Wärtsilä will retrofit a platform supply vessel for ammonia propulsion

Finnish engine maker Wärtsilä will supply an ammonia dual-fuel engine, a fuel gas supply system and an exhaust after-treatment system for the retrofit.

PHOTO: Offshore platform supply vessel Viking Energy. Eidesvik

The offshore platform supply vessel, Viking Energy, is owned by the Norwegian shipping company Eidesvik Offshore and chartered to oil and gas major Equinor.

The conversion is expected to be completed in 2026, Wärtsilä added.

Fuelling ships with ammonia

The four-stroke engine can run on ammonia in addition to conventional marine fuels, according to Wärtsilä. It will be equipped with selective catalytic reduction (SCR) technology to reduce nitrogen oxide emissions from burning ammonia.

The fuel supply system includes a purge gas treatment system, which removes residual gases from fuel lines, tanks and other components where gas has accumulated. This process helps prevent the accumulation of ammonia in the fuel supply systems.

Purge gas treatments typically use nitrogen to flush out any remaining fuel in the piping, a process known as nitrogen purging. Since nitrogen is an inert gas, it stabilises the pipeline environment and reduces the risk of safety incidents.

Since ammonia is a hazardous and toxic substance, the engine features an additional safety measure known as an "ammonia release mitigation system." Wärtsilä explains that this system breaks down ammonia emissions into nitrogen and water, significantly reducing ammonia emissions to less than 30 parts per million (ppm).

“Due to the need for high cleanliness of the fuel, proper filtering upstream is installed and embedded in the system,” Wärtsilä added.

Need for pilot fuel

Ammonia as a fuel requires a pilot fuel, such as diesel, for ignition because its high auto-ignition temperature makes it difficult to burn readily or sustain combustion. Four-stroke ammonia engines may require as much as 30% pilot fuel.

By Konica Bhatt

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