Mannheim, July 13, 2017 The cogeneration power plants that “Energie & Management” magazine designates as “cogeneration power plant of the month” are highly innovative as well as economically and ecologically efficient. However, only few of them require as much planning skill as the cogeneration power plant in the former “Engelsburg” air-raid shelter in Lübeck’s borough of St. Lorenz-Süd. The building that had been built as a shelter in the early 1940s and that is also known as “Engelsburg” (Angel’s Castle) was purchased by Stadtwerke Lübeck in 2015. By setting up another cogeneration power plant in the “energy bunker”, the Hanseatic city has expanded its cogeneration park to a total of 11 CHP plants. Stadtwerke Lübeck has thus come closer to its goal of generating about 50 percent of the power sold from eco-friendly, regenerative energy sources and energy-efficient combined heat and power generation by 2020. The energy supplier’s heat network currently supplies about 250 buildings and institutions in the region with heat energy. All of the eco-friendly CHP power is fed into Lübeck’s medium-voltage grid.

Cogeneration Power Plant Construction Represents Challenge for Planners and Installers

The conversion of the massive graded air-raid bunker into a cogeneration power plant was very difficult in terms of the construction planning and implementation. For example, concrete walls with a thickness of 2.5 m had to be penetrated in order to provide access and ventilation slots for the CHP (combined heat and power) plant. The openings that were cut from the exterior wall using a diamond saw yielded about 25 m³ of concrete rubble. The curvature of the exterior wall was another challenge for the installation of the combined heat and power plant in the Engelsburg, as all cable ducts and pipes had to be adapted to this structure.

To satisfy the requirements for graded buildings, it was also necessary to minimize the openings and limit them to one side of the energy bunker. Moreover, the three exhaust flues were merged, and chimneys were erected on the roof of the about 75-year-old round bunker.

High Flexibility of the Cogeneration Power Plant Ensures Maximum Energy Efficiency and Security of Supply

A natural gas-powered MWM TCG 2020 V20 gas engine with an output of 2.2 MW_el and 2 MW_th forms the core of the new CHP plant. The cogeneration power plant is supported by two natural gas boilers, an electric boiler, and two heat storage units. In this way, the flexibility of the power and heat generation and the security of the energy supply have been optimized.

Meanwhile, the district heat network of Lübeck’s municipal utility provider comprises 11 MWM gas engines with a total output of about 17 MW_el.

The energy bunker cogeneration power plant is set to go live this year. The natural gas-fired power plant is designed for about 6,000 operating hours a year, feeding in approximately 12 million kWh of electrical energy into Lübeck’s power grid. With the installed boilers, the cogeneration power plant will also supply the district heat network with about 20 million kWh of heat energy a year. The MWM cogeneration power plant in Lübeck has truly deserved the title “cogeneration power plant of the month June 2017” – not only because the state-of-the-art combined heat and power plant has been set up in a historical air-raid shelter, but also due to the precise installation, the extensive planning prior to the installation, and the high flexibility of the energy-efficient power plant.

Further Information

• MWM cogeneration power plants and CHP plants
• MWM TCG 2020 gas engine
• Press release: Energy Bunker in Lübeck – Distributed MWM Cogeneration Power Plant in Former “Engelsburg” Air-Raid Shelter Generates Eco-Friendly Energy
• Reference case: Stadtwerke Lübeck, Germany
• Cogeneration
• “Energie & Management” magazine: Cogeneration power plant of the month June 2017: Stadtwerke Lübeck further expands its cogeneration power plant park with a view to maximum flexibility (German)