Methane is a powerful greenhouse gas, over 80 times more effective than carbon dioxide in trapping heat (GWP20). It remains in the atmosphere for about a decade, so reducing emissions can lower methane levels quickly. However, technologies for methane removal are far less developed than those for carbon dioxide. This is because methane is harder to break down, and there has been limited research investment, and public awareness is low. Most methane sources emit at low concentrations, below 1000 parts per million, where current destruction technologies do not work effectively.

We have tested the Methane Eradication Photochemical System (MEPS), a technology that destroys methane even at very low concentrations, such as in barn ventilation air. Field trials at cow and pig barns, and a biogas plant in Denmark, showed MEPS could remove methane efficiently, using less than 1 kilowatt-hour of energy per gram of methane, while also reducing ammonia, hydrogen sulfide, and foul odors. A prototype container unit is now being tested on a working dairy farm.

We are also investigating the iron salt aerosol (ISA) method, which enhances natural atmospheric processes that remove methane. Its effectiveness depends strongly on local air chemistry, especially nitrogen oxides and ozone levels.