Rothe Erde in Germany's first wind farm for an industrial plant

Dortmund. For the first time in Germany, an industrial plant was connected directly to a wind farm at the beginning of June. In future, the thyssenkrupp Hohenlimburg rolling mill will be supplied with an annual average of 40% of its electricity from renewable sources. The plant requires 110 gigawatt hours of electricity per year, which corresponds to around 80 percent of the electricity requirements of the neighboring town of Iserlohn. The green electricity project at thyssenkrupp Hohenlimburg is a role model: it has the potential to save 11 percent of the site's CO2 emissions in a first step and can be expanded further. The efficient and safe operation of the four wind turbines is also ensured by bearings from Rothe Erde.

 “The decarbonization of the industry is of increasing and central importance in order to achieve the climate targets and is one of the key projects in the context of climate protection. We are proud that we can make a contribution with our solutions and components,” explains Jörg Esken, Account Manager at Rothe Erde. The four Enercon E-138 wind turbines with a height of around 160 meters have a rotor diameter of 138 meters.“ The slewing bearings from Rothe Erde are used as azimuth bearings, between the tower and nacelle, and as main bearings behind the hub. In addition to a secure hold on the nacelle, they ensure optimum wind yield and thus the highest possible energy yield,” says Jörg Esken. For this purpose, the nacelle is adapted to the respective conditions and optimally aligned with the wind. A double-row four-point bearing with an outer diameter of a good 3.5 meters is used at this point.

Maximum efficiency even under high loads

In addition, the main bearing is located directly behind the hub and connects it to the nacelle and the generator. “This bearing is in continuous operation and has to compensate for high loads every time the wind turbine rotates. It is also important that the bearing rotates as 'smoothly' as possible and thus transfers the energy from the wind to the generator, which produces the electricity, with as little loss as possible.” A so-called TRB-TRB bearing set is installed here. This consists of two tapered roller bearings in an O arrangement, one of which is installed on the hub and the second directly in front of the generator. This saves space in the already narrow nacelle and ensures a high load capacity in this special arrangement.

55 million kilowatt hours per year

The four wind turbines are connected to the thyssenkrupp Hohenlimburg plant grid via a direct line around three kilometers long. This means that the majority of the more than 55 million kilowatt hours generated by the wind farm each year can be used directly without drawing on the public grid. Only surplus quantities, for example when the wind is strong or the plant's demand is low, are supplied to other Group sites via the public grid. “The Hohenlimburg project is an absolute pilot project. Direct delivery from wind farm to industrial plant is the most efficient way of bringing new energy and industry together,” explains Klaus Schulze Langenhorst, founder and Managing Director of SL NaturEnergie, which operates the plant.

thyssenkrupp Hohenlimburg has around 1,000 employees and produces the hot-rolled, so-called Hohenlimburg medium-wide strip. The main customers are the cold rolling industry, the automotive industry and its suppliers, as well as the sawmill and agricultural machinery industries. The switch to green electricity from wind turbines is a real milestone for the long-established company: “Even with the green electricity from the first four wind turbines, we can cover an annual average of 40 percent of our simultaneous electricity requirements,” explains André Matusczyk, Managing Director of thyssenkrupp Hohenlimburg GmbH, adding: “We are thus saving a considerable amount of grid fees and relieving the burden on the public power grid through the direct connection. With this cooperation project, we are breaking new ground in order to make our site sustainable in the long term. We are also lowering our own CO2 footprint and reducing the CO2 intensity of our products - we are taking the climate transition seriously.”