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Reduce your carbon footprint with the new MAN L21/31DF-M methanol GenSet

The maritime industry is decarbonizing and methanol is currently one of the leading fuels among the alternative fuel solutions. Following the market demand and rising interest, we hereby introduce the new MAN L21/31DF-M methanol GenSet - the first small-bore dual-fuel methanol GenSet in our portfolio.

MAN Energy Solutions in Frederikshavn, Denmark is home of the MAN L21/31DF-M, our first small-bore GenSet fueled by methanol.

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reduction of lifecycle greenhouse gas emissions possible with e-methanol
conventional L21/31 engines in service

Proven GenSet design

The foundation of this new engine is based on the current L21/31 GenSet and its well-proven technology, which has already accumulated more than 110 million operating hours, with thousands of engines in service.

Key benefits

  • Low-emission fuel

    This engine runs on methanol or conventional fuels. When powered by green methanol, it has the potential to reduce greenhouse gas emissions. The possibility to operate GenSets on green methanol as drop-in fuel further increases the fuel-flexibility.

  • Reliability and low fuel consumption

    The new engine type keeps up the reliability and low fuel consumption of the MAN L21/31, ensuring security of power supply and handling of load steps with confidence. The power range spans 1,000-1,980 kW which makes this auxiliary engine the ideal candidate for most merchant vessels.

  • Retrofit options

    A methanol conversion will be available as retrofit for existing MAN 21/31 GenSets with delivery from 2025 onwards.

Perfect design features for efficient and reliable operation

The L21/31DF-M comes with a cost-optimised, low-flashpoint fuel supply system which makes it a competitive solution. 

Furthermore, the port fuel injection (PFI) concept provides additional simplicity and an attractive capital outlay. And it is based on proven components. 

Long time between overhaul intervals will save you time and costs on engine maintenance and will give you additional flexibility for the planning of your maintenance slots.

MAN L21/31 engine rendering

Technical specifications

DescriptionMain data


210 mm
Stroke310 mm
Speed900 / 1,000 rpm (60 Hz / 50 Hz)
Output1,000 – 1,980 kW
Cylinder configurator5 – 6 – 7 – 8 – 9
Available fuelsHFO, MDO, MGO, LSFO, ULSFO, Biofuels, MeOH
Emission limitIMO Tier III with SCR after-treatment


Optimized port fuel injection

The port fuel injection (PFI) system uses a methanol injection nozzle installed outside the combustion chamber. This simplified design removes the risk of blocked nozzles in diesel mode and reduces investment costs thanks to its easy installation and integration with standardized components.

MAN SaCoS control system and cybersecurity


MAN SaCoS ensures fast and reliable data-transfer between the engine and the power management system in the control room by easy cable connection.

The engine control system is attached to the engine and features a user-friendly color display in multiple languages. The electric speed governor enables fast response.

Perfect match for MAN B&W ME-LGIM two-stroke methanol engine


The first MAN B&W ME-LGIM came into service in 2016. Since then, we have accumulated more than half a million running hours on methanol alone, which provides a solid base for new developments. The L21/31DF-M is a perfect match for this methanol-fueled propulsion engine.

What makes the new methanol-fueled MAN L21/31DF-M GenSet special? Watch our 3D engine animation to find out more about the working principles, and also the Port Fuel Injection system.

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Service solutions for your equipment

MAN PrimeServ offers a range of modernization solutions for optimizing the reliability, availability, and economic efficiency. MAN’s upgrade and retrofit solutions are tailor-made to customers’ specific applications and equipment.

Go to MAN PrimeServ


Are you ready for green methanol?

Newbuild or retrofit? What are the costs? What are the benefits? Take the lead in sustainable shipping by contacting us today!

Contact us

Continue reading

  • PrimeServ Assist Four-stroke Brochure
    pdf, 4140 KB

Inside the making of a methanol GenSet

With the first two-stroke dual-fuel MAN B&W ME-LGIM methanol engines propelling large container ships across oceans, MAN engineers from Holeby and Frederikshavn, Denmark, are now developing the ideal match for onboard power: a small-bore GenSet capable of running on conventional fuel, biofuels and green methanol
Read the full story

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Related News

Tuesday, February 6, 2024

MAN PrimeServ and C.C. JENSEN Sign Cooperation Agreement

Global agreement covers use of lube-oil units within marine and power retrofit segments that optimise environmental benefits

At a recent ceremony in Copenhagen, MAN Energy Solutions and C.C.JENSEN (CJC®) – the global leader in oil maintenance – signed a Cooperation Agreement regarding the promotion and sales of CJC products by MAN PrimeServ, MAN Energy Solutions’ after-sales division. Kim Kjaer, Global Segment Manager, signed the agreement on behalf of CJC; while Serghei Nastas, Head of PrimeServ Omnicare, Marine & Power, represented MAN Energy Solutions.

Kjaer said: “C.C. JENSEN and MAN Energy Solutions have had a strong and powerful technical cooperation for decades. A significant result of this relationship has been the development of solutions that have assisted our mutual customers in achieving clean and dry oil, in the process improving the reliability of oil and equipment, as well as reducing energy consumption and CO2 footprints. As a natural next step, we now add the mutual promotion of these CJC solutions. At C.C. JENSEN, we are very proud of the cooperation and see it as an important quality stamp.”

PrimeServ Omnicare, an MAN Energy Solutions aftersales product centre, is responsible for helping the PrimeServ network extend its service portfolio beyond the standard MAN Energy Solutions scope through concluding global agreements with various OEMs, such as C.C. JENSEN. The new Cooperation Agreement aligns with MAN Energy Solutions’ strategy of ‘Moving big things to zero’ as C.C.JENSEN’s product will, among other benefits, help improve the CII (Carbon Intensity Indicator) rating of marine vessels. 

Nastas said: “Our vision at PrimeServ Omnicare is to help our customers reduce the CO2 footprint of their existing assets by offering technical solutions from our partners that are simple to install and operate, and which have an immediate impact – both on the environment and customer budgets. With the C.C. JENSEN lube-oil filtration system, we have found such a solution. As part of a pilot phase during 2023, the market showed great interest in its solution and I look forward to continuing our good cooperation with C.C. JENSEN." 

Agreement terms

CJC has already collaborated on MAN PrimeServ retrofits for a considerable period of time, paving the way for even greater involvement now throughout the entire MAN Energy Solutions network. MAN Energy Solutions, with its excellent access to the marine and power markets, finds that CJC lube-oil units fit perfectly with its own decarbonisation strategy. 

The new agreement:

  • applies globally (excepting Brazil, Japan, Korea and Norway);
  • means CJC will offer local support to customers and MAN Energy Solutions;
  • will focus on the marine and power sectors.
About the product

The C.C. JENSEN lube-oil filtration system provides an innovative alternative to conventional separators for cleaning oil, offering significant cost savings through simple technology for maintaining lube oil in both two- and four-stroke engines.

Simultaneously, it lowers the environmental impact by reducing energy and oil consumption. The system not only fulfils OEM demands for cleanliness but also delivers a substantial reduction in fuel consumption and an improved CII rating, aligning perfectly with MAN Energy Solutions’ vision for a greener shipping industry.  

Typical drivers for retrofitting this new technology include significant savings of:

  • 97% in energy savings;
  • up to 60% reduction in oil consumption;
  • 99% reduction in lube-oil sludge.

About Omnicare

For over a century, MAN PrimeServ has been a leading provider of high-quality service solutions and technical support for all MAN equipment. Under the name Omnicare, MAN PrimeServ extends the same standard of service to equipment from non-MAN manufacturers with the goal of bringing simplicity, cost-efficiency, and improved environmental performance to its customers.


C.C.JENSEN – the global leader in oil maintenance with more than 70 years of experience – designs and manufactures CJC® offline oil-filtration solutions for the removal of particles, water, acidity and oil-degradation products (varnish) from hydraulic oils, lube oils, gear oils, diesel fuels, etc.

Kim Kjær –


  • PR CC Jensen Coop Agreement_EN
    PDF, 317 KB English


  • crop_011_SoMe-NORMANNfoto
    JPG, 449 KB English


Nils Søholt

Trade Press Marine

Group Communications & MarktingMAN Energy SolutionsTeglholmsgade 412450 Copenhagen SVDenmark

t +45 33 85 26 69

Available languages

Set course to net zero with methanol GenSets - MAN L21/31DF-M

Watch the recording of our MAN ExpertTalk, where we introduced our new engine type: the small-bore four-stroke MAN L21/31DF-M GenSet for methanol operation.

You can look forward to hearing about this new GenSet type, the Port Fuel Injection (PFI) concept, the fuel gas supply system and the possibility to operate these GenSets on green methanol and biofuel oils.

    Register now