Trains vs Planes: Is Rail Always the Low Carbon Option?

But Pearce argues that companies are often a little judicious with the facts behind these claims — Eurostar, for example, is fairly quiet when talking to the green market about the fact its low emissions are due to French nuclear power, and while Virgin's pendolino trains claim a pretty low carbon output, many of their other trains are still powered by dirty diesel (the UK is way behind Europe on electrification, which would cut emissions greatly). Fred also argues that rail companies use some pretty optimistic numbers about their occupancy rates to calculate emissions per passenger km:

"Delve further into the data and it turns out that not all Virgin trains are anything like as clean as the Pendolinos, whose green credentials the firm advertises. Catch its most modern diesel train, the Voyager, and it emits 74g per passenger kilometre when travelling half-full — almost three times as much as the Pendolino.
Suddenly, that 78% claim has shrunk. In fact, if you catch a Voyager when it is just a quarter full — and I've been on plenty of those — then your emissions per kilometre travelled are about the same as sitting in a fullish plane. More leg room, but no greener."

Now comparing a quarter full train with a full plane is not very informative, in my book. Yes, low passenger numbers affect the emissions per passenger km, but were someone to take the plane instead of the train for this reason, surely they would just be making matters worse? To my mind the important thing here is the potential each mode has to be green — so let's compare full planes to full trains, if we're trying to help travelers decide which is greener.

I do agree with Pearce that there is huge room for improvement, and he is also right to suggest that it is crazy to use national emissions averages for passenger km by rail to calculate emissions produced by inherently low occupancy trains, like sleepers. But as Pearce himself points out, electrification, regenerative breaking, and many other technologies on the horizon offer a very real possibility of huge emissions savings. And compare those potential emissions savings with airlines, where high fuel costs seem to have rung out most of the low hanging fruit already, and I'm pretty sure rail travel comes way out on top once more.

Let's keep the pressure on the railways and plane operators alike — emissions reductions must occur everywhere, and fast. And let's remember that the greenest passenger km is always the one not travelled — so staycations, telecommuting and video conferencing are all still top of the list.