Countries that signed the 2015 Paris Agreement committed to keeping the average global temperature rise “well below” 2 degrees Celsius. Every five years, they are to issue “nationally determined contributions” (NDCs), which describe their actions to reduce greenhouse gas (GHG) emissions and adapt to the effects of climate change.
Countries will thus need to track their carbon emissions not only at the national level, but also at the scale of individual “super-emitters”. This includes power plants, megacities, refineries, and massive factories, which account for nearly half of total GHG emissions produced by humanity.
The EU intends to launch its “CO2M” (Copernicus Anthropogenic CO2 Monitoring Mission) pair of satellites in late 2025 or 2026 to assist with this.
An important proof-of-concept for CO2M
However, scientists have demonstrated that tracking at the source is already possible, even with existing satellites, for “super-emitters” such as Poland’s Bechatów power plant. They used five years of measurements from NASA’s satellite “Orbiting Carbon Observatory 2” and the instrument OCO-3, which has been attached to the International Space Station since 2019.
This success is significant because the OCO missions were intended to measure carbon emissions at much larger spatial scales.
“We show for the first time that it’s already possible to measure changes in CO2 emissions from a large power plant using observations from existing CO2-tracking satellites,” said Dr. Ray Nassar, an atmospheric scientist at Environment and Climate Change Canada in Toronto and the study’s first author.
Europe’s largest power plant
The Bechatów lignite-fired (brown coal) power plant is Europe’s largest thermal power station and the world’s fifth-largest. Units are sometimes decommissioned and replaced, but more often than not, units are shut down for maintenance.
To be useful, satellites and instruments like OCO-2 and OCO-3 must be able to detect changes in CO2 emissions caused by changes in operation—as Nassar and colleagues demonstrate for the first time.
CO2 is emitted by the 300-meter-high Bechatów stacks and carried by the wind as an invisible plume 10-50 km long and 550 metres above Earth. OCO-2, which orbits the Earth at a height of 705 kilometres, passes close to or directly over Bechatów every 16 days. OCO-3 orbits at 420 km altitude and frequently passes over or near Bechatów. OCO-3 can also scan back and forth across a region, providing better local coverage or a broader view.
Not every flyby or overpass is appropriate
Satellites can only assess CO2 “enhancement”—extra CO2 emitted by a source—when there are no clouds and the plume does not pass over large bodies of water or mountains. They calculate “XCO2,” which is the average CO2 concentration across a column directly below, by subtracting the current background value (locally, 415 ppm) around the plume.
Between 2017 and 2022, OCO-2 and OCO-3 produced ten suitable datasets about the CO2 plume above Bechatów.
There is a high level of agreement between observed and predicted data
The measurements from space were compared to estimates for Bechatów’s emissions based on its known daily power generation output. The measurements turned out to be very close to the daily forecasts. This demonstrates that, even today, existing satellites can track emissions for installations like Bechatów in near-real time. For example, OCO-2 detected a significant but transient drop in emissions from Bechatów between June and September 2021, owing to maintenance shutdowns.
CO2M is free to operate
The results are encouraging. They suggest that CO2M, with a combined spatial coverage roughly a hundred times greater than OCO-2 and OCO-3, will be able to meet future demands.
“The ability to obtain the most precise information about CO2 emissions from’super-emitters,’ such as the Bechatów power plant, around the world will increase transparency in carbon accounting and, hopefully, help to reduce these emissions,” Nassar said.
“This future capability will result in improved CO2 emission information at the scale of countries, cities, or individual facilities, enhancing transparency under the Paris Agreement and supporting efforts to reduce climate-change-causing emissions.”