Green electricity from a tiny tunnel

The electric arc furnace (EAF) requires a significant amount of electrical energy. This energy is provided to us by Austrian Power Grid on the outskirts of the works, roughly 1,600 meters from the steelmaking plant. The electricity is transmitted from there through a microtunnel to the EAF.

Die Nutzwasserleitung wurde vor einigen Jahren mit der selben Methode umgesetzt.

Underground without posing an obstacle

The preliminary project phase initially considered an above-ground installation for transmission of the electricity. But the superior characteristics of an underground power line soon became apparent. The underground solution avoided having to deal with all of the extra installations on the works premises and the unattractive appearance of overhead lines.

 

Advantages of microtunnels in the transmission of electricity

The system consists of vertical shafts that are connected to each other by horizontal underground tunnels. Excavation work is only required for shaft construction, while the tunnel sections are drilled underground. The cables can be laid once the required infrastructure has been installed in the shafts and tunnels. The cables are water-cooled during operation.

Microtunnel made by voestalpine

The four shafts have an inner diameter of 12.4 meters, while the tunnels with a depth of roughly 25 meters have a diameter of 2 meters. The shaft locations are located near SK VOEST, the company's medical facilities, BG83 and the new LD3 substation. The underground microtunnel is almost completely straight, making it only 1,700 meters. In contrast, the shortest aboveground supply road is 4,000 meters long. 

Excavation work for the shafts will begin in the second quarter of 2024. The tunnel sections between the shafts will be drilled beginning in April 2025, after which the electrical equipment will be installed in time for initial operation of the EAF.

Facts and figures 

  • Microtunnel: 1700 meters in length, outer diameter of 2.6 meters, inner diameter of 2 meters, depth of 25 meters.
  • Shafts: 12.4 meters in diameter, 25 meters in depth
  • 20,000 cubic meters of water remains in the tunnel during operation.

About greentec steel

The greentec steel project of voestalpine is an ambitious step-by-step plan that makes a valuable contribution to the achievement of the climate goals. As a first step, the voestalpine Group plans to replace two blast furnaces with two electric arc furnaces (EAFs) by the year 2027. The investment volume amounts to roughly 1.5 billion euros. 

CO2 emissions can be reduced by around 30% by 2029 by making this switch from the blast furnace to the EAF. This corresponds to a savings of nearly 4 million tons of CO2 per year, amounting to almost 5% of the carbon emissions in Austria. This makes greentec steel the largest climate protection program in Austria. 

The two electric-arc furnaces will enable voestalpine to produce roughly 2.5 million tons of carbon-reduced steel by the year 2027, roughly 1.6 million tons in Linz and 850,000 tons in Donawitz. Learn more about greentec steel here.