Saturday - July 28, 2012

Old Tech Comes Back Stronger And Greener

Ok, none of this is really new news. It’s just something that I find interesting, and I’m going to try to write about it ... quickly. That’s my challenge for today.

Back in the post WWII period, the US Navy developed a system to hide their ships from sonar using air bubbles. This is called the Prairie-Masker system. A couple of thin bands are attached around the hull of a ship, and air is pumped through little holes on the bands. This makes lots of tiny air bubbles, and if the ship is in motion the under water part of the hull is covered with them. The difference in acoustic properties between the hull, the water, and the air bubbles causes internal ship noises to be reflected back into the ship, and thus it is harder to find with sonar.

Experiments at the time also showed that the ships seemed to use a bit less fuel. Eventually Prairie-Masker became declassified, and now the idea has been greatly enlarged, studied under advanced computer simulation, proved in several sea trials and real world experiments, and is being put in place on several of the largest new bulk carriers and cruise ships being built. These super giant ships already use the most modern hull designs, engines, and every other efficiency enhancing trick, so the bubble curtain’s 6% efficiency improvement is even more impressive. Sure, that’s a lot down from the theoretical 50% gain, or the postulated 25% gain, or even the controlled sea trial proof-of-concept 13% gain; 6% is a real world number, and when you are talking about hundreds of thousands of tons of fuel oil, 6% starts adding up to some real money real fast.

This post has pretty much already been written though, so look at the neat pictures, and then go here if you want to know some more. Or here.  This version tells it short and sweet too. Hey, there’s a 1 minute video if you want. One thing I do find a little misleading is the “green bias” in the stories that expresses fuel savings as reductions in CO2. But as they say ... whatever floats your boat.

But another article I ran across, that said how ship’s hull efficiency could be increased by heat, using the Leidenfrost effect:

Named for its discoverer, German doctor Johann Gottlob Leidenfrost, the Leidenfrost effect is the phenomenon wherein a liquid, when exposed to a solid that is significantly above that liquid’s boiling point, forms an insulating vapor layer between itself and that solid. This is the reason that water droplets dance across a sufficiently-hot skillet, instead of just evaporating on the spot.

Applying that principle to a ship, Chan believes that a hull kept at an outer temperature significantly above the boiling point of water, should cause a low-friction vapor layer to form between that hull and the water.

Once upon a time in the bad old days of Dangerous Education, college professors used to demonstrate the Leidenfrost effect by dipping their finger in and out of a crucible of molten lead. Right there in the classroom, without any air scrubbers or other safety equipment. While demonstrating to the class how the molten lead could set little strips of wood on fire, they’d dampen their finger on the sly and stick it in and pull it right out without getting burned. Science In Action! and students paid attention, you betcha!

Ok, so if the bubble hull thing is more important as a CO2 reducing device, and a hotter hull is more efficient ... let’s try pumping the exhaust gas from the engines into the bubble makers. Hey, your Mercury outboard motor does it’s exhaust under water, so why not the big ships too? Actually, I’m pretty sure the Leidenfrost effect is all or nothing. A little heat won’t make a difference. But pumping the exhaust (already well scrubbed and cooled by the latest ship pollution control/waste energy capture systems) into the ocean might capture a tiny bit more CO2.

Container Lines Set to Repeat Mistakes in Supply Glut: Freight

Maersk and rivals such as Hapag-Lloyd AG and CMA CGM SA lost money last year as high fuel costs exacerbated a price war. In addition to raising freight rates in response, they pooled or idled ships and reduced speeds to curb vessel supply. The decline in the index indicates those price increases are reversing as ships are added back to the world fleet.
...
Flagging European trade, too many container ships and signs that container companies are turning to rate cuts should prompt investors to stay away from shares in A.P. Moeller-Maersk, Frans Hoeyer, an analyst at Jyske Bank A/S in Silkeborg, Denmark, wrote in a May 21 note. Hoeyer advises investors to reduce their holdings of Maersk stock.

So the container shipping industry is having problems. They’re pushing efficiency - economies of scale - to all-time highs, building the biggest bulk carriers and container ships ever made. Mega ships bigger than aircraft carriers with a crew of just 13. They’ve got all kinds of energy saving tricks on their ships, and now they’re giving the bubble hull thing a go. But the world economy keeps slowing down, and to survive this industry needs to grow. In a stagnant economy they suffer, and new ship orders get canceled or reduced. High speed transits get slowed down, dropping their on-time efficiency rates. And that in turn slows other businesses, who have come to rely on international shipping timeliness so accurate that they can run the most minimal and flexible Just In Time inventories. Now that’s failing. The downward economy is a death spiral; it’s self-reinforcing.



PS - Oh, Mr. President? The entire world paradigm shifting business of container shipping? WE BUILT THAT. Not a cent of government investment. The whole international ocean shipping business? WE BUILT THAT. Not a government in the history of civilization has managed to pave the oceans; ships go where they will and they always have. Ports to unload cargoes? Dockyard facilities? Offshore islanding for crude oil tanker unloading? All built by capitalism. Private ventures. Profit motives. Ok, sure, some cities may have invested in their ports, or offered tax breaks, or policed most of the corruption out of the longshoremen. But it’s in their best interests to do so: more business means more tax dollars. And the ports were there before the cities saw them as tax revenue sources. They were there before the cities ever invested a dime in them. They got there without teachers - for thousands of years sailors didn’t need to know how to read. They got there without police or firemen - at sea, sailors do both jobs, or they die. And they got there without infrastructure; as I’ve said, the sea is it’s own highway network, and ships have been delivering things and trading since they were skin boats or hollow logs. The land routes often started as game trails to the beaches, and towns grew up along the trade routes, not the other way around. So trade was first. Then towns and cities. Then government. Then infrastructure, education, and non-production specialization. But trade was first. And to make trade happen, somebody somewhere had to produce more of one thing than he needed, and found a way to get together with someone similar who had things that he wanted. So production specialization - wood carving, grape farming, beer making - driven to excess by the profit motive, came along around the same time that trade began. Tens of thousands of years before government.

Ok, this still took me too long to write. But I’m getting better. Now, off the internet. Enough.

Posted by Drew458     on 07/28/2012 at 08:04 AM   
Filed Under: • planes, trains, tanks, ships, machines, automobiles •  
• Comments (1) • Trackbacks(0)  Permalink •  

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