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OA260
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(LNG) Powered Ferries/Cruise Ships. The Way To Go?

Sat May 11, 2013 10:32 am

An interesting new development with gas power in the Ferry/cruise industry. Is this the way to go ?


Nordic ferries go gas-powered

The Finnish flag is fiercely clacking at the stern as the Viking Grace carves through spring ice, past scores of small islands on the route between Stockholm in Sweden and Turku in Finland.

A maritime revolution is taking place in this narrow waterway and its archipelago of hundreds of small islands. The Viking Grace, a brand new cruise ferry, is fuelled entirely by liquefied natural gas (LNG) and is the first of a new generation of green passenger ships.

"It's very important for us at Viking Lines to be a pioneer and save our environment," says Captain Magnus Thornroos on the ship's wide bridge.

Down in the bowels of the ship, the engines are running on 100% gas, although they are capable of using old-fashioned diesel as a back-up propellant if necessary.

http://www.bbc.co.uk/news/world-europe-22457141

Also another interesting article here :

http://www.worldcruiseindustryreview...-sep10/WCR024_lng-alternatives.pdf
 
comorin
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Sat May 11, 2013 12:44 pm

Does LNG constitute an explosion risk?

Thanks
 
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Mortyman
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Sat May 11, 2013 1:58 pm

While LNG Powered cruiseships / ferries might be something New, smaller LNG Powered regional car ferries has been in operations both in Norway / Europe and the USA for a couple of years now.
 
ltbewr
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Sat May 11, 2013 2:04 pm

What could happen is to require the use of LNG for cruise ships, cargo ships and utility ships in and certain distance from harbors to reduce local/regional pollution.
 
prebennorholm
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Mon May 13, 2013 1:38 am

Quoting ltbewr (Reply 3):
What could happen is to require the use of LNG for cruise ships, cargo ships and utility ships in and certain distance from harbors to reduce local/regional pollution.

What will happen is that from 2015 fuel regulations will change for shipping in the Baltic Sea, the North Sea and the English Channel. Maximum sulphur contorts is reduced from 1% to 0.1%. That is parallel to what we saw for land based transport 20 - 30 years ago.

That will increase shipping fuel costs considerably. And since LNG is sulphur free, then it becomes economically more attractive as substitute for diesel oil.

Quoting comorin (Reply 1):
Does LNG constitute an explosion risk?

Yes.

But correctly managed the risk is low.

LNG tankers have been navigating the waters around the world for decades, as far as I know without major accidents. Anyway, when such a ship enters for instance Boston Harbor, then all other shipping is put on hold to avoid the risk of collision.

30 years ago a Royal Danish Navy frigate accidentally fired a Harpoon missile in the middle of a busy ferry route. Since the missile had not been programmed for a specific target, then it automatically seeked the nearest object, which happened to be a summer cottage colony on the coast 20 miles away, since the two ferries incidentally were both in their harbors. Four houses were destroyed and well over a hundred were damaged to various degree. Since it was autumn, nobody got hurt. Due to a Harpoon design fault McDonnell Douglas paid for the damage (US Navy had experienced the same thing shortly earlier).

Such things shall not happen with LNG powered passenger ships around.
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L410Turbolet
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Mon May 13, 2013 1:48 am

I might have just poor reading comprehension, but I still don't understand what is the relation between the Harpoon accident and LNG-powered vessels or rather how would the difference in fuel prevent such accident?
 
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Mon May 13, 2013 2:43 am

Quoting OA260 (Thread starter):
is fuelled entirely by liquefied natural gas (LNG) and is the first of a new generation of green passenger ships.

???

LNG is a fossil fuel. In a few years natural gas will be responsible for more carbon emissions than coal over the entire world.

Here in the US, extraction of natural gas includes controversial shale fracking processes, the pumping of million of gallons of salt water into the shale to force the natural gas to the surface.

Yes, it is better than burning oil, but it is not clean energy or green energy.

[Edited 2013-05-12 19:45:28]
 
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Mon May 13, 2013 6:19 am

Quoting prebennorholm (Reply 4):
30 years ago a Royal Danish Navy frigate accidentally fired a Harpoon missile in the middle of a busy ferry route. Since the missile had not been programmed for a specific target, then it automatically seeked the nearest object, which happened to be a summer cottage colony on the coast 20 miles away, since the two ferries incidentally were both in their harbors. Four houses were destroyed and well over a hundred were damaged to various degree. Since it was autumn, nobody got hurt. Due to a Harpoon design fault McDonnell Douglas paid for the damage (US Navy had experienced the same thing shortly earlier).

And this relates to LNG powered ships in what way?
 
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Mon May 13, 2013 1:20 pm

Quoting kiwirob (Reply 7):
And this relates to LNG powered ships in what way?

Well, I guess no one shall ask "what's that funny red button doing here" whilst a ferry powered by LNG is within 20 miles range of a frigate.
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Mon May 13, 2013 8:43 pm

LNG tankers have been steamships that use the boil-off gas to fire the boilers. It makes sense, although steam is less efficient than internal combustion, because the fuel is "free" (either they burn it or vent it to air).

But a ferry does not carry LNG as cargo, so would it use a gas turbine engine, then? Or can Diesels be run off LNG, too?
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rwessel
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Tue May 14, 2013 2:15 am

Quoting DocLightning (Reply 9):
LNG tankers have been steamships that use the boil-off gas to fire the boilers. It makes sense, although steam is less efficient than internal combustion, because the fuel is "free" (either they burn it or vent it to air).

Not really. Big boilers driving steam turbines usually do better than ICEs. In fact, many of the gas turbine power plants are combined cycle, where the exhaust from the turbine is used to boil water to drive a steam turbine (usually good for another 30-50% power output). The advantages of gas turbines are small size and rapid startup and response.

Quoting DocLightning (Reply 9):
But a ferry does not carry LNG as cargo, so would it use a gas turbine engine, then? Or can Diesels be run off LNG, too?

Diesels (and gas turbines) can run off pretty much anything from methane to vodka. That's very much *not* the case for Otto cycle engines, which require a fuel not ignite during the compression cycle. Your fuel injection system may need some modification depending on the type of fuel, of course - an injector designed to pump a liquid is likely to do poorly when presented with a gas). Many trucks and busses run on LNG fueled diesels. For some reason, in these parts it seems like it's become universal for garbage trucks (or, if you're a cynic like me, it's become universal to paint "powered by natural gas" on the side of garbage trucks...).
 
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Tue May 14, 2013 2:16 am

Quoting L410Turbolet (Reply 5):
I might have just poor reading comprehension, but I still don't understand what is the relation between the Harpoon accident and LNG-powered vessels or rather how would the difference in fuel prevent such accident?

LNG wound not prevent such an accident. But should it - or something similar - happen, then on an LNG powered ship rescue boats or floats would not be needed.

Quoting DocLightning (Reply 9):
Or can Diesels be run off LNG, too?

Diesel engines can be made to run on LNG. This new ship, mentioned by the thread starter - Viking Grace - is diesel powered. A diesel engine may run on any type of fuel, from hydrogen to heavy fuel oil. The fuel injection system has to be adapted to the fuel which is used.

Since Viking Grace is made to be able to also run on oil, then it has two different fuel injection systems.
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Tue May 14, 2013 1:01 pm

Quoting rwessel (Reply 10):
Not really. Big boilers driving steam turbines usually do better than ICEs.

What ICEs ? In the context of ships you're talking about the biggest baddest and most efficient diesel engines in existence.

I was reading recently about LNG tankers and they don't vent cargo nowadays, and don't burn boil-off either, it's more cost effective to cool it and send in back in the tank.
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Tue May 14, 2013 1:17 pm

Quoting OA260 (Thread starter):
"It's very important for us at Viking Lines to be a pioneer and save our environment,"
Quoting rfields5421 (Reply 6):
Yes, it is better than burning oil, but it is not clean energy or green energy.

  

Agree the quote in the OP is a very poor use of language.

Quoting rwessel (Reply 10):
Big boilers driving steam turbines usually do better than ICEs. In fact, many of the gas turbine power plants are combined cycle, where the exhaust from the turbine is used to boil water to drive a steam turbine (usually good for another 30-50% power output). The advantages of gas turbines are small size and rapid startup and response.

I watched one of those cable shows where they were assembling a large ship and they used huge diesels to drive alternators to create electricity for the motors driving the screws. They didn't say what if anything was done with the exhaust. It'd seem something could be done with the exhaust, which still has a lot of heat energy in it. If nothing else, it could be used for a turbocharger to boost the pressure of the feed air. I'm not sure if this was the case or not.

Quoting Aesma (Reply 12):
What ICEs ? In the context of ships you're talking about the biggest baddest and most efficient diesel engines in existence.

Is not a diesel an internal combustion engine?
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Tue May 14, 2013 3:43 pm

Yes, he's claiming that turbines can be better but large ships have used turbines in the past and they're not common anymore, so I contend that diesel must be more efficient. There was also the maintenance troubles linked with the needed gearbox.

http://en.wikipedia.org/wiki/W%C3%A4rtsil%C3%A4-Sulzer_RTA96-C

That thing is turbocharged.
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prebennorholm
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Wed May 15, 2013 2:22 am

Quoting Aesma (Reply 14):
http://en.wikipedia.org/wiki/W%C3%A4rtsil%C3%A4-Sulzer_RTA96-C

That thing is turbocharged.

Sure it is. Practically all large ship engines are two stroke turbocharged. But Viking Grace does not use that 80 MW monster engine which you linked. It has instead four much smaller 7.6 MW engines from the same manufacturer.

The world's largest container carrier - MS Emma Maersk - has that 80 MW monster. It has four large exhaust turbines from ABB in Switzerland. Three of them power the chargers. The fourth turbine powers an electric generator.

The exhaust then passes a high pressure boiler that runs a steam turbine which powers another electric generator.

Then it passes a low pressure boiler for the same purpose.

Electric power from all three generators then powers an electric motor which is built around the propeller shaft.

All this boosts overall engine efficiency from 45% to 51%.
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Wed May 15, 2013 2:40 am

Quoting rwessel (Reply 10):
Diesels (and gas turbines) can run off pretty much anything from methane to vodka. That's very much *not* the case for Otto cycle engines, which require a fuel not ignite during the compression cycle.

Nobody has ever explained this to me. I'm fascinated. OK, so why are Otto cycle engines so common in cars while Diesels are common in large applications?

Quoting rwessel (Reply 10):
Not really. Big boilers driving steam turbines usually do better than ICEs.

I read somewhere (maybe here: http://socialeyezer.com/wp-content/u...rumpy-Cat-Disappointment-Meme.jpg) that the reason why ICEs have replaced steam is because they burn up to 50% less fuel.

A powerplant burns coal, which you can't really burn in an ICE, AFAIK. Apparently Mr. Diesel did try coal dust in an engine, but he correctly predicted that it would severely damage the machine. However, one of steam's great inefficiencies is that decoupling of fuel consumption and engine power. In a ship (or any vehicle), consumption must be high well before departure (as long as two days in some of the old ocean liners) to pressurize the steam system and often the boilers were kept fired in port because ships would only stay there for a few hours. That is a major cause of inefficiency. Power plants operate continuously and at or near maximum capacity, so that removes part of the inefficiency.

But steam is and always will be less efficient thermodynamically than diesel because of the basic energy flow. In an internal combustion engine, heat expands a gas that transfers its mechanical energy to some collection mechanism, be it a piston head or a turbine blade. Thus, energy must change states twice: from heat to gas expansion and from gas expansion to mechanical work. In the steam engine the energy flow is from heat to heat (overcoming the boiling point of water), and then to gas expansion, which then must be transferred over a distance to a piston head or turbine blade. There is an extra energy change there, not to mention the energy transport. Each step leaks energy in the form of entropy. Steam just can't compete with an internal combustion engine powered by the same fuel. The proof is in the pudding: no more steamships are scheduled for construction in the merchant fleet. Not even LNG carriers. (I'm not counting nuclear-fired steamships, which are very unusual in commercial use, anyway).

I read on my link above and elsewhere that QE2's conversion from steam to Diesel saved about 250 tons of fuel or GBP12M per year.

The big remaining advantage of steam: if it can make heat enough to boil water, you can use it for power. Be it wood scraps from a paper mill, unused sugar cane, surplus animal fat, or heat from a controlled fusion reaction, you can use it as fuel for a steam engine.

Quoting prebennorholm (Reply 11):

Since Viking Grace is made to be able to also run on oil, then it has two different fuel injection systems.

Would it be able to switch back and forth between the two quickly (flip a switch), or would someone have to modify the engine each time?
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Wed May 15, 2013 10:04 am

Injection systems can deal with gas and liquids, that's what is done in LPG/petrol/CNG cars and there is no modification of the injection. I think with diesel the problem is that they use very high pressure injectors for diesel fuel, that may not work with a gas.

Quoting prebennorholm (Reply 15):
The fourth turbine powers an electric generator.

The exhaust then passes a high pressure boiler that runs a steam turbine which powers another electric generator.

Then it passes a low pressure boiler for the same purpose.

Electric power from all three generators then powers an electric motor which is built around the propeller shaft.

All this boosts overall engine efficiency from 45% to 51%.

Interesting, I didn't know that.

Quoting DocLightning (Reply 16):
A powerplant burns coal, which you can't really burn in an ICE, AFAIK. Apparently Mr. Diesel did try coal dust in an engine, but he correctly predicted that it would severely damage the machine.

You can use coal and even wood in an ICE, you just need to make a gas out of it, thanks to a gazogène, ubiquitous in WW2 France since there was no gasoline :

http://hfr-rehost.net/http://upload.wikimedia.org/wikipedia/commons/3/3a/Peugeot_402B_Limousine_%C3%A0_Gazog%C3%A8ne.JPG
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prebennorholm
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Thu May 16, 2013 12:08 am

Quoting DocLightning (Reply 16):
Would it be able to switch back and forth between the two quickly (flip a switch), or would someone have to modify the engine each time?

I don't know the details. But they call it a "dual fuel engine", so I would assume that it is more like flipping a switch than modifying the engine.

Even if the engine may not need modification, then it can easily be a lot more than just flipping a switch. It might be needed to manually close and open valves on the feed lines to the injectors on each cylinder, and it might be needed to manually operate the gearbox which powers the injection pumps. But that's pure guesswork.
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Thu May 16, 2013 5:48 pm

So I do wonder about the safety situation. For those who don't understand:

With liquid fuel like fuel oil, a leak is a big mess and a big danger.

With LNG, there is a nitrogen jacket around the tank, but if it is forceably ruptured by an external force (hitting a sharp reef, hitting an old WWII mine, collision with another vessel...stranger things have happened) the entire tank will go up in one big explosion. That would be like an atom bomb going off. There would be nothing remaining of the ship and its occupants larger than about the size of a charred M&M (at least you'd never know what happened).

So how is this risk managed?

Then again, the LNG shipping industry has had an excellent safety record. If an LNG tanker were to go up, you'd hope very much it wouldn't be in port because the explosion would rival the largest nuclear weapons ever made.

Quoting Aesma (Reply 12):
I was reading recently about LNG tankers and they don't vent cargo nowadays, and don't burn boil-off either, it's more cost effective to cool it and send in back in the tank.

Yup. Apparently the last steam-powered LNG tankers were built in 2008 or 2009. Those were built to cannibalize cargo (boil-off) in the boilers. Apparently, LNG is more expensive than diesel and it's more cost-effective not only to burn diesel rather than cargo, but to use electricity from that diesel to cool the LNG boil-off and return it to the tanks.
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Aesma
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Thu May 16, 2013 6:28 pm

Well that situation might reverse with shale gas having caused natural gas prices to crash, that is unless oil crashes soon due to shale oil.

As for an explosion, I don't think it's that easy, there is not enough oxygen around for anything big to happen.
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Thu May 16, 2013 8:43 pm

Quoting Aesma (Reply 20):
As for an explosion, I don't think it's that easy, there is not enough oxygen around for anything big to happen.

In a catastrophic tank failure of the sort that sends a massive flood of boiling cryogenic and highly-flammable fuel. This would be a Boiling Liquid Expanding Vapor (BLEV) explosion.

Here's one set off on purpose as a demonstration: http://www.youtube.com/watch?v=UM0jtD_OWLU
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Sat May 18, 2013 8:34 am

Quoting Aesma (Reply 12):
What ICEs ? In the context of ships you're talking about the biggest baddest and most efficient diesel engines in existence.

You're right, the biggest marine diesels are more efficient than equivalently sized steam turbines. I was misremembering some numbers, although that's a relatively recent phenomenon.
 
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Sat May 18, 2013 4:50 pm

Quoting Aesma (Reply 20):
Well that situation might reverse with shale gas having caused natural gas prices to crash, that is unless oil crashes soon due to shale oil.

It happens already. Latest issue of Trains Magazine there is an article about BNSF, owned wholly by Warren Buffets holding company started to convert their locomotive fleet from Diesel to LNG, cutting off about 50% of their fuel bill annually, which amounts to savings of 1 to 1,5 billion US$.
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Sat May 18, 2013 7:07 pm

Quoting rwessel (Reply 22):
You're right, the biggest marine diesels are more efficient than equivalently sized steam turbines. I was misremembering some numbers, although that's a relatively recent phenomenon.

Back when the SS United States was built, there were diesel ships, but they didn't have the power that a steam plant could produce. Diesels have grown in size and improved in efficiency.

Leaving nuclear-powered military vessels aside, the only remaining steamships being built for commercial service were LNG tankers because their fuel was "free" from boil-off. Why they chose steam until 2008 or so I don't know. I figured it was because you couldn't use LNG in a recip, but apparently that's not the case.
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Kiwirob
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RE: (LNG) Powered Ferries/Cruise Ships. The Way To Go?

Sat May 18, 2013 8:17 pm

Quoting DocLightning (Reply 24):
Back when the SS United States was built, there were diesel ships, but they didn't have the power that a steam plant could produce.

The Deutschland class cruisers used diesels, 40,000kw worth, highly innovative for the time and a portent for things to come.

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