Advising on and Designing the Electrical Engineering for Salzgitter Flachstahl’s SALCOS® Program
Electrical Engineering for Green Steel Production
Salzgitter Flachstahl GmbH aims to reduce the CO2 footprint of its steel production by up to 95 percent by the end of 2033. It wants to have products from this route on the market in 2026. The necessary adjustments to the steelworks are being made as part of the SALCOS® (Salzgitter Low CO2 Steelmaking) program. This includes the development of climate-friendly process engineering and a new energy supply, because green steel needs green electricity – lots of green electricity. Fichtner is supporting Salzgitter Flachstahl not only in civil engineering, but also in the design of the power grid, which has to be restructured for this purpose, and the planning of electrical installations.
The SALCOS® program from Salzgitter Flachstahl GmbH aims to produce steel with almost no CO2 emissions. This is made possible by direct reduction plants in which iron ore is reduced to sponge iron using hydrogen. Immense quantities of hydrogen are required for this, some of which is to be produced on site in a climate-friendly way through electrolysis. The electrolysis requires electricity. In addition, the metallurgy needs to be switched from conventional converters to electric arc furnaces (EAF) in order to process sponge iron – and this requires much more electrical energy. The plant’s power demand is therefore rising sharply.
Instead of using coal, as is currently the case, iron ore can also be reduced using hydrogen. The resulting “green” sponge iron has an iron content of up to approx. 95 percent.
(Picture: Salzgitter Flachstahl)
The Production of Green Steel Requires a Lot of Green Electricity
In order to cover part of the power demand by climate-friendly means, Avacon Natur GmbH has erected and operates seven wind turbines with a total capacity of 30 MW for Salzgitter Flachstahl on its company premises. The steelworks also (already) draws electricity from TenneT’s transmission grid. The power grid needs to be adapted so that the electrical energy can reach the large consumers in the plant. This is because around 400 MVA more power will need to be made available after completion of only the first SALCOS® phase in 2026, when around 30 percent of steel production will be CO2-free. This additional capacity is roughly equivalent to the electrical connected load of 20,000 single-family homes.
Salzgitter Flachstahl’s energy operations division had already developed ideas for expanding the plant’s power grid and the feed-ins from the power grid operator TenneT to the plant, as the existing 220 kV connection cannot supply the additional 400 MVA for the new electric arc furnaces and the new process plants. TenneT is therefore building a new feeder on the 380 kV line from Wahle in Lower Saxony to Mecklar in northern Hesse. The planning and implementation of that new line was also supported by Fichtner as part of the ProVAN grid expansion project. An approximately 500 m-long 380 kV line will run from the nearby Bleckenstedt Süd substation to the plant. It was also clear that new switchgear would be needed.
Bird’s eye view of the new high-voltage switchgear; the gas-insulated switchgear is located in the building.
(Picture: Siemens Energy)
Power System Study and Design of the Electrical Installations by Fichtner
Salzgitter Flachstahl has long put its faith in Fichtner’s consulting and planning expertise for the conversion and expansion of its plant’s power grid (see text box). The main tasks of the current contract that was awarded in 2021 are a power system study, target grid planning and the design of key electrical installations that need to be built due to the higher power demand.
A new, more powerful substation is required at the plant to transform the voltage from 380 kV to 220 kV and 30 kV for the plant’s internal high and medium-voltage grid. In addition to the power transformers, the substation also includes a high-voltage switchgear. Since an outdoor switchgear would require more floor space than is available, a compact, gas-insulated switchgear (GIS) is being built on the plant premises. Fichtner also designed a new 30 kV medium-voltage switchgear including switchgear building and transformer stand.
A Trusting Collaboration Going Back Almost 20 Years
Be it a familiar problem or a new challenge – when it comes to the energy systems at Salzgitter Flachstahl GmbH’s plant, the company has for almost 20 years put its trust in working with Fichtner. In 2005, Fichtner was involved in the expansion of the power grid at the 220/110 kV level, and later provided planning and consulting services for the construction of the new power plant. We remained in contact even when there were no major projects to work on. For example, Fichtner has helped to keep the grid models up to date in recent years. This is now proving to be an advantage for the client and for us as the contractor, because we were able to build on an existing, reliable information base when designing the power grid for the SALCOS® project.
Support with Coordination on Site
Since 2020, Fichtner has been supporting the SALCOS380kV project office on site in implementing the planned switchgear. Various companies have been contracted to construct the switchgear, with Fichtner checking their performance with respect to contractual conformity and quality. In doing so, Fichtner ensures that the specifications from the tender documents, which Fichtner had previously prepared, are adhered to. Our tasks also include supervising the technical interfaces between the individual companies.
We at Fichtner are supporting the SALCOS® project with these and many other services (see text box) – and we are proud to be accompanying a pioneer in an energy-intensive industry on its path to decarbonization.
Civil Engineering Services from Fichtner for SALCOS®
In addition to electrical engineering, Fichtner is also providing comprehensive civil engineering services for SALCOS®. For example, the general planning of a switchgear building, which is required in part for the 30 kV power supply to the electrolysis plant, includes two transformer troughs as an additional structure. Among other things, this places high demands on the concrete technology, as these troughs must be designed to be impermeable to liquids.
Fichtner has also been entrusted with the project planning and structural engineering for the approximately 120 m-high HYTEMP® Tower. This supporting structure, with a load of almost 3,000 tons, is used by the direct reduction plant to transport and temporarily store the sponge iron at a temperature of around 600 °C and is being erected on top of the energy building. The energy building itself houses the 240-ton furnace transformer for the electric arc furnace, which has to be situated in an iron-free environment due to its high amperage. In view of these high loads, the tower’s foundation requires 116 bored piles with a length of 34 meters. In this cramped construction site, the interface between the two process chains of direct reduction plant and electric arc furnace must be coordinated with all project participants.
The Fichtner Group is thus involved in the civil engineering of all three SALCOS® subprojects – electrolysis, direct reduction plant and electric arc furnace.
July 2024
Featured image: Salzgitter AG
Dr. Bernhard Lutz
Projects Director in the Electrical Systems Networks Division
Herbert Bussmann
Projects Director Electrical Engineering
Sezai Olgun
Senior Project Engineer in the Electrical Engineering Department
