Wärtsilä 31SG Balancer gas engine

The Wärtsilä 31SG Balancer is a four-stroke, spark-ignited, lean-burn gas engine generating set. It is designed to provide flexible grid capacity even in adverse weather conditions and enable renewables to perform as the lowest-cost, most resilient power source for grids worldwide.

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Wärtsilä 31SG gas engine generating set

The Wärtsilä 31SG Balancer gas engine offers 8% more power and over 50% efficiency, lowering the cost and risk of the renewable transition through flexible, resilient capacity. The new engine technology is designed to provide power producers with fast-ramping balancing power, which can be scaled up as the share of renewables in power systems increases. The engine can start and ramp up rapidly to support intermittent renewable generation so that the lowest cost cleanest energy technology can become the dominant power source.


Key benefits of the Wärtsilä 31SG Balancer gas engine

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  • Lowers your cost per kW with 8% more power, you need fewer engines to meet demand
  • Fast starting and loading capabilities: connects to grid in 30 seconds and reaches full load in 2 minutes
  • Runs on natural gas, biogas, synthetic methane and is capable of hydrogen blending
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  • Simplified plant construction for cost-efficiency
  • Integrate a growing number of renewables with scalable and intelligent plug and play modules
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  • Optimised maintenance to ensure safe and reliable operations. 
  • Guaranteed Asset Performance
  • Optimised performance and reliability supported by Wärtsilä Lifecycle solutions

Cost-efficient and fast plant construction

With our cost-efficient plant construction based on prefabricated, high-quality power plant modules, you can start generating power faster. The design allows you to pick and choose the desired functionality and equipment based on your project need.

The heart of the plant is the power unit that consists of the engine and the essential equipment. This can be installed on location in days instead of weeks to start generating power more quickly for lower costs and faster ROI. The power unit can be complemented with process modules that enable easy integration of auxiliary equipment, process media, and filtration. We also provide electrical modules that enable integration of the low voltage and medium voltage systems.


Wärtsilä 31SG Balancer plant environment

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Power to grid 


Electrical efficiency


Electrical power

Technical data for the Wärtsilä 31SG Balancer gas engine

Wärtsilä 31 SG Balancer gas engine generating set
Cylinder configurations20V
Cylinder bore310 mm
Piston stroke430 mm
Engine speed750 rpm (50 Hz), 720 rpm (60 Hz)
Performance *
 Wärtsilä 31SG Balancer
Rated electrical power (kW)12 762 (50Hz) 12 372 (60Hz)
Electrical efficiency (%)50.2 (50Hz) 50.4 (60Hz)
Heat rate (kJ/kWh)7 165 (50Hz) 7 142 (60Hz)
Loading and unloading
 Connected to gridFull load
Regular start time (min:sec)00:30< 5:00
Fast start time (min:sec)00:30< 2:30 
Shut-down time (min)< 2
Ramp rate (hot, load/min)> 100%
Minimum Load
Unit level10%
Plant levelEqual to minimum load of one unit
* 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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