Marzahn combined heat and power plant, Berlin

Commissioned in 2020, the Marzahn combined-cycle gas turbine power plant is an important milestone on the road to fossil-free energy generation in the German capital. It can alternate flexibly between full and partial load operations and thus balance out the fluctuations in the power grid that arise as renewable energies are fed into the grid. The Munich branch of PORR Civil Engineering was responsible for the main construction work for the power plant as well as the planning and turnkey construction of the block control room, the administrative building, the building that houses staff and storage facilities and the workshop, and the garage.

A logistical masterpiece
The central component of the plant is the power block, which houses the two turbine houses, the two transformer buildings, the boiler house, the feedwater pump house and the switching station. The project represented a major logistical challenge right from the start owing to the ambitious timetable, the need for concurrent planning and the numerous subcontractors at work simultaneously. The high occupational health and safety standards of the power plant operator Vattenfall were maintained at all times despite the complexity of the construction site. This meant that the lifting devices of the individual trades, some of which were working directly next to each other, had to be re-coordinated over and over again for safety reasons.

In addition to the foundation slabs for the steel structure, a turbine foundation, a turbine platform, two staircases reaching heights of up to 45m, and the switching station building that presented considerable geometric challenges were all erected in a very confined space. The towers for the staircases, which were constructed as climbing formwork, posed an especially high challenge for the civil engineering team. In deference to the tight schedule, very rapid-setting concrete was used. The staircase towers were also heated and covered with insulating frost mats over the weekends.

Complex turbine platform
The turbine platform is another masterpiece of civil engineering. It sits on six vibration dampers at a height of 15m, where it serves as the supporting structure for the turbine and the generator. An auxiliary structure was erected between the columns and transoms for the concrete pour. This structure was able to support a total of 45t of reinforcing steel, 170 built-in parts, and 280m³ of concrete. The high reinforcement ratio and installation tolerances of 10mm for the formwork and built-in parts meant that the reinforcements had to be inserted with the utmost concentration. In view of the high compressive strength requirements, a special concrete formulation was developed, which was tested in advance in a series of trials, and monitored with temperature sensors during concreting and subsequent hydration.