Energy of the future

Higher efficiency, less CO₂, greater independence: Salzgitter Flachstahl had good reasons for the fundamental renewal of its 70-year-old power plant and power supply grid.
A company like Salzgitter AG very thoroughly calculates and debates alternatives before undertaking investments to the tune of hundreds of millions of euros. But when it came to the comprehensive modernization of the power plant in Salzgitter, all the experts quickly agreed: It's worth it! The investment would increase the power plant's efficiency from 30 to 40% and reduce dependency on external power companies.

In 2006 the most important large aggregates, two new power plant units, each with just under 100 MW net electrical capacity, were completed after an old turbo generator had already been replaced by a new one. At the same time, the Salzgitter Flachstahl power supply grid was fundamentally renewed in work that lasted until 2010. At the commissioning, Michael Bock, head of Salzgitter Flachstahl GmbH energy operations, said, “Due to the improved efficiency, we are now generating an additional 350,000 MWh a year with the power plant. This is electricity that we previously had to buy externally." This means that the project benefits both the company and the environment. "Because the Salzgitter Flachstahl power comes practically completely from the cupola furnace gases generated during steel production and originating in the coking plant, blast furnace and steel mill, we are significantly reducing CO₂ emissions while cutting electricity purchases: calculated against Germany's national energy mix, this is around 200,000 t CO₂ each year," say Dr. Jens Traupe, head of Salzgitter AG's Environmental Protection and Energy Policy Department.

The old power plant went online in 1940. With its five stacks, it has been a landmark in Salzgitter ever since and has long been a protected monument. But naturally the power plant was modernized a number of times through the decades. Nowhere is the interaction of old and new more obvious than in the grid command center: Until the futuristic new headquarters were commissioned, the 70-year-old control center was still in operation with its instruments and displays that are more reminiscent of a silent movie such as "Metropolis" than a 21st century command center. But it functioned perfectly to the end.

The power plant is the motor that drives the Salzgitter plant. After the new power plant units had been commissioned, the total electricity produced in the City of Salzgitter amounted to some 1.2 million MWh, which would be enough to supply a large city such as Braunschweig with its 250,000 inhabitants.
The production of process steam for the drive units of the blast furnace blowers, the vacuum systems in the steel mill, and the gas exhauster in the coking plant is almost more important for energy extraction than generating electricity. A total of around 1.5 million tons of steam per year are exploited to produce energy. On top of that, the power plant supplies the City of Salzgitter with long-distance heat.
As part of the investment program, Salzgitter Flachstahl GmbH's 70-year-old power supply grid was also fundamentally renewed and converted to 110 kV. Henning Schmidt, head of the power plant, names the measure's benefits. "These are reduced power transformation losses thanks to modern transformers and a grid with greater stability."

Ulrich Grethe, Chairman of the Salzgitter Flachstahl board and member of the group management, concludes positively, "By renewing the key units and the power distribution network, we took a forward-looking path that reduces dependency on external power suppliers and allows economic objectives that would have been inconceivable without these measures."