Quantifying the impact of residential heat pumps on primary substations under critical cold events: A UK case study

To achieve net-zero emissions by 2050, the UK government is relying on the large-scale deployment of heat pumps to facilitate the decarbonization of the residential heating sector. However, this deployment will inevitably pose significant challenges to the future power grid, especially during cold winter nights. Based on 10 substation cases, this study analyses the potential impact of the future widespread adoption of heat pumps across the UK on residential electricity distribution networks across four scenarios: (1) monthly peak demand analysis, (2) critical cold event, (3) monthly peak demand with thermally upgraded homes, and (4) thermally upgraded homes during a critical cold event. The findings reveal severe network vulnerability: under baseline conditions, several substations experience peak-time overloads at a mere 7%-10% heat pump penetration. During simulated critical cold events with elevated supply temperatures (55 °C), network stress becomes unsustainable, restricting penetration thresholds by up to 18 percentage points and extending overload durations to an extreme 136 h. Crucially, the implementation of housing thermal upgrades serves as a vital mitigation strategy, capable of recovering penetration capacity by 1 to 13 percentage points and reducing extreme congestion by up to 57.5 h. This study underscores that coupling heat pump deployment with rigorous building fabric improvements is an absolute prerequisite for safeguarding future grid resilience.