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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

Thursday, February 15, 2024

MAN 21/31 Mk2 PLO GenSets for Antarctica Cruise Ship

Chilean tour operator, Antarctica21, chooses MAN engines once more for diesel-electric set-up for new 94 metre newbuild; follows similar ship from 2019 with same engine type

Chilean shipbuilder, ASENAV (Astilleros y Servicios Navales S.A.), has ordered 4 × MAN 6L21/31 Mk2 PLO (Part-Load Optimised) GenSets for a 94-metre, passenger cruise-ship newbuilding for Antarctica21, the world’s leading provider of air-cruises. The ‘Magellan Discoverer’ will be slightly larger than a similar ship in the Antarctica21 fleet, the ‘Magellan Explorer’ from 2019, which has the same engine type installed and can also boast of a PC6 polar-ice classification.

ASENAV is the largest private shipyard on the Pacific and Caribbean coasts, adding significant value when promoting MAN engines aboard notable vessels all across America.

Each GenSet will come integrated with MAN Energy Solutions’ proprietary LP-SCR (Low-Pressure Selective Catalytic Reduction) system that delivers NOx-reduction rates of up to 90% in fulfilling the latest IMO environmental requirements. The engines will be built at MAN Energy Solutions’ facility in Aurangabad, India where a very compact RAMME PM (Permanent Magnet) alternator will also be integrated.

Jaime Vásquez, President of Antarctica21, stated: “We are delighted to reaffirm our partnership with MAN Energy Solutions Chile by selecting the 21/31 Mk2 PLO engine for our new polar vessel. This engine sets the standard for the lowest fuel consumption in its category. Our continued trust in MAN Energy Solutions after-sales service in Chile, renowned for its reliability and expertise, reinforces our decision.”

Gerardo Schneeberger – Head of Sales, Chile – MAN Energy Solutions, said: “We are very proud of this repeat order by Antarctica21 at ASENAV for MAN 21/31 engines. This displays great trust in MAN technology and further cements the solid foothold that our small-bore, four-stroke, medium-sized engines have established in the Chilean market. The unique capabilities offered by PrimeServ Chile’s 24/7 service within all Chilean territories have also been key to winning this order.”

Christian Kamm – Sales Manager Europe, Marine – MAN Augsburg, said: “The optimised MAN 21/31 Mk2 PLO GenSet improves fuel efficiency without additional costs and combines classic engine-design principles with innovative technology. The integrated SCR system will also ensure the protection of the pristine marine environments that this cruise ship will operate in.”

MAN 21/31 engine

The MAN 21/31 Mk2 PLO engine maintains a significantly reduced fuel-consumption (up to 9 g/kWh@75% MCR) with the longest times between overhaul in its class. It also comes equipped with MAN’s modern Safety and Control System (SaCoSone). Furthermore, the Mk2 engine is capable of burning conventional fuels like HFO/LSFO, MDO and MGO, complying with new ISO 8217:2024 fuels, as well as sustainable fuels like biodiesel FAME and HVO-100.

The 21/31 Mk2 PLO engine is designed as ‘methanol-ready’ with ‘Approval in Principle’ from the DNV classification society for retrofit to methanol operation as a green fuel at a later date, should it be required.

Originally designed in 2000/2001 with the goal of providing a compact and robust engine, the 21/31 engine is characterised by its easy installation and maintenance. To date, between ordered and delivered engines, the 21/31 has accumulated sales of some 2,750 units.

The MK2 PLO GenSet was introduced to the market in spring 2023 and has already made some 30 sales, especially within the offshore wind and cargo/passenger ferry segments.

About Antarctica21

Antarctica21 specialises in fly-and-sail expeditions to the White Continent. The company was founded in 2003 by adventurers who believed there was a better way to travel to the Antarctic Peninsula. Before Antarctica21, travellers who wanted to reach the Peninsula had only one option: a two-day cruise across the notoriously rough seas of the Drake Passage. Since then, however, the company’s boutique expeditions have offered a more comfortable alternative. A two-hour flight takes guests from Punta Arenas, Chile, directly to King George Island, where they then board their expedition ship. No stormy crossing. No seasickness. Just quick, total immersion in the Antarctic experience. The company’s ships accommodate a maximum of 76 guests, offering flexibility and access that larger vessels can’t match. Guests embark and disembark efficiently, so time ashore is focused on savouring every moment of a travel experience unlike any other.


  • PR 21.31 Antarctica21 cruise_EN
    PDF, 283 KB English


  • 6L2131MkIIPLO_GenSet_original
    JPG, 335 KB English
  • Antartica21_Magellan2_Exteriorior
    JPG, 721 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