Emission deadlines concentrate minds

01 Apr 2012
Graphic of MAN’s second-generation EGR system (shown in orange) integrated with its host engine

Graphic of MAN’s second-generation EGR system (shown in orange) integrated with its host engine

While facing increasingly competitive and often volatile market conditions, ship operators have the added challenge of finding cost-effective solutions to all-pervasive environmental controls; David Tinsley looks at some of the options.

The intensification of regulations governing allowable emissions of nitrogen oxides( NOx) and sulphur oxides (SOx) has spurred considerable technological endeavour by the industry, such that a raft of solutions is in place or under development. However, issues related to costs, availability, and supply logistics remain of vital concern to many fleet operators, while a natural hesitancy towards largely untried systems or designs influences the pace of product take-up.

In addition to the focus on noxious pollutants, the regulators’ attention to greenhouse gas emissions, through impending, mandatory mechanisms intended to ensure an energy efficiency standard for ships, adds a whole new dimension to the ship design and engineering process.

IMO’s Marpol Convention Annex VI imposes limits on NOx and SOx in accordance with both global requirements and more stringent regional criteria, applicable to ships in geographically defined emission control areas (ECAs). An ECA can be designated for SOx and particulate matter (PM), or for NOx, or for all three types of emissions. The Baltic Sea and the North Sea (including the English Channel) were the first two ECAs, subsequently followed by the North American ECA, encompassing most of the US and Canadian coastline. The US Caribbean ECA, covering the waters around Puerto Rico and the US Virgin Islands, has more recently been adopted by the IMO.

Vessels sailing in ECAs will be required to burn fuel with an ultra-low sulphur content of no more than 0.1% from 2015 onwards. The edict allows for the alternative measure of adopting suitable abatement technology in conjunction with the continued use of heavy fuel oil.

The mandated sulphur level in ECA waters had already been cut from 1.5% to 1.0% in July 2010. The requirement for a further 90% reduction in the space of just five years has put the industry under some pressure, and most especially as regards ferry operators and the ro-ro sector. Companies running ships within the ECAs will be compelled to either switch to distillate fuel, raising concerns over future availability as well as the considerable price premium incurred, or will have to adopt alternative technical solutions, such as shipboard exhaust cleaning plant, or use gas as fuel.

Of the three options for meeting ECA requirements, LNG fuel has the lowest emissions of all ‘local’ pollutants NOx, SOx and PM, as well as the lowest CO2 emissions. LNG is the only solution which can alone meet both the 2015 SOx criteria and also the new ceiling on NOx to be introduced in 2016 under the IMO’s Tier III provisions.

IMO’s forthcoming 0.1% sulphur cap in ECAs is set to be underscored by a revised EU Sulphur Directive, duly aligned with the IMO regulations. In the meantime, the EU’s January 2010-introduced directive 2005/33/EC has imposed a 0.1% limit on sulphur emitted by ships berthed or anchored in EU ports.

Outside the ECAs, the worldwide sulphur limit, trimmed from 4.5% to 3.5% with effect this year, is due to be cut to 0.5% in 2020, unless a review reveals a prospective lack of low-sulphur fuel, in which case implementation will be delayed to 2025.

In the light of the pressing timetable for implementation of new ECA sulphur controls, a switch to marine gas oil is perhaps the easiest measure incurring the lowest investment. However, such a strategy would potentially raise bunker costs by 70%-plus, making for dramatically higher running costs over time.

Interferry, the trade association for the ferry business, considers that the use of LNG fuel is not a realistic option for the industry in general, since the cost of converting existing vessels to run on gas can be prohibitive, while the LNG fuel supply infrastructure is as yet inadequate as a whole.

The development of exhaust scrubber technology has been supported by operators, through shipboard tests and also by applications starting in the European shortsea domain. The benefit of this solution is that it allows the continued use of heavy fuel oil bunkers, while reducing SOx emissions to the requisite, extremely low or negligible levels. For many companies, typical operating margins could make ultra low-sulphur fuel an uncompetitive option, leaving exhaust gas cleaning equipment as the only practical solution, despite the extra up-front costs.

Although there are concerns in the shipping industry over the technical and financial feasibility of scrubber systems, and while the 2015 deadline is seen as problematic from the standpoint of implementing such plant throughout fleets, a recent clutch of contracts for such equipment testifies to the increased interest in the technology.

A prototype exhaust gas scrubber developed by Aalborg Industries, now part of Alfa Laval, in cooperation with MAN Diesel & Turbo, and designed to virtually eliminate SOx, has proved successful in application onboard the DFDS trailership Tor Ficaria. The plant has been tested and evaluated in the course of the vessel’s regular sailing pattern between Gothenburg and Immingham.

The ‘Flower’-class ro-ro freight carrier Tor Ficaria is powered by a single, two-stroke main engine. However, for ro-ros with more than one engine, as is the case with a high proportion of such tonnage, such after-treatment solutions raise important issues of space, weight and cost. Specialist equipment suppliers have acknowledged the need for further development of scrubber technology, with the aim of producing more compact and ‘smarter’ units.

Installation of Wärtsilä’s first full-scale, seagoing SOx scrubber plant was completed on the 14,000dwt Finnish shortsea trader Containerships VII in August 2011. The unit is located on the port side of the funnel casing, treating the exhaust gas flow from the vessel’s single Wärtsilä 64-series, wide-bore medium-speed main engine. A prototype SOx removal plant developed by Wärtsilä underwent tests at sea through 2008 and 2009 onboard a 14,700dwt Finnish tanker.

Another initiative in the short-sea sector saw the fitting of a dry scrubber plant developed by Couple Systems to the 6,400dwt German cargo vessel Timbus in 2009. Repeated analyses have demonstrated the effectiveness of the system, achieving SOx reductions in excess of 99%, cutting sulphur emissions to under 0.1%. In addition, the plant has cut PM emissions by some 80%.

Genoa-based shipowner Ignazio Messina has endorsed Hamworthy Krystallon’s seawater scrubber technology for the auxiliaries in its new generation of 45,200dwt multipurpose ro-ro vessels tailored to the company’s Mediterranean and African service network. This will allow the genset engines to be run on residual fuel with a sulphur content of up to 4.5% while in port in Europe, ensuring compliance with the EU’s 0.1% sulphur cap. Provision has also been made for the future installation of a scrubber to serve the two-stroke MAN 7L70ME-C8 main engine, so as to ’future-proof’ the ships against the upcoming 0.1% sulphur limit in ECAs.

Hamworthy Krystallon recently sealed a contract with Hyundai Heavy Industries for the delivery of the first full-vessel scrubber system to an 84,000m3-capacity LPG carrier newbuild ordered by Norwegian owner Solvang. The outfit will comprise one unit serving the main engine exhaust and a combined unit for the three auxiliaries, allowing the ship to operate in all waters on heavy fuel oil. Krystallon is now part of Wärtsilä following the latter’s acquisition of Krystallon parent Hamworthy.

A further commercial breakthrough for scrubber technology was signified by the contract award to Wärtsilä for systems to be fitted in six newbuild bulk carriers designed to trade on the Great Lakes and St Lawrence Seaway. The integrated scrubber solution nominated by Canadian owner Algoma Central Corporation for its Equinox bulker series is claimed to remove more than 97% of the SOx emissions, so that heavy fuel oil can be used within the North American ECA.

A milestone in marine diesel engine environmental standard was attained last year through Hitachi Zosen’s completion of the world’s first IMO Tier III NOx-compliant two-stroke diesel. The MAN six-cylinder S46MC-C8 prime mover powers a 38,000dwt dry cargo vessel. The seminal solution adopted to raise the engine’s performance to meet the Tier III limit, due to enter force on 1 January 2016, has entailed the use of an integral selective catalytic reduction(SCR) system, to cut NOx by at least 70% at each load point in the load cycle, and more than 80% overall.

MAN emphasised that the arrangements do not simply constitute an engine with an added SCR plant. Rather, the plant represents a bespoke system, comprising an optimised propulsion/emissions package made up of the engine, engine control and SCR systems.

Insofar as the low-speed, two-stroke engine sector is concerned, a companion solution by MAN to meet the Tier III edict on NOx is exhaust gas recirculation(EGR). The company has released a compact, second-generation EGR system, and attracted an opening order for an installation in a 4,500TEU Maersk containership newbuild. The entire EGR has been integrated into a single unit, forming part of the engine as a charge-air cooler. The configuration is expected to provide the basis for the company’s future Tier III NOx EGR-fitted engine programme.

Another avenue to Tier III compliance is the use of gas fuel. However, as the supply infrastructure for LNG will not be sufficiently developed by 2016, engines with back-up fuel capability are needed, namely dual-fuel engines. DF machinery is therefore of considerable interest to engine makers and buyers alike, with Wärtsilä having stated last year that the DF concept is spearheading the company’s technological drive in engine design. When a DF engine is running on gas, it already complies with IMO Tier III criteria relating to NOx.

Societal concerns over greenhouse gas emissions will exert a growing influence on the shipping industry. In effect, mandatory controls on carbon dioxide (CO2) emissions from ships are set to be implemented at the start of 2013 through the Energy Efficiency Design Index (EEDI) and the Ship Energy Efficiency Management Plan (SEEMP).

The EEDI, applicable to newbuild bulkers, tankers, gas carriers, containerships, general cargo carriers and reefer vessels contracted or laid down from 1 January 2013 onwards, is the IMO’s technical instrument for regulating greenhouse gas emissions from shipping through design and engineering measures. The index is basically a measure of grams of CO2 deriving from all shipboard machinery relative to tonne-miles (nautical miles) of transport work.

Solutions for improving the EEDI include a reduction in installed power, through lower ship speed and/or improved hull and propeller hydrodynamic efficiency, use of optimised or ’tuned’ engines with a lower specific fuel consumption, use of low carbon fuels including LNG, and adoption of innovative energy technologies, such as waste heat recovery systems.

While vessel speed reduction and engine de-rating is an attractive option in meeting EEDI targets, and is a trend much in evidence in the containership sector, cutting speed is invariably not a commercially viable option in certain spheres, not least in ro-ro and ferry trades, where transit time performance has a signal bearing on competitiveness. These and other types of vessel will be encompassed by subsequent implementation phases for EEDI.

Technology-based measures and an integrated approach to overall energy efficiency in optimised ship design will hold ever-greater sway. Higher volume production of the more advanced equipment and systems could gradually reduce the capital expenditure premium, making for faster payback times.

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