[ 79 ] ONBOARD benefits are highly dependent on the wellto-wake methane slip. For this reason, LNG is generally regarded as a transition fuel until ‘cleaner’ alternatives such as green hydrogen or green methanol are available and affordable. P&O Ferries wasn’t convinced about the long-term benefits of LNG fuel and saw a greater promise in diesel-battery hybrid propulsion. Norway with its myriad of fjords and ferry services has been at the forefront of battery propulsion for its vast fjord ferry fleet. Operating in full-electric mode, these rather small double-ended ferries somehow keep a hybrid element, with a diesel engine being required to cover longer distances when, for instance, the ships need to be drydocked. 15 MINUTES OF ZERO EMISSIONS For ships the size of P&O Pioneer operating on a short stretch of sea, going full electric is possible providing the ports offer high-voltage rapid charging facilities. Neither the Port of Dover nor the Port of Calais have these facilities in place, so P&O Ferries took the bold step to somehow implement battery technology, using peak shaving to charge the 1,160 individual XALT Energy batteries. Located in four battery rooms (two fore, two aft) outboard of the B/5 double skin on Deck 2, the batteries are charged by just one of the four Wärtsilä 16V31 gensets which each have an output of 9,760 kW at 750 rpm and 100 per cent of maximum continuous rating (mcr). Running at 85 per cent mcr, the single generator not only recharges the batteries in approximately 40 minutes, it also provides the hotel load when alongside in port. With a full battery load, P&O Pioneer has a 15-minute autonomy when sailing at a 17.6knot service speed. At sea, it is usual for only one generator, plus the battery system acting as a second generator, to be in operation in order to contribute to the 40 per cent reduction in fuel consumption compared with the Spiritclass. Stowed side-by-side in a main engine compartment fore and aft, the four ultraeconomic Wärtsilä gensets are very compact, featuring ABB’s Power2 two-stage system which further improves power efficiency and helps achieve up to five per cent in fuel savings and up to 60 per cent of NOx emissions. Designed to burn ultra-low sulphur content marine diesel oil, the generators have independent fuel systems and provide electrical power to the propulsion system which is transferred electrically to each ABB Azipod via a motor controller and electric motor. Combining the thruster, bow thruster, stern thruster and rudder functions in a single 360-degree podded propulsor, the four Azipods are of the compact DO1600 type rated at 7.5MW each. Unlike the larger versions typically used on cruise ships, the DO1600 allows for easy maintenance which can be performed while the ship remains in operation. As befits a double-ender design, many systems are duplicated. This also applies to the fin stabilisers with each pair being optimised for use in a single direction, guaranteeing a smooth crossing regardless of which direction the ferries are sailing. “ The four ultraeconomic Wärtsilä gensets are very compact, featuring ABB’s Power2 twostage system which further improves power efficiency and helps to achieve up to five per cent in fuel savings and up to 60 per cent of NOx emissions”
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