The First 72 Hours: Power for Emergency Shelter

The design basis for emergency power is not peak load but 72 hours — the typical window between roads being cut and fuel resupply resuming. Three constraints follow. First, fuel autonomy: onboard fuel must be sized for 72 hours of base load, not for how long the plant runs at full output; many designs are dry by the second day. Second, black start: with the grid entirely down, the system must establish voltage and frequency without any external source, storage first and the engine synchronising afterwards. Third, load prioritisation: lighting and communications, then medical refrigeration, with heating and cooling allocated by time of day. A common order of magnitude: a 50-person shelter draws roughly 3–5 kW of base load (1 kW lighting, 1 kW communications and charging, 0.5–1 kW refrigeration, intermittent pumping), or about 250–350 kWh over 72 hours, with the battery carrying the night and the engine bulk-charging by day. When reports in July 2026 grouped temporary camps, disaster relief and outdoor hospitality as one application class, this is why: they share a design logic and differ only in timescale.