Space-Based CO2 Observations Quantify Emission Reductions

According to the Paris Agreement, nations must monitor greenhouse gas emissions at the level of individual “super emitters,” such as power plants, in almost real-time.

Bełchatόw power station in central Poland. Image Credit: Pawel Brzozowski/Shutterstock.com

For the first time, researchers indicated that this is possible using data from current satellites and equipment, such as NASA’s OCO-2 and OCO-3 (connected to the International Space Station), both of which are designed to detect emissions at considerably wider spatial scales.

This proof-of-concept shows that the EU’s ‘CO2M’ pair of satellites, scheduled to launch in 2025 or 2026 and with a combined coverage 100 times bigger than OCO-2 and OCO-3, should be capable of meeting future demands.

Countries that signed the 2015 Paris Agreement committed to limiting the average global temperature rise “well below” 2 °C. Every five years, they will release what are known as “nationally determined contributions” (NDCs), which describe their activities to decrease greenhouse gas (GHG) emissions and adapt to the effects of climate change.

Countries will consequently need to monitor their carbon emissions not only at the national level but also at the scale of individual “super emitters” such as power plants, refineries, megacities, and massive factories, which account for approximately half of total GHG emissions produced by humans.

The EU intends to launch its “CO2M” (Copernicus Anthropogenic CO₂ Monitoring Mission) pair of satellites in late 2025 or 2026 to assist with this.

However, researchers have shown that monitoring at the source is already achievable, even with current satellites, for “super emitters” such as Poland’s Bechatów power station. They used five years of readings from NASA’s satellite “Orbiting Carbon Observatory 2” (OCO-2; launched in 2014) and the equipment OCO-3, which has been attached to the International Space Station (ISS) since 2019.

This outcome is significant because the OCO missions were intended to quantify carbon emissions at much broader spatial scales.

Here we show for the first time that it’s already possible to measure changes in CO₂ emissions from a large power plant, with observations from existing CO₂-tracking satellites.

Dr. Ray Nassar, Study First Author and Research Scientist, Environment and Climate Change Canada, Toronto

The study was published in the journal Frontiers in Remote Sensing.

The lignite-fired (brown coal) power plant in Bechatów is Europe’s largest and the world’s fifth largest. Units are often decommissioned and replaced, but more often than not, units are taken down for maintenance. To be effective, satellites and instruments such as OCO-2 and OCO-3 must be able to detect variations in CO₂ emissions caused by changes in operation, and Nassar and colleagues have now demonstrated that this is possible. 

CO₂ is emitted by the 300 m high Bechatów stacks and propelled by the wind as an invisible plume 10–50 km long and 550 m above Earth. OCO-2, which orbits the Earth at a height of 705 km, comes close to or directly above Bechatów every 16 days. OCO-3 orbits at 420 km altitude and frequently passes above or near Bechatów. OCO-3 may also scan back and forth across a region, providing superior local coverage or a broader view.

Satellites can only measure CO₂ “enhancement,” or excess CO₂ released by a source, when there are no clouds and the plume does not pass over large bodies of water or mountains. They calculate “XCO₂,” the average CO₂ concentration throughout a column directly below, by removing the present background value (locally, 415 ppm on average) around the plume.

Between 2017 and 2022, OCO-2 and OCO-3 produced ten appropriate datasets about the CO₂ plume above Bechatów.

The researchers compared the space measurements to estimates for Bechatów’s emissions based on its documented daily power generation output. The findings turned out to be very close to the daily forecasts.

This demonstrates that even today, current satellites can monitor emissions for installations like Bechatów in near-real time. For example, OCO-2 reported a significant but transient drop in emissions from Bechatów between June and September 2021 owing to maintenance shutdowns.

The findings suggest that CO2M, with a combined spatial coverage nearly a hundred times bigger than OCO-2 and OCO-3, may be able to meet future demands.

The capacity to get the most precise information about CO₂ emissions from ‘super emitters’, such as the Bełchatów power plant, across the globe will boost transparency in carbon accounting. And hopefully, it will ultimately help to reduce these emissions. This future capacity will lead to improved CO₂ emission information at the scale of countries, cities, or individual facilities, enhancing transparency under the Paris Agreement and supporting efforts to reduce emissions causing climate change.

Dr. Ray Nassar, Study First Author and Research Scientist, Environment and Climate Change Canada, Toronto

Journal Reference

Nassar, R. et al. (2022) Tracking CO₂ emission reductions from space: A case study at Europe’s largest fossil fuel power plant. Frontiers in Remote Sensing. doi.org/10.3389/frsen.2022.1028240.