German satellites measure simultaneously for the first time from power plant emissions

Researchers at the Max Planck Institute for Chemistry in Mainz and the University of Heidelberg, first used the German environmental satellite Enmap (environmental mapping and analysis program) to simultaneously detect two major air pollutants, carbon carbon (CO2) and nitrogen dioxide (NO2).

The newly developed method allows for extremely accurate tracking of industrial emissions from space, allowing for detailed analysis of atmospheric processes. The results were published in the Journal of Environmental Research Letters.

Carbon dioxide (CO2) and nitrogen oxides (NOx) are one of the most important anthropogenic air pollutants that affect climate, health and air quality. Satellite measurements are considered an important tool for independent emission monitoring. However, there were major restrictions in the past. Many sensors have spatial resolutions that are too rough to reliably detect isolated emission sources such as power plants.

Atmospheric processes, such as chemical reactions of nitrogen oxides such as clouds, also complicate data interpretation. In the case of CO2, high background values ​​often mask relatively weak ejection signals.

NO2 measurements are often used to estimate CO2 emissions based on known emission ratios, as NO2 and CO2 are released together. However, up until now, no equipment has been able to simultaneously detect both gases with high spatial resolution.

The method currently presented closes this gap. For the first time, both gases can be measured simultaneously and at high resolution directly above the source of the emissions. This opens the door to more transparent and independent satellite-based emission monitoring.

Enmap: High-resolution perspective

Atmospheric trace gases such as Co₂ and no₂ leave distinctive absorption patterns in sunlight and can be detected using spectrometers. Equipment with very high spectral resolutions is usually used for satellite-based measurements. They can analyze the fine absorbing structure of gases in reflected sunlight, but usually achieves only spatial resolution of 3-5 km.

In contrast, the German Earth Observation Satellite Enmap was originally designed for remote sensing of land surfaces. It provides images with very high levels of spatial detail of 30 x 30 meters, but has a relatively low spectral resolution.

Now, new research shows that reliable measurements of trace gases are possible, even for equipment not specifically designed for atmospheric observation.

“We were able to use ENMAP data to determine the distribution of CO2 and NO2 in emission plumes from individual power plants, such as those from the Highberd region of Saudi Arabia and South Africa. He is currently working for the European Medium-Distance Weather Forecast (ECMWF) in Bonn.

From measurement to application

This means that the Enmap satellites can be used to determine CO2 and NOX emissions from individual power plants simultaneously, at high resolution. Furthermore, the NOX/CO2 ratio can be derived from this. This allows you to draw conclusions about the technology, efficiency, and mode of operation of the system. In the future, such ratios can be used to estimate CO2 emissions based on NO2 data.

This data also provides new insights into the chemical conversion of NO to NO2 within the discharge plume. Until now, this central process of atmospheric chemistry could only be studied through complex aircraft measurement campaigns. Using satellite data provides a great advantage in this context as it allows for the global, consistent and comparable detection of industrial pollutant emissions.

“Our research shows how high spatial resolution satellites can contribute to target monitoring of future industrial emissions, in addition to large-scale missions such as CO2M satellites in Europe,” summarises group leader Thomas Wagner. Environmental Satellite opens up a new perspective on global satellite-based monitoring systems for air pollutants and greenhouse gases.