As we all know from rhymes at school, “in fourteen hundred and ninety-two, Columbus sailed the ocean blue”, and since then a very large number of ships have crossed the Atlantic and the other seven seas. Unlike the Santa Maria, in the 20th century the vast majority of them have been powered by a fossil fuel of some kind. On Wednesday I read an article in the Guardian about an idea that could change that, at least to some extent. Putting sails back on ships could be a way to make them greener, and crucially for the shipping companies, consume less fuel (which like all fossil-based fuel in the world is becoming increasingly expensive).

Companies such as Skysails are promoting this technology as a cost-saving measure for freight shipping companies, with the slogan “Turn wind into profit” (which reminds me of an amusing advert). Because of the significant contribution to climate change caused by shipping (due to the large number of goods we trade around the world), making freighting by greener must be a good thing (although localising economies so less stuff is shipped is a key part of the solution too).

But how green is cargo ship travel for passengers? Various people have taken this option as an alternative to flying (including Kate, the founder of Loco2; you’ll be able to read blogs about the experience soon) but as yet there is little information available about the CO2 emissions per person because of the fact that the ships are (of course) primarily carrying cargo, not people. This makes it difficult to ascertain the contribution of individual passengers to the overall carbon emissions.

One argument (discussed here) says that because the ship is travelling anyway to get the cargo to its destination, the passengers’ travel is irrelevant, and therefore the journey can be seen as carbon neutral. That’s all well and good whilst we’re talking about a small number of pioneers taking the opportunity to have a trans-Atlantic adventure, but it’s not going to work for large number of passengers (the main risk involved with scaling up passenger numbers is that we’ll go down the polluting cruise ship route).

A way to look at cargo ship travel that takes into account the passenger contribution is to work it out in terms of weight. This is the method that the mighty Barbara Hadrill used to calculate the emissions on her massive adventure to Australia. Barbara worked out that the freight ship leg of her adventure (Singapore – Darwin) produced 285,760 grams CO2 for 2350 miles (see her August 2006 blog).

Calculating in terms of weight is far from an established method, but it is logical, and should help us to think about the comparative advantages of each mode of transport, both in terms of CO2 and fuel efficiency (which is an increasing concern for all of us given massively rising energy costs).

Right off the top of my head, the method goes something like this (I may come back and improve on this as I talk to people about it):

• Think about a humble passenger cabin on a cargo ship where all other space is used as efficiently as possible (because the more cargo the ship holds, the more cost-effective the freighting). This is going to be far better in CO2 terms than a decadent cruise ship where not only the cabin, but the whole ship is engineered around comfort and entertainment, rather than simply getting as much cargo (human or otherwise) from A to B on as little fuel as possible. For a cruise ship calculating the CO2 emissions per person is simply a case of dividing the total emissions by the number of passengers (as that’s the only purpose of the voyage), but for a cargo ship we need to take into account the fact that it’s carrying cargo as well.

• Let’s assume a cargo ship can carry 3000 tonnes of cargo (that’s 3 million kg) and that a person weighs 65kg (about 10 stone). In this situation (if my calculations are correct) the passenger would be responsible for 0.002% of the overall CO2 emissions of the journey. I couldn’t find a fuel consumption figure for a typical trans-Atlantic journey (the nearest I got was here) but we can safely bet that 0.002% of it isn’t very much. Now obviously this assumes that to carry everyone that efficiently we’d need to cram all the passengers into containers like they were cargo, and that would be mental, but it does give us a useful indication of the terms we can view the issues in.

The basic conclusion (and we probably didn’t need to do such ludicrous calculations to work it out) is that using space more efficiently when travelling is a good thing. What it doesn’t tell us unfortunately, is a comparable CO2 per km figure for passenger cargo-ship travel versus air travel (or other means). There’s still work to be done on this, and I’ll be continuing to dig around places like the New Scientist and sustainable shipping sites to try and find more answers.

In the meantime, I’ll leave you with two thoughts:

• There needs to be a clear distinction between greenhouse gases that cause climate change (a very pressing global concern) and other pollutants such as Sulphur Dioxide that cause local environmental damage (an immediate concern for some, but not something that will affect all of us).
• We need to think about the feasible efficiency advances available in shipping/ferries (such as solar power) versus the feasible efficiency advances available in aviation (such as airships) and then make bold decisions about mass transportation on that basis.

Coming soon: smaller boats powered by the wind and the sun…

Post thumbnail: Mr T in DC

Fear not dear readers, my madness had not escalated to delusions of grandeur. I was not under the impression that I was divinely ordained to save you all from a natural disaster. I had not secreted two of every species of the animal kingdom in my backpack (only a couple of badgers). But I could see land for the first time in weeks, and I liked it.

Pelicans soared overhead as we rounded the corner into the Port of Guadeloupe. Dolphins swam ahead announcing our arrival with underwater megaphones; a solitary dove flew above us, carrying the twig of hope. And then the sea parted to reveal volcanic beaches, looming mountains, palm trees, and people! Enter the Caribbean.

I only had 6 hours to spend on this lovely island so there was no time to waste. I dashed around at a very un-Caribbean pace, flitting between the brightly coloured buildings like a humming bird. From Colonial era buildings that were crumbling on their shaky foundations, to open front patisseries and boulangeries that laced the air with the smell of freshly baked bread, the evidence of the French was everywhere. I’d travelled for a fortnight and found myself on a tropical island, but still in the EU.

This is a weird and wonderful feeling let me tell you. 28 degrees in the shade, sipping an espresso and eating a croissant that was paid for in Euros, butchering the French language, and watching waves lap against the dock as bizarre birds dashed between the trees. It was a lazy Sunday morning and perhaps the best possible introduction to the laid back life that we all associate with this part of the world.

The main export of Guadeloupe is bananas and back on the ship they were busy loading the cargo. But more than that, we were also unloading some of our freight onto the island. Sadly, thanks to years of exploitation, Gaudeloupe has become dependent on its parent country, and as an official overseas region of France Guadeloupe now receives significant imports from it’s European sugar daddy.

But there was no time to think about all this global trade, import-export, exploitation jazz. Before I knew it the sun was setting and we were due back on the boat. Cradling a bottle of rum that some of the crew had requested, I returned to my cabin, feeling very pleased with myself about making it this far.

Next stop, Columbia: a strange port where enormous barges sidled up to our ship to load their cargo and we were unable to disembark. This was one part infrastructure, there being insufficient depth for our boat near the shore, and one part security. The captain informed us that, perhaps unsurprisingly, Columbia is renowned for drug smugglers sneaking aboard to get their wares north of the Panama Canal.  Sneaky sneaky. That night was spent peering out of the window at the giant cranes as they effortlessly placed 10 tonnes pallets in the hold, and considering where I might hide all those woodland animals I’d smuggled from the UK.

Only three sleeps later and we were in Costa Rica. And true to my hypothesis, the journey really had been more important than the destination. I arrived with a great sense of achievement, and waved goodbye to my friends amongst the crew with genuine sadness. Bring on the proverbial cheese! The next stage of the adventure was waiting.

Little did they know that I had spent half the morning choreographing a jigsaw puzzle celebration dance, and the other half doing cartwheels in a boiler suit I found under my sofa. Boredom can drive you to some terrible things, but none were so bad as my decision to read a Danielle Steele novel.

My lovely sailor buddies, Viktor, Alex and Andrev, from Russia, Lithuania and Ukraine respectively, were bringing me great joy and I was slowing developing a social life on the boat. I had a phone in my cabin and I would let out a squeal of delight whenever it rang. Viktor called to say he’d found another Abba DVD; Andrev could see a whale from the bridge and wanted to know if I needed to borrow his binoculars, and Alex pretty much just phoned for a chat. However, this social life only occurred after they finished work and so I was forced to spend the rest of the day with myself.

On arrival I’d begun by exploring the boat. It was two hundred metres end to end, with cargo stowed above and below deck. There was a teeny tiny swimming pool, a dartboard without darts, a ping-pong table and a library with a wide selection of Polish literature.

Although the entertainment facilities left a little to be desired, my cabin was lovely, far better than I had expected and a pleasure to be in. Twin beds in one room, adjacent to an en-suite bathroom, complete with miniature soaps. Next to that was my own private day room with a desk, sofas, calendar (to count down the days) and plenty of space for important time-fillers like prancing around in my lifejacket.

I read my book during the day, taught myself some Spanish, attended the frequent meals (brunch, elevenses, afternoon tea) and slaved away over my 1000 piece jigsaw. I visited the TV room and enjoyed a private screening of Miss Congeniality, and part 4 of 5 in a VHS box set on the history of the Great British Railway. Why this video was there remains one of life’s great mysteries, and thinking about it kept me occupied for some hours. But even with this weighty issue on my mind, boredom started to creep in.

By day ten my jigsaw dance was second to none, my tan was coming along nicely and I was quite sure I could pinpoint our exact location on the map. I’d had a go at steering the boat, studied the weather reports, and begun to identify constellations from a celestial sailing poster on the bridge. All things considered I was having a jolly good time. But then something terrible happened.

As if possessed by some crazed housewife, I found myself in the library plucking the solitary English book from the shelf: a Danielle Steele romance. The name of the book escapes me. I think I’ve blocked it out. But the cover was pink, I should have known better.

But with time to kill and a lack of entertainment I was fooled into thinking it was a good idea. Boy meets girl, girl is secretly a princess, love ensues…what did I expect?! As I finished the novel a fit of insanity took over me. I abandoned my stance on littering and sent the book flying into the depths of the Atlantic. I felt I had done the world a great service.

As I watched the book float away, its pages already under attack from the corrosive salt water I felt my sanity return. Somehow by throwing that book to its watery death I had freed myself from the boredom. Suddenly the time was flying past. Time flies like an arrow, fruit flies like a banana. Day 14. Land was in site!