Everllence has completed what it says is the world's first conversion of a B&W S90 two-stroke engine to dual-fuel methanol operation following sea trials of Cosco Shipping Lines' container vessel Cosco Shipping Libra.

The 20,000+ TEU container ship's 11S90ME-C engine was retrofitted to an 11S90ME-LGIM (Liquid Gas Injection Methanol) unit, according to the engine manufacturer.

Everllence PrimeServ — the company's after-sales division — partnered with Cosco Shipping Heavy Industry on the project, which covered engineering, project management, installation, commissioning, and sea trials.

As part of the development process, Everllence invested in a dedicated 4S90 testbed engine in Japan that was commissioned in early 2025. The testbed validated the S90 engine's methanol performance under real operating conditions, the company said.

"We're proud to support Cosco Shipping Lines and Cosco Shipping Heavy Industry — and the maritime industry as a whole — in taking this step toward decarbonising shipping," commented Michael Petersen, senior vice president and head of Everllence PrimeServ Denmark.

"This highlights Cosco Shipping Lines' role as a first mover and presents a practical path for reducing emissions from Everllence S90 engine vessels. It also showcases Everllence's capability to deliver large-scale retrofit projects."

Petersen noted that the company has completed 26 dual-fuel conversions with a larger pipeline across various alternative fuels.

Market potential

Looking beyond the Cosco Shipping Libra retrofit, Everllence believes the potential for further large-bore retrofits is substantial, with over 300 vessels worldwide currently equipped with S90-class engines and therefore potential candidates for similar conversions.

"While the journey toward full decarbonisation will require collaboration across the industry, this achievement demonstrates that large-scale conversions are both technically proven and commercially viable," Petersen added. "This opens a practical pathway towards accelerating the maritime energy transition together with our customers."