Gas storage supplies 25-30 % of gas consumed in winter, and plays a crucial role in our security of supply. If a major source of supply to Europe were to be interrupted for any reason, a high level of gas storage could help to meet demand in the short and medium term, and thus give the EU and its Member States more time and space to develop longer-term solutions. So far, gas storage has mostly been treated as a national competence, since it forms part of the ‘structure of energy supply’ that Article 194 TFEU enshrines as the ‘right’ of Member States. However, Article 194 TFEU also considers that security of supply in Europe is an EU competence, and the main justification for EU action is a threat to its energy security from the Russian invasion of Ukraine. Gas storage levels vary considerably by Member State (see Figure 1), with five countries (Germany, Italy, the Netherlands, France and Austria) accounting for 73 % of total EU gas storage capacity. A number of Member States have no gas storage capacity of their own at all and thus would have to rely on facilities in neighbouring countries.