The invention relates to a plant complex for steel production comprising a blast furnace for producing pig iron, a converter steel mill for producing crude steel, a gas-conducting system for gases that occur when producing the pig iron and/or the crude steel, and a power-generating plant for electricity generation. The power-generating plant is designed as a gas-turbine power-generating plant or gas-turbine and steam-turbine power-generating plant and is operated with a gas that comprises at least a partial amount of the blast-furnace top gas that occurs in the blast furnace and/or a partial amount of the converter gas. The plant complex additionally comprises a chemical plant and a biotechnological plant, the power-generating plant, the chemical plant and the biotechnological plant being arranged in a parallel setup with regard to the gas supply. The gas-conducting system comprises an operationally controllable gas-distributing device for dividing the streams of gas.