trains and planes on the carbon battlefront

It's interesting to watch the railway and airline lobbies wage battle for the hearts of environmentally-conscious long-distance travellers. Trains and planes are competing with each other in a growing number of markets, but on the alternative fuels front, airlines are at a distinct disadvantage.

Given security of supply, railways could switch to biodiesel immediately, and trials have begun using blended fuels. (Interestingly, the first biodiesel-fueled trains were run in 2002 by Indian Railways.) Despite the marketing hype, it's not so clear that this would cut carbon emissions; but it would at least reduce dependence on fossil fuels, and the Indian approach of making biodiesel from plants such as jatropha, mahua and karanji would create jobs while avoiding some of the pitfalls of biofuels.

Then there's the approach of using electrified trains - in cities, at least - which removes the need for liquid fuel altogether, making it possible to use a mix of any energy sources that can be fed into the grid: wind, sun, sea... The solar panel on your roof could be doing its bit to get you to work in the morning.

Meanwhile, the airlines aren't giving up the fight. If they have fewer alternative fuels immediately available, they figure they can at least earn points by participating in climate change research to see what their impacts are, and what can be done. They've also got the fallback position of encouraging passengers to purchase carbon offsets, but have a long way to go, as a miniscule proportion of air travellers currently purchase offsets, and many of these are virtually worthless tree-planting exercises.

Sir Richard Branson is sitting pretty with a foot in both camps. In true Branson style, there's the $25 million Virgin Earth Challenge to see who can come up with the killer carbon reduction app. But as he has pointed out, the answer is not only about fuels and technologies. It's also about standards and operating procedures. Sometimes we just have to change the way we do things to reduce carbon outputs, and Sir Richard maintains that airline procedures could be tweaked to achieve just that. He has proposed towing aircraft to the runway, and the International Air Transport Association (IATA), which represents 250 airlines, says that "an overhaul of air traffic control operations could result in a 12 per cent reduction [in emissions] if it meant planes didn't have to circle while waiting for a landing slot."

They can fiddle - for now - but it is likely that the current round of climate change negotiations at the UNFCCC will bring international travel under the carbon emissions umbrella from which it is currently exempt. And as Climate Ark notes:

No government - or airline - will admit it, but limiting the number of flights individuals and airlines are allowed could be the long-term solution. Some economists argue that we are already going down the road towards carbon rationing. The only difference between carbon trading and carbon rationing is that in the former system, those who exceed their allocation, or ration, can buy in extra credits. In the future, this option may become prohibitively expensive, or illegal.

[Update on 27 January 2008: An article in the Guardian today points out some of the current thinking about improved airplane construction methods to reduce weight, new types of engines, and operational procedures that would reduce carbon impacts of air travel. Some believe that planes could halve their fuel consumption by 2020.]