LNG - The Way Ahead

The quest for green fuel has been the highest priority since the beginning of the 21st century. Its quite evident from the fact that various amendments for environmental protection, promotion of green shipping & introducing the concept of EEDI have surfaced. Shipping industry, which is considered the lifeline for global trading is becoming a threat to the world for its emission of various particles, NOx, SOx etc. 

Amid all these deliberations at various global levels of the shipping industry; engineers, naval architects & scientists have come up with advanced technologies to curb the demand and the environmental problems of the industry. One such technological advancement has been the introduction of LNG as a marine propulsion fuel.

Prior to the introduction of LNG fueled vessel market, it was primarily used as 'the boil off' gas on LNG carriers.It was utilized in marine boilers and duel fuel engines. The major purpose of LNG as fuel was to cut out the emissions. Results show that LNG is capable of reducing Carbon-dioxide emissions by 20%, NOx by 85-90%, and nearly a 100% reduction in SOx and particle emissions. 

Basically, a marine LNG engine is used as a dual fuel engine that uses natural gas and bunker fuel( Heavy Fuel Oil, Light Diesel Oil) to convert chemical energy to mechanical energy. This is because of the large tank space occupied by the LNG(density is less than air) and limited bunkering options. As a result only a very few small ships that to close to the shore run on complete LNG engine. Figure 1 shows the layout of a LNG propulsion plant.

Fig. 1: LNG Tank, Engine & propeller connections.
( Image Courtesy: DNV ) 

Cold LNG (liquid gas) is stored in the two insulated flasks (yellow tanks) forward of the engine room. This setup is then connected to the evaporator system which converts the liquid fuel into a low pressure warm gas and is supplied to the gas engine, which turns the propeller through a reduction gear. The engine also supplies the vessel's electrical load by means of a generator driven off the gearbox. 

However, the advantages of dual - fuelled engine have proved to be extremely effective, this includes:

• Operational flexibility.
• High efficiency.
• Low emissions.
• Operational cost advantages.

At present it may be a marine fuel and replace the heavy fuel oils. There is no problem to prepare the gas turbines and boilers (for steam turbines) for burning natural gas. It affects continuous combustion – this is an advantage for these engines. 

By reason of efficiency LNG as a marine fuel in diesel engines can be used as – two and four stroke. The propositions are dual fuel (DF) or three fuel (TF) engines. The engines may work on heavy fuel oils, if necessary on marine diesel oils (during manoeuvres or low loads) and of course on natural gas. In case the two stroke diesel engine works on natural gas it is needed to inject a pilot dose of liquid fuel (more often 1% of marine diesel oil) for the facilitation of self-ignition of the fuel-air mixture. The natural gas is injected to the cylinder under pressure about 25-35 MPa (it is a problem to use high pressure compressors). In the case the four stroke diesel engines the natural gas is passed to the air inlet channel under a pressure of about 0.5-0.6 MPa (more convenient pressure), and a pilot dose of MDO or HFO is needed too. The dual fuel engines are not sensitive to gas quality and the load.

LNG vs HFO

The price of LNG depends on the HFO price, but it is often cheaper. Taken into account the LHV(Lower Heating Value) of fuels and theirs prices, the cost of LNG is about 60% of HFO. On gas carriers the cost of boil-off gas is decreasing due to savings of re-liquefaction process. Natural gas prices (including LNG) has been reduced the last two years due to the introduction of shale gas in the US market. This is a reason that LNG has improved its competitiveness to HFO, especially on ECA (Emission Control Area) where it is needed to clean the exhaust gases. 

The cost of LNG storage and the much needed safety equipment increase its cost. On a long stay (due to the shipyard) the fuel tanks must be emptied because of fuel vaporization. On the other hand LNG is a very pure fuel. The operational costs of engines are decreasing. The engines are in the better technical condition and the number of emergency situations and failures is decreasing. This is money too! 

However, the methane emission for the LNG pathway is eight times higher compared to the HFO pathway and accounts for 20% of the total GHG emissions for LNG. This contribution is mainly from the combustion of LNG. This means that the performance of the engines plays a major part in the overall performance of LNG as a marine fuel since a small increase in the methane slip will increase the environmental footprint for LNG. As a curiosity it can be seen that if the methane slip from the LNG engine increases with only 12.2%, then HFO will be the most environmental friendly fuel in a life cycle perspective. 

In my opinion LNG will be competitive with HFO taking into account only the price during the next 20 years, later it will be still better. Taking into account all the other parameters the LNG competitiveness is better. Figure 2 shows the existing ECA and possible inclusions to the areas in the future. 

Fig. 2: ECA Zones around the world.
( Image Courtesy: NORUT)

If you take a deeper look into how much sulphur & Nitrogen (oxides) reduction the ECA's have achieved, you would definitely be astonished by the level of the stringent goals set to curb SOx & NOx emissions as per the IMO Tier III regulations.

Fig. 3: Sulphur emissions Vs. Years.
( Image Courtesy: Google Images)

LNG Supply & Pricing

Various estimates of annual consumption of fuel oil for marine fuel are reported. The IEA reports that bunker demand in 2010 was 235 million metric tonnes, comprising approximately 180 million tonnes of residual fuel based products and 55 million tonnes of distillate fuel products. This is equivalent to about 180 million metric tonnes of LNG - nearly 75% of worldwide LNG trade in 2012.

Worldwide LNG demand is projected to grow at more than 5% annually through 2020. Asia – Pacific LNG demand in 2012 represents nearly 70% of global demand and Potential projects that Asia –Pacific demand will continue to pace global demand. Supply must expand rapidly to meet worldwide demand and premium priced Asia Pacific demand in particular.

Fig. 4: Amount of LNG supplied Vs. Years
( Image Courtesy: DNV)

Fig. 5: Price of LNG supplied Vs. Years
( Image Courtesy: DNV)

Pros & Cons

Pros:

• No need to install further treatment for NOx.
• Potential CO2  reduction ( about 20% every journey).
• Much lower maintenance.
• Cheaper than HFO.
• Spills disappear when in contact with water.
• Meets Tier III & SECA requirements.
• Stored at atmospheric pressure.
• Finally, the most important of all more gas reserves than oil.

Cons: 

• Not much infrastructure development.
• Chances of methane slip.
• Skilled & trained crew required for to operate LNG as fuel.
• Few places to bunker making route scheduling less optimized.
• More space required for gas system on board.
• Safety aspects increase complexity of the supply chain, ship design & operation.

Conclusion

The use of LNG as ship fuel promises a lower emission level and, given the right circumstances, lower fuel costs. So even if there is an increase in the GHG's due to release of methane(very less though) for the sake of reduction of SOx & NOx emissions, the overall results & efficiency is a lot better and greener. Until we find any new or better mode of green propulsion, the use of LNG will definitely help us delay the apocalypse!LSD

Article By: Tanumoy Sinha

Recommended Readings: 

1. Costs and Benefits of LNG as Ship Fuel for Container Vessels

2. LNG AS MARINE FUEL - Frederick Adamchak, Amokeye Adede Poten & Partners

3. LNG - The Pros and Cons (Wartsila)

An Interview with Parks Stephenson

Parks Stephenson

He was the Project Manager and chief forensic analyst in the team of Naval Architects who investigated and analysed the Titanic wreckage. The results of the findings were featured in a National Geographic special, while he co-authored and illustrated the book, "Exploring The Deep: The Titanic Expeditions" with James Cameron.

Graduating in Naval Science from the United States Naval Academy, Parks has had a dynamic multidisciplinary career all along. Currently, he works as the Systems Engineering Manager at Moog Inc. 

In this interview with Learn Ship Design, we get a glimpse of the challenges faced in the expedition and similar marine forensic projects and the secret behind his success in multidisciplinary efforts.

It You were an integral part of the research outcome of Titanic’s so called Achilles Heel. In reference to that, how would you describe the structural problems Titanic had ?

I don’t find that the Olympic-class ships had any significant structural weaknesses.  When I first started studying Titanic, the fact that she broke apart during the sinking seemed to suggest that there might have been some sort of structural weakness somewhere.  But after years of study of both the Titanic and Britannic wreck sites, where we could, for the first time, look at the wrecks from an architectural perspective, we increasingly found evidence that the design of that class of ship was actually quite robust.  Britannic’s structure has not noticeably sagged despite her lying on her side (where the loads are different than the structure was originally designed to support) and the fact that Titanic’s mid section broke into large chunks (with decks still supported by large uptakes) demonstrate that the H&W engineers took measures to mitigate potential problems in their up-scaling of previous designs.  Added to this was Olympic’s maintenance record until her end of life…she required no more, and maybe even less, re-work to her structure than her peers in order to keep her in service.

Share with us one unforgettable moment that you came across, during the Titanic’s scientific expedition. 

My most memorable moments came during the discovery of the Marconi and Turkish Bath rooms.  I had done much research into those rooms beforehand and it was interesting to compare what I expected to what was found.  In the case of the Marconi Room, it was entirely unlike what we expected.  In the Turkish Bath, it was almost exactly what we expected. The lessons learned from this experience helped to shape my forensic analysis going forward.  Another single moment happened during my dive to the wreck.  Our submersible passed over the starboard fidley grate that Lightoller claimed to have been first pinned against, and subsequently expelled from, that grate.  Unseen in the 2D imagery, but obvious when seen with the naked eyeball, was that the grate in question is actually bulged out from some pressure originating from within the ship.  This was physical confirmation of Lightoller’s account, which was very exciting to see…the past had a physical connection to the present.

What according to you, are the fundamental barriers faced during any marine forensic project?

The main barrier is time and budget…there never seems to be enough of either.  A wreck’s exploration does not submit easily to someone’s planned budget or schedule.  In Titanic’s case, especially, another factor is the pre-conceived notions of an entire community of “experts” and enthusiasts, who will defend what they think they know of the story against any rebuttal, any evidence, against it.  Unfortunately, in a popular story like Titanic’s, there is also a lot of pseudo-science conducted in order to make headline-grabbing charges, like we saw recently with the “brittle steel” and “weak rivet” theories.  For example, actual scientists would demonstrate the fragility of a steel under freezing conditions without really understanding the historical context; in this case, not accounting for the fact that there was an operating boiler room, generating heat in excess of 100 degrees F, on the other side of the steel.

Your journey from being a Naval Officer to working on the aeronautical sphere, then as an analyst in marine investigation, authoring books and producing documentaries and movies. How has it been all through? What is the driving force behind the multi-disciplinary You, Parks?

I have a natural curiosity that drives me in more areas than just Titanic. I feel that mysteries can be solved if we can just look past the myths that grow around the events and see them from their most fundamental perspective. In order to distinguish myth from fact, though, one needs evidence, and in the case of Titanic, the wreck itself is our last and most definitive source for evidence. I am not interested in just Titanic, I want to understand what really happened in history so that we can learn, and react to, the correct lessons today.

Should students pursuing Naval Architecture be academically exposed to guided projects related to marine forensics? Do you think that would create a better understanding of the subject if universities took this initiative? 

Any forensic effort should of course include schooling in the basic disciplines to that effort.  But one should also be more rounded, so that one can “think out of the box.”  A naval architect, for instance, should strive to sail in the ships in which he/she builds (or similar).  But even that’s not enough.  If one is exploring a shipwreck, one must also understand the time period in which she sailed, understand the thought processes of the individuals who sailed in her…see the world of that time through their eyes.  Myth begins when people put their own perspectives, their own time prejudices, on a study of the past.  When a story becomes too pat – as is Titanic’s, in my opinion – then that is the time to question our understanding. To answer your question properly, though, I do believe that any education into a given forensic field should come with practical experience. It is not enough to just learn about the subject, one must also practice it before one can really become qualified.

Parks, Titanic II hopefully sails out in 2016. Will you take the first voyage? 

If a berth is offered to me, I will go. But I am somewhat ambivalent to the entire project.  There is no replicating Titanic, no matter how exact they capture the details of the original.  In my opinion, there are actually attempting a replica of Olympic.  Titanic is really nothing more than Olympic with a disaster added, and since they cannot offer a disaster as part of their cruise package, the ship can never be Titanic.  Besides, the new ship can never BE the old ship…we live in a different world than the one in 1912.  You will be sailing on a ship whose design is not suited for the modern commercial world, with modifications to try and make it competitive enough to stay economically viable.   As students of naval architecture, pay very close attention to any news you can gather about how the ship’s construction is progressing, and how often the design will change during the course of construction.  Ask yourself…what kind of ship will result?  Will she be a treasure, or a mongrel?

Highly Mechanised Weapon Handling Systems

The Queen Elizabeth Class aircraft carriers will be the biggest and most powerful surface warships ever constructed for the Royal Navy and will represent a step change in capability, enabling the delivery of increased strategic effect and influence around the world.

  

The Queen Elizabeth Class will be utilised by all three sectors of the UK Armed Forces and will provide eight acres of sovereign territory which can be deployed around the world. Both ships will be versatile enough to be used for operations ranging from supporting war efforts to providing humanitarian aid and disaster relief.

                                

Highly Mechanised Weapon Handling Systems

The HMWHS provides mechanical handling facilities for moving palletised munitions around the deep magazine and weapon preparation areas, and a series of weapons lifts to connect the magazines, hangar, weapons preparation area, and flight deck.

The components in question are 56 so-called 'moles', which do the lifting and carrying of the palletised munitions in the magazine. The HMWHS system consists of a network of two versions of these prime movers, which traverse forward and aft (longitudinal, version one) or port and starboard (athwartships, version two), each able to lift and move a payload to locations within its predefined area of travel. The moles can transfer payloads between each other, so the payloads can be located anywhere within the magazine.

The two mole versions are different shapes to enable lifting and lowering of the palletised munitions in the correct orientation, onto the set stowage and transfer positions, and are equipped with electric traverse and lift drives, allowing accurate positional control within the magazine. A number of lifts provide interconnection between the magazines and the hangar, weapons preparation area, and flight deck, and a unique mechanism enables the mole to access the lift platform without needing to disengage and re-engage the pinion from the rack. The magazines are unmanned, with all the moles controlled from a central location, so personnel are required only where munitions are being prepared for storage or use.

A significant challenge in manufacturing the moles has been the achievement of the tight tolerances introduced following completion of the demonstration phase, to speed up assembly.Factory acceptance testing took place at Babcock's site at Whetstone, Leicester, and included dimensional and functional tests and inspections of the parts and mole drive and lifting systems.                                        

The moles have now been delivered to the Aircraft Carrier Alliance's central warehouse, ready for installation once the fixed rail equipment and lifts have been installed. As the moles are fully reassembled, installation will involve placing them in the magazine and electrically connecting them to the rest of the system via an energy chain system. "The moles are a critical component of the HMWHS and successfully completing FATs for all moles marks an important milestone in delivery of the system." 

Babcock Integrated Technology director Matt Hatson comments. "The HMWHS is the first maritime application of shore-based commercial warehousing processes using automated systems with all-electric control, adapted for safe transport and stowage of munitions in a warship environment. Munitions can be delivered, in bulk, to the point of use at rates that could not be achieved manually, whilst minimising the manpower requirement in what is traditionally a labour-intensive process, thus delivering reduced through-life cost, as well as a saving in onboard living accommodation requirements." Production of the final software solution for the HMWHS integrated control system, and manufacture of the various mechanical, electrical, hydraulic and pneumatic sub-systems making up the HMWHS are now underway, of which successful completion of FATs for all moles is part.

The final equipment for the full HMWHS for the first carrier was be delivered by May 2013, and for both vessels by February 2015.Babcock has also been active in working with the shipyards to support the design integration and build strategies. A joint installation strategy has been developed using Babcock's system knowledge and ship build experience, to maximise installation and testing opportunities. Babcock will maintain responsibility for overall installation and quality of work, as well as performing the testing required to demonstrate the system meets ACA requirements. The system in-service support package is being developed with the MoD and Royal Navy.

QE Class Aircraft Carrier Details and Specifications

• Country/Owner/Operator: UK        
• Builders: BAE Systems Surface Ships, Thales Group, Babcock Marine (see below for more details).           
• Cost to Build: £3,5 billion (US$5,520 billion), which is exactly £7 billion for the two carriers of the QE Class by the 2008 contract.           
• Year of service: The end of 2017, fully operational by the end of 2020 (with HMS Prince Of Wales 2  years behind). On HMS QE sea trials to begin 2017, flight trials – 2018.      
• Expected service life of up to 50 years.         
• Homeport: (Her Majesty’s Naval Base) HMNB Portsmouth, one of three UK operating bases for the Royal Navy (along with HMNB Clyde and HMNB Devonport).       
• Capacity/Crew: 1450 (1600 company+aircrew), complement 686+, max 40 aircraft (which is double the existing UK carriers capacity).       
• Length Overall: 932 ft (284 m).       
• Width/Beam: Overall/flight deck 239,4 ft (73 m), waterline 128 ft (39 m).            
• Height: 184 ft (56 m) overall/from keel to masthead.                     
• Weight and Displacement: 65,600 tonnes (64,600 long t) at deep/full load. This is about 3 times the size of the Royal Navy’s current aircraft carriers of the Invincible class. For the construction of the two UK future aircraft carries a total of 80,000 t. of steel is used.
• Top Speed: 25 kn (29 mph or 46 km/h).
• Range: Up to 10,000 nautical miles (19,000 km).

Watch the videos shared in the Recommended Visuals section below for a visual tour of the HMS Queen Elizabeth. LSD

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Article By: Siddhi Indulkar

Recommended Visuals: 1) Video tour of HMS Queen Elizabeth.

                                            2) Time lapse of HMS Queen Elizabeth.

Slow Steaming Strategy

Slow steaming has earned its place as a very commonly used term in the current shipping industry. It is a strategy that shipping companies have on the top of their priority list, and it affects the entire industry, right from the cargo owners to the global supply chain. 

Looking Back

Something happened in the year 2008, that made the entire world think again. Being the major industry that drives the world economy, shipping was supposed to be the pioneer in the thinking process. There was a heavy downturn in the global economy that resulted in reduction in the demand of transportation capacity. Freight rates fell. The worse was still to come. In the years prior to 2008, there was a shipping boom. Order books were full and new ships were on the production line. By the time the record-high deliveries were made, recession hit the industry and new ships were rendered useless. Projects still under development were cancelled. Number of ships sailing the oceans considerably reduced. Idle ships were not the only trouble. There was more. 

The global financial crisis triggered the rise in fuel costs. Higher fuel costs in the time of crisis means diminishing profits and soaring losses for the shipping companies. Operation costs shot up. In short, world trade languished.

The Idea

The major issue that hit the shipping companies was high fuel costs. The only way to tackle the issue was to reduce the consumption of fuel in ships. For that, engines would have to be run on power ranges below their normal operating range. As a result, the speed at which the ships had to sail, were to come down by a few knots. 

You can look at it from the other perspective too. In ships, the power consumed is proportional to the cube of velocity of the ship. So a minute change in a ship's speed can affect the power and fuel consumption to a large extent. (See Figure 1)

Fig. 1: Correlation between ship speed, required engine power and fuel consumption
(Image Courtesy: Wartsila Technical Journal, 2010)

Maersk Line, the world's leading container shipping company used this property of ships to survive through the recession. They reduced their speeds from 27 to 22 knots, that is,  a 19% reduction in speed. That reduced the hourly main engine fuel consumption to 58%. In some cases, further reduction of speeds to 18 knots reduced the fuel oil consumption to 75%. Engines were operating at about 40% of their rated capacities, fuel costs were saved, and Slow Steaming Strategy was born. 

The Domino Effect

The strategy triggered a chain of other factors as soon as it was adopted by Maersk Line. One ton reduction in fuel consumption reduced the carbon dioxide emissions by three tons. Consumption of engine cylinder oil was also reduced nearly by the same percentage, which reduced solid particle emissions. 

But the pioneers had to convince two different sectors which were an integral part of shipping. One, the engine manufacturers, who believed that their engines were not designed to operate efficiently at only 40% of load capacity. Two, their customers, for whom the time of delivery was about to be affected due to slow steaming. 

In 2008, Maersk approached engine manufacturers MAN Diesel and Wartsila to research the effects of engine operations below their design load level (MCR). In late 2008 and early 2009, both the companies published letters of No Objection for low load operations. However, it required extensive maintenance and inspection of machineries onboard.

The other issue with slow steaming was longer time of deliveries, which customers felt, would slacken the global supply chain. Maersk convinced the customers that slow steaming would delay the deliveries, but it would provide more guarantee for safe delivery of goods. This was also offset by another issue. If you remember, due to the recession, more ships remained idle than those which sailed. This was a perfect chance for ship owners to increase their fleet. More ships, low speed, guaranteed safety of goods. And they made a revolutionary strategy out of the global recession. 

Expressed Concerns

Propeller and Engine Efficiency

Marine propellers are designed for an optimum RPM for maximum propulsion efficiency. Slow steaming when incorporated in existing ships, would reduce the RPM levels, therefore decreasing the efficiency of the propeller. Thus it is natural that when the entire main engine and propulsion system is operating at low load levels, the overall system is no longer an optimised one. So the marine engineers and engine builders were initially reluctant to embrace the concept. However, when Wartsila investigated into the matter, what they reported, pushed slow steaming strategy even further. In their reports, they published that their engines could efficiently operate even at low loads up to 10% MCR. It was also discovered that the loss in propeller efficiency was actually offset by the cost savings due to reduced levels of fuel consumption. Some ships also got their propellers replaced to sync with the low load levels. Wartsila and MAN Diesel upgraded their engines to specially designed slow steaming kits. Ships in which, replacements were not done, the engines were to be kept efficient with rigorous maintenance of the main engine and machineries like turbochargers, boilers and blower systems. 

Poor Combustion

Due to low load operation, combustion of fuel in the cylinders is insufficient, resulting in poor atomisation and deposition of soot layer within the cylinder. Regular maintenance is required. Marine engineers are required to clean the cylinder linings before the engines are again fired to full load.

Cold Corrosion 

During slow steaming operation, the engine temperatures are generally lower than what it is designed for optimum performance. As a result, corrosive vapours condense, corroding the interiors. Again, maintenance is the key.

Minor Concerns

Other than the major factors which require regular maintenance for efficient performance, there are few which might affect the performance due to slow steaming practices. In low load operating conditions, the propeller is subjected to low RPM, which increases the probability of propeller blade fouling. Hull fouling probabilities also increase, which require periodic underwater surveys and cleaning. 

Solutions and Acceptance of the Strategy

Inspite of a few issues that popped up during the development of this strategy, it proved to be an overall economic boon to the industry, going by the fuel cost savings. Carbon dioxide emission levels came down, ships that were idle joined the fleet and brought in more revenue even in the years of recession thanks to slow steaming strategy. World's leading manufacturers Wartsila and MAN Diesel joined the initiative and upgraded their engines with special kits designed for slow steaming. Following the success of Maersk Line due to this concept, other shipping companies have adopted the same strategy for efficient shipping. Initially tried on only container ships, now the strategy is being successfully applied to bulkers. That is quite an evidence of the fact that the domino effect is still on.LSD

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Article By: Soumya Chakraborty

Recommended Readings: 

1) Marine Engineer's experience in slow steaming operations.

2) Slow Steaming - A viable option? (By Wartsila)

3) Slow Steaming practices in the global shipping industry. (By MAN Diesel)