The British needed 5000 to 6000 trees to build a single (large) warship, back in the day. That's quite a lot of wood if you ask me. In fact, that's a pretty big forest.

Ships' funnels are generally placed aft, and their speed means you've got a nice headwind blowing your exhaust gases away from the ship - you're just out of luck if the wind is in your back and going slightly faster than your ship.

The air you breathe standing outside on a ship is quite clean, probably a lot cleaner than the air most of us are breathing right now.

Multi-hull designs actually increase drag because they have a larger wet surface. They are also much more expensive to build and to maintain.

Filtering out the worst of the exhaust gases, specifically the sulfur oxides they're referring to in the article, isn't feasible on board ships. It's much easier to remove the sulfur in a refinery, but this simply doesn't happen because refineries don't want giant mountains of sulfur in their backyard. Leaving it in and burning it up is just the most economic thing to do.

This has been developed and put into use by a German company: SkySails. They report fuel savings of up to 30% in some conditions.

And yes, cutting speeds by about 10% reduces fuel use for the same distance by about 20%. This happens all the time in economy dips. Since fuel is the largest cost in shipping and its share in total costs keeps rising, it's an easy way to save a lot of money by offering up a little time. Maersk, the big container line, has reduced the operating speed on its ships from 22 to 20 knots because of the global economic recession. This is a pretty hard thing to do for them, because their ships operate on a schedule and have to stick to it, so changing operating speed means changing the schedule worldwide.

In other types of shipping such as bulk carriers and tankers, this practice is much more common. When there is little demand, ships can go slower to save money so they make more profit per job. When the economy is doing well and demand is high, shipping prices can suddenly skyrocket. In this case, sailing a little faster is the best way to transport more cargo in the same time, and thus complete more jobs. In fact, increasing speed is the short-term version of building new ships: it virtually creates more carrying capacity instantly. Building a ship takes months or years, so it can't be used to respond to sudden changes in demand.

I'll quote some math I did about a year ago in this post.

Exactly. The "50 million times more" thing is about sulfur oxides emissions, and honestly this number doesn't seem extraordinary to me. Diesel oil and gasoline have virtually no sulfur in them, while the Heavy Fuel Oil (HFO) that powers most ships is about 2% sulfur.

HFO is what's left when all the "good stuff" is extracted from crude oil. This "good stuff" is mostly shorter hydrocarbons such as methane, ethane, propane and butane (gases with 1 to 4 carbon atoms in them), gasoline (roughly 5 to 7 carbon atoms) and diesel oil (8 to maximum 21 carbon atoms).

What's left is an incredibly dirty, viscous, and nearly useless goo (asphalt is one other use, there aren't a whole lot). It still has a high energy density which makes it a decent fuel, but it's so viscous (because it consists mostly of very long hydrocarbon molecules) that you have to heat it up to around 80 degrees centigrade (176F) to even pump it into an engine. It also has high amounts of pollutants, because all the "clean" stuff has been taken out and you're left with all the dirty stuff. It is technically possible to remove most of the sulfur from this goo, but that means refineries would end up with giant piles of sulfur that nobody wants, and they'd have to dispose of it somehow. That's a cost refineries aren't willing to pay, so they just leave it all in to be burned up.

Legislation is being made to reduce HFO use in some heavy traffic areas (such as the North Sea in Europe), forcing ships to switch to clean diesel fuel in those areas. Of course, shipowners are against this because diesel is about 3 times as expensive as HFO. If all the ships in the busiest sea in the world suddenly start burning diesel fuel, you can expect the price to go up for everyone. Which is why we keep on burning the bad stuff.

Just needs some reverse engineering.

If you'd purely travel through time and go back ten seconds, you'd see the Earth 297.7 kilometers away just before you the vacuum of space kills you.

Separating time and space travel makes for some very boring science-fiction.

If I were offered one free one-way trip to the past, I'd go back 2000-2500 years and help Greek or Roman civilization a bit. If possible and/or allowed, I'd bring a book such as Fundamentals of Physics, along with a high quality ruler and quartz watch. After learning the language, you could start giving lectures about physics and all the great inventions and discoveries that changed our world since then - of course, without giving their real inventors credit. After all, they don't exist.

You could discover steam engines and steel, and use that to build trains and giant ships. You could build crossbows, trebuchets, perhaps discover gunpowder, and conquer the world. You could save millions of lives by building sewers and introducing basic hygiene. You could draw a map of the world and send out ships to discover new and uncolonized lands and continents.

You could do a million things, each of which might make you the richest and most powerful man on earth. And you could do them all.

Then again, by going back in time and just investing in the right things you could be the richest man on earth in today's world as we know it, which may be more exciting.

I don't like to nitpick*, but that chart mentions Saudi Arabia 13% + Iraq 6% + Kuwait 2% = Middle East 21%.

* That was a lie. I love to nitpick.

You cannot reach infinity, therefore you can't reach the end of the series, therefore you can't reach the 1 at the end of the series. Which means you can't use the 1 at the end of the series to disprove the proof.

The whole point of "infinity" is that there IS no end. You can't say "but suppose there is" and use that to prove something.

You're comparing cycling to swimming here. You can go on for a few hundred meters without pedaling on your bike, but you'll be still in the water after a few meters if you stop swimming.

Depending on the size and speed of the ship, without engine power you'll be dead in the water after a few miles. Ships most definitely use their engines 100% of the time at sea.

Your math seems solid, but taking the Emma Maersk as an example doesn't quite work.

Container ships carry time-critical goods, meaning they have to be fast. The Emma Maersk is among the fastest cargo ships in the world, doing 25.5 knots. Tankers sail much slower, for example the Hellespont Alhambra does 16.5 knots, which is quite fast for a tanker. Lower speed means you need less engine power, which means you consume less fuel. While the Emma Maersk has an 80MW main engine and five auxiliary engines of 6MW each (totaling 110MW), the Hellespont Alhambra makes do with a main engine of 36.9MW along with three auxiliary engines generating 1.5MW each (totaling around 41.5MW).

Another difference is that containers have a very low density, meaning container ships have a relatively low deadweight tonnage (carrying capacity). The Emma Maersk can carry 156,907 tonnes, the Hellespont Alhambra can carry 442,470 tonnes.

This means the Hellespont Alhambra carries 2.82 times the amount of cargo, using only 37.7% of the Emma Maersk's fuel while running at 64.7% of the Emma's speed. This means it is (2.82*0.647/0.377) 4.84 times as efficient as the Emma Maersk.

Napkin math aside, they'd use smaller tankers for this, since Alaska doesn't have any ports that can accommodate supertankers with their 24m (80ft) draft.

They probably wouldn't use crude oil carriers, more likely product carriers which usually carry stuff like gasoline or gasoil. These products are much easier to clean than crude oil, a high pressure fresh water/detergent mixture would probably do the trick. A couple more fresh water rinses would get all the detergent out.

Lining the tanks with rubber isn't feasible. Tankers have on-board cargo pumps located just above the keel (the lowest possible location). Cargo pumps have to be at this level to be effective, otherwise you'd never get a high enough pressure at the pump inlet, causing all sorts of problems such as cavitation. For more information, check out Wikipedia's page on Net Positive Suction Head.

Lining the tanks with rubber would block the pipes going to the cargo pumps, and since you can't use shore-based pumps to unload the cargo, there'd be no way to unload except with a pump lowered into the tank through one of the manholes. That would only allow for very small pumps to be used (they'd have to fit through a manhole), meaning it would take weeks or months to fully unload the ship.

Sure, you could worry about that, but do you think the world would be a better place if nobody was doing this research?

I understand what you're saying, I just think it's weird. Seperately, almost all of Google's projects would receive near universal praise (exceptions being, among others, privacy nuts and the whole wi-fi data collecting scandal). Yet somehow a lot of people are criticizing them just because they're all being done by Google.

No, I'm not wearing a Google T-shirt while writing this. It's in the laundry.