Wärtsilä 31SG gas engine

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 of the Wärtsilä 31SG gas engine

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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%.

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    Bremen, Germany
  • Benndale, Missisippi, USA

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

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    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 be the only power plant that can restart the Dresden grid in case of a power blackout.

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    DREWAG_ (1920 x 690 px)

Our proudest numbers

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Power to grid 


Electrical efficiency


Electrical power

Technical data of the Wärtsilä 31SG gas engine

Wärtsilä 31SG gas engine generating set 
Cylinder configurations20 V  
Cylinder bore310 mm  
Piston stroke430 mm  
Engine speed750 rpm (50 Hz), 720 rpm (60 Hz)  
Performance * 
 WÄRTSILÄ 31SGWÄRTSILÄ 31SG Efficiency optimisedWÄRTSILÄ 31SG Balancer
Rated electrical power (kW)11 777 (50 Hz) 11 377 (60 Hz)10 790 (50 Hz) 10 389 (60 Hz)12 762 (50Hz) 12 372 (60Hz)
Electrical efficiency (%)51.5 (50 Hz) 51.6 (60 Hz)52.0 (50 Hz) 52.1 (60 Hz)50.2 (50 Hz) 50.4 (60 Hz)
Heat rate kJ/kWh6 986 (50 Hz) 6 971 (60 Hz)6 922 (50 Hz) 6 907 (60 H)7 165 (50 Hz) 7 142 (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% 
Minimum Load 
Unit level10% 
Plant level1% 
* Rated electrical power and electrical efficiencies are given at generator terminals at 100kPa ambient pressure, 25°C suction air temperature and 30% relative humidity, and without engine driven pumps. Power factor 1.0 (site). Electrical efficiency and heat rate with 5% tolerance. Site conditions, fuel and applicable emission limits may have an impact on performance figures. Please contact Wärtsilä for project-specific performance data. Emission figures for LBF must be evaluated case by case. Catalyst systems are designed based on project specific requirements. Certain fuel components are poisonous for catalyst elements. Maximum amount of these components to be limited in the fuel in applications where catalyst system is installed.
Disclaimer: The information contained herein is provided for informational purposes only and may not be incorporated, in whole or in part, into any agreement or proposal. No representation of any kind is made in respect of any information contained herein and Wärtsilä expressly disclaims any responsibility for, and does not guarantee, the correctness or the completeness of the information. The calculations and assumptions included in the information do not necessarily take into account all the factors that could be relevant in a particular case. Information herein shall not be construed as a guarantee or warranty of the performance of any Wärtsilä technology, equipment or installation.


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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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