Liquefied natural gas (LNG) is produced when natural gas is cooled down to -160 degrees. The gas is compressed, which is why the volume of LNG is approximately 1/600 of the gas volume under normal conditions. Prior to the liquefaction of gas, components are removed from it which could corrode the liquefaction equipment or cause blockages. This is why LNG is even purer than regular natural gas. The regasification takes place at the admission terminal.
The liquefaction of natural gas makes the transport and storage of natural gas easy and economic while also providing easy access to the energy source around the world. The advantage of LNG over natural gas is the possibility to supply natural gas to the areas which are not connected to the natural gas network, and to exchange the fuel used on roads, railways, in air and maritime transport with LNG-based gaseous fuel and transport smaller quantities. The biggest disadvantage of LNG is the relatively high cost of the liquefaction and regasification processes.
Supplying Tallink Megastar with LNG is the first project of this kind that Eesti Gaas has implemented. This topic is becoming increasingly relevant – notably, the sulphur content of marine fuel cannot exceed 0.10 per cent since 2015.
There are three possibilities to fulfil this requirement: start using special fuel with low sulphur content, install purification equipment, or start using liquefied natural gas. LNG offers a good combination of ecological and economical benefits while enabling to save on fuel costs and comply with the environmental protection norms. The European Union has adopted a plan of action which foresees the development of an LNG bunkering network between the main ports of the member states by the year 2025.
The widespread use of LNG in land transport received a significant legislative impetus with a directive of the European Union which states that all the member states must replace the fuels used in transport with renewable fuels to the extent of 10%. According to the estimation of the Ministry of Economic Affairs and Communications, this requirement in Estonia could be covered with biomethane to the extent of 3-4%. Natural gas, in compressed (CNG) as well as liquid (LNG) form, is leading the way. The EU has established minimum requirements for the member states regarding the refuelling infrastructure of LNG and CNG. According to that, the goal is to cover the network of the EU main roads with CNG filling stations every 150 km and LNG filling stations every 400 km by the year 2025.