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.
Rolling blackouts are a common or even a normal daily event in many developing countries,where electricity generation capacity is underfunded or infrastructure is poorly managed. In well managed under-capacity systems blackouts are planned and schedules are published in advance to allow people to work around them. In poorly managed systems 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.
Since 2007, South Africa has experienced multiple periods of rolling blackouts which are locally referred to as load shedding by the state-owned energy company Eskom. This was initially caused by the country's demand for electricity outstripping supply, and as time progressed, later exacerbated by ageing power infrastructure, poor maintenance, and the slow completion of new power stations. It was recently revealed by Eskom's former spokesperson Sikhonathi Mantshantsh, that widespread tender corruption and the sabotage of power infrastructure by employeesis one of the primary reasons for continuing load shedding. 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.On October 23 rolling blackouts were introduced in Kyiv and its oblast. Rolling blackouts were introduced in all Ukrainian regions on October 25.
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),or during natural disasters such as heat waves. In California rolling blackouts occurred in June 2000 and in January, March and May 2001. The 2021 Texas power crisis involved rolling blackouts caused by the February 13–17, 2021 North American winter storm and lack of winterization. The Late December 2022 North American winter storm resulted in rolling blackouts in parts of the eastern US.
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:
|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.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.
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.
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 hotor cold weather can cause demand spikes.
In the case of South Africa, failing and aged infrastructure, lack of maintenance and alleged corruption in the country's African National Congress-led government in the running of their primary electricity provider, Eskom, is the direct cause of rolling blackouts.[ citation needed ]
A power outage is the loss of the electrical power network supply to an end user.
Eskom Hld SOC Ltd or Eskom (Afrikaans: Elektrisiteitsvoorsieningskommissie) is a South African electricity public utility. Eskom was established in 1923 as the Electricity Supply Commission (ESCOM). Eskom represents South Africa in the Southern African Power Pool. The utility is the largest producer of electricity in Africa, and was among the top utilities in the world in terms of generation capacity and sales. It is the largest of South Africa's state owned enterprises. Eskom operates a number of notable power stations, including Matimba Power Station and Medupi Power Station in Lephalale, Kusile Power Station in Witbank, Kendal Power Station, and Koeberg Nuclear Power Station in the Western Cape Province, the only nuclear power plant in Africa.
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 easily stored, so utilities have traditionally matched demand and supply by throttling the production rate of their power plants, taking generating units on or off line, or importing power from other utilities. There are limits to what can be achieved on the supply side, because some generating units can take a long time to come up to full power, some units may be very expensive to operate, and demand can at times be greater than the capacity of all the available power plants put together. Demand response, a type of energy demand management, seeks to adjust in real-time the demand for power instead of adjusting the supply.
Electricity in Pakistan is generated, transmitted, distributed, and retail supplied by two vertically integrated public sector companies, Water and Power Development Authority (WAPDA) responsible for the production of hydroelectricity and supplied to the consumers by the power distribution companies (DISCOS) under the Pakistan Electric Power Company (PEPCO). Currently, there are 11 distribution companies and one National Transmission And Dispatch Company (NTDC) all in the public sector, and the Karachi Electric (K-Electric) for the city of Karachi and its surrounding areas. There are around 42 independent power producers (IPPs) that contribute significantly in electricity generation in Pakistan.
An electrical grid is an interconnected network for electricity delivery from producers to consumers. Electrical grids vary in size and can cover whole countries or continents. It consists of:
Medupi Power Station is a dry-cooled coal-fired power station built by Eskom near Lephalale in Limpopo province, South Africa. The station consists of 6 generating units with a nameplate capacity of 800 MW each bringing the total installed capacity of 4,800 MW.
The utility electricity sector in Bangladesh has one national grid with an installed capacity of 25,700 MW as of June 2022. Bangladesh's energy sector is not up to the mark. However, per capita energy consumption in Bangladesh is considered higher than the production. Electricity was introduced to the country on 7 December 1901 under British rule.
The Ceylon Electricity Board - CEB, is the largest electricity company in Sri Lanka. With a market share of nearly 100%, it controls all major functions of electricity generation, transmission, distribution and retailing in Sri Lanka. It is one of the only two on-grid electricity companies in the country; the other being Lanka Electricity Company (LECO). The company earned approximately Rs 204.7 billion in 2014, with a total of nearly 5.42 million consumer accounts. It is a government owned and controlled utility of Sri Lanka that takes care of the general energy facilities of the island. The Ministry of Power and Energy is the responsible ministry above the CEB. Ceylon Electricity Board (CEB), established by an CEB Act No. 17 of 1969, is under legal obligation to develop and maintain an efficient, coordinated and economical system of Electricity supply in accordance with any Licenses issue.
The energy policy of Pakistan is formulated and determined by the federal, provincial, and local institutional entities in Pakistan, which address the issues of energy production, distribution, and consumption of energy, such as gas mileage and petroleum standards. Energy policy requires the proper legislation, international treaties, subsidies and incentives to investment, guidelines for energy conservation, taxation and other public policy techniques.
Energy in Ukraine is mainly from gas and coal, followed by nuclear and oil. The coal industry has been disrupted by conflict. Most gas and oil is imported, but since 2015 energy policy has prioritised diversifying energy supply.
Two severe power outages affected most of northern and eastern India on 30 and 31 July 2012. The 30 July 2012 blackout affected over 400 million people and was briefly the largest power outage in history by number of people affected, beating the January 2001 blackout in Northern India. The blackout on 31 July is the largest power outage in history. The outage affected more than 620 million people, about 9% of the world population, or half of India's population, spread across 22 states in Northern, Eastern, and Northeast India. An estimated 32 gigawatts of generating capacity was taken offline. Of the affected population, 320 million initially had power, while the rest lacked direct access. Electric service was restored in the affected locations between 31 July and 1 August 2012.
Energy in California is a major area of the economy of California. California is the state with the largest population and the largest economy in the United States. It is second in energy consumption after Texas. As of 2018, per capita consumption was the fourth-lowest in the United States partially because of the mild climate and energy efficiency programs.
The Electricity sector in South Africa is an important part of energy in South Africa. Most power stations in South Africa are owned and operated by the state owned enterprise, Eskom. These plants account for 80% of all the electricity produced in South Africa and 45% of all electricity produced on the African continent.
In Ghana, dumsor is a persistent, irregular, and unpredictable electric power outage. It is usually caused by a power supply shortage.
The South Australian blackout of 2016 was a widespread power outage in South Australia that occurred as a result of storm damage to electricity transmission infrastructure on 28 September 2016. The cascading failure of the electricity transmission network resulted in almost the entire state losing its electricity supply, affecting 850,000 SA customers. Kangaroo Island did not lose its supply, as the Kangaroo Island power station had been built to supply the island for the contingency of a failure in the power cable under the Backstairs Passage.
The South African energy crisis or load shedding is an ongoing period of widespread national blackouts of electricity supply. It began in the later months of 2003 towards the end of Thabo Mbeki's second term as president, and continues to the present. The South African government-owned national power utility, and primary power generator, Eskom, and various parliamentarians attributed these rolling blackouts to insufficient generation capacity.
In February 2021, the state of Texas suffered a major power crisis, which came about during three severe winter storms sweeping across the United States on February 10–11, 13–17, and 15–20. The storms triggered the worst energy infrastructure failure in Texas state history, leading to shortages of water, food, and heat. More than 4.5 million homes and businesses were left without power, some for several days. At least 246 people were killed directly or indirectly, with some estimates as high as 702 killed as a result of the crisis.
The Renewable Energy Independent Power Producer Procurement Programme (REIPPPP) is an initiative by the South African government aimed at increasing electricity capacity through private sector investment in solar photovoltaic and concentrated solar, onshore wind power, small hydro, landfill gas, biomass, and biogas. As of 2023, a total of 123 projects have been awarded to the private sector. Private sector investment totalling R256 billion has been committed to the REIPPPP. Four of the six Bid Windows have come online, totalling 6200 MW of installed capacity.