Plane Vs. Coach
In the comments to my last post, my old friend Philippe challenges the notion that carbon emissions / pollution from air travel is substantially worse than that generated by road travel (in this case, coach). Philippe used a website called Carbon Debt Calculator and came up with the following numbers…
Dublin – London 300miles
Driving emissions: 160kg CO2
Flying: 130kg
Train: 90kg
This flabbergasted me. It flew in the face of everything I’d been reading about the carbon emissions of air travel. Could it be true that flying 300 miles emits less CO2 than driving the same distance? This didn’t just fly in the face of everything I’d been reading, it flew in the face of common sense! How could it be, that the fuel consumed by picking up a 737 and hurling it into the air at 600kph to a height of 30,000 feet would be less than that consumed by rolling a far lighter vehicle the same distance along flat surfaces?
So I decided to do a little research. I couldn’t verify that Phil’s numbers are indeed the ones produced by the Carbon Debt Calculator (I can’t seem to get it to work… if I type 300 miles into the air travel box and hit ‘calculate’, it responds with “0 tons of CO2”). But based upon barely two hours of internet research and some excel spreadsheetery, I can confidently state that the Carbon Debt Calculator is a total bunch of arse should Philippe’s numbers be representative.
It’s just wrong.
First up: The Coach
The Dublin-London trip is complicated a little by a 70 mile stretch of water between the two. But in the interests of making this a more general (and therefore useful) comparison, let’s assume that both vehicles travel the same distance. In reality I suspect that the 70 mile “piggyback” that the coach receives from the predominantly freight-carrying ferry would reduce the total emissions generated by the journey.
OK… let’s work out the CO2 emitted by the coach on the 300 mile trip between Dublin and London. The vehicle was run by Bus Éireann who use Scania Irizar PB buses. According to the manufacturer, they get 8.15km per litre (let’s call it 7km to take account of potentially inflated claims by the manufacturer). Using a 1:0.62 conversion rate, that’s 4.3 miles / litre.
So the coach will consume approximately 70 litres of fuel during the trip. From here (PDF) we discover that the specific gravity of diesel is 0.88. That equates to a weight of 0.88 kg/litre. So the trip burns 61.6 kg of diesel oil. Remember…
When fuel oil is burned, it is converted to carbon dioxide and water vapour. Combustion of one kilogram of fuel oil yields 3.15 kilograms of carbon dioxide gas. Carbon dioxide emissions are therefore 3.15 times the mass of fuel burned.
Calculating the Environmental Impact of Aviation Emissions | An Oxford University Study (download PDF)
So the total CO2 generated by my 300 mile coach journey is roughly 194kg. Based on 85 passengers per coach, that’s 2.3 kg per traveller.
And now: The Plane
For this I’ll mostly be sourcing my data from the above-cited “Calculating the Environmental Impact of Aviation Emissions”. This is a fairly short report, but I recommend you download and read it. It’s interesting stuff.
With respect to our 300 mile journey, Table 1 of the report allows us to calculate the fuel consumed by a 737 between Dublin and London. Ryanair (they of the 99cent flights) have a fleet of Boeing 737s, so we’ll use them as our plane of choice. And according to that table, the 737 will consume approximately 2,200kg (2.2 tonnes) of fuel covering that distance.
Using the same factor of 1kg fuel = 3.15kg CO2, it appears that the 737 will emit 6,930kg of CO2 (almost 7 tonnes). Based on a capacity of 189 passengers, that results in 36 kg per traveller.
This is not a trivial difference… 2.3kg Vs. 36kg. It demonstrates that emissions generated by flying are a whole order of magnitude greater than covering the same distance by coach. What it doesn’t factor in, however, is the difference between emissions made at altitude and those made at ground level. The Oxford University report spends most of it’s time grappling with this issue and proposing a variety of metrics (multipliers) to take into account the altitude. For instance, it suggests that “the full climate impact of aviation is deemed to be between 2 and 4 times greater than CO2 alone”.
So best case scenario, you’re actually looking at 2.3kg Vs. 72kg per passenger.
Carbon offsetting: A bunch of arse
In the comments, it was also suggested that I could take the convenient and comfortable flight and then offset the carbon emitted either through a payment to a carbon-neutralising fund, or through “good works” of some kind.
Merrick‘s article “Carbon offsets are a fraud“ is a good place to start on this subject. The simple reality is this: Carbon offsetting is a fraud. See? Just like the title to Merrick’s article. The planet has two carbon cycles. One takes place over geological periods of time and includes the carbon locked in fossil fuels. The other takes place over far shorter periods – the life-cycles of plants and animals.
You cannot compensate for the burning of fossil fuels by planting trees. It’s as simple as that.
But even more fundamentally. And this is the kicker. I have a very serious moral problem with the attitude that carbon-offsetting engenders. The suggestion that flying to London is OK so long as I pay someone to plant the trees to capture 72kg of carbon per flight. It’s the whole notion of paying to pollute. Of placing a cash value on environmental damage. Quite aside from it being profoundly undemocratic, it’s just plain wrong.
We don’t own the environment, and we have an obligation – to those that follow us – to minimise the damage we do. One option is to do just that… take the obligation seriously… actively minimise the damage you do (2.3kg Vs. 72kg). The other option is to ignore how much damage you’re doing and hope that by giving someone some cash (based on absurd estimates generated by rose-tinted websites) that they’ll be able to fix the problem at a later date sometime maybe.
Sorry, but that option’s just not good enough.
A quick word on my methodology with the Carbon Debt Calculator website: since it’s meant to calculate carbin emissions over a year, the lowest unit was one ton. So I multiplied the miles by 100 when performing the calculations, got the tons and divided by 100. With such small distances as 300 miles it would always come up to 0 otherwise.
This is not to say that it’s correct; your calculation is much more accurate I think.
Now if you use http://www.carbonneutral.com//cncalculators/flightcalculate.asp
the results come out as .1 ton of CO2 for a flight Dublin – London.
So we are roughly agreed on the flight emissions (the web calculators still underestimate by a factor 50% – maybe plane fuel has a smaller specific gravity?).
Now for the coach.
This http://www.carbonneutral.com///calculators/travelcalculate.asp
(using the same trick mentioned above) yields 20kg.
But I think your figures are closer to the truth Jim. The only one I would dispute would be the 85 passengers, but even assuming 40 it would leave us with a best case:
Plane: 100kg
Coach: 5 kg
Thus proving that the online calculators leaves something to be desired and that plane travel is much more carbon intensive. Sorry for the miscalculation and I will try to address your second point about buying carbon neutrality soonish.
July 13th, 2006 | 5:21am
by Philippe
The specific gravity of jet fuel is indeed smaller than diesel, but only very slightly (0.82 as opposed to 0.88). But bear in mind that’s not relevant here; I took the weight of jet fuel directly from the Oxford study – already listed in kilograms.
85 is the theoretical capacity of the coach, and on both outward and return journeys it was close to full. Bear in mind, I also used the theoretical maximum capacity of the 737 (according to Ryanair they get 189 passengers into each plane). I’ve often been on short-haul flights with a few dozen empty seats. So it seemed best to use the theoretical maximum capacities for both rather than scale both down by an arbitrary amount.
No worries. Now and then every internet user is guilty of taking information at face value without checking up on it. I’ve done it.
Hell, until I did that calculation I hadn’t verified it either. As I say, I’d read several articles which claimed that carbon emissions from aviation are many times worse than other forms of transport, but I’d never made a direct comparison and run the numbers myself.
July 13th, 2006 | 10:32am
by Jim
Now for “Carbon offsetting: A bunch of arse”
First let me agree with Jim and Merrick that merely planting trees does not look like a convincing way to go. However, there are many other ways in which you can reduce carbon emissions elsewhere, by investing in alternative energy or energy saving efficiency.
One example (from carbonneutral.com again) is replacing Kerosene lamps in Sri Lanka with solar panels. Coming back to your Plane vs Coach question, let’s say you decide to dedicate just 2 of your 8 “extra” hours towards buying solar panels – let’s put that at 20 quid. It’s hard to figure out from the website exactly how much CO2 you can “buy”, but it’s in the tons.
The end result is that you will have spewed out a few hundred kilos of CO2 with your one trip but will have prevented a few tons from being emitted in the next year.
Now about the kicker: “placing a cash value on environmental damage. Quite aside from it being profoundly undemocratic, it’s just plain wrong.”
How else do you propose to make decisions on allocating resources? How do we decide as a society how much to allocate to reducing emissions vs health spending, education, scientific research, the arts etc..?
July 13th, 2006 | 5:27pm
by Philippe
That’s right Jim, facts and figures: once more distracting you from what’s going on beneath the surface. See The Theory of Relativity is a Load of Pish
July 13th, 2006 | 6:58pm
by Pisces Iscariot
Does the 3.15 factor work on diesel and kerosene? Does jet fuel produce more or less CO2 per kg than diesel in the coach?
July 14th, 2006 | 10:35pm
by RA
I recently read an article in the FT which really struck me in light of our discussion here. I think it could be “exhibit A” in the future trial of conspicuous consumption. I’ll go ahead and quote it in its entirety. The last line says it all…
A civil aviation experience
By Tyler Brûlé
Published: July 1 2006 03:00 | Last updated: July 1 2006 03:00
You don’t know this yet but your summer holiday plans are about to change. Instead of the week on Salina, the three weeks in Maine, the trip to inspect the cabin you’re building in Chile or the 10 days on Mykonos you’re now going to be boarding a flight to Tokyo Narita, jumping in a cab to Haneda and sampling domestic air travel as it should be. I know this sounds like an enormous sacrifice but if you care about the way you get from A to B, have some funds to invest or simply enjoy new experiences then do as I did earlier in the week and sample a new benchmark in civil aviation.
My trips to Tokyo are normally crammed with mad taxi scrambles to track down obscure bars and cafés, the odd meeting, perhaps an interview and too-late nights belting out the clutch of songs I’ve mastered since I joined the karaoke circuit. In London, Zürich and New York I’m a creature of habit, but in Tokyo I’m generally up for anything. So when my colleague Noriko interrupted a shopping incursion at Tomorrowland in Shibuya and suggested I get myself into a taxi because we were flying down to southern Japan for the evening I made my way out of the store, on to Meiji-dori and bundled myself into the back of a Toyota Crown Super Deluxe cab. Having just stepped off the SAS flight from Copenhagen I wasn’t that keen on spending another 90 minutes in the air. But when Noriko explained that she’d got us some tickets on Starflyer, it was all change.
You might recall I mentioned Starflyer, Japan’s newest airline, some weeks back because of its super-chic, all-black livery and inspired branding concept. At the time I’d only had positive, first-hand reports from people who’d sampled it and I’d been desperate to try it myself since it launched in late March. Unfortunately my last few trips to Japan haven’t allowed for any side trips further than Meguro, so the surprise jaunt on a shiny new airline was better than anything Shinjuku could have offered on a Monday in June.
I asked the driver to speed to the airport but to allow for a small diversion via Akihabara to buy a camera. I’ve given up on digital cameras and had already found a second-hand camera shop dealing in exclusively film cameras. It took about five minutes to select a titanium Contax T3 in mint condition. At £300, it was also a bit of a steal.
Arriving at Haneda, I parked myself at the Curry House at Terminal One for a heaping plate of hamburger curry rice and waited for Noriko to arrive with our tickets. By this time I had already documented the all-black- and-white check-in area and asked for the staff to pose in their skinny black suits. Tickets in hand we breezed through security (a concept that Haneda has mastered and pretty much every other airport in the world should copy) and went straight to the aircraft for the 20.40 flight down to Kitakyushu. At the moment Starflyer only flies between its base in southern Japan and Tokyo’s domestic airport but has plans to launch services to Nagoya, Seoul and Shanghai in the next 36 months. Backed by a host of local investors, perhaps the most interesting name to have put in capital is sanitary-ware giant Toto of all-spraying, blowing and singing toilets fame.
On board, Starflyer’s management and branding consultant Tatsuya Matsui have done their best to challenge every convention that makes civil aviation such a soul- destroying experience. Where most carriers would never dream of using black in the cabin, Starflyer’s gone for all-black leather seats in its A320 with a generous seat pitch and have added touches that include adjustable foot massagers on the leg-rest, seat-back TVs as standard in its single-class configuration and a cocktail table you can fold down if the middle seat is empty. On the trolley there’s organic apple juice, beer, coffee from Tully’s, petit-fours from Carré de Chocolat and absolutely no meal service.
As for the pricing structure, Starflyer has positioned itself as a lower-cost carrier by doing away with galley space and wardrobes and staffing its aircraft with only three flight attendants. Given that food retailers in Japan’s airports offer up bento boxes stuffed with every delicacy imaginable, a meal service isn’t really necessary and the lack of food is more than compensated for by crew who keep pouring juice and pass out blankets and headphones as part of the pre-flight service.
I don’t rave about shorthaul airline service very often, but Starflyer has come up with a service concept and brand image that other airlines need to experience and build on. As for your summer holiday, give the airline a whirl to witness that there’s still hope for commercial air travel and do a ryokan tour of Kyushu rather than the 30 minutes I spent there before flying back up to Tokyo.
http://www.ft.com/cms/s/f609d8aa-081f-11db-b9b2-0000779e2340.html
July 16th, 2006 | 6:13am
by Philippe
There are a lot of problems using such carbon calculators. Phillippe’s technique of multiply and divide by 100 certainly produces a better result than the zero Jim got, but it’s still way wrong.
Planes use huge amounts of fuel in take-off and landing, far more than when cruising along. Thus a 300 mile flight produces more CO2 per passenger mile than a 3000 mile flight.
Then there’s not only the seat occupancy mentioned, there’s the type of plane (eg the people running the new Cambridge-Oxford flights say a seat on their full plane is no worse than a driver-only car; they use a prop plane which is less polluting than a jet).
Also there’s where your seat is (cramming more people into Economy Class is more efficient than the vast spaces used for each First Class passenger).
By the same token, boats are not as sustainable as people imagine – the space and weight per passenger is very large indeed. There are those who’ve argued that a flight to New York emits less CO2 than the boat.
Still, we need some sort of ballparking to let us get an idea, and when the numbers come out so vastly different as the coach vs the plane to London, it’d take a very weird mind to say the plane was the better option.
Philippe’s right that some offset projects are not carbon sinks, and these can have genuine merit. For example, one of the World Cup’s offset schemes was to install simple methane-capture systems in India so people can cook off cow dung methane rather than burning kerosene.
The problem I have is that we’re only doing this stuff as a way to permit ourselves to live unsustainably, instead of doing it because it needs doing. It’s like being a child slave dealer but clearing your conscience by giving some of the money you make off it to nurseries and adoption services.
As Jim says, it’s profoundly undemocratic to put a cash value on environmental damage.
To say the rich can keep their high-pollution lifestyles by buying them says the changes have to come from elsewhere. Elsewhere than the rich? that’d be the poor, then.
Philippe wonders how else we can allocate resources other than placing a cash value on them.
One alternative would be carbon rations, a fixed amount the same for each person, and – most importantly – these would be non-tradable.
Most current proposals for this have a tradability factor, and these are held to be good because the less polluting people can make money out of selling their spare rations to the more polluting.
This, however, lets the richest carry on with frivolous consumption and gives the poor a strong incentive to sell what they would have used for more essential activities.
If they were non-tradable, it would be more democratic.
Additionally, if there were some kind of reward or incentive for those who consumed under their quota, it could encourage drastic reduction without permitting the frivolous and unsustainable activities – such as holiday aviation – that simply have to stop.
Climate change is here and it will get worse. The difference the people of the next 30-50 years can make is ‘how much worse’? Severe, or catastrophic? Literally hundreds of millions of lives hang in the balance on this. There is no more important issue.
I suspect that if we had lifespans of 400 years, if we had to live with the longer term consequences of this, we’d be taking a very different approach. If that’s so, we have no excuse for inflicting this on people yet to come who have no voice just because we won’t personally have to answer to them.
Conversely, if we were the people living with the effects of climate change, what would we be asking the people of today to do? Would we accept their desire for short-haul flights and year-round strawberries?
If we wouldn’t do it to ourselves, we shouldn’t do it to others.
July 19th, 2006 | 11:06am
by Merrick
I would feel morally superior because I live in an area where I can walk to everything I need (except for work), but I will be contributing to the overall problem by flying up North in a couple of weeks. !
It’s good to see you back and ranting about peak oil again 🙂
July 20th, 2006 | 4:13am
by L
Can someone explain the physics behind the ratio of CO2 produced to fuel burned? How is possible to create more weight than there was there to start with, particulary when burning fuel creates both CO2 and water?
September 25th, 2006 | 3:46pm
by Albert Weatherill
Sure thing Albert. It’s really quite simple once you get your head around it.
When you burn a carbon-based fuel, what you’re actually doing is raising the temperature of the carbon until it oxidizes (reacts with the oxygen in the air) which it does explosively… i.e. with a flame. Each carbon atom then bonds with two oxygen atoms and it is these two extra atoms that provide the “extra” weight (i.e. it’s not really “extra” at all, it’s being drawn from the air you’re burning it in… hence why a fuel fire can be extinguished by depriving it of air / oxygen)
As for the CO2 and water bit, there’s actually two separate (though obviously related) chemical reactions at work. First you’ve got the oxidization of carbon. It’s a simple…
C + O2 -> CO2
But it’s when you burn hydrogen, that you get water. And of course carbon-based fuels tend to contain hydrogen – hence the “hydrocarbon” label. So the excess hydrogen in the fuel is what reacts with the oxygen in the air to produce water.
I hope that’s clear?
September 25th, 2006 | 6:07pm
by Jim
[…] The theme that generates most google hits is the carbon dioxide emissions of planes versus coaches. Which pleases me, as I know those people are finding the info they’re looking for (the blog post they arrive at has some basic introductory data and links to an authoritative PDF). I’m less clear, however, whether the person who arrived looking for “groovy multiple mocks” was happy with the information they found. And was the person who wanted “explain quiet thinking” any the wiser for having visited? Quiet thinking? Are there really people out there somewhere… thinking too loudly? And I’d love to think that I helped the person who searched for “weird wacky tourist travel strange unusual signs places road trip united states”, but sadly I doubt I did. Maybe next year. […]
October 2nd, 2006 | 3:49pm
by The Quiet Road » Blog Archive » Brokeback to the future and incoming traffic
[…] NOTE: The environmental benefits of taking the coach are established, and discussed, in this entry. Posted in Miscellanity, Public Transport Follow responses to this entry via the RSS 2.0 feed. Leave a response, or trackback from your own site. […]
February 21st, 2007 | 4:55pm
by The Quiet Road » Blog Archive » Travelling Dublin-London
The article is quite interesting. I always wondered where these numbers come from when people calculate that air travel emits less greenhouse gases.
I also agree that there is no such thing as carbon emission compensation. I always tell people that when you are burning fossil fuels, you are burning dinosaurs and that they won’t get back into the earth again. I’m not sure that this makes sense but the point is burning fossil fuels is an irreversible process. You can’t compensate for it – I mean without making artificial oil again. 🙂
July 15th, 2018 | 5:42pm
by Max