More thinking on ferry travel
There I was on the Oscar Wilde a few weeks back. Its the very nice Irish Ferries boat that links Rosslare,Ireland to Roscoff, France. With two young kids this is the comfortable way of driving from France to Ireland, forget that landbridge stuff and the extra 800km ( for me at least ).
So I got talking to one of the ship's engineers and asked him a few questions about passenger numbers, fuel consumption etc. and it was all pretty edifying. John said ( well I'll call him John, don't want him getting in trouble ) that the ferry uses on average 70 tonnes of intermediate-fuel-oil ( IFO 180 or IFO 380 ) on a crossing which is about 550km each way.He also said that the traffic split was predominantly passenger/car traffic from May to October and freight for the rest of the year. Having previously sailed with Irish Ferries in December and February I can confirm that it is indeed trucker heaven at those times of year.
I asked him about the impact of weather and the loading factor of the ship and Pat said ( I'll call him Pat now ) that it didn't make a huge difference. In really bad weather and crazy tides with a full load the fuel usage could go as high as 90 tonnes per trip and on beautiful days with a tailwind and an empty hold that could drop to 60 tonnes per trip.
Its not that surprising that the load factor of the ship doesn't have a huge affect on the fuel consumption when you consider that the maximum cargo load of the ship is 5250 metric tons of deadweight (DWT). If the ferry is chockablock with a full car load of 580 cars, each weighing around 1.2 tonnes ( average figure including passengers luggage etc ) this has the ferry using only around 700 tonnes, 13% of its capacity.
Anyway thats not really what I wanted to say. We now have real world consumption for a car ferry, 70 tonnes of fuel to carry 580 cars over 550km.
The 70 tonnes of oil equates to emissions of 204 tonnes CO2e. Divvying this up between the 580 cars give us 350 kg CO2e per car per one-way trip.
To put this in perspective, if Aer Arann was to do the same trip in one of their efficient ATR-72's with a full load on a comparable journey, e.g. Waterford, Ireland to Rennes, France, the emissions per person would be 56 kgCO2e per one-way trip. See atmosfair for the flight calculations. ( note, they assume 80% occupancy but I've changed used 100% in the 56kg figure to compare with a full car-ferry. )
In the example above, ferry travel, even with 5 passengers in car, comes out worse than flying in emissions terms. What it does highlight is that it's nigh impossible to take an off the shelf figure for ferry travel. Each ferry company has its own emissions profile and only when they start providing hard facts to their passengers that the comparison with air-travel can become meaningful. The figures I've shown might give a hint at whats stopping them from doing so.
P.S. The figures I've derived above differ somewhat from previous calculations. See a previous blog entry and report for more details.
P.P.S. Thanks to Seamus for the details ( not his real name either, I hope I haven't narrowed it down too much by now )
September 17th, 2008 at 12:40 pm
Interesting calculation, and confirms calculations I’d seen elsewhere about high-speed ferries in particular being as fuel-hungry as planes — not surprising really, given that they are essentially jet engines on water. Likewise long-haul train journeys: all that sleeper accommodation means fewer passengers are carried, and fuel consumption per passenger kilometre is similar to flying.
Mary Mulvihill
September 30th, 2008 at 2:30 pm
Mary, it depends how the long haul train journeys are powered.
If you are travelling through France, the likelihood is you are being powered by nuclear-generated electricity, so pretty good from a direct climate impact point of view - not that I am arguing in favour of nuclear. German rail also gives you an option to offset…if you believe in that mullarkey.
September 30th, 2008 at 2:34 pm
Thanks for this. Still leaves me in a quandry about how to get home for Christmas: seems like the holyhead-DL ferry could have the same impact as the flight from Brussels. I don’t think I am willing to give up all the ‘love miles’, as Monbiot proposes….
Anybody planning to sail from Holyhead in mid-December?
June 29th, 2009 at 4:21 pm
I had a query about a trip from Manchester to Dublin, which was the cleanest option.
Quick calculations.
Flight : 51kgCO2e ( 292km * 175gCO2e/km DEFRA figures. We get 292 km from the straight line distance, 265, increased by 10% to allow for non-ideal flight path )
Ferry : 11.5kg CO2e ( 100km * 100gCO2e/km, DEFRA figures )
Train : 12kCO2e ( 200km * 60gCO2e/km, DEFRA )
So about 26kg extra by flying oneway.
The defra figures can be seen here
Before you make the jump on the train, work out how much extra it will cost you to save that 26kg ? Then work out the equivalent cost for a tonne of CO2. If the cost is over €50/tCO2 then you could look at some way of spending your money better. Maybe there’s a green electricity supplier that just a bit more expensive than your current one and thats why you haven’t made the switch ? Well, maybe if you took the flight and put the money saved toward green electricity the overall CO2 balance would be positive.
N.B. I’ve posted a comment on July 28th 2010 to include a mutiplier on the aviation emissions.
July 1st, 2009 at 1:41 pm
What about the high altitude effect of aircraft emissions? I frequently take the c. 7hr journey hook of Holland-Harwich, to see loved ones and because I pledged not to fly some time ago. I am clinging to the reassurance that aircraft emissions at high altitude multiply the climatic effect of its emissions… and what about other gases, not just CO2? It all gets very complicated. Although without doubt the key is to stay local and minimise travel whereever you can.
July 28th, 2010 at 1:10 pm
As you say, Elinor, it all gets very complicated. The non-CO2 effects of aircraft emissions are what are addressed in this document from the Stockholm Environment Institute.
A bit heavy but there’s no simple way of explaining this. The recommendations of this study are that the direct CO2 emissions, which are directly related to fuel consumption, should be multiplied by 2, at least, to represent the global warming effects of airtravel in a 20 year time frame.
In my reply on June 29th I put flying from Manchester to Dublin at 50kg, using the base DEFRA figures. We should then multiply this by 2 to get a more representative figure of global warming impact. This now puts airtravel at 100kg of CO2 equivalent (CO2e), or 76kg CO2e more than the train ferry option.