ECO SHUTTLE TANKER DESIGN MAKES MARK

The first of a pair of Aframax DP2-class sisters incorporating tenets of the Teekay-initiated E-Shuttle Tanker programme, Altera Wave was handed over at the beginning of January by Samsung Heavy Industries and is destined for North Sea service. The design features an LNG dual-fuel electric power and propulsion system with the capability to also burn liquefied gas derived from evaporated oil cargo, complemented by a battery pack for flexible power distribution and blackout prevention.

The newbuild has been brought under the aegis of Altera Infrastructure Norway, the successor to Teekay Offshore Partners. During 2019, Teekay Corporation sold its remaining interest in Teekay Offshore to New York Stock Exchange-listed Brookfield Business Partners, and the shuttle tanker specialist was rebranded as Altera in January 2020.

Altera Wave is the fifth LNG-fuelled offshore loader of the E-Shuttle Tanker generation to join the Altera fleet, having been preceded by the four Suezmax DP2 units of the 129,800dwt Aurora Spirit series over the course of 2020. The Samsung-built quartet is deployed in North Sea contract of affreightment work. The second Aframax newbuild, Altera Wind, is nearing completion at the contractor’s Geoje yard on the Korean peninsula.

The four main diesel gensets are based on the Wartsila 34DF medium-speed dual-fuel engine in its eight-cylinder layout. The latest version of the well-proven 34DF can produce 500kW per cylinder at 750rpm. Although dependant on the contractually specified rating, the plant in the new shuttle tanker could therefore nominally achieve a maximum continuous output of 4,000kW per engine, for a total 16,000kW power concentration.

The configuration differs from that in the four preceding Suezmax vessels of the Aurora Spirit class, each of which has two 12-cylinder vee-form models and two nine-cylinder in-line units of the 340mm-bore 34DF series.

As well as curbing SOx, operation in gas mode achieves IMO Tier III NOx compliance without exhaust gas aftertreatment, reduces CO², and virtually eliminates soot and smoke.

While LNG will be the ship’s primary energy source, with the scope to fall back on fuel oil, the prime movers’ secondary fuel will be recovered and liquefied volatile organic compounds(VOC) mixed with LNG. On the Norwegian continental shelf especially, offshore oilfield operators face stringent regulations relating to VOC emissions, formed and given off during loading and transportation, as the gases are harmful to the environment due to the high methane content. Those organisations have therefore to consider every facet of their activities, including shuttle tanker engagement.

The solution developed for harnessing VOC thereby contribute towards energy savings while addressing heightened ecological standards.

Electrical energy is fed to a pair of propulsion motors acting on two shaftlines culminating in Brunvoll controllable pitch propellers. The critical requirement for precise manoeuvring and station-keeping in adverse conditions is reflected in the adoption of three retractable thrusters and a tunnel thruster, all of Brunvoll make.

The 1,800kWh battery pack trims fuel consumption and lessens emissions by peak shaving, as well as enhancing safety by guarding against blackouts and, for instance, replacing power from a single generator if required when in DP mode. Norwegian reports indicate that a trial demonstrated the tanker’s ability to maintain around six to seven knots for nearly 20 minutes solely on battery power. The installation figures in the extensive array of DNV class notations, through the society’s Battery (Power) accreditation.

On 24 January, in the course of her positioning voyage from South Korea, Altera Wave bunkered LNG in Malaysian waters of the Singapore Strait by way of a ship-to-ship (STS) transfer. The delivery was made by Cryo Shipping using Avenir LNG’s 2020-built, dedicated LNG bunker vessel Avenir Advantage. The shuttle crude carrier thereby became the largest LNG-fuelled merchant ship to date to have been supplied with LNG from a bunker tanker in Asia.

PRINCIPAL PARTICULARS – Altera Wave