Designing an energy system that cannot be switched off

The usual framing of energy security is about who sells you fuel. That matters, but it is only one variable. The more useful framing treats security as a property of how a system is built, and the principles involved are general enough to state on their own.

Diversity

More than one supplier, more than one route, more than one fuel. A system with two suppliers is not twice as secure as one with a single supplier; it is categorically different, because the second one gives the first a reason to behave.

Storage

Storage converts a supply interruption into an inconvenience. Gas storage measured in months rather than days is the difference between negotiating and capitulating, and Ukraine's underground storage capacity is a genuine strategic asset for exactly this reason.

Interconnection

Physical links to neighbouring systems, in both directions, with market rules that let power and gas actually flow. An isolated system has no options; a connected one has as many options as it has neighbours.

Dispersion

Many small generating units rather than a few large ones. Less efficient per megawatt and far harder to disable, which is the trade-off Ukraine has been making deliberately.

Demand reduction

The cheapest and least discussed. Insulation, metering and efficient equipment reduce the volume that has to be supplied at all, and a unit not consumed cannot be interrupted.

Repairability

Spares held in advance, crews trained and standard designs so that a component from one site fits another. Nothing is invulnerable; what matters is how quickly it comes back.

You can write these five principles for a company too, and I have: do not depend on one supplier, hold stock, find a second route, do not put everything in one place, reduce what you need. At national scale they look different but they are the same principles. What twenty years has taught me is that resilience is not a budget line but a small redundancy built into every decision.