Security of energy supply has traditionally been understood in terms of availability: ensuring that sufficient volumes are physically present in the system. Price, in this context, was largely a reflection of scarcity. Today, however, the issue is not only whether energy is available, but under which conditions it can be accessed.

We can understand this shift in recent developments. Tensions affecting key transit routes, particularly in the Middle East, have raised concerns about energy security. Yet these concerns emerge in a context where no immediate major physical gas supply shock is observed. Volumes remain available, demand has not declined (OIES, 2026), but the system is not necessarily stable. And this reflects a more profound structural change.

As we have argued in recent joint work, since now price shocks in Europe’s gas system are not necessarily proportional to physical disruptions (Sesini and Kneebone, 2026), Europe can face a gas crisis without a gas shortage. The reason is that vulnerability no longer sits primarily in physical supply volumes, but in the mechanisms that connect supply to demand.

As a result of policy responses to the 2022 crisis, today Europe is more deeply embedded in global gas markets, where supply is more flexible but more contested, and where access to the commodity is increasingly mediated through price, altering the nature of exposure and transforming risk from volumes to prices. In this context, volumes still matter, but they are no longer sufficient on their own: disruptions do not need to remove physical supply to generate stress. In fact, they operate through expectations, logistics and competition for marginal volumes.

This mechanism is not specific to gas but reflects dynamics across globally traded energy markets (e.g., oil markets). A significant share of flows transits through a limited number of maritime chokepoints, one of which is the Strait of Hormuz, alone accounting for about one-fifth of global oil trade (EIA, 2023). Disruptions affecting these routes do not necessarily eliminate resources, but they affect the conditions under which those resources move. Delays, rerouting or higher transport costs can quickly translate into price volatility. Price, in this context, becomes the primary transmission channel of geopolitical risk.

This has important implications for how security of supply is understood. A system may be diversified across suppliers, yet remain highly exposed to global price formation. Replacing pipeline dependence with maritime dependence shifts the location of vulnerability rather than removing it. At that point, security of supply, therefore, becomes less about the availability of volumes per se, and more about the conditions under which those volumes can be secured and priced over time.

This shift complicates policy choices. During the 2022–2023 crisis, large-scale interventions to shield consumers from high prices were justified by the magnitude of the shock. Today, in globally integrated systems, price signals are not a side effect but a coordinating mechanism. High prices attract supply; suppressed prices may divert it elsewhere.

Yet, not all forms of dependence are equivalent. When risk is mediated through prices, the structure of supply determines the degree of exposure to global volatility. Systems with a higher share of domestically controlled energy sources are structurally less exposed to external price shocks. This is not because they are insulated from global markets, but because price shocks are less likely to translate into payments to external suppliers. This distinction is not captured by simple price comparisons, but becomes critical in systems where vulnerability operates through volatility rather than physical scarcity.

Paying for imported fuels implies a continuous external financial outflow, while investing in domestic energy systems retains value within the economy. This has implications not only for how security of supply is managed, but also for how it is valued. If exposure materialises through price volatility and access under uncertainty, then security cannot be assessed solely through cost metrics such as €/MWh. To this end, systems that reduce exposure to external shocks, through diversification, storage, or domestic energy production, generate a form of value that is not fully captured in market prices. They reduce volatility, enhance system stability and retain economic activity within the system.

In that sense, security of supply should not be factored in merely as a constraint on efficiency, but as a form of system value, a social dividend, that accrues over time by reducing exposure to uncertainty and the associated cost of instability. If security was once defined by the availability of volumes and now increasingly determined by the conditions under which those volumes can be accessed and stabilised over time, it is likely to evolve further, towards a broader system dimension, where the ability to manage exposure to price volatility and uncertainty becomes a defining feature of energy system design.