Emissions Initiatives Pay Off

The environmental objectives set out in ClassNK’s Joint R&D for Industry Program continued to be realized through 2015, as long term projects to cut ship emissions through technical innovation reached fruition.

Initiated in 2009, ClassNK’s Joint R&D for Industry Program supports over 300 projects that address the key challenges facing shipping on safety and the environment. In line with the legislative timetable, the last 24 months have been particularly fruitful for initiatives involving vessel emissions.

The Program supports collaborative research with shipping companies, shipyards and marine equipment manufacturers, and has taken in everything from ship structures and hydrodynamics, to hull coating and voyage optimization. However, air emissions has been a major subject since the Program’s inception, with technical innovation representing the route to compliance with shipping’s environmental agenda.  

ClassNK participates across a range of projects focused on developing technologies required to address the advancing restrictions of NOx and SOx emissions. These cover selective catalytic reduction and exhaust gas recirculation for NOx reduction, exhaust gas scrubbers for SOx reduction, and dual fuel engines that minimize both types of emissions when running on gas.  

Exhaust Gas Recirculation

In recent months, results from NOx emissions projects within the Program’s framework have been especially prominent in the two-stroke marine engine segment. One milestone was reached in August 2015, when a 34,000 dwt bulk carrier for owner Shikishima Kisen K.K. from The Hakodate Dock Co., Ltd. became the first ship to feature a new low pressure Exhaust Gas Recirculation (EGR) system. 

The system, developed by Mitsubishi Heavy Industries Marine Machinery & Engine Co., Ltd. and Mitsubishi Kakoki Kaisha, Ltd., is believed to be the world’s first low pressure EGR that recirculates the exhaust gas from a turbocharger using a two-stroke marine diesel engine. Initial and running costs for low pressure EGR are lower compared to high pressure EGR systems.

The low pressure EGR, installed in a Mitsubishi 6UEC45LSE Eco B2 engine, meets IMO’s MARPOL Annex VI Tier III requirements to cut NOx from ships by 76 percent (compared to Tier II) in emission control areas for keels laid on or after January 1, 2016. The technology suppresses the NOx by changing the characteristics of engine combustion conditions. A decrease in oxygen in the scavenging air lowers the combustion temperature, in turn lowering NOx emissions. Part of the low pressure exhaust gas emitted is recirculated from the turbocharger outlet to a turbocharger intake, for after treatment by an EGR scrubber. 

Subject to evaluation in commercial operations, this system is destined for uptake by NYK Bulk & Projects Carriers Ltd., and for deployment in the wider ‘Tier III market’.

Two Strokes

As far as wider two-stroke engine applications are concerned, MAN Diesel & Turbo is proceeding with EGR systems development with licensees. Kawasaki Heavy Industries, for example, is trialing a combined emission reduction system including EGR and water emulsified fuel system on a pure car truck carrier newbuilding for K-Line, as part of a development project involving shipbuilder Japan Marine United. Meanwhile, Mitsui Engineering and Shipbuilding is developing EGR technology for slow speed engine application as part of collaborative efforts with NYK Line and Monohakobi Technology Institute.    

Given that only around 15 vessels driven by two-stroke engines are equipped to meet Tier III to date, with most operating on a trial basis, the efforts of ClassNK’s Joint R&D for Industry Program on developing EGR are invaluable to helping owners and operators meet emissions requirements.

SCR

An alternative method of meeting Tier III emissions restrictions while sticking with diesel is selective catalytic reduction (SCR). SCR is an after-treatment solution, through which NH3 derived from an injection of urea causes the NOx in the exhaust gas to react, forming H2O and N2 on the surface of the catalyst. 

Joint R&D for Industry Program research projects covering SCR technology have included certification methodology work, the performance of different types of catalysts, the influence of exhaust gas temperatures on SCR durability, sulfur content in fuel oil, trial NOx measurements, ammonia slip, installation and operations. In fact, as long ago as 2011, ClassNK provided the guidelines for the installation of SCR systems which summarize standard design specifications from safety aspects for using ammonia solutions or urea solutions as reductant agents. The Society has also issued several Statements of Compliance for SCR-fitted engines complying with the Tier III emission limits. 

MHI-MME itself already has a low pressure SCR system for the upstream installation of two stroke turbochargers, developed within the “Super-clean Marine Diesel” research project by the Japan Ship Machinery & Equipment Association (JSMEA). Earlier this year, ClassNK also verified that the SCR system developed jointly by Mitsui O.S.K. Lines, Namura Shipbuilding and Yanmar meets Tier III NOx limits, for three power generators of a MOL-operated oceangoing freighter for a demonstration test scheduled for 2016. 

Meanwhile, ClassNK issued a “statement of fact” covering SCR-fitted two-stroke engines manufactured by Hitachi Zosen and developed jointly with engine licensor MAN Diesel & Turbo in 2011. A 6S46MC engine was initially installed on a 38,000 dwt general cargo ship for onboard trial. The Hitachi Zosen solution received the Marine Engineering of the Year 2014 from the Japan Institute of Marine Engineering on July 27, 2015.

LNG

Two-stroke marine engines running on LNG can also meet Tier III requirements, by introducing lean-burn combustion to reduce peak temperatures and NOx emissions – without needing either SCR or EGR. Dual fuel engines of this type have been developed by Wärtsilä. On the other hand, two-stroke dual fuel engines featuring high-pressure gas injection (GI) need a combination of SCR and EGR to comply because they generate local high temperature peaks, increasing NOx emissions.

If recent product announcements have focused attention on NOx emissions from vessels running on two-stroke engines, this should not overshadow the four-stroke engine market, where Tier III choices are already mature. More than 500 ships are estimated to already be operating to its provisions. Here again, the options are EGR or SCR for marine diesel engines, or adopting the dual fuel/gas approach, although in this case it should be noted that Tier III-compliant DF four-strokes have been commercially available for many years.

Niigata Power Systems Co., Ltd., meanwhile, has a complete line of SCR systems for marine diesel engines ranging from 550 to 6,600 kW for main propulsion engines, with its first unit delivered nearly 20 years ago. ClassNK recently issued a “statement of fact” that the new and compact 28AHX medium-speed marine diesel engine combined with an SCR system from Niigata fully complied with IMO NOx Tier III Limits. 

Developments at Niigata are now focusing on compact SCR design solutions as part of the “Super-clean Marine Diesel” research project overseen by JSMEA.

Without Fear or Favor

In light of the fast developing options, ClassNK is striking the critical balance between in-depth involvement in R&D and its neutrality as an advisor on the technical choices facing owners. In short, its pivotal role includes the ability to step back and base its advice on different vessel operating profiles, outlining the pros and cons of each option without fear or favor.

The society note that SCR has a high NOx reduction rate of more than 90 percent with lower installation costs compared to EGR, except for large-sized engines such as main engines for VLOC, VLCC or large container carrier. However, they point out that SCR is a space-hungry option, and additional urea costs need to be factored in for the solution, which may cost more than the additional fuel consumed using EGR. SCR operation can also be limited by exhaust gas temperature, meaning that operation at low load may be difficult. 

ClassNK also weighs SCR’s need for performance spot-checking, intermittent maintenance or even replacement against the EGR’s need to discharge wash water from the scrubber and to dispose of the residue generated by the washwater treatment system.

“In summary, there is an initial cost issue on whether to select SCR or EGR to meet NOx restrictions, but the total cost effectiveness of systems depends on engine size, trade area, and the amount of time each individual ship spends operating within an ECA,” says Y. Shibata, General Manager of ClassNK’s Machinery Department.

NOX Emissions

NOx emissions progress commanded the marine technology news agenda through 2015, and the SOx emissions issue rumbles on in the run up to regulatory review at IMO, set to be completed by 2018, which will decide whether stricter global controls should apply from 2020 or 2025. For the moment 3.5 percent sulfur content is permissible in fuel oil used outside ECAs, but this is limited to 0.1 percent within ECAs unless alternative abatement technology is used. The global limit is set to be reduced to 0.5 percent, either from 2020 or 2025. 

Technical choices to meet these requirements are already clear, however, having been forced by the January 2015 deadline on SOx emissions within ECAs. The main body of owners operating within ECAs have chosen to run on more expensive fuel grades, although some have chosen the abatement technology that enables continued use of heavy fuel oil (HFO) via an Exhaust Gas Cleaning System (EGCS). A small number of operators have used the opportunity to construct newbuildings, making the more radical switch to gas.  

Uptake decisions may change once wider restrictions are applied, and here too ClassNK has been preparing for any eventuality.

It released the third version of its Guidelines for Gas Fueled Ships at the start of 2015, with its updated expertise closely associated with developments within the Joint R&D for Industry Program. Niigata, for example, completed development of a smaller DF engine in 2012 under the Program, while Daihatsu finished developing a four stroke DF marine engine in 2014.

Gas Engines 

In terms of gas engines fit for incoming SOx emissions restrictions, ClassNK’s expertise has also been deepened in the low-speed segment, where it has been supporting Diesel United Ltd., to develop a DF engine under license to Wärtsilä. Here, developments appear particularly exciting, given the growth potential offered by opportunities to import US shale gas into Japan. A full scale testing of a 6-cylinder (X72) Wärtsilä DF engine installed at DU’s Aioi Works began in February 2015, envisaged as being applicable to large LNG carriers.  

DU’s interest in low-speed DF solutions is also expected to expand its sales activities to engines such as the X62 type, with a focus on conventional bulk carriers as well. 
For shipping as a whole, however, the availability of sufficient quantities of low sulfur fuel is expected to remain an issue, with the uptake of exhaust gas scrubbers likely to become a mainstream solution. Accordingly, ClassNK released new Guidelines for Exhaust Gas Cleaning Systems (EGCS) in October of 2014, developed jointly with Japan’s National Maritime Research Institute (NMRI) to offer comprehensive explanations of the contents of the IMO guidelines. These cover open and closed loop EGCS solutions, and the hybrid approach that takes in both solutions.

In this case, ClassNK is again at the forefront of technical developments as far as EGCS solutions for global shipping are concerned. Within the Joint R&D for Industry Program, Mitsubishi Heavy Industries, Ltd. and Mitsubishi Kakoki Kaisha, Ltd. (MKK) are behind Japan’s first hybrid SOx scrubber system, which features both freshwater and seawater exhaust gas scrubbing. The freshwater system can scrub fuel with 3.5 percent sulfur content to meet the 0.1 percent sulfur content limit, while the seawater system scrubs to a level of 0.5 percent sulfur content fuel oil to comply with anticipated global limits.

MHI and MKK are installing systems on a 7,500 unit Pure Car Truck Carrier in a joint project with ClassNK, Kawasaki Kisen Kaisha, Ltd. (“K” Line) and Japan Marine United Corporation as part of ClassNK’s Joint R&D for Industry Program, with the ship’s delivery due in 2016. 

ClassNK has been supporting the safe installation and operation of the system onboard, as well as making use of data and experience gained from the research to support its certification and emission verification activities. 

Here again, therefore, ClassNK has positioned itself to offer detailed advice on the costing of the EGCS option, taking into account initial outlay, estimated savings over time compared to a switch to lower sulfur content fuels, and the payback period. In late 2015, the society notes that, while the decline in bunker pricing has challenged thinking on future investments across shipping, one of the interesting exceptions may be the EGCS. Although bunker prices have dropped, the difference in price between marine gas oil and heavy fuel oil has decreased though continue to exist, and so the principles of the EGCS case themselves remain unchanged.

World’s Smallest Wet Scrubber

The society has also been involved in an interesting project on EGCS solutions as part of the Joint R&D for Industry Program that merits separate mention, through which Fuji Electric is looking to develop the world’s smallest wet scrubber. The system features cyclone desulfurization, previously deployed in land-based exhaust gas cleaning, in a first marine application and is reckoned to occupy less than half the volume of alternatives. The system has been tested onboard ship, applying a one MW-class SOx scrubber for an auxiliary engine which satisfied prescribed specifications and performance.

If further evidence were needed of the priority given by ClassNK to the technical innovations required to limit pollution from ships, then it is worth noting that collaborative projects extend overseas. NYK Line, MTI, Alfa Laval and ClassNK have already teamed up with Singapore-based Nanyang Technological University and Sembcorp Marine Technology Pte. Ltd., to research EGCS technology. Moreover, emissions from ships were given priority in the MOU signed between ClassNK and the Maritime and Port Authority of Singapore early in 2015 covering joint R&D and technical innovation projects centered in the South East Asian hub. With regulations set to increase in scope, ClassNK will continue working with partners to help develop innovative solutions for the entire maritime industry.