Electrification can trigger rapid growth in peak demand uncertainty

Mai Shi , Michael Craig

Electrification of space heating shifts weather-sensitive energy use onto power systems, driving peak electricity demand and its uncertainty. We quantify uncertainty in residential and commercial peak electricity demand across the contiguous United States by generating 256,200 county-level, hourly demand simulations across 14 heat pump penetration levels and 100 climate trajectories. penetrations rise, the relative spread between median and extreme realizations of annual peak demand grows nonlinearly. Across northern regions, a critical transition period spanning only a 10-20% increase in heat-pump penetration, typically around 20-40% penetration, drives more than 60% of total uncertainty growth. This transition occurs when systems shift from summer-only to summer or winter peaking, and increases underestimation risk when using historic weather. Preparing for this transition period is critical for planning reliable systems.