Greenhouse gas emissions can now be measured by satellite

Researchers at the Institute of Environmental Physics (IUP) at the University of Bremen have developed a method that allows the greenhouse gas emissions of individual steelworks to be measured from space. The values obtained from satellite data enable an independent assessment of the amount of greenhouse gases for the first time, so that decision-makers in politics, business and science are no longer solely dependent on the information provided by steel manufacturers.

Germany is currently investing billions to significantly reduce greenhouse gas emissions from steelworks. This is to be achieved primarily by switching to hydrogen operation. But how do you measure the amount of greenhouse gases that are produced during the production process? "Until now, we have been largely dependent on the information and calculations provided by steel manufacturers," says Dr Heinrich Bovensmann from the Institute of Environmental Physics (IUP) at the University of Bremen. "We have now developed a method that can be used to measure and calculate these emissions independently – using satellite data on the composition of the atmosphere."

The production of steel generates large quantities of carbon dioxide (CO2) and carbon monoxide (CO). In 2022, for example, German CO2 emissions from pig iron and steel production amounted to around 23.5 million tonnes, according to the Federal Environment Agency. The IUP researchers have known that these emissions can also be detected from space since the large peat fire in Emsland in September and October 2018: "This was not an open fire, but one that smouldered in the ground," says Heinrich Bovensmann. "Such a fire produces a particularly large amount of carbon monoxide, which we then also made visible with the highly accurate images of the Sentinel-5P Earth observation satellite launched in 2017." But what was also visible was a carbon monoxide plume from the Ruhr area – that of the largest German steel site in Duisburg.

Postdoctoral researcher Oliver Schneising from the IUP team became interested in these emissions and also examined satellite data with regard to other German steel sites with integrated smelting works. Here he was able to prove beyond doubt that carbon monoxide was being released in Duisburg, Dillingen, Salzgitter Bremen and Eisenhüttenstadt. "The primary steel production worldwide is predominantly carried out using the so-called Linz-Donawitz process. In this process, oxygen is blown onto carbon-rich pig iron to minimise the carbon content by oxidation and thus obtain high-quality low-carbon steel," explains the Bremen scientist. "The carbon monoxide (CO) released in the process can be better determined from space using the new generation of satellite sensors than the greenhouse gas CO2 itself."

In order to determine the CO emissions from the remote sensing measurements, the Bremen researchers led by Schneising took a close look at the meteorological conditions – in particular the wind – at the time of the measurements. "We determined the CO emissions of the above-mentioned steel sites and compared them with the CO2 emissions reported by the steel manufacturers for the same period of time," says Schneising. "This analysis shows a very high correlation between CO and CO2 across all locations. This justifies determining CO2 emissions from the CO observations." The method developed by the IUP research group has now been published in a renowned scientific journal after expert review.

The work of the Institute of Environmental Physics on this topic is part of a comprehensive research initiative funded by the German Federal Ministry of Education and Research (BMBF). It is entitled "Integrated Greenhouse Gas Monitoring System for Germany" (ITMS) and is led by the German Weather Service and the Max Planck Institute for Biogeochemistry. "The ITMS project aims to develop and implement a system that combines atmospheric observations from the ground, from the air and from space with high-resolution emission inventories and high-resolution atmospheric models and uses them to monitor and document greenhouse gas sources and sinks," explains Dr Heinrich Bovensmann from the IUP, which coordinates the Bremen participation for the institute. "The University of Bremen is jointly responsible for a large part of the activities. It coordinates the activities in the field of observational data, with continuously collected observations from measurement networks and satellites playing an important role."