In recent times, the increased accessibility of natural gas vehicles and filling stations has meant that natural gas vehicles have become progressively essential as a way to reduce our dependency on oil and address the issues of transport emissions and air pollutants. 

Ordinarily, natural gas has a lower energy density compared to diesel and gasoline. To maximise its energy density and offer a longer driving range for vehicles, natural gas should either be compressed and stored in high-pressure tanks or cooled and stored in highly insulated cryogenic tanks.

There are fundamentally three types of CNG stations: 

• Fast-fill
• Time-fill 
• A combination of the two. 

Typically, retail stations use fast-fill and fleets that have central refuelling and the ability to fill overnight use time-fill. The costs of installing natural gas infrastructure varies based on size, capacity, and the type of natural gas:

• LNG (liquefied natural gas)
• CNG (compressed natural gas)
• or both. 

It also varies in the way the natural gas is dispensed (fast-fill or time-fill).

In Estonia the first documented attempts for establishing filling stations, a CNG network, can be traced back as far as 2004, when individuals related to the driving school industry in South Estonia, had the idea to build CNG filling stations. Eesti Gaas AS sells two products at its filling stations - CBM (compressed biomethane) and CNG. The chemical composition and quality of the two products are the same and both are suitable for a CNG car. In addition, LNG is used in transport but there are currently no LNG stations in Estonia. Passenger cars mostly use CNG. There are currently eight filling stations in Estonia and three filling stations are under planning.

Understanding the local gas grid is often the first step in the development of gas refuelling infrastructure. The present gas network creates a lot of opportunities to add new filling stations. The systematic digitalisation of the natural gas transmission network in Estonia began in 2000 and was mostly completed by 2006. Nevertheless, in the following years work continued in the refinement and specification of the gas refuelling infrastructure.

Furthermore, the project covers some background principles related to the EU Project of Common Interest (PCI) in and around the Gulf of Finland and a major infrastructure project in and around the Baltic Sea, which aim to better interconnect energy networks towards a single energy market in Europe.