Power Outage/ or Blackout (2024)

Primary reference(s)

EIS Council, 2019. Black Sky Hazards. Electric Infrastructure Security (EIS) Council. Accessed 9 October 2020.

FEMA, 2018. Be prepared for a power outage. US Federal Emergency Management Agency (FEMA). Accessed 9 October 2020.

Pescaroli, G., S. Turner, T. Gould, D.E. Alexander and R.T. Wicks, 2017. Cascading Effects and Escalations in Wide Area Power Failures: A Summary for Emergency Planners. Accessed 9 October 2020.

UK Cabinet Office, 2017. National risk register of civil emergencies 2017 edition. UK Cabinet Office, London. Accessed 9 October 2020.

Additional scientific description

Power outage can manifest in various forms, including transient faults, brownouts, and blackouts. They may initiate from both the supply and demand side. In some cases, power outages also materialise as the result of a situational response, such as in order to prevent worse consequences (e.g., rolling blackouts).

Event severity of power outages may exceed the ordinary by far; for instance, the Electric Infrastructure Security Council defines a Black Sky Hazard as “a catastrophic event that severely disrupts the normal functioning of our critical infrastructures in multiple regions for long durations” (EIS Council, 2019). The process of full restoration of the electricity network after the total or partial shutdown of the grid is sometimes termed as black start (UK Cabinet Office, 2017).

Terminology and definitions may vary, even significantly, across operational contexts and agencies.

Metrics and numeric limits

Metrics are in place to capture the many facets of a power outage. Some of these metrics are derived from standards such as IEEE 1366-2012 (IEEE, 2012).

Duration/frequency/occurrence time. For electric power utilities, commonly used reliability indicators include the System Average Interruption Duration Index (SAIDI) and System Average Interruption Frequency Index (SAIFI). In power outages analysis and reporting, it is common to refer to short- to long-duration events as a function of the specific legislative and operational context. For instance, the US Department of Homeland Security (2017) refers to a “long-term (+72 hours) interruption”, while in general customer interruptions are considered as power outages even if much briefer. Important figures are those related to occurrence times of the failure event chains.

Magnitude and size. Typical indicators assess the affected parts and quotas of the grid, the estimated electricity not provided, or the geographic extent of the event. Power outages are often described as local, regional, national, cross-national, up to global. However, geography-based reporting may depend on jurisdictions and generally it is not possible to find an official definition on the size of blackouts (Galbusera and Giannopoulos, 2018).

Number of users affected. Figures typically considered are the number of people or households affected, or similar indicators for industries and businesses, sometimes accompanied by spatio-temporal details (Galbusera and Giannopoulos, 2018).

Economic indices. Indices in use to evaluate supply interruption-related costs include, the Interruption Energy Assessment Rate (IEAR), Value of Lost Load (VOLL), and Willingness to Pay (WTP) (e.g., €/kWh). A comprehensive impact quantification should account for both direct and indirect costs (Galbusera and Giannopoulos, 2018).

Examples of drivers, outcomes and risk management

Power outages are associated with cascading and systemic risks rooted at the intersection between physical, societal, functional and organisational dynamics (Pescaroli and Alexander, 2016). Since the early 2000s, larger impacts of power outages have been associated with growing and varying demand, network size and complexity, as well as market deregulation (Helbing et al., 2006). Triggering events include failure of operation, failure of equipment or material damage, human errors, aging infrastructure, and damage caused by natural hazards on equipment, facilities and lines (Amin, 2002; Little, 2002; Petermann et al., 2011; Karagiannis et al., 2017). Directly and indirectly targeted malicious acts include cyberattacks, terrorist acts, or electromagnetic pulse attacks (Amin, 2002; Linkov et al., 2013). The impact of power outages can be amplified if the outage happens in concurrency with climate-related extreme events (e.g., cold waves, heatwaves) (Klinger et al., 2014).

Petermann et al. (2011) illustrated that power outages can heavily disrupt societal and economic functions both directly (due to the lack of energy they rely on) and indirectly (e.g., through interdependencies). According to Pescaroli et al. (2017), the effects of power outages are associated with direct threats to life (e.g., impacts on the health sector, water shortages, or disruption of heating and cooling); indirect threats to life (e.g., increased need of vulnerable population, loss of cash flow); and challenges for operational capacities (e.g., loss of efficiency of emergency services).

Risk management strategies include national and international risk assessments, development of policies and practices for continuity management, training and exercises for complex scenarios involving multiple interdependent failures, assessment of new technologies (e.g., microgrids, cashless transactions), and the improvement of crisis communication before, during and after power outage events (FEMA, 2018).