"Bunker" isn't a type of fuel, thats just what it is called when store aboard a ship (the "bunker" is where coal used to be stored). Large ships burn about a dozen different types of fuel oils.
Cargo ships are also the most carbon efficient means of transporting goods. Better than trucks, trains, and planes.
> Cargo ships are also the most carbon efficient means of transporting goods. Better than trucks, trains, and planes.
A lot of cargo companies have been running the ships at half speed to conserve fuel. With margins so slim and some cargos not on a tight schedule, it works fairly well. This also reduces emissions.
The size of the sails / solar / wind turbine to replace this would be...? You get the idea.
As for carbon reduction, the engines already run at ~50% efficiency so there is little waste. The amount of carbon produced is the reality of pushing such a huge weight through the water.
I should have made it clearer in my post but I wasn't suggesting replacing diesel engines with Sail power, just augmenting it in the same manner as the SkySails (see response from jk4930 and markdown).
I also don't see why covering the deck in solar panels, or installing some form of wind turbine, wouldn't go some way to reducing the demand from diesel power generators.
There are a lot of people looking at fuel efficiency as well as carbon/sox/nox emmissions. For the companies running ships, the more efficient the plant is, the more money they save on fuel. About ten years ago we did a rough back of the envelope calculation in one of my engineering classes when I asked a similar question. The extra weight of the solar panels would negate any small benefit they would provide plus the cost of maintaining extra equipment. A lot modern ships run a shaft generator which uses the power from the shaft turning the propellor to turn an alternator to make electricity. When the ship slows down at the end of the trip, they go back to running smaller 'port' generators.
Covering the decks in panels is going to be a non-starter for containerships where a large percentage of the cargo is carried on deck. Even for tankers with (relatively) open decks, that's not going to work to hot because of the significant amount of piping that crisscrosses the decks.
In either case, I don't think you understand just how brutal the maritime environment is. A typical oceangoing ship has steel panels at main deck level dented in from the impact of the sea. I don't think solar panels are going to hold up so well.
Unless you can find a way for that wind turbine to both generate electricity and work as a "sail" so it propels the ship, it is just going to add drag that is counterproductive to the problem you're trying to solve.
There's a solar-powered research ship, the Tûranor. It is entirely decked over in solar cells, and spreads "wings" to extend its surface area. The hull design is very efficient. The ship averages 5 knots.
Oceangoing cargo ships maintain speeds of up to about 25 knots. In recent years, many have practiced "slow steaming", cutting their speed in half to save 30% of their fuel needs (and doubling transit times).
By contrast, sailing ships averaged around 8 knots -- though one of the characteristics of sail is that your speed is much less predictable (and hence, shipping schedules). The ships were also much smaller than today's freighters, for various reasons. While it's possible that we could build larger sail-powered or hybrid ships today, they'd probably still be much smaller than fossil-fuel driven ships. Other alternatives include biofuels (most likely pelletized wood and/or cellulose).
Canals were one of the original killers of sails and some of the proposals don't solve that problem (the hybrid approaches do). The modern sail will probably make a reappearance, but the current problem is the margins and capacity are such that not a lot of new generation ships are being built. I would expect that once you see car carriers adopt new technology the the rest will follow.
I didnt make a judgement, just pointing out a fact. That they are the most carbon efficient doesnt mean it couldnt be improved/replaced in the future however.
I just find it funny how politicians in my country try to save carbon emissions by enforcing a speed limit on highways or only let newer cars into the city areas...it just doesnt make no difference at all on a global scale.
You did make a judgement: You compared the entire output of global shipping's carbon costs to just one (admittedly car-loving and industrious) country's intracontinental transport costs. You thought that this was somehow relevant and interesting to the conversation. You phrased it in such a way to make it out as a travesty. Yes, you made judgement.
It's still widely open to misinterpretation. Does it refer to the carbon emissions while they pass through the canal, or is it the total carbon emissions of all ships that have passed through the canal? Is the statistic just showing that lots of ships go through the canal in a year?
Well to be fair, regardless of its suitability as a long term viable fuel source, it is nasty stuff. It's basically tar. It has to be kept heated to about 70c less it become to viscous and can't be pumped anymore and heated even more before being used in the engine.
"That they are the most carbon efficient doesnt mean it couldnt be improved/replaced in the future however."
The fact that transporting things by sea is ORDERS OF MAGNITUDE more efficient means that it is the last thing to improve-replace.
"I just find it funny how politicians in my country try to save carbon emissions by enforcing a speed limit on highways or only let newer cars into the city areas...it just doesnt make no difference at all on a global scale."
Politicians use to be ignorant of science. Having said that, cars and trucks are the biggest polluter in the world.
I couldn't care less about "carbon emissions", but combustion particles, specially diesel from big truck, are really nasty for the environment.
Also, large cargo ships are one of the easier things to run on nuclear power. Take the Nimitz class carriers, for example, basically unlimited range and a 20 year refuelling cycle. Political palaver aside. Which makes shipping a relatively easy thing to fix if we ever perceive the need. (Though I'm not convinced several thousand nuclear reactors at sea is a brilliant idea). Edit: spelling and grammar.
Driving slower improves fuel efficiency (to a point). Newer engines designs, improved fuels, and engine emission control have had a huge impact on vehicle exhaust emissions and CO2 output per distance.
Cargo ships are also the most carbon efficient means of transporting goods. Better than trucks, trains, and planes.