Wärtsilä 31SG

The most efficient gas engine, Wärtsilä 31SG, is a four-stroke, spark-ignited, lean-burn gas engine generating set. With its world class open-cycle efficiency and unparalleled dynamic capabilities, it reduces environmental footprint and lowers the total cost of ownership.

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Wärtsilä 31SG gas engine generating set

Wärtsilä 31SG is well suited for baseload production, balancing renewables and industrial applications where reducing carbon emissions while producing reliable power is crucial. Its capability of fast starting and stopping and ability to run on sustainable fuels secures low emissions and high efficiency. It also meets the specific needs of combined heat and power (CHP) plants, for example steam generation, hot or chilled water or a combination of the above. Wärtsilä engine power plants can be delivered both as EPC and Equipment Delivery contracts.

Key benefits

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  • World-class open-cycle efficiency enabled by 2-stage turbocharging system
  • Synchronises with the grid within 30 seconds from start command
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  • Adaptability for various gas qualities
  • Capable of hydrogen blending
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  • Excellent load following capabilities
  • Cost efficient maintenance

Customer stories

  • Bremen, Germany

    Wärtsilä and Uniper enable a revenue-adding transition from coal to gas for public utility swb Erzeugung in Bremen, Germany. When delivered in mid-2022, the flexible CHP power plant will decrease swb’s CO2 emissions by up to 75%.

    Bremen, Germany
  • Benndale, Missisippi, USA

    Enabling an increase in variable generation with more flexible capacity that can rapidly start up when needed.

    Benndale, Mississippi, USA
  • DREWAG, Germany

    Wärtsilä’s state-of-the-art gas engine technology will provide flexibility and black start capability to DREWAG, the local utility company in Dresden, Germany. The combined heat and power (CHP) engine power plant will produce electricity and district heating simultaneously. Upon completion, it will be the only power plant that can restart the Dresden grid in case of a power blackout.

Our proudest numbers

30 sec

Power to grid 


Electrical efficiency


Electrical power

The details

Technical data

Engine generating set
Cylinder configurations20 V 
Cylinder bore310 mm 
Piston stroke430 mm 
Engine speed750 rpm (50 Hz), 720 rpm (60 Hz) 
 WÄRTSILÄ 31SGWÄRTSILÄ 31SG Efficiency optimised
Rated electrical power (kW)11 777 (50 Hz) 11 377 (60 Hz)10 798 (50 Hz) 10 396 (60 Hz)
Electrical efficiency (%)51.5 (50 Hz) 51.6 (60 Hz)52.2 (50 Hz) 52.3 (60 Hz)
Heat rate kJ/kWh6 986 (50 Hz) 6 971 (60 Hz)6 901 (50 Hz) 6 886 (60 H)
Loading and unloading
 Connected to gridFull load
Regular start time (min:sec)00:30< 5
Fast start time (min:sec)00:30< 2
Stop time (min)< 2
Ramp rate (hot, load/min)> 100%
Minimun Load
Unit level10%
Plant level1%

Product leaflet

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Build your own power plant







> 500MW

Liquid fuels

Natural gas

Liquid fuels and gas

Flexible baseload (>6000 running hours annually)

Intermediate load (2000 - 6000 running hours annually)

Peaking and grid stability (<2000 running hours annually)


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