Natural Gas Transport and Logistics

Natural gas is considered the cleanest fossil energy resource and for this reason, despite its non-renewable origin, it is considered fundamental in the energy transition path. According to the Net-Zero Emission scenario of the IEA, the production cycle of natural gas is closely linked to that of hydrocarbons and is similar in terms of logistics, although with due peculiarities.

Natural gas is found in a gaseous state in ambient conditions so its handling is more complicated than that of oil and coal: its energy density is much lower. The choice of the most advantageous system for the transport of natural gas depends on several factors, such as: the distance, the daily volumes to be transported, the overall availability of natural gas (reserve), the onshore/offshore location of the field, the distance from the coast, etc.. The two main alternatives for transportation are:

a)       Compressed Natural Gas or CNG: the gas remains in the gas phase and is brought to high pressure at room temperature;

b)       b) Liquefied Natural Gas or LNG: the gas is brought into the liquid phase by cooling it to a temperature below - 161.4 °C, the boiling temperature of methane at ambient pressure.

Traditionally, the most common way to move large quantities of natural gas is by transporting it in the gas phase under pressure through pipelines (called methane pipelines). These infrastructures physically connect natural gas fields with major consumption areas, sometimes crossing entire continents for thousands of miles.

Alternatively, natural gas is transported over much greater distances in the form of liquefied gas, allowing international trade. Large quantities of liquefied natural gas (LNG) are moved by LNG carriers in a similar way to oil. Unlike oil, however, LNG logistics require marine liquefaction terminals at the port of departure and regasification terminals at the port of arrival: at these terminals the LNG is returned to gaseous state and usually integrated into the pipeline system.

LNG has seen a strong expansion in the last period as it can be used as a low carbon emission fuel for heavy fleets. It also makes possible the methanization of areas that are difficult to connect (an example in Italy is Sardinia). In this context, LNG coastal storage terminals are being developed to complement regasification infrastructures.

Fundamental to natural gas logistics are storage facilities. As the LNG market evolves, the need for natural gas storage in liquid form is emerging. However, the most common and relevant technology in natural gas storage is geological storage, integrated with the pipeline system. Natural gas is in fact pressurized and injected into large depleted fields or other geological structures suitable for the purpose, in order to ensure large (and strategic) quantities of energy reserves. To date, this storage system is the only one that can guarantee a seasonal flow rate. In Europe, Italy is the second country after Germany for natural gas storage capacity (17853 million m³).