swb Erzeugung + Wärtsilä

Reference case

Flexible combined heat and power plant (CHP) enabling coal phase-out in 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%.

Flexible CHP for a decarbonised energy system

The public utility swb Erzeugung is paving the way for renewable generation by replacing an old coal-fired combined heat and power (CHP) plant with flexible gas generation. The new CHP power plant will be connected to the district heating network of the city of Bremen and feed electricity to the German grid to balance out renewable energy sources.

Powered by the latest Wärtsilä technology, the new CHP gas engine power plant offers heat and flexible baseload in the winter and shaves peaks in energy demand in the summer, all the while making great economic sense for its owners.

The natural gas power plant will be run by nine Wärtsilä 31SG gas engine generating sets and a Wärtsilä heat recovery system. The W31SG engine has the highest electrical efficiency and fuel economy on the market, while also offering fuel flexibility for an optimised energy future. Thanks to its modular design, the engine power plant runs with outstanding performance at any load, both in CHP and power-only mode. The modular design also significantly reduces the plant’s maintenance time and costs, improving its availability and reducing the need for spare parts.

A tailored lifecycle solution for power plants

The Bremen power plant is delivered under an EPC contract with a three-year Wärtsilä Guaranteed Asset Performance agreement, which guarantees the performance of the engines and auxiliary equipment, and comprises all power plant maintenance services including spare part supply. Part of the energy service agreement is training swb personnel, and swb has the option to extend the agreement for seven more years of shared maintenance with Wärtsilä. Safe plant operation is further supported by Wärtsilä’s digital asset diagnostics and remote capabilities, such as monitoring and analysis. 

This is the third ca 100-MW CHP power plant Wärtsilä delivers to Germany. Wärtsilä has a strong presence in Germany with 1.300 employees across nine locations in the country. 

WhoSWB Erzeugung
What105 MW flexible CHP power plant
HowEPC (Engineering, procurement & construction)



This is what we are achieving


MW of electrical output


MW of district heating output


reduction in swb's CO2 emissions

Efficient and sustainable power and heat generation is extremely important, both for our company and for the German energy sector in general. We are going to replace an outdated coal burning plant with a modern, clean, reliable and extremely efficient solution, which will provide the flexibility needed today.

Dr. Torsten Köhne, Chief Executive Officer, swb Erzeugung GmbH & Co. KG, Bremen

How we did it

Challenge icon


  • Requirement for quick response to the volatile day-ahead and intraday electricity markets
  • Need to ensure power plant performance and optimise its maintenance
  • Demand for flexible heat and energy generation to balance renewable energy sources
  • Commitment to environmentally friendly and profitable gas generation to replace old coal-fired power plant
Solution icon


  • Ultra-flexible gas engines, capable of reaching full load within a few minutes
  • A 3-year Wärtsilä Guaranteed asset performance agreement, including all maintenance services and remote support
  • Wärtsilä 31SG engines with the highest efficiency and fuel economy on the market
  • Multi-unit Wärtsilä CHP power plant with high operational flexibility
Benefit icon


  • Maximising revenue with power plant capable of being dispatched exactly as needed
  • Guaranteed engine and auxiliary equipment performance and optimised maintenance costs
  • Reducing environmental footprint and lowering total cost of ownership
  • Flexible generation, allowing efficient heat and energy production at any load

"This new plant will reduce our CO2 emissions by 550 000 tons per year - you would have to plant 40 million trees to get the same effect"

Coal phase-out is imperative in order to fight the climate crisis. In this video Sushil Purohit, President of Wärtsilä Energy, and Dr. Torsten Köhne, CEO of swb Bremen, discuss how the new combined and heat power CHP plant will bring the balance needed between costs, efficiency, reliability, availability and climate protection.

The main details

Customerswb Erzeugung GmbH und Co KG
Consortium leaderUniper
TypeWärtsilä CHP flexible gas engine power plant
Operating mode Flexible baseload in wintertime, flexible peak load in summertime
Gensets9 x Wärtsilä 31SG
Total output105 MW for power + up to 93 MW for district heating
Fuel Natural gas
Lifecycle solutionA 3-year Guaranteed asset performance agreement with an option for seven more years
Bremen, Germany

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