A team of researchers from the University of Córdoba has discovered the composition of a Roman perfume with a “smell of patchouli” that is more than 2,000 years old. All this after having found a small ointment in Carmona (Seville). This gives us an idea of what the Romans who lived in that area of the Guadalquivir smelled like. However, do we know what the natural gas in the subsoil of the Guadalquivir Valley smells like? Like nothing!

Natural gas is a combustible mixture of hydrocarbon gases and in its pure form it is colourless, odorless and formless. That is to say, not only doesn’t have a a physical form, but also has no color or smell. The methane found in the Guadalquivir basin, a biogenic gas, is produced when microorganisms, called methanogenic Archaea, remineralize organic matter in reducing environments.

In order to detect it, suppliers intentionally add odor. They scent natural gas with different chemical compounds as an olfactory alert and thus it is easily detectable.

In Spain, our national gas system (ENAGAS) uses TETRAHYDROTHIOPHENE (THT C4H8S) Tetramethylene Sulfide / Thiolane, injecting it into transport positions, so that it is odorized when it reaches the distribution chain and end customer.

The discovery in 2019 during archaeological excavations of the perfume from the 1st century AD reminds us that natural gas, another valuable finding in the Guadalquivir area in the 1950s, is part of the wealth of the region, which Romans saw back then.

The perfume is also a useful anecdote to learn about the innovation around the extraction and use of natural gas, as among many others, scenting it to make it an identifiable gas.