Scientists at Pennsylvania State University have explained the mechanism behind one of the earliest stages of coal formation.

The authors of the new work studied methoxyl groups in coal samples from around the world to show that organic material eventually turns into stone due to the activity of microorganisms.

The methoxyl group contains a carbon atom and three hydrogen atoms connected to an oxygen atom. The latter can attach to any number of sites in a large molecule. When it comes to carbon, it attaches to a carbon atom in one of its ring bonds.

According to the authors, methoxyl groups in coal tend to form into methane, but this process has so far been poorly understood. To better understand what’s going on, the scientists used stable carbon isotopes in the remaining methoxyl groups.

They found that organic material eventually becomes carbon under the influence of microorganisms. They tested other options and noted that the isotope profile did not match what would be found if methane was formed due to heat, acidity, or catalytic reactions. This means that only the option with microorganisms remains.

Geochemists claim that coal is formed under the influence of temperature, acids, or catalysts. But our results are inconsistent with these mechanisms. They show that microbes directly consume the methoxyl groups of coal, transforming coal and producing methane.

Research text

The authors note that this discovery will help to efficiently extract methane from coal deposits.