MAN Energy Solutions Logo
  • EN


    The future is dual-fuel



    Maximize return on your future fuel strategy

Scroll down

Committed to supporting a sustainable shipping industry

Our global team of experts is continually developing class-leading technologies that enable you to meet your environmental and commercial goals, as well as today and tomorrow’s regulatory standards.

Retrofitting a dual-fuel engine is one of the most effective ways to drive greater efficiency and profitability from your fleet. A dual-fuel conversion gives you the fuel flexibility to take advantage of optimal fuel prices; it can make sure your vessel complies with IMO emissions targets and can extend the operational lifetime of your vessel, which means a greater return for your investments.

Diesel to dual-fuel gas conversion

One of the biggest retrofit options is to convert an existing diesel engine to a dual-fuel gas engine. This enables you to switch between diesel and gas as necessary, to both reduce operational costs and take advantage of optimal fuel prices as they arise.

In addition, using alternative fuels, such as LNG, ethane, LPG, or methanol, mean you can greatly reduce SOx, NOx, CO2, and particulate matter, enabling you to comply with global environmental regulations, secure worldwide port access, and meet your own sustainability targets.

Watch all our MAN ExpertTalks on dual-fuel conversion

Learn more from our Retrofit Experts

By loading the video you agree to YouTube's privacy policy.

Load video

By loading the video you agree to YouTube's privacy policy.

Load video

By loading the video you agree to YouTube's privacy policy.

Load video

NOx reduction
More than
SOx reduction
More than
CO2 reduction

A retrofitted vessel generates 35 times less CO2 emissions compared to a new build vessel.

Pontus Berg, Executive Vice President, BW LPG Ltd

Read the full story

By loading the video you agree to YouTube's privacy policy.

Load video

The project scope of a dual-fuel conversion

The scope includes changes to the main engine, installation of a Fuel Gas Supply System (FGSS), and the installation of bunker tank(s) or integration into an existing gas cargo system. In addition, MAN Energy solutions can also provide turnkey solutions that include the FGSS.  


The following explanation is based on an LNG conversion.

Engine conversion

The engine conversion mainly consists of rebuilding existing engine parts to enable the installation of a gas safety system and a fuel injection system.

This includes exchanging the existing cylinder cover and fuel oil pipes, and adding gas injection valves, gas control blocks, and gas chain pipes. Additional parts may also need changing, which is determined by a detailed study of your engine.


As with any dual-fuel engine, to deliver efficient gas injection the conversion requires a complete Fuel Gas Supply System (FGSS). The main function of this, together with a Gas Valve Train (GVT), is to pressurize and vaporize LNG from liquid to gas by increasing the pressure to 300 bar and 45°C, so that it can be injected into the engine.

In recent years, MAN Energy Solutions has developed a Pump and Vaporizer Unit (PVU) that is interlinked with our main engine control system and forms a main part of the FGSS.

Bunker tanks or an integration

If the vessel does not already operate with gas as a cargo, bunker tanks for your chosen fuel will be required. This is an important decision and can be one of the project’s largest financial considerations.

Choosing the right bunker tank(s) depends on several factors, such as tank type, size, location, and price. If the vessel you are converting is a gas carrier, you can benefit from an integration to the existing cargo system.

The Retrofit Process in Detail

By loading the video you agree to YouTube's privacy policy.

Load video

By loading the video you agree to YouTube's privacy policy.

Load video

Performance outcomes

Once converted, your vessel will operate on the same principles as before, with the same operational profile and load responses as with an ME-C engine. The main benefits of converting to a dual-fuel engine are significantly reduced emissions, enhanced operational flexibility, increased sustainability, and greater long-term value.

Which vessel types can be converted?

Any ME-C engine with a bore size of at least 50 can be converted for dual-fuel operation.

It is also important that a parent engine exists, which is a reference engine that has the same specifications as the engine you wish to convert to. The technical specification of the engine is needed to prepare emission calculations and ensure class approvals.

If a parent engine does not already exist, it will have to be built before a conversion can begin. Alternatively, the existing engine output can be aligned to an already existing reference engine.

Read up on our latest news

Continue reading

  • Dual-fuel conversion
    pdf, 20548 KB
  • ME-GI/GIE pump vaporiser unit for LNG and ethane
    pdf, 3716 KB

Ready to start?

Are you looking to increase the efficiency, longevity, and profitability of your vessel with a dual-fuel retrofit conversion? Simply contact us and we’ll be in touch to start exploring your options.

Talk to our experts

MAN with red helmet working on product

Explore more topics