by any car. That’s quite a revelation.

Group travel

But now look how it all changes when four people travel together - perhaps a family holiday.

The CO2 emissions for them all to go by train amount to 178kg. Still less polluting than flying, which would pump out 226kg in total.

But the Toyota Prius with 4 people only emits 73kg: much greener than flying but also less than half the CO2 emissions of travelling by train. And at 209kg, even the Range Rover becomes greener than going by air.

Fuel efficiency

The research was carried out by Dr Kenji Takeda of the School of Engineering Sciences at the University of Southampton.

Dr Kenji Takeda

"Flying has become much greener per passenger," he argues. “The industry has a self-imposed target of cutting CO2 emissions by 50 per cent by 2020. Fuel efficiency has doubled in aviation over the last 40 years and this represents a doubling of the rate of improvement of previous decades. It is a much more aggressive target than you will find on railways or among car manufacturers. Aviation will close the gap."

Airbus says its giant A380 double decker uses 3.1 litres / 100km per passenger. That’s 90 miles to the gallon, something no current petrol or diesel car can achieve. Of course the distances are much greater and the rate of growth in long haul travel, particularly in the Far East, represents an enormous environmental challenge.

But Dr Takeda’s research is about the emissions of short-haul domestic travel for which there is a viable surface alternative.

"In the case of diesel powered trains the margin to air travel is really not very big. It’s very different in France and Japan where the trains are far cleaner."

Dr Takeda says the figures are as reliable as one could hope to get, based on emissions statistics from the manufacturers in each transport mode.

"It comes down partly to load factor. Most aircraft are over 80 per cent full, whereas the average load factor on trains measured over a year is closer to 50 per cent.

"Rail has been making good progress. But we’re largely diesel based in this country and unless the Government makes a choice to switch to electric power its figures are not going to change at the same rate as either aviation or car manufacturing.

"An electric train is three to four times more environmentally friendly than a diesel. It’s maybe five to ten times more environmentally friendly than a car, depending on the model. An electric train is three to four more friendly than a Toyota Prius. So put three to four people in the Prius and it becomes comparable to travelling by train in terms of CO2 emissions.

“So car designers are catching up in environmental terms.”

The aviation industry spends billions of pounds a year on reducing pollution. That is mainly because CO2 emissions are directly related to fuel consumption, and airlines operate on very tight profit margins. If the fuel price rises even a small amount, it has a dramatic impact on business. The incentive to cut consumption, and therefore cut emissions, is enormous.

Southampton railway station

"Aviation knows pollution is a big issue, and this is one of the most hi-tech industries in the world," says Dr Takeda. "Some of the brightest people in the world are working on the problem. I'm not saying the rail industry has fewer bright people, but the pressure to research and produce more fuel efficient, less polluting machinery is not so intense. And yet environmental performance is one of rail's best selling points."

Counting the cost

Let's go back to the routes between Southampton and Edinburgh. Most people cost their journeys in money terms, not CO2. And here comes another surprise.

One person driving in a Toyota Prius will spend £28.11 in petrol. Short of hitch-hiking, it is by far the cheapest way to get there. The Range Rover will drink roughly twice as much: £59.13. So you would be better off flying, because Flybe’s standard fare is £52.99, including taxes and charges.

But the standard train fare, says Dr Takeda, is £106. It’s twice the price of flying and more than three times the cost of taking a small family car. And it’s not even the quickest, so a premium for speed is unjustified.

For one person travelling alone, the train may still be the greenest way to travel. But it comes with a hefty price tag.

“The real conclusion here is to share a car, or go by train if you can afford it. But if you are an environmentally conscious traveller and making the trip alone, don’t be afraid to fly.”

Research results summary:

CO2 Emissions for one person
Rail (CrossCountry): 74 g/pax.km
Air (Flybe): 81 g/pax.km
Car (Prius):104 g/pax.km
Car (Range Rove)r: 299 g/pax.km

CO2 emissions for four people
Rail: 178 kg total
Air:  226 kg total
Car (Prius):73 kg total
Car (Range Rover): 209 kg total

Cost for single passenger
Rail: £106.00
Air: £52.99
Prius: £28.11
Range Rover: £59.13

Arriva CrossCountry Voyager
Flybe Bombardier Dash 8 Q400
Toyota Prius Hybrid 1.5 VVT-i automatic
Range Rover TDV8 HSE 3.6L automatic