PRESS RELEASE Commercial Marine

Rolls-Royce launches new flexible mtu exhaust gas aftertreatment system for ships

Posted on September 10, 2025

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  • mtu Flex SCR enables yachts, tugboats, and ferries to enter emission-controlled areas
  • Space requirements of the new SCR generation reduced by 42%, weight by 40%, LCC by 15%
  • Launch in combination with mtu 16V 4000 M65L engines, further versions to follow

Rolls-Royce is now introducing new, even more flexible and compact exhaust aftertreatment systems in combination with the 16-cylinder mtu Series 4000 engine for yachts, tugs, and ferries. The new generation of mtu SCR (selective catalytic reduction) systems requires up to 42 percent less space and weighs almost 40 percent less. Further advantages include an increased service life of the ceramic SCR material (substrate) to 18,000 operating hours (depending on the load profile) and a 15 percent reduction in life-cycle costs. Rolls-Royce will gradually offer the new generation of the mtu Flex SCR system for other mtu engines as well.

“This modular new exhaust aftertreatment system can be even better tailored to the specific needs of our customers and offers them many advantages for their voyages in emission-controlled areas,” explained Denise Kurtulus, Senior Vice President Global Marine at Rolls-Royce Power Systems. Rolls-Royce has set itself the strategic goal of supporting its customers in their business with sustainable and efficient solutions.

Ships with integrated propulsion systems (mtu engines and SCR systems) in the power range between 2,176 and 2,560 kilowatts can be operated in areas with particularly strict emission controls (IMO Tier III). IMO Tier III emission control areas (ECAs) include, for example, the Baltic and North Seas and the North American coast. The mtu SCR system reduces nitrogen oxide emissions by 75 percent compared to IMO II limits.

Rolls-Royce offers its customers maximum installation flexibility: Compared to the previous mtu system, ship operators can save up to 42 percent space with the new Flex SCR. The components can be installed horizontally, vertically, upright, or suspended in the engine room, depending on requirements. Rolls-Royce has also reduced the weight of the new exhaust aftertreatment system by almost 40 percent compared to the previous mtu Cube Box product.

In terms of flexibility, shipyards and ship owners also benefit from the ability to switch the dosing of the reducing agent on and off. This may be the case when they are traveling from one emission-regulated area to another. It is the proven actively controlled system in which emissions are continuously measured upstream and downstream of the SCR system. This ensures optimal and compliant operation of the exhaust aftertreatment system and minimal dosing of the required reducing agent.

About Rolls-Royce Holdings plc

  1. Rolls-Royce is a force for progress; powering, protecting and connecting people everywhere. Our products and service packages help our customers meet the growing need for power across multiple industries; enable governments to equip their armed forces with the power required to protect their citizens; and connect people, societies, cultures and economies together.
  2. Rolls-Royce has a local presence in 48 countries and customers in over a hundred more, including airlines and aircraft leasing companies, armed forces and navies, and marine and industrial customers. 
  3. Through our multi-year transformation programme, we are building a high-performing, competitive, resilient and growing Rolls-Royce. We are building the financial capacity and agility to allow us to successfully develop and deliver the products that will support our customers through the energy transition.
  4. Annual underlying revenue was £17.8 billion in 2024, and underlying operating profit was £2.46 billion.
  5. Rolls-Royce Holdings plc is a publicly traded company (LSE: RR., ADR: RYCEY, LEI: 213800EC7997ZBLZJH69)5.
  6. Rolls-Royce Power Systems is headquartered in Friedrichshafen in southern Germany and employs more than 10,350 people. The product portfolio includes mtu-brand high-speed engines and propulsion systems for ships, heavy land, rail and defence vehicles and for the oil and gas industry. The portfolio also includes diesel and gas systems and battery containers for mission critical, standby and continuous power, combined generation of heat and power, and microgrids. With its climate friendly technologies, Rolls-Royce Power Systems is helping to drive the energy transition.

www.rolls-royce.com

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