Rolling blackout

From Wikipedia, the free encyclopedia

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 shutdown in which electricity delivery 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 company to avoid a total blackout of the power system.

Rolling blackouts are a measure of demand response 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 capacity or inadequate 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 stations taken offline unexpectedly.

In developing countries[edit]

Rolling blackouts are a common or even a normal daily event in many developing countries,[1] where electricity generation capacity is underfunded or infrastructure 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 describes the widespread expectations for intermittent unexpected power outages due to rolling blackouts.

South Africa[edit]

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. 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.


During 2022 invasion of Ukraine, Russia conducted multiple attacks on energy infrastructure of Ukraine.[2][3][4][5] On October 23 rolling blackouts were introduced in Kyiv City and Kyiv region.[6][7] Rolling blackouts were introduced in all Ukrainian regions on October 25.[8]

In developed countries[edit]

Rolling blackouts in developed countries sometimes occur due to economic forces at the expense of system reliability (such as in the 2000–01 California energy crisis),[9][10] or during natural disasters such as heat waves.[11] In California rolling blackouts occurred in June 2000 and in January, March and May 2001.[12] The 2021 Texas power crisis involved rolling blackouts caused by the February 13–17, 2021 North American winter storm and lack of winterization.[13] The Late December 2022 North American winter storm resulted in rolling blackouts in parts of the eastern US.[14][15][16]

2011 Tōhoku earthquake[edit]

After the 2011 Tōhoku earthquake and tsunami, Tokyo Electric Power Company 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:[17][18]

Time 15 March 16 March 17 March 18 March
6:20–10:00 Block 3 Block 4 Block 5 Block 1
9:20–13:00 Block 4 Block 5 Block 1 Block 2
12:20–16:00 Block 5 Block 1 Block 2 Block 3
15:20–19:00 Block 1 Block 2 Block 3 Block 4
18:20–22:00 Block 2 Block 3 Block 4 Block 5


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.[19] 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.


When blackouts are scheduled in advance, they are easier to work around.[20]

The speed at which blackouts roll may be adjusted so that no blackout lasts longer than a certain limit. For instance, in Italy, the 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.[21][22]


In some countries, generating capacity is chronically below demand.[23][24][25][20] Assorted factors may prevent adequate investment in generation.[26] Alternately, generating capacity may temporarily decrease below demand due to power station outages[27] or loss of renewable capacity due to the wind dropping[22] or the sun shining less.[28] Natural disasters can also abruptly reduce supply by damaging power plants.[26] A lack of fuel makes some types of power plant useless.[29] Industrial accidents and poor maintenance can also take generation capacity offline.[30][31][32] Conflict can disrupt fuel supply,[33] as well as damage or destroy generating and delivery infrastructure.[34][8]

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.[35][22]

Demand spikes can also cause blackouts. Unusually hot[20][36] or cold weather[37][38][39][21] can cause demand spikes.


  1. ^ Agarwal, Anshul; Khandeparkar, Kedar (June 2021). "Distributing power limits: Mitigating blackout through brownout". Sustainable Energy, Grids and Networks. 26: 100451. doi:10.1016/j.segan.2021.100451. S2CID 233918608. Retrieved 14 June 2022.
  2. ^ "Russia targets Ukraine energy and water infrastructure in missile attacks". the Guardian. 31 October 2022. Retrieved 11 November 2022.
  3. ^ "Ukraine Reports More Russian Strikes on Energy Infrastructure". VOA. Retrieved 11 November 2022.
  4. ^ Sukhov, Oleg (19 October 2022). "Intensified Russian attacks on Ukraine infrastructure unlikely to achieve Kremlin's goals". The Kyiv Independent. Retrieved 11 November 2022.
  5. ^ "Another mass attack on Monday morning: Russia hits energy infrastructure across Ukraine". The Kyiv Independent. 31 October 2022. Retrieved 11 November 2022.
  6. ^ "Rolling blackouts Kyiv city and oblast intended to stabilize the grid". Retrieved 11 November 2022.
  7. ^ Rolling blackouts start in Kyiv as Ukrainians urged to save power
  8. ^ a b "Rolling blackouts implemented in all Ukrainian regions on Oct. 25". The Kyiv Independent. 25 October 2022. Retrieved 11 November 2022.
  9. ^ Bonsor, Kevin (2001). "How California's Power Crisis Works". HowStuffWorks.
  10. ^ "The California Crisis". Frontline.
  11. ^ Harvy, Ben; Shepherd, Tory (8 February 2017). "Rolling Blackouts Ordered as Adelaide Swelters in Heatwave".
  12. ^ Brown, Marilyn A. (2004). "Obstacles to Energy Efficiency". Encyclopedia of Energy. Elsevier Inc. pp. 465–475. doi:10.1016/B0-12-176480-X/00172-8. ISBN 9780121764807. Retrieved 14 June 2022.
  13. ^ Walsh, Dominic Anthony (16 February 2021). "What's Happening in Texas With the State's Power Grid". NPR.
  14. ^ "MLGW: No rolling blackouts after TVA rescinds order". 23 December 2022. Retrieved 23 December 2022.
  15. ^ Williams, Javon; Montgomery, Charles. "Many customers throughout North Alabama experiencing power outages, TVA cancels rolling blackouts". Retrieved 23 December 2022.
  16. ^ "Thousands of Middle Tennesseans impacted by power outages during dangerous cold". News Channel 5 Nashville (WTVF). 23 December 2022. Retrieved 23 December 2022.
  17. ^ "Implementation Plan of Rolling Blackout on and After Tue, March 15, 2011" (Press release). Tokyo Electric Power Company. 14 March 2011.
  18. ^ "Shūkan Keikaku Teishi Imēji" 週間計画停止イメージ [Weekly Planned Outage Image] (PDF) (in Japanese). Tokyo Electric Power Company.
  19. ^ McDonnell, Tim (24 November 2019). "The Powerlessness of Nigeria's Tech Startups". NPR.
  20. ^ a b c "Unscheduled loadshedding irks people in Punjab". The Nation. 2 October 2011.
  21. ^ a b "Newfoundland outages worsen amid sudden 'generation problems'". 5 January 2014.
  22. ^ a b c Gerein, Keith (9 July 2012). "Rolling electricity blackouts strike Edmonton and across the province". The Vancouver Sun. Archived from the original on 18 July 2012.
  23. ^ "Electricity and power shortage holding India back".
  24. ^ Range, Jackie (28 October 2008). "India Faulted for Failure to Improve Power Supply". The Wall Street Journal.
  25. ^ "India offers Pakistan electricity to curb load-shedding". The Express Tribune. 20 April 2011.
  26. ^ a b "Mail and Guardian – Govt chose guns over power stations".
  27. ^ "ERCOT may initiate more blackouts Wednesday night, Thursday morning". The Dallas Morning News. 2 February 2011.
  28. ^ "SA power: What is load shedding and why is it happening?". ABC News. 9 February 2017.
  29. ^ "Tripped coal stations add to load shedding burden". Business day live. 5 December 2014. Retrieved 6 December 2014.
  30. ^ The citizen. 4 November 2014 Retrieved 6 December 2014. {{cite news}}: Missing or empty |title= (help)
  31. ^ "Eskom admits another coal-storage silo at Majuba is cracked". Business day live. 21 November 2014. Retrieved 6 December 2014.
  32. ^ "This is a catastrophe: electricity expert". Moneyweb. 6 December 2014. Retrieved 6 December 2014.
  33. ^ Ukraine turns off reactor at its most powerful nuclear plant after 'accident', The Independent (28 December 2014)
    Ukraine Briefly Cuts Power to Crimea Amid Feud With Russia Over NATO, New York Times (DEC. 24, 2014)
    Coal import to help avoid rolling blackouts in Ukraine — energy minister, ITAR-TASS (December 31, 2014)
    Rolling blackouts in Ukraine after nuclear plant accident
    Mashable (Dec 03, 2014)
    Ukraine to Import Coal From ‘Far Away’ as War Curtails Mines, Bloomberg News (Dec 31, 2014)
  34. ^ "Ukraine war: Kyiv set for longer power cuts after air strikes". BBC News. 29 October 2022. Retrieved 11 November 2022.
  35. ^ Lauren Johnston (2 June 2004). "Enron tapes anger lawmakers". CBS Evening News.
  36. ^ "SA heatwave forces blackouts to cope with electricity demand, angering Government". ABC News. 9 February 2017.
  37. ^ Farangis Najibullah (13 January 2008). "Tajikistan: Energy shortages, extreme cold create crisis situation". EurasiaNet. Retrieved 8 February 2008.
  38. ^ Situation Report No. 4 – Tajikistan – Cold Wave/Compound crisis (25 February 2008) United Nations Office for the Coordination of Humanitarian Affairs
  39. ^ Heinz, Frank. "Outages Suspended, But Conservation Critical". NBC 5 Dallas-Fort Worth.