Kayrros, a satellite data analytics firm, recently published research analyzing trends in methane emissions as observed from space. Kayrros’s report claims that U.S. methane emissions show a concerning “risk of significantly increasing” in 2022 following drops during COVID-19.
Media coverage of the study drew broader conclusions. The Washington Post ran a story on the research titled “World pledged to cut methane. Emissions rising instead, study finds.”
While the research findings are interesting, and the data collection method used has great potential to measure future methane leaks, the findings are far too narrow to justify broad claims about worldwide methane emissions.
Kayrros measures atmospheric greenhouse gas emissions by analyzing satellite data. Government agencies, environmental nonprofits, and oil and natural gas companies alike have all invested heavily in satellite technology with the eventual goal of being able to pinpoint and measure emissions from space in near-real time.
For example, ExxonMobil and several other energy companies are working with satellite operator GHGSat to use the technology for more effective methane emissions monitoring, as well as for testing several other detection methods. As ExxonMobil’s Staale Gjervik explained:
“By testing the most promising methane detection technologies in a field environment, we are providing viable solutions that can be adopted by other producers to detect and reduce methane emissions. We are applying scientific rigor and taking aggressive steps to find commercially scalable and affordable solutions for all operators.”
But despite broad enthusiasm and large-scale investment in satellite emissions monitoring technology, satellites are still limited in their ability to consistently, reliably, and accurately measure volumetric methane emissions. At present, space-based methane detection is effective for observing large and anomalous instances of methane emissions. The technology is less effective at being able to attribute emitted methane to a specific source in a timely way that allows for quick mitigation on the ground.
Some limitations, like the geographic coverage and revisit rate of a single satellite in orbit, will improve as more satellites are added to different constellations. Other limitations, like the observational capabilities of existing detection instruments, will take more years and additional research and development to overcome.
Kayrros does not own or operate any of its own satellites; rather, the company analyzes commercially and publicly available datasets. In the case of the company’s methane report, Kayrros analyzes data from European Space Agency (ESA) satellite Sentinel-5P. Sentinel-5P has one payload, TROPOMI, an earth imaging device that covers wavelength bands between ultraviolet and shortwave infrared.
As the satellite passes overhead, the TROPOMI instrument scans a wide swath of the Earth’s surface. According to a Congressional Research Service analysis, “such a wide swatch scans a large area but typically lacks the resolution to distinguish individual features such as specific oil and gas facilities.”
Leveraging TROPOMI data, Kayrros has developed a proprietary, satellite data-based “full-inversion” model to measure methane emissions from key onshore oil and gas producing regions. A full-inversion method involves an algorithm that allows the company to determine volumetric emissions measurements from satellite data.
In April 2022, The European Space Agency supported a study assessing the utility of the satellite data-based “inversion method” in measuring GHG emissions. The authors claimed that using atmospheric inversions could be a novel way to “improve checks and consistency of national inventories to more accurately reflect global emissions.”
The ESA described the type of analysis used by Kayrros as “novel” and promising, but admits that results derived from the type of analysis used in the paper tend to diverge significantly from nationally reported GHG inventories:
“Significant discrepancies between the inversion values and the corresponding national reports. … Methane emissions were found to be higher using the inversion method compared to most national reports.”
Since Sentinel-5P methane data was first made available in March 2019, Kayrros’s paper analyzes methane emissions from the period 2019 to 2022. Naturally, this time window compares economic activity under COVID-19 to activity after economies generally reopened in 2021 and 2022. Despite the global pandemic – a large externality – taking place during this time period, Kayrros says the data are evidence that “global methane emissions so far appear to be going in the wrong direction.”
Kayrros’s measurements of methane emissions cannot be compared with pre-2019 data. Due to the high degree of difference between satellite-based estimations of methane emissions and nationally-reported methane emissions – as described in the ESA study – the data presented in Kayrros’s report cannot be compared with national GHG inventories before or during the period analyzed.
The company’s claim that the data are evidence that “global” methane emissions are accelerating may turn out to be true, but the statement is not necessarily backed up by the data. Due to Sentinel-5P’s orbit and the TROPOMI instrument’s characteristics, the data is only reliably available for certain regions of the world. Consequently, Kayrros’s study analyzes methane emissions data from oil and gas producing regions in the United States and in the Middle East. Large emitters like China, Russia, and India are notably absent from the study.
Kayrros claims that in the first quarter of 2022, Permian methane emissions may have reached record-highs. However, satellite-based methane measurements are not comparable to historical GHG national inventories:
“In the first quarter of 2022, Kayrros Methane Watch shows Permian methane emissions have continued to increase and appear to have reached their highest level on record, even as U.S. Energy Information Administration (U.S. EIA) data point to a slight decline in Permian oil production to 4.38 Mb/d, from 4.39 Mb/d in the previous quarter.”
The company also claims that methane emissions in the the Appalachian basin increased in the first quarter of 2022. Although Kayrros admits that its conclusions around Appalachian basin methane emissions have a high degree of uncertainty, it uses that absolute methane emissions findings to derive a very specific estimate of methane intensity in the region:
“Quarterly data suggest Marcellus and Utica methane emissions growth accelerated significantly in Q12022, however, although the confidence interval for that quarter is relatively large.
The methane intensity of Marcellus and Utica gas production jumped to 0.14 kg/ GJ in Q12022, its highest level since Q3 2020, from 0.11 kg/GJ on average in 2021.”
In fact, the confidence interval is relatively large for the entirety of the paper’s findings. In the paper, Kayrros acknowledges the limitations of research method and dataset used:
“Basin-level estimates have an uncertainty factor of 10-20 percent due to the scope of Sentinel-5P coverage, not including simulation modeling-related uncertainties.”
Lastly, Kayrros’s analysis relies on three years’ worth of data derived from one satellite instrument in one orbit. This sample has natural limitations and risks, including the reliability of the single instrument.
