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Kraftwerke Mainz-Wiesbaden AG + Wärtsilä

Reference case

Flexible combined heat and power (CHP) plant supporting the green energy future in Germany

Germany’s ambitious plan for its energy transition, the “Energiewende”, offers the country’s energy producers new revenue-adding avenues for renewable-friendly energy production. Less than an hour outside Frankfurt, the municipal energy producer Kraftwerke Mainz-Wiesbaden AG (KMW AG) recognised the benefits of greater flexibility in sustainable power production and invested in a balancing CHP power plant from Wärtsilä. 

KMW AG’s new flexible CHP power plant runs on natural gas and supplies the city of Mainz with 100 MW of power and 96 MW of affordable and efficient district heating – the latter reaching approximately 40,000 households. The new natural gas power plant sports 10 agile W34SG engines, which, together with the plant’s modular design, will allow KMW AG to operate on high efficiency at any load – a real benefit in Germany’s future decarbonised energy system.

A favoured technology for an optimised energy future

Through its new balancing solution, KMW AG is complying with the renewed Combined Heat and Power (CHP) Act, whereby Germany has committed to increase its share of electricity produced by CHP power plants to 25% by 2025. To meet this target, the act favours flexible and environmentally friendly engine-based CHP power plants.

By 2050, Germany aims to produce 80% of its energy through renewables, making its energy system more sustainable and drastically lowering greenhouse gas emissions. The intermittency of the renewable energy system shapes the pricing structure within the European Energy Exchange (EEX) and fluctuations in price determinants reward fast-acting generation for grid stability. With its new fast-starting power plant, KMW AG can sell its electricity to the EEX whenever pricing is favourable.

Power plant lifecycle optimisation that guarantees availability and reliability

KMW AG’s balancing power plant is delivered under an EPC contract together with a comprehensive 15-year power plant maintenance agreement that guarantees availability and reliability of the plant. Wärtsilä’s range of maintenance services include on-site support and online monitoring, which is conducted via Wärtsilä’s condition-based maintenance concept (CBM) combined with expert analyses. This way, the condition of the equipment is monitored, and maintenance needs are instantly identified, increasing the availability of the plant, and allowing for better predictability of operations. 

WhoKraftwerke Mainz-Wiesbaden AG
What100 MW flexible CHP power plant
HowEPC (Engineering, procurement & construction

This is what we achieved


MW of electrical output


MW of district heating output


households district heated in Mainz-Wiesbaden 

Unlike traditional CHP power plants based on coal-fired units or gas turbines, Wärtsilä gas engines can be started and stopped without limitations within just 2 minutes. This is our answer to the increasingly volatile power market that results from greater levels of renewable energy. It makes us the future partner of renewables.

Jörg Höhler, CTO at Kraftwerke Mainz-Wiesbaden AG

How we did it

Challenge icon


  • Profitable power generation in a market with increasing levels of renewables

  • Financial and timing risks in construction

  • Professional maintenance of the power plant over a long period of time

Solution icon


  • A ultra-flexible Smart Power Generation plant that allows for benefitting from volatile prices

  • Full EPC delivery

  • 15-year maintenance agreement that guarantees availability and starting reliability

Benefit icon


  • Reliable district heat and power supply to the city of Mainz and revenues from short-term trading

  • One EPC supplier with full responsibility for both timelines and costs

  • Guaranteed availability of power plant due to condition based monitoring

The main details

CustomerKraftwerke Mainz-Wiesbaden AG
TypeWärtsilä CHP flexible gas engine power plant
Operating modeCombined heat and power, operating in the reserve markets
Gensets10 x Wärtsilä 20V34SG
Total output100MW for power + up to 96MW for district heating
FuelNatural gas
Lifecycle solution A 15-year maintenance agreement with performance guarantees. The maintenance agreement also includes online monitoring and support.

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