Dr Michael Traut, Research Associate at the Tyndall Centre, University of Manchester

While switching to liquefied natural gas (LNG) bunkers may solve the shorter term problem of reducing certain ship emissions such as SOx, they will not address the wider challenge of reducing the sector's GHGs, Dr Michael Traut, Research Associate at the Tyndall Centre, University of Manchester, has told Ship & Bunker.

The comments will no doubt come as a surprise to many in the industry as considerable backing, including a significant amount of state funding in Europe, has already been put into developing LNG as a viable alternative to traditional bunkers.

Indeed, echoing comments from many others in recent years, at last month's LNG Fuels Summit in Amsterdam, Michael Shaap, general manager of Titan LNG declared that "I think everybody concurs by now that LNG is the future marine fuel."

Regulations addressing ship emissions to date have been predominantly focused on reducing SOx.

Following MARPOL Annex VI's coming into force in 2005 we now have emissions control areas (ECAs) in Europe and North America limiting the sulfur content of bunkers to 0.10 percent, and later this year the IMO will decide on whether the current 3.5 percent global sulfur cap will drop to 0.50 percent in 2020 or 2025.

LNG bunkers are being touted as the perfect solution for marine to solve the challenge of meeting these increasingly tighter emissions limits, and in the context of MARPOL Annex VI it is easy to see why.

LNG not only produces negligible emissions of sulfur oxides (SOx), meaning they will meet all current and any future sulfur caps, nitrogen oxide (NOx) emissions are typically reduced by some 90 percent, meaning owners that make the switch to LNG would also be safeguarding against the proposed future NOx caps.

Green House Gases

When it comes to GHGs, shipping currently has no explicit commitment to reduce them, and it was not referenced in the recent COP21 global climate deal.

Nevertheless, Traut explains that the IMO is now under increasing pressure to make sure shipping does its part to reduce GHGs in line with the goals of COP21.

And while some ship owners such as Japan's NYK Line say they are specifically looking at LNG "in order to meet the tightened regulations on CO2 emissions from vessels," this is one area where the advantage of LNG over traditional bunkers is much less pronounced.

In fact even the most ambitious estimates of future LNG bunker adoption put emissions levels well above what is needed to meet the requirements of COP21, he says.

"We need to acknowledge that there's a gap between where we need to be, and where we're heading at the moment, and get serious about really tackling it," said Traut.

In terms of where we're heading at the moment, he points to the 3rd IMO greenhouse gas study; "There's a really broad range of scenarios to predict demand for sea transport, and to see how shipping will develop. All of them see growth in emissions, and out of 16 presented only one sees emissions drop back to current levels by 2050.

"So I discount LNG as it doesn't seem to be a long term solution. While it reduces some greenhouse gas emissions, the CO2 emissions reduction is actually pretty small to non-existent when you look at the complete lifecycle. There are also concerns about methane slip. Also, what savings are made through the use of LNG would also likely be offset by an increase in shipping."

In terms of where we need to be, Traut says that is a reduction in overall emissions.

"If you look at the Paris Agreement, the goal is to hold the global temperature increase to well below 2 degrees, and ideally 1.5 degrees. You can translate those temperature targets in GHG targets. You can argue that shipping should make the same reductions as other sectors, or you could say because it's vital - or as it has been called, the servant of world trade - it should be granted more emissions space than, say, aviation where a lot of the emissions come from recreational use - people going on holiday etc.

"But whichever way you put it, very drastic reductions in shipping emissions must be made. We need to aim for decarbonisation."

Traut says that one of the biggest challenges at the moment is that it is unclear if shipping can make the required emissions reductions.

"We lack knowledge about how, and how much shipping's CO2 emissions can be reduced," he said.

"Is it possible? My research aims to answer that question, and we'll only find out if we try."