User:EamoWiki

Definition
Atmospheric Methane Removal is a proposed method to enhance the natural process of atmospheric methane oxidation. It is a case of biomimicry.

Atmospheric methane has increased since pre-industrial times from 0.7 ppm to 1.9 ppm. Methane is the cause of ca. 30% (0.5 °C) of current global warming. Global methane emissions approached a record 600 Tg CH4 yr−1 in 2017

Atmospheric Methane Oxidation is a natural process which occurs in the atmosphere under sunny conditions in the presence of a catalyzer. The process oxidises methane (CH4) into carbon dioxide (CO2) and water (H2O).

1 CH4 + 2 O 2 => 1 CO2 + 2 H2O

The catalyzer, in 95% of all cases, is  •OH, in 1-5% of all cases Iron(III) chloride (FeCl3).

The occurrence of natural atmospheric methane oxidation by FeCl3 has been shown in field tests in 2023

Chemistry of Methane Removal
Most atmospheric methane is removed in nature by OH radicals. Chlorine atoms are produced, for example, by photolysis from the FeCl3 stemming from iron-containing airborne dust aerosol particles in the oceanic boundary layer:FeCl3 + hv  à  FeCl2 + oCl

Methane oxidation is initiated by the chlorine atoms:

CH4 + oCl  à HCl + oCH3

The resulting methyl radical is unstable and oxidises naturally to CO2 and water:

3.5O2 + 2oCH3 à 2CO2 + 3H2O

In EAMO the catalyzer Iron(III) chloride (FeCl3) is used because chlorine atoms (radicals) oxidize methane at least 16 times faster than OH. The impact of chlorine chemistry on the atmosphere is well known.

Additional Benefits
Fine particles dispersed in the atmosphere can serve as Cloud Condensation Nuclei and thereby cause Marine Cloud Brightening

Eventually all FeCl3 particles are washed out of the air and fall on land or water, where they dissolve into Iron compounds and salt. EAMO would contribute to Iron Fertilization (OIF) of both the sea and the land