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Offshore Marine Technology: 4th Quarter 2015

The concept of autonomous, unmanned vessels ­ much easier to dismiss, even five to 10 years ago, as a flight of fancy ­ is gaining serious traction within the industry.

Rolls-Royce, for instance, is currently forging ahead with a partner-based programme to assess the viability of rolling out crew-free vessels ­ starting with sub-100m loa boats and craft, though possibly encapsulating large ferries, cargo carriers and tankers at a later date. Meanwhile, Canadian architect Robert Allan Limited is planning its first autonomous, tele-operated tug class, in the form of the RAmora project.

This trend may ultimately spell bad news for seafarers but, from an operational viewpoint, unmanned vessels have the potential to eliminate all considerations related to ‘the human element’ of maritime accidents ­ recognised by the bulk of P&I clubs as the leading cause for at-sea accidents ­ and thereby saving both money and time for vessel and offshore facilities.

So it is not entirely surprising that automation has also been vaunted as a potential solution for FLNG units, most notably in the form of class society DNV GL’s Solitude concept.

Cost considerations
Most FLNG units, by necessity, are located (or planned for location) in remote offshore gas fields. Typically, this entails the effort and expense of sourcing either helicopter transport or crew transfer vessels (CTVs) for shore-to-facility technician transfers.

Helicopters may get shore-based technicians to the FLNG site in a timely manner, but chopper hire is expensive and there are obvious restrictions as to the amount of technicians who can be transported per trip.

The costs linked to the above considerations ­ not to mention the outlay required for food and supplies ­ could be cut significantly if a truly autonomous, unmanned FLNG facility was to be realised. Indeed, DNV GL has calculated that, while the creation of an unmanned FLNG unit would require an up-front 5% increase in capital expenditure, it could also result in a 20% reduction in annual operational expenditure in the long term.

Thinking out loud
Elisabeth Tørstad, chief executive, DNV GL Oil & Gas, tells Offshore Marine Technology: “Cost reduction lies in low manpower, maintenance and logistics. With no personnel on board, personnel risk can be eliminated by using autonomous units to handle typical inspection and maintenance tasks.

“As a result, it would not be necessary to build living quarters, thus enabling simplified safety systems to focus on better protection of the topside equipment.”

The Solitude concept was developed by DNV GL as part of its Extraordinary Innovation Project (EIP), which is focused on the viability of unmanned FLNG facilities. The society is keen to stress that Solitude is “not an attempt to present a mature FLNG design”, but rather “our way of thinking out loud to form discussions and call for further collaboration within the industry”.

 “The intention of our concepts is to create ideas and inspire both the maritime and oil and gas industries for innovations,” Tørstad says. “We have seen elements from previous concepts being picked up and used, but it is unlikely that all of these will materialise exactly as described.

“We are currently in a phase of discussing particular aspects of the concept that are of interest to clients in order to develop specific work packages that may be followed through with individual clients or perhaps more widely through our joint industry projects [JIPs] where appropriate.” She reveals that DNV GL has already received “significant interest” in Solitude from clients involved in FPSO projects.

The basic set-up
So, what does the Solitude concept actually comprise? The basic design is for an FLNG unit with a modular topside, the capacity to store up to 250,000m³ of LNG / 30,000m³ of liquefied petroleum gas (LPG) and the capability to produce up to 2 million tonnes of LNG per year.

The facility would ideally utilise fuel cells, rather than high-maintenance gas turbines, to generate power; ‘ideally’ because, as DNV GL acknowledges, this form of environmentally friendly technology needs to be developed further in order to meet the needs of a fully functional, power-hungry FLNG unit.

However, the rapid advances in fuel cell technology witnessed over the past few years ­ particularly within the Scandinavian fast ferry sector (a real hotbed for green ship innovation at present) ­ indicate that this ideal set-up is certainly not far-fetched. Tørstad cites the example of the 92.2m x 21m OSV Viking Lady, which has been successfully using fuel cell technology to assist in powering its operations since 2009.

Of course, sceptics may feel uncomfortable with the concept of an unmanned FLNG unit, and some industry players have queried what would happen in the event of a serious accident, such as an onboard fire or malfunction. These are certainly challenges that need to be addressed by DNV GL and its future partners in this project; while the personnel-free nature of the Solitude concept at least guarantees that no workers will be injured or killed, there is the question of raising an effective response to any incidents that do occur.

To this end, the Solitude concept also proposes the presence of a human-crewed, onsite support vessel, which would be able to swing into action should a serious problem be detected. Tørstad continues: “Transportation of personnel and life support goods are reduced and will be replaced with docking for delivery of modules, which enables safer transfer operations and supplies.”

The Solitude concept model proposes the addition of a docking station for the onsite support vessel and for other special purpose vessels. It is hoped that this method of accessing the FLNG unit will prove safer and quicker than having to rely on ‘walk to work’-style hydraulic gangways and/or crane-/rope-access crew transfer solutions.

Robotic monitoring
With no personnel on board, a network of wireless sensors would act as a virtual sentinel, supplying information to a high-end condition monitoring system developed for fault detection, proactive maintenance and repair planning. With a decent satcomms solution installed, the system would be accessible from shore, enabling the unit operator to remotely monitor all onboard developments.

The FLNG unit’s ‘crew’ would consist of ‘autonomous inspection and maintenance units’, or, in simple parlance, robots. DNV GL proposes that the unit’s topside should be outfitted with a “system of rails that run along each process train, providing these robots with access to all the equipment”.

Tørstad comments: “Sophisticated monitoring systems that can predict and detect component failure for all operational parameters can react quickly, as a result of the station support vessel that will be providing the initial emergency response. For instance, the blow-down rate is usually restricted by radiation exposure limits for the crew. However, with no people onboard the FLNG unit, the flaring rate could be increased.

“A gas fire can be stopped within 10 seconds rather than in minutes, as is the case with many conventional onboard systems. This time difference could spell the difference between total asset loss and a short-term production interruption.”

Addressing future concerns
While some of these autonomous technologies may need to be developed or refined in future, others are available now, Tørstad points out. However, given the stakes involved, there is no room for complacency, and the class society is well aware that the industry needs to pull together to develop the technology required for such a concept.

“Some regulatory and technical risks still need to be addressed,” she says. “These include: increased risk through sensors and autonomous units replacing eyes and ears; risk of dropped modules damaging equipment and tanks on the topside; and longer response time in case of unforeseen events requiring human operators. Therefore, it is essential to design robust, autonomous equipment and control systems to replace humans for many operational and maintenance tasks.”

The realisation of the Solitude concept is certainly an ambitious task, and it will be interesting to watch as the project develops. However, consider this; 10 years ago, the idea of battery-powered vessels seemed hopelessly utopian. In the last few years, we have seen so much development on this front ­ to the extent that DNV GL is working towards the establishment of a Marine Battery Forum and predicts that, by 2020, “most medium and large passenger-carrying vessels will have some form of battery onboard” ­ that the very notion has shifted from a ‘quaint fantasy’ to a dedicated series of exhibitions, conferences and case studies. The potential cost-saving benefits are certainly enticing; now the offshore oil and gas industry needs to ask: how do we get the robots to perform? Development of reliable automated “eyes and ears” will be crucial to the success of proposals such as the Solitude project.

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