One of the cornerstones to reach a decarbonised energy system by 2050 is the inclusion of a set of flexibility solutions into the energy system to cover the need for flexibility on all timescales. Such flexibility services can come in different ways such as sector coupling, energy storage, flexible generation, enhanced interconnection, or demand-side management. As stated in the ETIP SNET Vision 2050, one of the main means to deliver this flexibility consists of upgrading and extending the pan-European transmission (electricity and gas) and local distribution (electricity, gas, heating and cooling) energy networks. The European Commission, in its Long-Term Strategy (COM(2018) 773) also considers the development of an adequate smart network infrastructure across Europe as one of the seven main strategic building blocks to reach a net-zero greenhouse gas economy.