Regional failure of the electricity network
| Impact | 5 |
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| 4 |
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| 3 |
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| 2 |
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| 1 |
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5 |
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| ID | 26b |
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| Risk theme | Accidents and system failures |
Impact & Likelihood
| 5 | Catastrophic |
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| 4 | Significant |
| 3 | Moderate |
| 2 | Limited |
| 1 | Minor |
| 5 | >25% |
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| 4 | 5-25% |
| 3 | 1-5% |
| 2 | 0.2-1% |
| 1 | <0.2% |
Background
A regional failure of Great Britain’s electricity network could impact millions and may result from extreme weather causing damage to local infrastructure. Severe winds could bring down overhead cables, or localised flooding might affect a specific power substation. In recent years, Great Britain has experienced smaller-scale regional electricity failures, including those caused by storms Arwen and Eunice in winter 2021/2022 where thousands of homes were left without power. As a result of the government’s post- incident review of these storms, industry has taken several steps to improve the electricity sector’s physical resilience to future severe weather events, as well as the protections and support available to consumers. These actions will aid in mitigating against larger-scale regional electricity failures.
Scenario
The reasonable worst-case scenario is based on a significant failure of the electricity network across several regions of Great Britain leading to the loss of power across the affected regions. Impacts would vary depending on which regions are affected and the scale of the disruption. This would result in some failures across utilities, causing disruption to public services as well as domestic households and businesses. It is expected that telecommunications systems and transport services (rail, road and aviation) would be disrupted due to the failure of electronic systems.
Key assumptions
This scenario is cause agnostic but would likely be the result of extreme weather, with greater impacts in winter. This is a regional scenario which would not cause nationwide disruption.
Response capability requirements
If caused by storms, forecasting would allow government, industry and local authorities to prepare. Specialist equipment and additional workforce would be required, including readying engineers and other workers, cutting down trees near infrastructure, setting up welfare stations for members of the public, and preparing back-up generators to reconnect small numbers of customers quickly. Urban areas would require a different response to rural areas due to higher population densities and infrastructure dependence. Network operators and Strategic Coordinating Groups would coordinate to provide welfare support to customers. Enhanced support, such as alternative accommodation, may be provided to the vulnerable.
Recovery
Most customers (domestic and business) would be reconnected on a staggered basis within hours. However, when damage is widespread, or impacts locations on the more remote parts of the network, it could take several weeks to fully restore all customers. This is due to the difficulties of accessing remote locations and the amount of time needed to repair physical damage.