Due to both processes and raw materials, conventional production of pig iron and steel generates various emissions such as CO2 but also sulfur dioxide (SO2) and nitrogen oxides (NOX).
voestalpine fully complies with the statutory limits regarding all of the aforementioned emissions. These parameters are verified and their annual loads determined by means of continuous measurements, periodic analyses, and material flow analyses. For many years, the company has consistently taken measures to reduce process-related air pollutants to the technologically achievable minimum. Aside from continual process optimization (so-called “process integrated (PI) measures”), state-of-the-art scrubbing facilities (so-called “end-of-pipe measures”) serve to minimize remaining emissions.
Comprehensive environmental measures have enabled the voestalpine Group over the past three decades to substantially reduce its emission levels. As a result, specific emissions of CO2 were lowered by about one-fifth, SO2 emissions by three-quarters, and NOX emissions by just under two-thirds; dust emissions have already been cut to almost zero.
However, the greenhouse gas emissions (GGE) must be eliminated first and foremost if the political climate targets are to be achieved. In steelmaking, this can be achieved solely by shifting to new technologies (some of which have yet to be developed) based on green electricity and/or green hydrogen (for more information, see the “Climate Action” chapter).
Greenhouse gas emissions
Due to the downturn in production, the direct greenhouse gas emissions (Scope 1) of the voestalpine Group’s roughly 130 production facilities declined in calendar year 2020 from 13.6 million tons to 12.4 million tons of CO2 equivalents. The Group’s crude steel production facilities in Linz and Donawitz, both of which use the blast furnace route, accounted for the lion’s share of these emissions. The data takes the carbon dioxide, methane, and nitrous oxide emissions into account.
The use of particular raw materials—especially coal and coke—introduces sulfur into the production process. Sulfur is emitted in the form of sulfur dioxide (SO2) during additional processing steps and when by-products (coke oven gas (COG) and blast furnace gas (BFG)) are used for thermal recycling.
While the specific SO2 emissions in calendar year 2020 were 0.46 kg/t of product and thus less than the previous year’s value of 0.49 kg, in absolute terms the SO2 emissions fell from 4.6 kt to 4.4 kt due to curtailed production.
Nitrogen oxides are generated through the operation of industrial furnaces and thermal recycling of by-product gases.
Due to the lower production volume, in calendar year 2020 voestalpine’s absolute NOX emissions fell from 6.1 kt to 5.0 kt. The specific NOX emissions per ton of product fell from 0.64 kg to 0.53 kg.
Captured dust emissions
Dust-laden exhaust air and exhaust gases that occur during production are captured and channeled to dedusting systems using state-of-the-art measures.
Year over year, the captured dust emissions per ton of product remained low in calendar year 2020, both in absolute terms (0.32 kt) and specifically (34 g).
Organic air pollutants
Organic air pollutants (i.e., volatile organic compounds (VOC)) are generated primarily during the thermal process stages of crude steel production and/or in connection with the associated combustion processes.
The VOC emissions have steadily declined since a state-of-the-art coal drying system was commissioned in calendar year 2018. They fell yet again year over year in 2020, both absolutely (from 0.17 kt to 0.15 kt) and specifically (from 18 g to 16 g per ton of product).