Marine Log - August 2008 - (Page 29) BY NICK BLENKEY POWER & PROPULSION WASTE NOT, WANT NOT S ky high bunker fuel prices may prompt more owners to look at the advantages of advanced waste heat recovery systems. And, as if that wasn’t enticement enough, so too should the increasing desire to shrink a ship’s carbon footprint. There’s nothing particularly new or hard to understand about the concept. A waste-heat recovery (WHR) system reuses excess exhaust-heat to generate energy for on-board electricity consumption. The associated reduction in fuel consumption results in a corresponding reduction in emissions. Of course, this “free power” isn’t actually free. You have to add more equipment—and, on the face of things, more equipment takes up space and means added investment cost, not to mention more maintenance. When bunker prices were lower, shipowners took a look at the extra degree of complexity of WHR systems and didn’t even bother to calculate the Return on Investment (ROI). MAERSK SPECIFIES WHR FOR 18 NEWBUILDS However, climate change and the high cost of energy have changed the shipping industry’s mind. Container shipping giant Maersk is emphasizing WHR as part of its commitment to green shipping because lower fuel consumption means lower emissions. Maersk’s experience indicates that an advanced WHR may mean less equipment in that it can reduce the number of diesel generator sets required on a large ship. It can also mean more payload, because reducing fuel consumption means less space is needed for fuel tanks. Maersk’s commitment to WHR is underscored by its choice of power plant for its recently announced series of eighteen 4,500TEU containerships from South Korea’s Hyundai. It has ordered 18 MAN B&W 6S80ME-C9 engines for the ships. The 6S80ME-C9 engine type is MAN Diesel’s most modern mark-9 design and is fully compliant with the new, Tier-II emission requirements. With a cylinder bore of 800 mm and stroke of 3,450 mm it produces 4,510 kW/cylinder at 78 rev/min. MAN Diesel says that the lower revolutions per minute gives a significant increase in propulsion efficiency, thereby contribut- Waste heat recovery (WHR) in world’s largest containership Emma Maersk ing to fuel economy and reduced CO2 emissions. The ships will make use of waste-heat recovery technology on all of the engines. That’s not too surprising, since Maersk has developed in a joint effort headed and integrated by the Odense been specifying WHR in all the large containerships built at its yard in cooperation with Wärtsilä, Siemens AG, Peter BrotherOdense Shipyard in Denmark since 2005. What is an eye-open- hood Ltd and Aalborg Industries Ltd. Exhaust gases from the ship’s 12RT-flex 96C low-speed, comer is that, according to MAN Diesel, this is the first time that an mon-rail engine (with a maximum continuous power output of Asian yard will install WHR systems of this size and efficiency. Presumably, the WHT system in the Hyundai-built ships will 68,640 kW at 102 rev/min) passes through an Aalborg dualpressure exhaust-gas economizer and the resulting superheated be similar to the systems in the Odense ships. The WHR system first introduced in the 7,000 TEU Gudrun steam is utilized in a 6 MWe Peter Brotherhood turbogenerator Maersk in 2005 (described in more detail in the October 2005 set. The turbogenerator set has both a multi-stage dual-presissue of ML) and utilized in subsequent Maersk ships was sure steam turbine and an exhaust-gas power turbine. The elecwww.marinelog.com AUGUST 2008 MARINE LOG 29 http://www.marinelog.com
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