In order to achieve the two-degree target agreed by the Paris Climate Change Conference, man-made carbon input into the atmosphere has to be limited to a quantity not greater than the amount of carbon that can be absorbed by sinks. In addition to the energy system, this also affects important industries such as the steel, cement and chemical industry, whose production structures are essentially based on the processing of fossil carbon compounds. If a net zero emission target really is to be achieved, a system change that includes the fundamentally different management of carbon-containing raw materials is also essential for these industries. This requires a considerable amount of renewable energy.