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Tuesday, March 16, 2021 

Rolls-Royce Power Systems has received EPA Tier 4 certification for its mtu propulsion systems based on the Series 4000 M65L 16-cylinder diesel engines.

The US EPA Tier 4 regulations are considered the most stringent emissions standard for marine applications, requiring the propulsion system to have very low particulate and nitrogen oxide emissions throughout its lifecycle. Rolls-Royce is working on EPA Tier 4 approval for additional cylinder variants of the mtu Series 4000 propulsion system and is gradually bringing them to market. Since 2018, Rolls-Royce has been offering the Series 4000 systems with IMO Tier III certification, which enables operation in special emission control areas (North American coast, Caribbean, North Sea and Baltic Sea).

Denise Kurtulus, head of marine business, said: "This means we have climbed to the king's class of emissions regulations with our engines for yachts and commercial vessels. I am pleased that we can now offer our customers these clean and powerful propulsion packages."

Rolls-Royce has successfully tested the system, which includes the engines and SCR exhaust aftertreatment, during test bench runs and around 10,000 hours of operation in ferries and tugs operated in the US by the San Francisco Water Emergency Transportation Authority (WETA) and Foss Maritime.

"Thanks to the great cooperation with our customers, we were able to collect the necessary data to reach this milestone. All voyages to date with the total of 10 mtu propulsion systems have been satisfactory. Customers can rely on our engines," said Christof von Bank, responsible for US marine sales.

Through further developments in the engines' turbocharging, combustion process and fuel injection, combined with the new mtu-SCR exhaust aftertreatment system, Rolls-Royce reduced NOx emissions by 75% compared to IMO II requirements and particulate emissions by 65% compared to EPA 3, without the use of a diesel particulate filter. Fuel consumption has been reduced compared to the previous generation of engines (to as low as 190g/kWh) and CO2-emissions correspondingly. For heavy-duty applications, Rolls-Royce increased engine power to up to 160kW/cylinder.

WETA is operating three high-speed ferries in San Francisco Bay with the new mtu propulsion systems, testing their emissions performance among other things. The 34-knot aluminium catamaran Pyxis, which entered service in 2019, was the first passenger ferry in the United States to field test the EPA Tier 4-compliant mtu engines. The largest tug shipping company on the US West Coast, Foss Maritime, has commissioned three of four new 82t bp escort tugs with EPA Tier 4-compliant mtu propulsion systems.

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