Narrow delivery windows make achieving efficiencies in LNG transfer time one of the biggest challenges FSRU operator Excelerate Energy faces
Excelerate Energy was one of the earliest movers in developing floating LNG, and carried out the world’s first commercial ship-to-ship transfer in February 2007. In the 12 years since, the FSRU concept has gained widespread acceptance for its combination of high flexibility and low cost when compared with traditional land-based facilities. Excelerate continues to be a major player, operating – among others – the Moheshkhali Floating LNG terminal in Bangladesh.
Transfer systems are integral to efficient operations of FSRUs, and Excelerate’s chief operating officer Edward Scott shared his perspectives on how approaches to LNG transfer have developed since the early days, the challenges operators must overcome, and the direction going forward.
“At this point our biggest challenges relate to increased frequency and the pace of operations now,” he says, noting that in Excelerate’s Pakistan project there are just 3.5 days between vessel deliveries.
“At a 36-38-hour transfer cycle you can imagine that any efficiencies that we can gain in the operational aspects of transfer systems are precious time that allows our crews to rest and get prepared for the next operation, bearing in mind that we’re simultaneously regassing and operating the vessel’s broader physical plant.”
While implementation of FSRUs has been transformative in the global LNG market, the actual changes to technology and procedures involved may appear incremental to the untrained eye, Mr Scott says.
The basic equipment involved has not changed drastically, but great strides have been made in areas such as control systems, installation methods, operating procedures, efficiency and reliability.
An example of how these operational procedures are optimised is the programme of training that must be undertaken by crews of LNGCs booked in to an Excelerate FSRU terminal. Senior officers undertake a training and certification program via remote learning before they even arrive at the terminal, followed by further familiarisation and transfer-planning training in person upon arrival.
One area where that has been a significant change is in the hoses used to connect the LNGC and the FSRU, Mr Scott says. He explains: “Our original system used a series of 8-inch hoses stepping down from the main manifold.
“It was pretty inefficient in terms of connection, disconnection and purging times, so for the last three or four years we’ve been developing a 10-inch system that will allow us to achieve better transfer rates for the hoses connecting the vessels.”
Recently, Excelerate has implemented what Mr Scott describes as a flange-connecting adaptor that uses quick-connect fittings to allow faster connection and disconnection of hoses than traditional stud-and-bolt systems.
“The [flange-connecting adaptor] reduces wear and tear on the crew as well as connect and disconnect time, which in turn reduces the overall time from vessel arrival to vessel departure,” he says. “We spent a great deal of time and resources working with a vendor to develop this, and now it’s deployed on both of our projects in Bangladesh. We’ve completed 34 transfers using this system, and it works very well.
“Given the offshore nature of that project and changing tides, and the difficult environmental conditions in Bangladesh, any time efficiencies that we can gain are very much value added for ourselves and the customer.
“We will apply systemic upgrades and enhancements on a case-by-case basis, [but] quite frankly we’ve got a proven system. The transfer rates work for all of our customers, so our focus is really on continued safety, efficiency and reliability.”
“Given the offshore nature of that project and changing tides, and the difficult environmental conditions in Bangladesh, any time efficiencies that we can gain are very much value added for ourselves and the customer"
One means of focusing on these goals is through the use of digital technologies, says Mr Scott, noting that STS transfer is about more than just the hoses, valves and bolts. “It’s the entire process of mooring and unmooring, and training pilots and mooring masters, and looking at different methodologies for fendering and designing mooring arrangements to be adaptable enough to accommodate different-sized ships and mooring configuration.
“We make an enormous investment in making sure we understand exactly what to expect before we show up on site for a new project,” he says, noting that for each new project a full simulation of the whole mooring cycle is undertaken. This takes into account local weather conditions, including historical data. Citing Bangladesh as an example, he notes that full motion studies incorporating both theoretical and physical modelling were undertaken to examine the whole system, with vessels arriving and departing in different conditions and with a holdback system to keep the heading constant throughout the year.
The company is undertaking integration of digital control systems for transfer as well, with Mr Scott estimating a 50-50 mix between digital and analogue controls. Data streams are gathered from various parts of the system such as the mooring load, ESD system status and ESD communications between vessels.
“Resupply capability is the single most critical part of supporting an FSRU, so we spend a great deal of time making sure that people are trained well and that we are using every tool at our disposal to make sure we keep operating safely and reliably,” Mr Scott says. “There aren’t any corners to be cut here. We are always looking for the best materials, vendors and suppliers to ensure everything we do is top rate.
“In terms of big innovations, there are some things out there we think are interesting. But we’re actually quite happy with the way our system operates at this point, and most of the industry is as well,” he says. “In this case I think back to the first thing my professor wrote on the board in the very first year of my engineering degree: ‘if it isn’t broken, don’t fix it.’”
Excelerate Energy’s ship-to-ship experience in figures