Observing steelworks from space: A novel method for estimating greenhouse gas emissions

Researchers at the University of Bremen’s Institute of Environmental Physics have developed a satellite-based method to quantify greenhouse gas emissions from individual steelworks. By analysing characteristic absorption signatures in spectral data acquired from space, the approach enables independent, facility-level emission estimates and provides a new tool for tracking industrial progress on climate change mitigation

Conventional steel production is a major contributor to global industrial carbon dioxide (CO₂) emissions, making the sector a central focus of climate mitigation efforts. In Germany, extensive investments are currently being made to substantially reduce emissions from steelworks, primarily by shifting from carbon-based processes to hydrogen-based production. However, reliable and independent measurements of these emissions are difficult to achieve comprehensively. Researchers have now developed a satellite-based method that offers a new perspective. Instead of measuring CO₂ directly, the approach focuses on carbon monoxide (CO), a by-product of conventional steelmaking. Most primary steel production worldwide relies on the Linz–Donawitz process, in which oxygen is blown onto carbon-rich pig iron to reduce its carbon content through oxidation, producing high-quality steel. During this process, substantial amounts of CO are generated. While CO₂ is difficult to monitor from space at the scale of individual industrial facilities, CO can be detected much more effectively with modern satellite sensors.

Using data from the TROPOspheric Monitoring Instrument (TROPOMI) aboard the Sentinel-5 Precursor satellite, the researchers carried out a systematic long-term analysis of all integrated steelworks in Germany, located in Duisburg, Dillingen, Salzgitter, Bremen, and Eisenhüttenstadt. From these satellite observations, they estimated facility-level CO emissions and compared them with the CO₂ emissions reported by steel manufacturers for the same period. The results show a very strong correlation between CO and CO₂ emissions across all analysed sites. This robust linear relationship justifies the use of CO as a reliable proxy for CO₂ emissions from modern conventional steelworks. After calibrating the CO/CO₂ emission ratio at the German facilities, the CO₂ emissions of comparable steelworks at other locations can then be derived directly from satellite-based CO emission estimates.

Until now, emission monitoring has largely relied on information and calculations provided by the steel producers themselves. The new satellite-based method offers an independent way to estimate emissions using observations of the atmospheric composition from space. As the steel industry undergoes a profound technological transformation, such approaches could become important tools for tracking progress, verifying reported reductions, and supporting transparent climate policy. The work contributes to the „Integrated Greenhouse Gas Monitoring System for Germany“ (ITMS), a research initiative funded by the Federal Ministry of Research, Technology and Space (BMFTR) that aims to establish a comprehensive monitoring framework by combining atmospheric observations from the ground, aircraft, and satellites with high-resolution emission inventories and atmospheric models.

 

 

Reference

Schneising, O., Buchwitz, M., Reuter, M., Weimer, M., Bovensmann, H., Burrows, J. P., and Bösch, H.: Towards a sector-specific CO/CO₂ emission ratio: satellite-based observations of CO release from steel production in Germany, Atmos. Chem. Phys., 24, 7609–7621, https://doi.org/10.5194/acp-24-7609-2024, 2024.