Fast rail can mean slower CO2 progress

As a new report shows, building high-speed rail links is sometimes less green than leaving passengers up in the air

Leo Hickman
guardian.co.uk, Monday 17 August 2009 15.08 BST

There has long been a rather sensible assumption that train travel produces far fewer emissions than going by plane for every kilometre a passenger travels. A figure that is widely quoted is that trains are broadly 10 times more efficient than planes when carrying the same number of people over the same distance. This statistic appears to originate from a Eurostar campaign that ran a few years ago, urging people to do their bit for the environment by going by train to Paris and Brussels rather than hopping on a cheap flight. It hinges on the fact that France's electrified high-speed lines are powered in large part by electricity generated from France's low-carbon nuclear power stations.
But today we learn via a government-commissioned report produced by consultants Booz Allen Hamilton that the proposed high-speed line between London and Manchester might not be so green after all. In fact, it could result in more emissions than if passengers took a domestic flight. Cue a modicum of embarrassment for Lord Adonis, the transport secretary, who just a couple of weeks ago said that switching 46 million domestic air passengers a year to a new multibillion-pound north-south rail line was, "for reasons of carbon reduction and wider environmental benefits, manifestly in the public interest".
Booz Allen Hamilton is arguing that when you factor in the energy required to build then operate the new high-speed line, it would generate more carbon emissions over a 60-year period than allowing passengers to fly the same route. Airlines have long argued that they don't require the same amount of infrastructure to operate as land-based transport does, and that this rarely gets taken into account during such discussions.
However, the report does suggest that building a London-Glasgow high-speed line would produce a net carbon saving over the same period. It explains these contrasting conclusions by noting that many people already go by train between London and Manchester, whereas on the London-Scotland route the train companies – which currently claim only 15% of the market share – have a much greater chance of winning over passengers from airlines. If the train operators were to achieve more than 62% of the market share then a high-speed line would make environmental sense, the report concludes.
While this research is unlikely to settle this debate once and for all – it was originally researched two years ago and Lord Adonis has promised a new report by the end of the year – it does highlight the enormous number of variables that must be taken into account when calculating the efficiencies of the various forms of transport. Last year, the Department for Environment, Food and Rural Affairs (Defra) had to reissue its CO2 emission factors for passenger flights after there were complaints from members of the public and interested parties that its 2007 figures had failed to include a range of factors, such as accurate passenger load factors, the carrying of freight on aircraft and the increased use of more modern aircraft. Once the recalculations had been completed, the figure for short-haul flights into continental Europe fell from 130.4 grams of CO2 per passenger kilometre (gCO2/pkm) to 98.3 gCO2/pkm. However, the figure for domestic flights actually rose from 158.0 gCO2/pkm to 175.3 gCO2/pkm. (Long-haul flights also rose from 105.6 gCO2/pkm to 110.6 gCO2/pkm.)
Defra also recalculated its figures for rail travel. It concluded that the average figure for "national rail" travel was 60.2 gCO2/pkm. It's a considerable improvement on domestic flights – almost three-fold, in fact – but it doesn't quite match the 10-fold figure commonly attributed to rail when compared to aviation. The new calculations also highlight the often forgotten environmental benefits of travelling by coach. As George Monbiot has highlighted in his book Heat and here on Cif, coaches are currently the most efficient way to transport large numbers of people across the country. Defra's new figure for coaches is 29.0 gCO2/pkm – twice as efficient as going by train and almost six times as efficient as flying. But, realistically, how is the government ever going to convince the majority of us to go by coach from London to Glasgow?
There is one universal truth, though, that most of us can agree on: the faster you go, the more fuel you require. The promised "High Speed 2" line between London and Scotland would allow trains to travel at speeds faster than 150mph. In June, Professor Andrew McNaughton, chief engineer of the High Speed 2 company, said that the line would ideally need to allow trains to travel up to 250mph – half the speed of an aircraft – meaning no tunnels and very few curves. But he admitted that if the new line was to ever boast its "green credentials", it would entirely depend on the government's future electricity generating policies.
So, as with motoring and the promised dawn of the electric car, we find a discussion about the environmental merits of competing modes of transport ultimately boiling down to how you source and generate the energy. Use renewables and/or nuclear to produce your electricity and you're already more than half way to your destination – namely, creating a decarbonised transport network. But continue to rely on fossil fuels to generate your power and you'll barely get beyond the station platform.