For Siem, it's a technology the Norwegian company is betting big on, with two others with the same design operating in the Norwegian North Sea for Total and Royal Dutch Shell, and it has commissioned two more that are being built in a shipyard in Gdansk, Poland, despite having no users signed up to use them yet.

Siem CEO Idar Hillersoy told Energy News that the two new vessels were being "built on speculation".

"We believe the market will ask for the technology in the future, so have taken the bold step of starting the build without a contract," he said.

LNG powered vessels have been operating in Norway for about 15 years, but Hillersoy said it was only in recent years that environmental and financial imperatives have started to bring the technology to the fore.

"The global fleet of LNG-powered vessels is growing in all areas of marine transportation, which is largely due to the environmental and operational benefits of the technology," he said.

"Our belief is that it will continue to grow and be adopted globally as the only really sustainable of powering marine transportation in all sectors."

Woodside's charter has an option to be extended for a further two years, and the oiler's chief operating officer Mike Utsler said the move made "perfect sense" given Australia was on track to become the world's biggest LNG producer, overtaking Qatar.

More than that, though, it opens up new business opportunities for Woodside, which is looking to position itself as the "partner of choice" by demonstrating the new capability on a broader basis for future partners.

"We want to differentiate Woodside from the thousands of other oil and gas companies competing in the world, and to do that we have to prove we're safe, reliable, highly efficient and highly innovative," he told Energy News at LNG18 yesterday.

"This is one more example of where we think Woodside, as an independent mid-sized oil and gas company, demonstrating its leadership in the industry and taking a leading position - be it in the areas of data technology, design technology and of environmental efficiency applications - [to] enable us to pursue being a partner of choice."

The new vessel will work on the North West Shelf, bunkering out of the Kings Bay supply base in Karratha supporting Woodside's operations across the NWS and Pluto.

Utsler said Woodside's intention was to look at how evolve from this first application to expanding to its entire supply vessel fleet becoming duel-fuel, as it is currently entirely fuelled by diesel.

Woodside operates 16 PSVs and OSVs on average.

Utsler said retrofitting in the LNG duel fuelling world was also a technology that is becoming very cost competitive, so it is applicable for consideration for the Perth major.

Woodside had two main motivations in inking the deal with Siem.

One is to drive an environmentally improved delivery of our own operations and be competitive against Article 6 regulations that aim to drive marine emissions reductions by 2020.

The other is that it allows the company to start demonstrating the capabilities of duel fuelling as a transport fuel in Australia that leads to "what we believe is a business opportunity", Utsler said.

"When you think about the iron ore cargo shipping, trains and trucking, this is a potentially significantly untapped market opportunity domestically for the use of LNG," he said.

"If you look in WA domestically, LNG is 0.2 million tonnes per annum supply capacity, yet there is a significantly larger opportunity in a cost competitive [way] to diesel and in an environmentally improved delivery performance, the benefits are great.

"Currently we are planning in this initial application first vessel for trucking and setting up portable bunkering at Kings Bay, so we'll truck LNG in from two suppliers."

One of these, Energy News has learned, is Wesfarmers.

"Longer-term we would be looking at how to utilise this amazing supply of LNG that we're already producing," he said.

"On a longer basis we'll be looking at bunkering options and opportunities which would allow us to expand and make available to not only meeting our internal needs but supporting an external supply of LNG transport fuel for on-land, marine and rail transportation capabilities."

Bunker supply ships will be another future generation of opportunity, he said, but the first priority is to meet the company's internal needs.

Woodside is looking at a trucking terminal that would allow it to leverage both the offloading and loading for truck transportation.

"Currently to do a turnaround of LNG transport fuelled vessels from Perth to Karratha they have to fuel portably, so you can see already an opportunity that emerge from that," he said.

"Longer-term from a vessel deployed bunkering aspect you can see scenarios where as we expand and develop greater marine operations and opportunities where marine bunkering could become an important part of building the chain of domestic LNG utilisation all across the Northern Territory-Western Australia coastline."

This, he said, could meet business needs including supporting power generation for the state's critical mining industry.