MAN Energy Produces Largest Company-Built Cluster 5 SCR Converter

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The order from MITSUI E&S Co. is the first selective catalytic reduction (SCR) catalytic converter for an ammonia-ready engine and as an exhaust gas after-treatment solution, can reduce NOx emissions by 90%.

MAN Energy Solutions produced the Cluster 5 Double Layer SCR catalytic converter for customer and licensee, MITSUI E&S. It is ammonia-ready, and the company’s largest SCR unit built to date. With a diameter of 3,900 mm and a total weight of 28 metric tons, the Cluster 5 Double Layer will be ready for series production soon. A final inspection from MAN Energy and MITSUI confirmed the quality of the product prior to its initial delivery and, after a successful water-pressure test, the SCR was shipped from Dalian, China to Tamano, Japan.

MAN’s exhaust gas after-treatment systems, like the Cluster 5 SCR, enhance cruise ship and cargo ship performance through emissions reduction, cost-efficiency, and improved operation as well as a potential reduction in NOx emissions by 90%.

“As the very first SCR for an ammonia engine anywhere in the world, this is a historic moment. As the largest, high-pressure SCR we have ever built, this marks a new milestone for our business,” said Dr. Daniel Struckmeier, Head of Sales & License Turbochargers & Exhaust Gas Treatment APAC. “The new equipment also passed its Factory Acceptance Test without any major issues, and I congratulate everyone involved in this ground-breaking project.”


MAN Energy’s SCR control systems are directly integrated into the engine-control system and adjusted to the fuel-injection system and turbocharger. Control-system integration improves the efficiency and reliability of the connected system. Upon integration of the SCR and optimized control strategies, fuel-oil consumption can be saved by up to 2.5 g/kWh. The component is also IMO Tier III compliant and increases efficiency for urea consumption.

In February 2024, MAN Energy fulfilled a genset and SCR order for a 94-meter passenger cruise ship newbuilding. The MAN 21/31 Mk2 PLO genset came equipped with a low-pressure SCR system that also delivers NOx reduction rates by up to 90%, similar to the Cluster 5 model.

“The optimized MAN 21/31 Mk2 PLO GenSet improves fuel efficiency without additional costs and combines classic engine-design principles with innovative technology,” said Christian Kamm, Sales Manager Europe, Marine, MAN Augsburg. “The integrated SCR system will also ensure the protection of the pristine marine environments that this cruise ship will operate in.”

MAN Energy and MITSUI also recently collaborated on a 100% hydrogen load test for MAN’s B&W two-stroke ME-GI (gas injection) engine. The ME-GI engine was first tested with different loads and operating conditions before successfully completing a hydrogen combustion test up to 100% load. MITSUI confirmed a greenhouse gas emissions reduction of up to 95%—the remaining 5% originated from the pilot fuel used during testing.

“We have worked closely with MITSUI on this research project and are very happy with the results achieved,” said Bjarne Foldager, Country Manager, Denmark, MAN Energy Solutions. “This proves the advantages and the flexibility of two-stroke engine technology and means that we are now also prepared for the future, not only for hydrogen derivatives but also for hydrogen as a fuel. MAN Energy Solutions closely follows the market to keep track of any significant developments and this test is a noteworthy progression.”