Are We Prepared?
18th February 2013 03:23 GMT

LNG has come to be a buzzword on the lips of many players in the industry today, with announcements for LNG terminals and LNG-fuelled newbuild designs popping up almost every day in the news over the past year or so.

According to a recently-released Lloyd’s Register study that projected the outlook for LNG bunker and LNG-fuelled newbuild demand up to 2025, 653 newbuilds (4.2% of all global newbuilds forecast to be delivered between 2012-2025) are expected to adopt LNG-fuelled engines over the next thirteen years on deep sea routes in a base case scenario that took into account current ECAs and a 0.5% global sulphur limit in bunker fuel implemented from 2020.

The propensity for newbuilds to be LNG-fuelled designs from 2020-2025 rose by 75% when the forecast LNG bunker prices were decreased by 25% in a high case scenario, whereas projected demand was zero in a low case scenario where forecast LNG bunker prices were increased by 25% and the implementation of the global sulphur limits shifted to 2023.

While LNG as a bunker fuel certainly looks to be an increasingly viable and attractive alternative to residual fuel oil in the face of tightening sulphur legislation and rising fuel costs, the infrastructure currently in place to support widespread adoption of this fuel is still in its infancy and would benefit greatly from further development. Keeping that in mind, there are a few things we should consider and prepare for before we embrace and adopt LNG as a long-term solution.

There are more than two sides to the density coin.

Though LNG looks to possess excellent energy density by weight on paper at approximately 55 MJ/kg, its actual volumetric density of around 0.4 – 0.5 kg/m3 tells an entirely different story altogether.

Not only does LNG’s low density bring its overall energy density to roughly half that of residual fuel oil or gas oil, it also implies that more space will need to be allocated for its storage. Factor in the need for LNG to be contained in special tanks, and this overall requirement goes up to as much as four times the space required for RFO or GO for the same amount of energy.

Additionally, constraints placed on tank size and locations within the overall ship envelope make the task of designing a LNG-fuelled newbuild even more of an uphill challenge than it already is compared to that for RFO/GO-fuelled ships, and this is even taking into account the new requirements in MARPOL Annex I, which stipulate that oil fuel tanks can no longer be formed by any part of the ship’s outer hull plating.

Another caveat to consider in world-wide trading would be the need to carry additional margins of product in light of the fact that LNG bunker supply will not be as readily available compared with RFO/GO, which can be obtained virtually anywhere, albeit not necessarily at the best prices.

While allowances can be made to accommodate this requirement at the design stage for ships meant to go on specific routes, it could potentially make any redeployment over the course of the ship’s life considerably more complicated.

How, then, does the energy density of LNG ultimately impact the ship owner? In the case of many vessels, this could mean the sacrifice of some cargo space in order for the ship to have the capacity for sufficient fuel for a ship’s journey, more if a dual fuel approach is taken.

Safety, Handling & Training.

As LNG is a flammable cryogenic hydrocarbon liquid that is not in its natural gaseous state, containment tanks will need to be maintained at a constant temperature of -163ºC. Following cargo type practice, the tank will need to be cooled by running LNG into it in a highly controlled manner, and then taking the resulting vapourised gas off until the required temperature has been reached. The tank temperature is then maintained by leaving a heel of gas in the tank, which is then recirculated and sprayed back into the resulting vapour space. The process is time-consuming and requires close attention paid to the tank, and the full tank volume will not actually be available for use.

On the other hand, RFO/GO tanks can be left empty for extended periods of time if required, and repeated run down to empty before being refilled with no problems (barring sediment issues) as the fuel will always be available as a liquid that can be handled readily.

The cost of manpower also becomes a question, depending how far the adoption of LNG goes for a vessel. In the case of a full LNG setup, the engine room could benefit from a simplified and cleaner system, though more advanced. This then raises the question of the engineer crew composition one would require – would fewer but more technically competent engineers be required, and if so, how much more would it cost?

Look at the big picture.

Even in light of some of the LNG-related technical challenges outlined above, there is still no denying that LNG makes a very compelling case for itself as one of the future fuels – there are no quality issues because ‘unclean’ gas cannot be liquefied, it has the potential to simplify engine rooms, is automatically ECA-compliant and significantly eases the ask of, where required, meeting Tier III NOx emission limits.

Tempting though it may be, however, it would be prudent to take a step back from the excitement, breathe, and consider all aspects of the big picture before taking that leap.

Andy Wright ,
18th February 2013 03:23 GMT

Comments on this Blog
agoetfme agoetfme
3rd September 2016
agoetfme agoetfme
3rd September 2016

Comments have been closed for this article.

Post your Comments on this Blog

Please sign in by clicking here to post comments.

Not registered? Click here and register for FREE.