Wärtsilä, RINA roll out new dual-fuel propulsion concept

Finnish technology group Wärtsilä and classification society RINA have announced a novel propulsion design that aims to achieve “immediate compliance with IMO 2023 targets.”


As disclosed, the new design features Wärtsilä 31DF 4-stroke engines operating with LNG fuel. The system sees a single engine being used for both propulsion and electric power.

Courtesy of Wärtsilä

“At Wärtsilä we are committed to leading shipping into a new era of higher efficiencies, lower operating costs, and greater environmental sustainability. This cooperation project with RINA is fully in line with these ambitions, and we see this propulsion arrangement as being an important and value-adding option for the coming generation of newbuilds,” Lars Anderson, Director, Product Management & Sales Support, Wärtsilä Marine Power commented.

So far, the conventional approach in ship design was to use 2-stroke engines for propulsion and 4-stroke engines for electric power generation.

With the new arrangement, it will require two 4-stroke dual-fuel engines, with options for electric power back-up from batteries or a small dual fuel generator when the ship is idle. The power output of the engine is ranging from 4.6 to 9.6 MW, at 720 and 750 rpm. 

The design can achieve a reduction of up to 50% from the Energy Efficiency Design Index (EEDI) reference level value, the company claims.

Specifically, at current shipping speeds, the system performance of the new arrangement provides at least the same, or better efficiency than an equivalent 2-stroke design.

At slower speeds, it has the potential to reduce fuel consumption and emission levels even further.

Overall, the arrangement is considered to be easier and less costly than traditional 2-stroke propulsion systems. 

“The … Wärtsilä 31DF engine enables ship owners to reduce fuel costs, while at the same time being proactively prepared for the fuels of the future,” Antonios Trakakis, Greece Marine technical Director at RINA pointed out.

The project is part of Wärtsilä’s long-term sustainability goals to optimise the technological and operational aspects of the marine industry.

In April, the company introduced a combined engine plus selective catalytic reduction (SCR) packaged product, made to comply with China’s Stage II marine engine emission standard.

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The standard will apply to inland waterway, coastal, river-sea, channel and fishing vessels operating in most rivers and around China’s major harbour areas.

The product is expected to be launched to the market in the third quarter of 2021.