The gaseous fuels are one of the key elements in decarbonization of the national economies of roughly all the European Union (EU) Member States. At the moment, the most prominent gaseous fuel in the EU is the natural gas, which, both in liquid and gaseous states, reaches its market via rather diverse routes (supply chains). Moreover, the EU’s energy sector dependence from the natural gas is quite significant, as, in 2020, the EU Member States imported 322 billion cubic meters (about 3145.76 terawatt-hours) of this fuel, which came from more than 10 locations worldwide. The natural gas, quite frequently also referred to as “conventional methane”, is important source of electricity and heat energy in the central and northern parts of the EU, which is used intensively throughout consumer groups – starting with the largest industrial consumers (such as heavy industry, steel production, chemical production etc.), energy generation utilities and ending with the smallest – households. However, being one of so called “conventional” or “fossil” fuels, the natural gas, despite its sustainability and wide potential of effective use, in the nearest future most likely is about to lose its role in the EU energy sector. According to decarbonization agenda, the natural gas is about to bridge the transition from current carbon intensive economy to the carbon neutral one in mid-21th century by blending with wide range of renewable gases (RG): biogas, biomethane (biogas upgraded to biomethane level), “green” hydrogen (produced during conversion of electricity from RES into hydrogen, via electrolysis) and synthetic natural gas. During the blending, RGs are expected to gradually replace the natural gas in the EU energy consumption, thus ensuring the gaseous fuel diversification throughout consumption range. However, this process is rather challenging not only from the theoretical and scientific, but also practical standpoint, and brings forward several risk factors, which must be identified, evaluated, analyzed and – which is most important – sustainably managed. These factors include but are not limited to political, socio-economic and engineering risks, which must be adequately addressed to make the EU energy transition in the gas sector as smooth, well regulated, well balanced and safe as possible.