2. Methane hydrates

Methane hydrate is made up of methane molecules (CH ₄ ), surrounded by a solid network of water molecules (H ₂ O) arranged in a cage, hence the name clathrate (from the Greek klathron, closure), also given to hydrates. The strength of the van der Waals bonds uniting the water molecules around the "encapsulated" molecule only enables these crystalline structures to be maintained under certain conditions of pressure (high pressure) and temperature (low temperature).