A microgrid that can disconnect from the wider system and keep a hospital, a base, or a water plant alive is one of the few tools that changes the human outcome of a long outage. The key word is can. Islanding has to be engineered and drilled, with fuel or generation that does not secretly depend on the grid it is supposed to replace.

Islanding means the breakers open, the local generation holds frequency and voltage, and the critical loads stay inside the island. If the generator needs a grid-fed pump, or the control system needs a network that just died, the island is a diagram. Drills are how you find that out on a Tuesday instead of during the storm.

Fuel is the quiet dependency. A tank on site is a different machine from a plan that assumes a truck will arrive from a terminal that has power and passable roads. Solar and batteries change the arithmetic only for the loads they were actually built to carry, and only while the equipment itself is intact.

Community-scale versions — a town hall, a school, a clinic — are more realistic than a fantasy of every suburb as a power island. They also require agreements written in advance about who is allowed in and what loads are critical.

The agreement is the unglamorous half. Who gets a cot, who gets a receptacle for a medical device, which lights stay on, and who tells the crowd at the door. Without that paper, the building with power becomes a dispute, and the operator spends the outage on the sidewalk instead of on the plant.

If your town has one, learn where it is on a calm day. If it does not, the household plan is the plan.

Ask what it covers. A campus that keeps one set of buildings alive may not keep the nearby apartments alive. The slide in a council meeting and the building you can actually walk to are not the same object. If there is no island, water, a way to cook that does not fill the house with carbon monoxide, medications, and a radio are the household substitute. They do not replace a water plant. They are what you have.