Tank containers are helping the worldwide spread of small-scale LNG in myriad ways.
Essentially a cryogenic IMO Type-C pressure vessel fitted in an ISO standard-size frame of either 20, 30 or 40ft long, the LNG tank container offers end-users in remote locations and with limited volume requirements a quick way to benefit from competitively priced, cleaner-burning natural gas.
ISO tanks’ intermodal design obviates the need for cargo transfers along the supply chain. The units can be lifted from flatbed road vehicle chassis to a flatbed rail car or loaded, using standard container-handling equipment, on a container ship.
The tanks can also act as static storage units. Many customers take delivery of full units and draw down their contents when needed, replacing them once empty.
LNG 20ft ISO tanks support several very small-scale distribution and bunkering operations, but Japan favours 30ft units for local and regional deliveries. Most projects that need a multimodal solution opt for 40ft units, however. These hold up to 43.5m3, or 17.25 tonnes, of LNG.
Each tank and its insulation system is designed to offer a maximum holding time. This is the time it takes for vapour pressure to build up inside the vessel, opening the pressure-relief valve to vent boil-off gas.
There is a correlation between fill levels and holding times. For most tank designs, a relatively low fill level of, say, 80 per cent will provide holding times of more than 75 days. National authorities usually allow fill levels of up to 95 per cent if the required holding time is well below the unit’s stated maximum.
Two recent LNG ISO tank market reports expect this sector to achieve compound annual growth of 8-9 per cent through 2022 – that’s almost twice the forecast growth rates for the LNG industry in general.
Island hopping
LNG World Shipping has looked before at how companies including Crowley Maritime affiliate Carib Energy and Grupo Sousa ship LNG in 40ft tank containers to Puerto Rico and to Madeira.
Barbados has also recently started to import LNG using ISO tanks. This Caribbean nation of 285,000 people uses imported oil products for 93 per cent of its energy needs.
Now, Barbados is replacing oil products with natural gas. Last year it became the second Caribbean island, after Puerto Rico, to import LNG in tank containers.
Barbados’ modest natural gas production covers 70 per cent of its growing gas needs. In April last year, it started to import four 40ft tank container loads of LNG a week to cover the shortfall.
Barbados National Oil Company’s (BNOC) small Woodbourne regasification plant processes the imported tankloads to meet the gas needs of Barbados Light & Power’s electricity-generating plant and nearby residential and commercial users.
The LNG comes from the 60,000 tonnes per annum (tpa) American LNG Marketing liquefaction plant in Hialeah, Florida. The tank shipments are delivered by truck to Miami and loaded on container ships bound for Barbados.
BNOC plans to build a larger regas plant and to import LNG by coastal tanker, replacing most power plant fuel oil feedstock with natural gas. In the meantime, it plans a fourfold increase in Woodbourne’s throughput capacity to step up its ISO tank imports.
New takers
Compania Transportista de Gas Canarias (Gascan) and its majority shareholder Enagás plan to build Canary Island regasification plants at Granadilla on Tenerife and Arinaga on Gran Canaria. These will supply local power plants with gas delivered by LNG carriers of up to 145,000m3. The terminals will also supply LNG as marine fuel.
Although permitting issues have delayed the regas terminal projects, the Canaries remains committed to LNG. Granadilla has already built a combined cycle power plant that can burn gas.
And so Enagás has started to ship tank containers to Tenerife, sourcing LNG from Huelva import terminal on the Spanish mainland, to supply customers making an early commitment to gas.
Indonesia learned from Japan’s ISO tank experience in preparing to introduce LNG tank containers. The tanks are filled at Bontang export terminal in Kalimantan for shipment to local customers in remote locations.
Indonesia is trying, wherever it can, to substitute diesel fuel with natural gas, in small power plants and to power heavy coal mining vehicles. ISO tanks have a role to play.
Since 1999, Japan-based Air Water Plant & Engineering (AWPE) has built some 300 cryogenic ISO tanks, mostly 30-footers, to deliver LNG by road, rail and ship to off-grid domestic customers.
These tanks feature the company’s composite insulation concept, which provides holding times between those offered by conventional perlite and superinsulation. Indonesia’s PT Pertagas Niaga, which is developing Bontang ISO tank-loading options, favours the AWPE tank design.
AWPE has strengthened its presence in the region, last year buying a cryogenic equipment manufacturing plant in Malaysia that was owned by Taylor Wharton. It is converting the facility to build ISO tanks.
Bontang terminal’s truck-loading bays can fill up to 72 LNG ISO tanks a day. Pertagas Niaga has commenced trials using ISO tank-delivered LNG to fuel mining vehicles. It plans to build up ISO tank shipments, initially along Kalimantan’s east coast, to Sangatta, Berau, Samarinda and Balikpapan, before developing similar services to remote islands in eastern Indonesia.
Bunker tanks
LNG-powered ships can use tank containers to deliver LNG to vessels moored jettyside and for bunker supplies.
In December, the 7,900 dwt roro cargo ship SeaRoad Mersey II entered service on the Bass Strait crossing between Melbourne and Devonport. It employs a bunkering system that no other LNG-fuelled vessel has attempted, based on a fleet of seven VRV-designed, 40ft LNG ISO tanks .
Every day in Melbourne, tractors remove three empty tanks from specialist loading bays on the ship’s stern-side weather deck and replace them with three laden units. The tanks are secured with six twist locks per unit, plumbed into the ship’s gas-burning fuel system via flexible cryogenic pipes connected to a common LNG manifold.
This bunkering arrangement requires each tank container to be connected to three ship-piping systems: the LNG-fuelling line to the engines, the link to the vent mast for the unit’s pressure relief valve and the inert gas system.
Meanwhile, Keppel Singmarine is building a pair of LNG-fuelled escort tugs ordered in December for affiliates of Royal Boskalis Westminster. These will also employ ISO units as bunker tanks.
CIMC will provide the 20ft tanks and each bunkering will replace one empty unit with a full one in a lift-on/lift-off operation.
Back in Florida, ISO tanks are working as fuel receptacles for rail transport. Florida East Coast Railway, like American LNG Marketing an affiliate of New Fortress Energy, is converting its 24 new Tier 3 locomotives to run on LNG. Cryogenic ISO tanks mounted on reinforced flatbed rail cars will serve as fuel tenders.
The LNG train fuel can be sourced from Hialeah liquefaction plant or from Bowden fuel transfer station in Jacksonville.
These innovative projects indicate that the future is looking bright for LNG ISO tanks.
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