“If the LNG terminal offshore Tuscany explodes, the Leaning Tower of Pisa will fall over”

This was stated by an Italian professor in the local newspaper during the approval phase of the now operational LNG terminal offshore the coast of Tuscany. To me it’s just another example that neither a PhD nor a Professor title is proof of a capability of rational thought. The fact is that an explosion of such magnitude is impossible. But let’s not get ahead of ourselves, let’s start with the basics.

The main safety aspects of LNG can be divided into two main topics:

• Cryogenic effects from LNG
• Flammability and explosion, including BLEVE and RPT

A spill of LNG might occur. A tank may rupture due to external impact. A flange may leak. A pipe may break. In such events, the initial consequence will be cryogenic effects from being exposed to a liquid at -163 degrees Celsius. Humans will freeze and steel will go brittle. Brittle steel may easily break and lead to secondary failures of other equipment.

Once the LNG has leaked, it will form a pool of liquid LNG. This pool will start to evaporate and form a cloud of gas, primarily consisting of methane. This gas will start mixing with air and once it reaches a mixture with between 5 and 15% gas, it is ignitable. The following sequence of events will depend on whether there is an ignition source, and whether the gas cloud is contained within a confined space.

Ignition source? Yes or no?

• No: The gas will continue to evaporate, disperse at ground level while cold, but start to warm and rise to the sky as methane is lighter than air, and thereafter drift away until the entire liquid pool is gone. Nothing will be left.
• Yes: The gas cloud will ignite.

If yes to above – Confined space? Yes or no?

• No: There will be an initial poof, not very violent, as the gas cloud ignites, and it will burn back to the pool as a flash fire. The gas will continue to burn as it evaporates off the LNG as a pool fire until the pool is gone.
• Yes: There will be an explosion causing overpressure and drag loads and potential damage on structures and buildings

Worst case scenarios for LNG accidents, such as the one described by the professor above, typically calculate an explosive release of all the energy in the cargo. This means that all of the 130 000 m3 of LNG stored in the terminal would have to leak, then evaporate to turn into 78 million m3 of gas, then mix with air to turn into 780 million m3 of ignitable gas/air mix (assuming 10% gas). If those 780 million m3 could be contained inside a confined space, then you would have a pretty potent bomb.

A balloon with sufficient resistance and a diameter slightly larger than 900 meter could make such a confined space. And of course you’d have to wait until all volumes are put into the balloon before igniting it. Needless to say, this is not a credible scenario. Another unlikely scenario is that all the gas evaporates and floats at ground level and avoids all ignition sources until a perfect moment when the whole gas cloud is within the 5-15% mix with air, and then ignites.

Most likely, the event causing the leak will also ignite the gas, causing only a low pressure flash fire and then there will be a continuous fire as evaporated gas burns off the liquid pool. This will be a catastrophic fire, similar to fires of any other fuel, but it will not cause explosive overpressures.

BLEVE is a phenomenon that can happen when a pressurised liquid gas tank is subjected to a sustained external heat source such as a neighbouring fire degrading the structural integrity of the tank. The degradation of the integrity can lead to a sudden rupture of the tank, and in the event of such a rupture the boiling liquid simultaneously expands and ignites causing a powerful explosion and thermal dose. BLEVE can only occur with pressurized tanks, it can’t happen to tanks with atmospheric pressure which is what is used for all large scale LNG terminals and ships.

RPT is a phenomenon that may occur when LNG is released onto water. The water will cause quick heat transfer into the LNG making it a superheated liquid. Once evaporations starts the LNG will evaporate instantly and cause a pressure pulse. RPT is a flameless explosion that can be compared with the cracking noises (small explosions) when heating cooking oil with small amounts of water inside. Significant damages caused by the phenomenon are not expected and have not been observed.

In addition to the main safety topics above, there are a few other special phenomenon of more operational interest:

• Roll-over may occur in tanks where the LNG is stratified, leading to a build-up of pressure in the lower layers which can eventually release causing sudden vaporization (boil-off). Normal procedure now ensures regular mixing to prevent stratification.
• Sloshing is the effect of waves inside LNG tanks on ships. The consequence of this may be damage to the tanks and potential leaks of LNG.

Yes, natural gas burns. And this is good news, because this is why it can serve as a fuel. Also, under certain circumstances, natural gas can cause explosive over-pressures  This is why any equipment utilized for gas and LNG must be designed in ways where the likelihood of events with high consequences are minimized. As an example, pressurized gas tanks must be located in places where external impacts are unlikely, or they must be shielded from such impacts. Another example is arrangement of equipment so that potential jet fires will not directly hit critical equipment.

In order to ensure safe design, risk management is an integrated part of the design process. To be more concrete, this is a process that follows certain defined steps: hazard identification – risk analysis – risk evaluation – risk treatment. This is a quantified process, so that it can ensure that the safety of the object is within whatever acceptance criteria that apply.

The risk analysis part of the risk management process can take many shapes and forms. It depends on what sort of risk needs to be analysed. There are various computer tools available for this analysis, for example tools for analysing the dispersion of gas clouds and the severity of fires and explosions. For a wide range of LNG leak cases, relatively simple tools can be applied, but for more complex geometries, then CFD (Computational Fluid Dynamics) models are needed.

With a proper risk management approach in both design and operation, gas and LNG are equally safe, or even safer than other fuels.

Should you wish to dive deeper into LNG safety, I can recommend a book by my colleague, Robin Pitblado: LNG Risk Based Safety.

In a conference in Singapore recently, BW Offshore presented their thoughts on gas fired power production for the future. The logic is quite simple; emerging countries will need loads of electricity in the years ahead, and in South East Asia as an example, as much as 40% is expected to be developed as small to medium scale plants (50-500 MW).

In all these locations, getting access to necessary land areas is going to be one of the challenges. Jetties, LNG storage tanks, re-gasification terminals, and power plants are all facilities that require a lot of space. BW Offshore’s solution practically moves everything to sea, and just sends a cable to shore. The solution offers quick deployment, minimal impact on land and environment, flexibility in use of the asset, and presumably good economics.

The unit would have LNG transfer arrangement to get cargoes of LNG from LNG carriers, it would have LNG storage tanks, it would have a re-gasification unit, and it would have a combined cycle gas turbine power plant. That is a hefty amount of equipment on board a ship, and detailed design has not yet been done, but there is no reason to believe this should be too difficult.

The unit could also serve double purposes, and both produce electricity and supply break bulk LNG to small scale consumers near-by. A true hub for LNG distribution and consumption.

The LNG value chain will continue to evolve over the coming years, and the FPPU is a welcome addition to the industry.

Bend it like BW Offshore – Photo courtesy of BW Offshore

1. A step-by-step description of LNG bunkering: LNG bunkering was a big story of 2012, and it will remain in focus for 2013. In this post, I presented a video describing how bunkering of LNG is being done for a fleet of ships in Norway.
2. LNG for small scale electricity generation: We presented a study of the challenges, environmental effects, and economic benefits of using LNG for small scale electricity generation, including a case study for Indonesia. While a much talked about topic, especially throughout Asia, in 2012, I think we will see significant projects moving forward in 2013.
3. Which marine fuel do you want to be cheapest: The most frequent question I faced in 2012 was “what will be the price of LNG?”. In this blog post I presented my answer: “I don’t have a clue, and nobody else has a clue either”.
4. LNG – All eyes on China: The engine of demand growth for LNG in 2012 has been China, and this is expected to continue. In this blog post I gathered some information from my mandarin-speaking colleagues to provide a status update on LNG in China.
5. LNG is the first step towards carbon neutral shipping: In 2012, I think we have seen that the world is about to take climate change more seriously. In this text, I justify that LNG fuel is the right move for the shipping industry even if natural gas is not carbon neutral. The logic is simple, the infrastructure opens for fuel cell technology and liquefied biogas. Let the future be carbon neutral.

With the best wishes for a merry Christmas and a happy new year! I hope to see you back here in 2013.

Delay causes at LNG terminals

1. Political delays: As in all other aspects of life, politicians are unpredictable also in the LNG industry. We see plenty examples where Authorities change their minds on locations, framework, partners, and all sorts of rather key parameters for an investment decision in an LNG project.
2. Unclear interfaces: When there are problems in the execution of a project, you can be pretty sure it is related to an interface between two or more contractors. It is almost impossible on beforehand to make the limits of each contract to exactly match each other, so close follow-up is necessary. It’s a bit like building a tunnel: When you start from both ends, you better make sure you meet in the middle.
3. Insufficient management and follow-up: The job doesn’t end when the contractor agreement is signed; it starts. Solving conflicts and problems as they arise is one thing, having foresight enough to minimize the amount of conflicts and problems is another.
4. Problems with new technology: When applying something new, there is always something that works slightly different than expected. And this may have unforeseen knock-on effects on other parts of the design.
5. Deliverables outside spec: In the quest for saving money, some may seek short-cuts reducing the quality of the sub-deliveries. This occurs on components and services all the way back up the supply chain; bad steel quality being one frequent example.
6. Design faults. Even engineers make mistakes. Typically this type of fault will also occur in an interface, where the work of two designers meet.

Luckily there are many experienced and knowledgeable people out there who are capable of delivering on these most challenging jobs, and there are several tools for managing, monitoring, and mitigating, to increase the probability of success.

The same motivation has been the underlying driving factor for the development of MARPOL Annex 6, concerning emissions to air from ships: specifically, one main focus is on reducing the emissions of SOx and NOx, and LNG has been developed as one option for compliance with these new requirements.

More recently, the focus has been swinging towards global emissions, also for the shipping industry. As it should in a world with increasing concerns about climate change. From a regulatory perspective, the only concrete things that have developed are the EEDI and SEEMP schemes, but they both concern themselves with energy efficiency, not with a fundamental change of how the industry propel their ships. Admittedly, the shipping industry displays vast opportunities for efficiency improvements, but this is not enough to meet future global emissions targets. The industry needs to take a more aggressive approach.

Unlike most other industries, though, the shipping industry has no carbon neutral alternatives even worth discussing. For land based power production, you can at least spend your time discussing wind, solar, biomass, and nuclear. For land based transportation you may discuss electric drivetrains, which potentially may become clean if the source of electricity is clean. But for shipping, these alternatives dont apply. If you were to go electric, you would have to fill the entire cargo area with batteries. If you were to go for bio based solutions, you would have to vacuum the world for organic material. A ship doesnt have enough surface area for solar to make sense, and it doesnt have enough stability to carry wind turbines on deck. Sails? sure, if we want to go back to accepting half year voyages at 8 knots in whatever direction the wind is blowing.

The best option shipping has for contributing to global emissions reductions, is to switch to natural gas. This will cut about 25% of CO2-equivalent emissions. This reduction, however, has recently been disputed from two angles; the methane slip in internal combustion engines, i.e. methane slipping unburnt through the engine, and the methane leakages along the natural gas value chain. The first has already been optimized by the engine suppliers to where it can be considered a minor issue. But the latter is much more difficult to quantify, as it depends largely on the source of natural gas and its production methods. Several studies indicate that there is still clear advantage for natural gas, but the message is clear: Switching to natural gas will not contribute much to reducing global emissions. At least not directly.

Natural gas is primarily methane, and methane is a potential gas for use in fuel cells. So once you already have methane onboard ships, this opens the door for more widespread testing and development of large scale fuel cells. The LNG fuelled offshore supply vessel Viking Lady has already supplied part of its auxiliary power demand with a fuel cell. As the fleet of LNG fuelled ships grows every one of them will become a potential customer for fuel cell suppliers, and hopefully this will speed up development. From a climate perspective, this will mean a 50% reduction in CO2 emissions.

Further, a key benefit of fuel cells is that they can run on various gases. And in the future we may have access to carbon neutral gases. Hydrogen from artificial leafs, or from algae feedstock, are examples of solutions being explored, and if that doesnt work out we can easily generate carbon neutral hydrogen from nuclear reactors.

In other words, by implementing LNG fuelled ships today, we effectively open the road towards carbon neutral shipping. It is the right thing to do. And there are no other plausible alternatives based on presently known and expected technologies.

Glutra - the first LNG fuelled ship in the world

Last week, I attended a LNG forum in Hong Kong, which was chaired by above mentioned Mr Regan. The forum was introduced by Mr Regan stating that the LNG industry is moving from an era of evolution into an era of revolution. It may have been something of a half joke, but the statement was nicely substantiated throughout the forum discussions:
- More spot trade: The volume of LNG changing hands on short term contracts keeps increasing. This will have an impact on LNG price formation, LNG shipping terms and rates, terms&conditions for sales and purchase agreements, and more. The uncertainty appears to be how much of an impact? and how soon?
- New sources of export: Shale gas, CBM, arctic. How much? how fast? And what will the impact be on availability and price of LNG?
- Floating: It has been researched for several decades, in fact for almost half a century, but finally we seem to see the beginning of an era of floating LNG production. Indications are it will be cheaper. Ten years from now, will floating solutions be the default?
- Downstream applications. We are quite familiar with it, here at this blog, so this time I will spare you details. Suffice to say, LNG will become a major fuel for trucks and ships!

That was last week, this week is World Gas Conference in Kuala Lumpur. I will make sure to report from the event towards the end of the week. In the meantime, the hashtag #WGC2012 on Twitter should provide the most interesting updates.

Just had the share a photo of the phenomenal venue for the World Gas Conference: Petronas Twin Towers. ]]> http://blogs.dnv.com/lng/2012/06/the-lng-revolution/feed/ 0 http://blogs.dnv.com/lng/2012/05/growing-confidence-in-lng-as-a-future-marine-fuel/ http://blogs.dnv.com/lng/2012/05/growing-confidence-in-lng-as-a-future-marine-fuel/#comments Fri, 04 May 2012 06:00:13 +0000 Lars Petter Blikom http://blogs.dnv.com/lng/?p=1209 Continue reading →]]> As part of a project to define the future design of container feeder ships for operation in the Baltic Sea, some of my colleagues have done a survey. They posed a set of questions to a range of ship operators in the Baltic Sea area, and some of the results are quite interesting from a LNG perspective. Other results may serve as weekend entertainment.

Some of the top ranking priorities are quite obvious. It would be strange if “operating costs” and “fuel efficiency” didn’t score rather high in a survey like this. Even in the shipping industry, which lives by its own set of economic indicators, this would be strange indeed.

If you are a reader from a different industry you may notice that not all items brought forward appear very futuristic, e.g. “optimal fuel consumption over wide speed range” may sound obvious, but actually most ships are optimised for easy construction, which gives a quite different output.

Not a popular finding among sailors I would guess, but “crew comfort” is among the lowest priorities. Perhaps this indicates that crew comfort is already at luxury level?

Next, the survey asks the ship operators what future solution they will be more willing to consider. Here it is very encouraging to see the high score for dual fuel engines. Actually, it is a bit surprising; I thought the operators were more sceptics. The study also indicates that they are much more comfortable with “dual fuel” than “pure LNG”. I guess the option to switch back to “normal” makes it easier to dive into the novel solutions. It will be interesting to see how this develops in later surveys when LNG has become more of a business as usual solution.

Container ships don’t want pods. We hear you, dear shipowners.

And we conclude with a small contribution to the frustrating task of forecasting future fuel sources: The respondents are quite confident that “LNG will become an important or dominant fuel type for the Baltic trade”. It is good to see that we here at DNV are in tune with our customers.

More information and analysis from the survey will be published next week. I’ll be sure to keep you posted.

Enjoy the weekend!

Natural gas is primarily methane, with small portions of heavier gases. Methane is a hydrocarbon gas with formula CH4, i.e. it is one carbon atom and 4 hydrogen atoms in the molecule. This formula is important to remember when we get to the environmental comparison to other hydrocarbons. Some properties of methane (ref Wolfram Alpha):

• Molecular weight: 16.0425 g/mol
• Density: 6.67151*10^-4 g/cm3
• Boiling point: -161,48 degrees celsius
• Vapor density: 0.55 relative to air

Since what we need the natural gas for is to produce energy, we are particularly interested in the heat of combustion values (ref Wikipedia):

• Specific heat of combustion for natural gas 54 kJ/g
• Specific heat of combustion for gasoline 47 kJ/g
• Specific heat of combustion for diesel 45 kJ/g

So, clearly natural gas offers more energy per mass than the other common fuels.

Back to the molecule. The basic hydrocarbon molecules are chains of carbon atoms connected together, and hydrogen atoms connected to the free spots along the chain. Then, by simple math, we see that with only one carbon atom in the chain you get the best ratio of hydrogen atoms per carbon atoms in the molecule. This translates directly into less CO2 produced in the combustion, simply because there are fewer carbon atoms available.

The emission reductions compared to oil products will broadly speaking be as follows, but this is dependent not only on basic chemical properties, but also on engine technology, combustion characteristics, etc:

• NOx: 85% reduction
• SOx: ~100% reduction
• Particles: ~100% reduction
• CO2: 15-20% reduction

So what has LNG got to do with this? LNG is just a transportation mode, it is not a separate source of energy, it is simply natural gas made liquid for transportation phase, It is regasified before it is used. The reason why it is made liquid is that methane requires 600 times more volume in gas phase than in liquid phase. Hence it is much more efficient to transport it in liquid phase.

In order to get the methane into liquid phase it needs to be cooled down below its boiling temperature of -161 degrees celsius. The LNG is transported at this temperature and at atmospheric pressure. This means the liquid methane is continously boiling during the transportation, and as long as the vaporized gas is released from the tank the pressure will not increase. This is just like boiling water at 100 degrees celsius; the temperature will not increase above 100 degrees, but there will be less and less water left in the pan.

Finally, we better touch upon the safety related properties of LNG. It is important to understand that LNG can not explode or burn. LNG first needs to evaporate and mix with air in gas phase. So if there is a leak and the vapour cloud mixes with air it will form an ignitable cloud when the mix contains between 5 and 15 % methane. Below 5% mix will not be enough too ignite, and above 15% will too much to ignite. Also, in order to get an explosion, instead of just a fire, the vapour cloud needs to be contained in an enclosed area.

There is much more details to discuss on each of the topics above, but this post was intended to be a quick intro, so I think we stop here.

An LNG carrier transports LNG at -161 degrees celsius and atmospheric pressure. The boil-off gas is either used in the ships engines or re-liquefied and sent back to the tanks.

First of all, LNG fuelled ships have been promoted and developed primarily for their indisputable positive impact on local emissions: Compared to oil based fuels, there are practically no emissions from LNG fuelled ships. It has also been stated that on top of this, there is a CO2 advantage, as the emissions from the combustion process are less. This comes from the simple fact that of all the fossil fuels, methane has the smallest amount of carbon atoms compared to hydrogen atoms in the molecules. So by chemical composition there is less carbon per content of energy, hence less CO2 is produced.

The journalists though seem to enjoy spinning up a story that LNG is not doing anything for the climate, perhaps even having a negative impact. And they seem to base their logic on two aspects:

1. Emissions of uncombusted methane from the engines
2. Emissions of CO2 through the value chain from well to engine

On both aspects, the journalists draw false conclusions:

1. For emissions of uncombusted methane they base their data on the first LNG fuelled marine engines ever installed, they miss the point that these engines are no longer in the product line of the suppliers. The new engines currently being promoted by the manufacturers and installed in new ships greatly reduce the discussed methane slip. We already discussed this in an earlier blog post when the topic was raised by a Norwegian industry magazine, Teknisk Ukeblad.
2. For lifecycle emissions from well to engine, there is no basis for shredding doubt of the performance of LNG. We are aware of two scientific studies addressing this issue, one performed by Chalmers University in Sweden, the other by TNO in the Netherlands. Both studies conclude that emissions from well to engine, i.e. excluding the combustion itself, are similar for oil and natural gas products, with a slight advantage for LNG. This means that the 20-25% reduction the engine suppliers are claiming for the combustion is not cancelled out by emissions elsewhere in the value chain.

It is worrying to observe that there is an increasing scepticism towards a measure that clearly has huge positive effects on local air quality because people uncritically buy into eachothers false perceptions.

It is even more worrying to see that these false perceptions are bought into by industry people and not only journalists. An example of this was last week’s blog post by Lloyds Register where Nick Brown states “there may in fact be legitimate concerns that LNG does not reduce CO2 emissions on a like-for-like basis with other fossil fuels“. I would really like to know what the basis for the legitimacy is… hopefully not only information from newspapers?

LNG will not save the world, but it is a contribution in the right direction

Offshore Supply Vessel "Viking Queen". Courtesy of Eidesvik

It’s always good for an office rat to get out of the office and take a closer look at some real equipment. So I appreciated very much my opportunity last week to visit the Viking Queen and learn about the technical choices and the experiences with this quite unusual ship.

First, some background: The Viking Queen is a 6000 ton supply vessel delivered to the shipowner Eidesvik in 2007. The ship’s purpose in life is to supply goods to offshore installations in the North Sea. It is unusual in at least two aspects: It has its accommodation area aft, and it is powered by LNG.

The first impression I have from the visit, is that the ship and its crew disproves the typical myth that LNG adds a lot of complexity to ship systems and associated operations. The picture series below starts at the bunkering station on deck where LNG is received through flexible cryogenic hoses from the quay. There are no requirements to double wall piping above deck, but inside the ship the piping needs to be routed inside bigger steel pipes. The fuel tank is a type C tank, which is inherently safe, and it is located in an area onboard where collisions will not harm it. From the tank, the LNG enters the cold box, which contains the pressure build up unit (PBU) which re-gasifies the LNG. As the fuel piping enters the engine room, the double wall piping requirement is substituted by a gas detection and ESD system, making the routing of pipes much simpler. The gas is routed through a few filters, and then into the engine combustion chambers. No pumps are involved, and no fuel treatment is necessary.

The second impression is related to the spirit of the crew. Clearly they are proud of their ship. A consequence of this of course is that everything is clean and tidy. No clutter around. And the crew are genuinely interested in the engines, systems, and equipment, making them much more likely to understand what is going on than an average crew. This is something I also observe with a slight touch of concern: There are no international or national legislation for training or skills of crew specifically related to LNG. Eidesvik has approached this by developing their own set of operational procedures and training requirements for their crew. Which is all good. But my concern is that not every ship operator in the world would be as proactive as Eidesvik in this respect.

A common question I get when speaking about LNG fuelled ships is “what about maintenance? Is it less maintenance with them?” I still don’t have any statistics to put forward on this topic, but on a qualitative basis, the feedback from Eidesvik was very positive:

• The engine and the systems themselves are very clean, reducing the need for cleaning before doing maintenance activities.
• There is less particles and corrosive components in the system, leading to reduced need for preventive maintenance. They have no increased maintenance intervals on certain components, and there is room for more of this.
• Eidesvik reported no LNG-related downtime on of their ships.

As stated by the chief onboard, “The Viking Queen is a better ship”. I would like to extend a thanks to Eidesvik, both their management, and particularly the crew onboard for openly sharing their experiences. And with LNG fuelled ships in operation since 2003, who would have more experience to share than Eidesvik?

The bunkering station on deck. A flexible hose from shore is connected to onboard flanges.

The LNG tank with isolated walls to minimize heat ingress from possible fires in neighbouring areas

Piping exits the double wall tube as it enters the engine room. The engine room is ESD protected so there is no need for double wall piping inside the engine room