Remote Sensing Technology

Methane Plume Imaging Technology

Light consists of a range of colors, or wavelengths. Methane gas absorbs certain wavelengths, altering the light and leaving a signature that is unique to methane. Methane plume imaging sensors are specially engineered to measure light at these wavelengths, capturing methane’s unique signature. As sunlight reflects off the Earth’s surface and passes through the atmosphere, a satellite equipped with this type of sensor can detect the presence and strength of a methane signature in the atmosphere. This data is then processed into plume images. The sensors measure total methane in the atmosphere between the surface and the sensor. This does not necessarily reflect methane concentrations at the surface. They can be used to estimate the concentrations at the surface and the emission rate combined with other data like wind speed. Multiple commercial satellite companies using this type of technology exist today. While each company uses their own unique sensor, they each follow the fundamental principles of science described above.

Plume imaging sensors are designed to have high spatial resolution, meaning they produce detailed images compared to other methane-detecting satellites. However, this high resolution comes with a tradeoff: plume imagers can only detect methane when its signature is strong, which requires high methane concentrations in small areas.

Methane plume imaging satellites are typically operated by commercial aerospace companies with data available for purchase.

Blue and red image of a methane plume over brown terrain. — Example of a methane plume captured from an aircraft, using a sensor with similar capabilities to those on satellites. The image is from June 2023. The red indicates the highest amount of methane in the plume, which is where the plume sources is located. The blue indicates a lower amount of methane in the plume, which is still enhanced above background levels of methane. The satellite images will be similar to those from aircraft.

Along with images of methane plumes, commercial plume imaging satellites typically estimate:

The location of the origin of the plume
The total concentration of the methane from the sensor to the plume origination at the surface
The emissions rate when the plume image was taken

Strengths:

Can detect methane emissions from individual sources
More frequent observations of large methane sources
High-spatial resolution (typically 30-40 meter) with the ability to cover large areas
Detect methane with high sensitivity

Limitations:

Less likely to detect diffuse area-wide sources of emissions or small point sources than large point sources.
Clouds and other atmospheric conditions can lead to gaps in data collection.
Satellites cannot scan “everywhere, every day”, but rather, must be pointed at specific pre-determined areas of interest.