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A rolling blackout, also referred to as rota or rotational load shedding, rota disconnection, feeder rotation, or a rotating outage, is an intentionally engineered
electrical power Electric power is the rate at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt, one joule per second. Standard prefixes apply to watts as with other SI units: thousands, millions and billions o ...
shutdown in which
electricity delivery Electricity delivery is the process that starts after generation of electricity in the power station, up to the use by the consumer. The main processes in electricity delivery are, by order: * Transmission * Distribution * Retailing See also * E ...
is stopped for non-overlapping periods of time over different parts of the distribution region. Rolling blackouts are a last-resort measure used by an
electric utility An electric utility is a company in the electric power industry (often a public utility) that engages in electricity generation and distribution of electricity for sale generally in a regulated market. The electrical utility industry is a major pr ...
company to avoid a total blackout of the power system. Rolling blackouts are a measure of
demand response Demand response is a change in the power consumption of an electric utility customer to better match the demand for power with the supply. Until the 21st century decrease in the cost of pumped storage and batteries electric energy could not be ...
if the demand for electricity exceeds the power supply capability of the network. Rolling blackouts may be localised to a specific part of the electricity network, or they may be more widespread and affect entire countries and continents. Rolling blackouts generally result from two causes: insufficient
generation A generation refers to all of the people born and living at about the same time, regarded collectively. It can also be described as, "the average period, generally considered to be about 20–⁠30 years, during which children are born and gr ...
capacity or inadequate
transmission Transmission may refer to: Medicine, science and technology * Power transmission ** Electric power transmission ** Propulsion transmission, technology allowing controlled application of power *** Automatic transmission *** Manual transmission *** ...
infrastructure to deliver power to where it is needed. Rolling blackouts are also used as a response strategy to cope with reduced output beyond reserve capacity from
power station A power station, also referred to as a power plant and sometimes generating station or generating plant, is an industrial facility for the generation of electric power. Power stations are generally connected to an electrical grid. Many p ...
s taken offline unexpectedly, such as an
extreme weather Extreme weather or extreme climate events includes unexpected, unusual, severe, or unseasonal weather; weather at the extremes of the historical distribution—the range that has been seen in the past. Often, extreme events are based on a locat ...
event.


In developing countries

Rolling blackouts are a common or even a normal daily event in many
developing countries A developing country is a sovereign state with a lesser developed industrial base and a lower Human Development Index (HDI) relative to other countries. However, this definition is not universally agreed upon. There is also no clear agreem ...
, where electricity generation capacity is underfunded or
infrastructure Infrastructure is the set of facilities and systems that serve a country, city, or other area, and encompasses the services and facilities necessary for its economy, households and firms to function. Infrastructure is composed of public and priv ...
is poorly managed. In well managed under-capacity systems, blackouts are scheduled in advance and advertised to allow people to work around them, but in most cases they happen without warning, typically whenever the transmission frequency falls below the 'safe' limit. These have wide-ranging impacts, and can effect the expectations of communities—for example—in Ghana
dumsor In Ghana, dumsor ( 'off and on') is a persistent, irregular, and unpredictable electric power outage. The frequent Ghanaian blackouts are caused by power supply shortage. Ghanaian generating capacity by 2015 was 400-600 megawatts, less than Gh ...
describes the widespread expectations for intermittent unexpected power outages due to rolling blackouts.


South Africa

Since 2007, South Africa has experienced multiple periods of rolling blackouts which are locally referred to as load shedding by the government owned energy utility
Eskom Eskom Hld SOC Ltd or Eskom is a South African electricity public utility. It was established in 1923 as the Electricity Supply Commission (ESCOM) and was also known by its Afrikaans name Elektrisiteitsvoorsieningskommissie (EVKOM). Eskom repre ...
. This was initially caused by the country's demand for electricity outgrowing its capacity to supply it, and as time progressed, later exacerbated by the aging power infrastructure, poor maintenance and the slow completion of new power plants. This has caused significantly severe damage to the South African economy and has played a large part in limiting the country's economic growth.


Ukraine

During 2022 invasion of Ukraine,
Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...
conducted multiple attacks on energy infrastructure of
Ukraine Ukraine ( uk, Україна, Ukraïna, ) is a country in Eastern Europe. It is the second-largest European country after Russia, which it borders to the east and northeast. Ukraine covers approximately . Prior to the ongoing Russian inv ...
. On October 23 rolling blackouts were introduced in Kyiv City and
Kyiv region Kyiv Oblast ( uk, Ки́ївська о́бласть, translit=Kyïvska oblast), also called Kyivshchyna ( uk, Ки́ївщина), is an Administrative divisions of Ukraine, oblast (province) in central and northern Ukraine. It surrounds, but ...
. Rolling blackouts were introduced in all Ukrainian regions on October 25.


In developed countries

Rolling blackouts in
developed countries A developed country (or industrialized country, high-income country, more economically developed country (MEDC), advanced country) is a sovereign state that has a high quality of life, developed economy and advanced technological infrastruct ...
sometimes occur due to economic forces at the expense of system reliability (such as in the 2000–01 California energy crisis), or during natural disasters such as
heat wave A heat wave, or heatwave, is a period of excessively hot weather, which may be accompanied by high humidity, especially in oceanic climate countries. While definitions vary, a heat wave is usually measured relative to the usual climate in the ...
s. In California rolling blackouts occurred in June 2000 and in January, March and May of 2001. The 2021 Texas power crisis involved rolling blackouts caused by the
February 13–17, 2021 North American winter storm A major winter and ice storm had widespread impacts across the United States, Northern Mexico, and parts of Canada from February 13 to 17, 2021. The storm, unofficially referred to as ''Winter Storm Uri'' by the Weather Channel, started out ...
and lack of
winterization Winterization is the process of preparing something for winter. Humanitarian aid In emergency or disaster response situations, such as managed by the UNHCR, winterization activities include the distribution of items including blankets, quilts, ...
. The
Late December 2022 North American winter storm From December 21 to 26, 2022, a historic extratropical cyclone created winter storm conditions, including blizzards, high winds, snowfall, or record cold temperatures across the majority of the United States and parts of Canada. Areas which ex ...
resulted in rolling blackouts in parts of the eastern US.


2011 Tōhoku earthquake

After the
2011 Tōhoku earthquake and tsunami The occurred at 14:46 JST (05:46 UTC) on 11 March. The magnitude 9.0–9.1 (M) undersea megathrust earthquake had an epicenter in the Pacific Ocean, east of the Oshika Peninsula of the Tōhoku region, and lasted approximately six minutes ...
,
Tokyo Electric Power Company , also known as or TEPCO, is a Japanese electric utility holding company servicing Japan's Kantō region, Yamanashi Prefecture, and the eastern portion of Shizuoka Prefecture. This area includes Tokyo. Its headquarters are located in Uchisaiw ...
implemented rolling blackouts. Its service area were divided to five blocks and blackouts were implemented from 6:20 to 22:00. The schedule from 15 to 18 March 2011 was as follows:


Effects

Intermittent access to electricity causes major economic problems for businesses, which incur costs in the form of lost resources, reduced patronage, or curtailed production if electrical equipment—for example refrigeration, lighting, or machinery—abruptly stops working. Businesses in areas that are subject to regular blackouts may invest in backup power generation to avoid these costs, but power backup is itself a cost because generators must be purchased and maintained and fuel must be regularly replenished.


Scheduling

When blackouts are scheduled in advance, they are easier to work around. The speed at which blackouts roll may be adjusted so that no blackout lasts longer than a certain limit. For instance, in Italy, th
PESSE
(''Piano di Emergenza per la Sicurezza del Sistema Electrico,'' Emergency plan for national grid safety) does not permit a controlled blackout longer than 90 minutes. In Canada, blackouts have been rolled so that no area had to spend more than one hour without power.


Causes

In some countries, generating capacity is chronically below demand. Assorted factors may prevent adequate investment in generation. Alternately, generating capacity may temporarily decrease below demand due to power station outages or loss of renewable capacity due to the wind dropping or the sun shining less. Natural disasters can also abruptly reduce supply by damaging power plants. A lack of fuel makes some types of power plant useless. Industrial accidents and poor maintenance can also take generation capacity offline. Conflict can disrupt fuel supply, as well as damage or destroy generating and delivery infrastructure. In electricity grids where power generators are paid a flexible market rate, power suppliers sometimes deliberately keep the generating capacity too low, or fake accidents that take capacity offline, to jack up prices. Demand spikes can also cause blackouts. Unusually hot or cold weather can cause demand spikes.


References

{{DEFAULTSORT:Rolling Blackout Power outages