Rolling blackout
Encyclopedia
A rolling blackout, also referred to as load shedding, is an intentionally-engineered electrical power outage
where electricity delivery is stopped for non-overlapping periods of time over geographical regions. Rolling blackouts are a last-resort measure used by an electric utility
company in order to avoid a total blackout of the power system. They are usually in response to a situation where 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 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 sufficient power to the area where it is needed.
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. Rolling blackouts in developed countries are rare because demand is accurately forecasted, adequate infrastructure investment is scheduled and networks are well managed; such events are considered an unacceptable failure to plan and can cause significant political damage to responsible governments. 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. Due to the shortage of electricity
, load shedding is extremely common in India
.
are common throughout India, adversely affecting the country's potential for economic growth. Even in the nation's capital of New Delhi
, rolling blackouts are common, especially during the hot summer season when demand far outstrips supply. Rural areas are the most severely affected; it is common for the 44% of rural households having access to electricity to lose power for more than 12 hours each day. States periodically and chronically affected by load-shedding are Delhi
, Uttar Pradesh
, Tamil Nadu
, Bihar
, West Bengal
, Assam
, Maharashtra
, Madhya Pradesh
, Rajasthan
and Andhra Pradesh
. States of Punjab
, Goa
, Orissa
, Gujarat and Kerala
are largely free of any load-shedding due to surplus power. Karnataka
still occasionally experiences power cuts.
. The Tokyo Electric Power Company, which normally provides approximately 40,000 MW of electricity, announced that it can only currently provide about 30,000 MW, a shortfall of 25 percent. This is due to the fact that about 40 percent of the electricity used in the greater Tokyo area is supplied by nuclear power
plants in the Niigata
and Fukushima
prefectures. Two of those plants, the Fukushima Dai-ichi
and Fukushima Dai-ni
, were automatically taken offline when the first earthquake occurred and have sustained major damage related to the earthquake and subsequent tsunami. Rolling blackouts of three hours were expected to last until the end of April 2011 and will affect the Tokyo
, Kanagawa
, Shizuoka
, Yamanashi
, Chiba
, Ibaraki
, Saitama
, Tochigi
, and Gunma
prefectures.
in Ireland's
power utility, the Electricity Supply Board (ESB)
, led to rolling blackouts. However, rolling blackouts have not occurred for this reason since 1991. For such eventualities, the ESB have a zone rota system in place. The country is divided into regions which in turn are subdivided into zones, referred to by the letter codes A, B, C, X, Y, and Z. During periods when blackouts may occur, advertisements are placed in the national newspapers informing customers which region and zone they are in, and at what times of the day they have a high, moderate or low risk of supply interruption. (Customers fortunate enough to live close to a hospital may find they are on a "priority line" and don't lose power at all). The authorities appeal to the public to conserve electricity (especially during hours of peak demand); however, if and when electricity demand exceeds available supply, supply is cut in some or all of the "high risk" zones. If there is still a shortfall once all the high risk zones have had power cut, then the "moderate risk" zones start experiencing power cuts. The level of risk in each zone changes every three hours moving from "Low" to "Moderate" to "High" and back to "Low".
, which provides over 95% of the country's energy usage. During the 1980s Eskom mothballed three of their coal-fired power stations, as there was an excess of generation
capacity at the time. With the demise of Apartheid in the 1990s came massive investment and economic growth. At the same time the government tried to deregulate the electricity supply industry by inviting the private sector
to build new power stations to meet the rapidly growing demand for electricity. Eskom was at the time prevented from building new power stations (including de-mothballing the three existing power stations) or from strengthening the transmission network. The transmission network is especially important in delivering power from Mpumalanga
, where the majority of the power stations are located, to other parts of the country such as KwaZulu-Natal
and the Western Cape
. With no bidders coming forward to construct new power stations, there was effectively no investment into new generation plants during the early 1990s, which eventually led to the shortage of capacity that was experienced in the 2000s.
In 1998, the Department of Minerals and Energy released a detailed energy review in which it explicitly warned that unless "timely steps were taken to ensure that demand does not exceed available supply capacity", generating capacity would reach its limit by 2007.
are only partially supplied by Koeberg nuclear power station
, with the balance of the energy supplied by the coal-fired power stations in Mpumalanga via the transmission network. In December 2005, a bolt left in Koeberg Unit 1 reactor after maintenance caused extensive damage to the rotor, resulting in it tripping out. Consequently, there was insufficient power to supply the Cape, with the transmission network only partially able to supply the electricity demand. As a result, rolling blackouts were implemented across the two provinces.
The blackouts and the accompanying brouhaha in the media resulted in Eskom and the government announcing a number of plans for new power stations, and Eskom started returning mothballed power stations to service as well as expediting plans to build new gas-fired power stations to support the Western Cape supply.
The situation came to a head on 24 January 2008 when the national grid was brought to near collapse. Multiple trips at a number of different power stations rapidly reduced the available supply, resulting in Eskom declaring force majeure
and instructing its largest industrial customers (mainly gold and platinum mining companies) to shut down their operations and reduce consumption to "minimal levels", just sufficient to evacuate workers that were still in the mines.
In January 2008, with no short- or medium-term relief available to ease the power shortages, Eskom warned the public that the country's electricity demand would exceed the supply until 2013 (when the first new power stations would be brought online).
Eskom also began recommissioning older power stations which had been mothballed in earlier decades.
faced its coldest winter in 50 years, and the country's energy grid began to fail. By February 2008 Tajikstan's energy grid was near collapse and there were blackouts in most of the country. Hospitals throughout the country were on limited electricity use, and nurses and doctors were forced to keep newborn babies warm with hot water bottles. There were reports of newborns freezing to death. The UN reported that with so much energy required to keep warm there was a danger of people starving to death.
of January to March 1974, introduced to limit electricity consumption, and thus conserve coal supplies which were severely reduced due to industrial action, meant that non-essential commercial users were only allowed to consume electricity for three days each week. Home electricity supplies were also limited in some areas.
In February 2011, North and Central Texas experienced rolling blackouts due to 50 power plants tripping offline. Temperatures ranged between 8 °F and 19 °F, the coldest in 15 years. The time of the power outages ranged from 20 minutes to over eight hours. Areas affected included Bell, Bexar, Brazos, Collin, Comal, Dallas, Delta, Denton, El Paso, Fort Bend, Guadalupe, Harris, Hays, Hill, Hidalgo, Hunt, McLennan, Montgomery, Navarro, Palacios, Smith, Tarrant, Travis, Webb and Williamson counties, as well as some counties in New Mexico, Including Doña Ana, Otero, and Eddy Counties.
The 2006 and 2011 blackouts were the only two to occur in two decades. However, the EPA under the Obama administration is to implement rules that will eliminate much of ERCOT's generation capability.
of the early 2000s, outages had indeed occurred previously. The outages were almost always triggered by unusually hot temperatures during the summer, which causes a surge in demand due to heavy use of air conditioning
. However, in 2004, taped conversations of Enron
traders became public, showing that traders were purposely manipulating the supply of electricity, in order to raise energy prices.
On December 13, 2003, shortly before leaving office, Governor Gray Davis
officially brought the energy crisis to an end by issuing a proclamation ending the state of emergency he declared on January 17, 2001. The state of emergency allowed the state to buy electricity for the financially strapped utility companies. The emergency authority allowed Davis to order the California Energy Commission to streamline the application process for new power plants. During that time, California issued licenses to 38 new power plants, amounting to the addition of 14,365 megawatts of electricity production when completed.
Rolling blackouts were again imposed in late August 2005 in Southern California
due to the loss of a key transmission line; the transmission line shut itself off because of a faulty sensor.
Most of California
is divided into 14 power grids, each containing approximately 7% of electricity customers in the state, creating a total of 98%. The remaining 2% are placed on a separate grid, where users such as hospital
s and police station
s are exempt from ever having their power deliberately cut off.
In a Stage 1 emergency only a general call for voluntary conservation is issued, while a Stage 2 emergency results in power being temporarily cut off to certain large users, primarily industrial concerns, who have agreed to this arrangement in exchange for lower rates. When a Stage 3 power emergency is declared, electricity to one of the grids is shut off for a fixed period of time, which can range from 60 minutes to 2½ hours. If after this period of time the Stage 3 emergency still exists, power is restored to this grid but then the next grid in the sequence is blacked out, and so on, until the situation is stabilized — the blackout thus "rolls" from one grid to the next.
In California
, each customer's electric bill includes the number of the power grid (from 1 to 14) that customer belongs to; this gives customers at least some advance notice of when their electricity might be turned off in the event of a Stage 3 emergency. The grids are set up in such a manner as to ensure that a large percentage of customers in the same neighborhood would not be blacked out concurrently, which could invite looting
and other related problems. Normal electricity customers can fall within the areas reserved for emergency use (if they are near a hospital or other critical infrastructure), in which case their electric bill will indicate a power grid of 99 and they will not be affected by rolling blackouts.
states (such as New York State and New Jersey
), "brownouts
" rather than rolling blackouts are implemented during power emergencies. In this scenario, instead of the power being cut off altogether to a certain percentage of customers, the voltage
is reduced by a certain percentage to all customers — the resulting dimming of electric lights being the origin of the term "brownout." Brownouts can cause significant damage to unprotected electronic equipment, but usually have no effect (other than reduced performance) on incandescent lights or some types of motors.
Power outage
A power outage is a short- or long-term loss of the electric power to an area.There are many causes of power failures in an electricity network...
where electricity delivery is stopped for non-overlapping periods of time over geographical regions. Rolling blackouts are a last-resort measure used by an electric utility
Electric utility
An electric utility is a company that engages in the generation, transmission, and distribution of electricity for sale generally in a regulated market. The electrical utility industry is a major provider of energy in most countries. It is indispensable to factories, commercial establishments,...
company in order to avoid a total blackout of the power system. They are usually in response to a situation where 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 may be more widespread and affect entire countries and continents. Rolling blackouts generally result from two causes: insufficient generation
Electricity generation
Electricity generation is the process of generating electric energy from other forms of energy.The fundamental principles of electricity generation were discovered during the 1820s and early 1830s by the British scientist Michael Faraday...
capacity or inadequate transmission infrastructure to deliver sufficient power to the area where it is needed.
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. Rolling blackouts in developed countries are rare because demand is accurately forecasted, adequate infrastructure investment is scheduled and networks are well managed; such events are considered an unacceptable failure to plan and can cause significant political damage to responsible governments. 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. Due to the shortage of electricity
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...
, load shedding is extremely common in India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
.
India
In 2004-05, electricity demand outstripped supply by 7-11%. Due to a chronic shortage of electricity, power-cutsPower outage
A power outage is a short- or long-term loss of the electric power to an area.There are many causes of power failures in an electricity network...
are common throughout India, adversely affecting the country's potential for economic growth. Even in the nation's capital of New Delhi
New Delhi
New Delhi is the capital city of India. It serves as the centre of the Government of India and the Government of the National Capital Territory of Delhi. New Delhi is situated within the metropolis of Delhi. It is one of the nine districts of Delhi Union Territory. The total area of the city is...
, rolling blackouts are common, especially during the hot summer season when demand far outstrips supply. Rural areas are the most severely affected; it is common for the 44% of rural households having access to electricity to lose power for more than 12 hours each day. States periodically and chronically affected by load-shedding are Delhi
Delhi
Delhi , officially National Capital Territory of Delhi , is the largest metropolis by area and the second-largest by population in India, next to Mumbai. It is the eighth largest metropolis in the world by population with 16,753,265 inhabitants in the Territory at the 2011 Census...
, Uttar Pradesh
Uttar Pradesh
Uttar Pradesh abbreviation U.P. , is a state located in the northern part of India. With a population of over 200 million people, it is India's most populous state, as well as the world's most populous sub-national entity...
, Tamil Nadu
Tamil Nadu
Tamil Nadu is one of the 28 states of India. Its capital and largest city is Chennai. Tamil Nadu lies in the southernmost part of the Indian Peninsula and is bordered by the union territory of Pondicherry, and the states of Kerala, Karnataka, and Andhra Pradesh...
, Bihar
Bihar
Bihar is a state in eastern India. It is the 12th largest state in terms of geographical size at and 3rd largest by population. Almost 58% of Biharis are below the age of 25, which is the highest proportion in India....
, West Bengal
West Bengal
West Bengal is a state in the eastern region of India and is the nation's fourth-most populous. It is also the seventh-most populous sub-national entity in the world, with over 91 million inhabitants. A major agricultural producer, West Bengal is the sixth-largest contributor to India's GDP...
, Assam
Assam
Assam , also, rarely, Assam Valley and formerly the Assam Province , is a northeastern state of India and is one of the most culturally and geographically distinct regions of the country...
, Maharashtra
Maharashtra
Maharashtra is a state located in India. It is the second most populous after Uttar Pradesh and third largest state by area in India...
, Madhya Pradesh
Madhya Pradesh
Madhya Pradesh , often called the Heart of India, is a state in central India. Its capital is Bhopal and Indore is the largest city....
, Rajasthan
Rajasthan
Rājasthān the land of Rajasthanis, , is the largest state of the Republic of India by area. It is located in the northwest of India. It encompasses most of the area of the large, inhospitable Great Indian Desert , which has an edge paralleling the Sutlej-Indus river valley along its border with...
and Andhra Pradesh
Andhra Pradesh
Andhra Pradesh , is one of the 28 states of India, situated on the southeastern coast of India. It is India's fourth largest state by area and fifth largest by population. Its capital and largest city by population is Hyderabad.The total GDP of Andhra Pradesh is $100 billion and is ranked third...
. States of Punjab
Punjab (India)
Punjab ) is a state in the northwest of the Republic of India, forming part of the larger Punjab region. The state is bordered by the Indian states of Himachal Pradesh to the east, Haryana to the south and southeast and Rajasthan to the southwest as well as the Pakistani province of Punjab to the...
, Goa
Goa
Goa , a former Portuguese colony, is India's smallest state by area and the fourth smallest by population. Located in South West India in the region known as the Konkan, it is bounded by the state of Maharashtra to the north, and by Karnataka to the east and south, while the Arabian Sea forms its...
, Orissa
Orissa
Orissa , officially Odisha since Nov 2011, is a state of India, located on the east coast of India, by the Bay of Bengal. It is the modern name of the ancient nation of Kalinga, which was invaded by the Maurya Emperor Ashoka in 261 BC. The modern state of Orissa was established on 1 April...
, Gujarat and Kerala
Kerala
or Keralam is an Indian state located on the Malabar coast of south-west India. It was created on 1 November 1956 by the States Reorganisation Act by combining various Malayalam speaking regions....
are largely free of any load-shedding due to surplus power. Karnataka
Karnataka
Karnataka , the land of the Kannadigas, is a state in South West India. It was created on 1 November 1956, with the passing of the States Reorganisation Act and this day is annually celebrated as Karnataka Rajyotsava...
still occasionally experiences power cuts.
Japan
Japan instituted rolling blackouts starting on March 14, 2011 due to power shortages caused by the 2011 Tōhoku earthquake and tsunami2011 Tōhoku earthquake and tsunami
The 2011 earthquake off the Pacific coast of Tohoku, also known as the 2011 Tohoku earthquake, or the Great East Japan Earthquake, was a magnitude 9.0 undersea megathrust earthquake off the coast of Japan that occurred at 14:46 JST on Friday, 11 March 2011, with the epicenter approximately east...
. The Tokyo Electric Power Company, which normally provides approximately 40,000 MW of electricity, announced that it can only currently provide about 30,000 MW, a shortfall of 25 percent. This is due to the fact that about 40 percent of the electricity used in the greater Tokyo area is supplied by nuclear power
Nuclear power
Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...
plants in the Niigata
Niigata Prefecture
is a prefecture of Japan located on the island of Honshū on the coast of the Sea of Japan. The capital is the city of Niigata. The name "Niigata" literally means "new lagoon".- History :...
and Fukushima
Fukushima Prefecture
is a prefecture of Japan located in the Tōhoku region on the island of Honshu. The capital is the city of Fukushima.-History:Until the Meiji Restoration, the area of Fukushima prefecture was known as Mutsu Province....
prefectures. Two of those plants, the Fukushima Dai-ichi
Fukushima I Nuclear Power Plant
The , also known as Fukushima Dai-ichi , is a disabled nuclear power plant located on a site in the towns of Okuma and Futaba in the Futaba District of Fukushima Prefecture, Japan. First commissioned in 1971, the plant consists of six boiling water reactors...
and Fukushima Dai-ni
Fukushima II Nuclear Power Plant
The , or Fukushima Dai-ni , is a nuclear power plant located on a site in the town of Naraha and Tomioka in the Futaba District of Fukushima Prefecture, Japan...
, were automatically taken offline when the first earthquake occurred and have sustained major damage related to the earthquake and subsequent tsunami. Rolling blackouts of three hours were expected to last until the end of April 2011 and will affect the Tokyo
Tokyo
, ; officially , is one of the 47 prefectures of Japan. Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the largest metropolitan area of Japan. It is the seat of the Japanese government and the Imperial Palace, and the home of the Japanese Imperial Family...
, Kanagawa
Kanagawa Prefecture
is a prefecture located in the southern Kantō region of Japan. The capital is Yokohama. Kanagawa is part of the Greater Tokyo Area.-History:The prefecture has some archaeological sites going back to the Jōmon period...
, Shizuoka
Shizuoka Prefecture
is a prefecture of Japan located in the Chūbu region on Honshu island. The capital is the city of Shizuoka.- History :Shizuoka prefecture was formed from the former Tōtōmi, Suruga and Izu provinces.The area was the home of the first Tokugawa Shogun...
, Yamanashi
Yamanashi Prefecture
is a prefecture of Japan located in the Chūbu region of the island of Honshū. The capital is the city of Kōfu.-Pre-history to the 14th century:People have been living in the Yamanashi area for about 30,000 years...
, Chiba
Chiba Prefecture
is a prefecture of Japan located in the Kantō region and the Greater Tokyo Area. Its capital is Chiba City.- History :Chiba Prefecture was established on June 15, 1873 with the merger of Kisarazu Prefecture and Inba Prefecture...
, Ibaraki
Ibaraki Prefecture
is a prefecture of Japan, located in the Kantō region on the main island of Honshu. The capital is Mito.-History:Ibaraki Prefecture was previously known as Hitachi Province...
, Saitama
Saitama Prefecture
is a prefecture of Japan located in the Kantō region of the island of Honshu. The capital is the city of Saitama.This prefecture is part of the Greater Tokyo Area, and most of Saitama's cities can be described as suburbs of Tokyo, to which a large amount of residents commute each day.- History...
, Tochigi
Tochigi Prefecture
is a prefecture located in the Kantō region on the island of Honshū, Japan. The capital is the city of Utsunomiya.Nikkō, whose ancient Shintō shrines and Buddhist temples UNESCO has recognized by naming them a World Heritage Site, is in this prefecture...
, and Gunma
Gunma Prefecture
is a prefecture of Japan located in the northwest corner of the Kantō region on Honshu island. Its capital is Maebashi.- History :The remains of a Paleolithic man were found at Iwajuku, Gunma Prefecture, in the early 20th century and there is a public museum there.Japan was without horses until...
prefectures.
Republic of Ireland
On several occasions in the 1970s and 1980s trade union strikesStrike action
Strike action, also called labour strike, on strike, greve , or simply strike, is a work stoppage caused by the mass refusal of employees to work. A strike usually takes place in response to employee grievances. Strikes became important during the industrial revolution, when mass labour became...
in Ireland's
Republic of Ireland
Ireland , described as the Republic of Ireland , is a sovereign state in Europe occupying approximately five-sixths of the island of the same name. Its capital is Dublin. Ireland, which had a population of 4.58 million in 2011, is a constitutional republic governed as a parliamentary democracy,...
power utility, the Electricity Supply Board (ESB)
Electricity Supply Board
The Electricity Supply Board , is a semi-state electricity company in Ireland. While historically a monopoly, the ESB now operates as a commercial semi-state concern in a liberalised and competitive market...
, led to rolling blackouts. However, rolling blackouts have not occurred for this reason since 1991. For such eventualities, the ESB have a zone rota system in place. The country is divided into regions which in turn are subdivided into zones, referred to by the letter codes A, B, C, X, Y, and Z. During periods when blackouts may occur, advertisements are placed in the national newspapers informing customers which region and zone they are in, and at what times of the day they have a high, moderate or low risk of supply interruption. (Customers fortunate enough to live close to a hospital may find they are on a "priority line" and don't lose power at all). The authorities appeal to the public to conserve electricity (especially during hours of peak demand); however, if and when electricity demand exceeds available supply, supply is cut in some or all of the "high risk" zones. If there is still a shortfall once all the high risk zones have had power cut, then the "moderate risk" zones start experiencing power cuts. The level of risk in each zone changes every three hours moving from "Low" to "Moderate" to "High" and back to "Low".
South Africa
The history and causes of rolling blackouts in South Africa are multiple. In South Africa the major producer and distributor of electricity is EskomEskom
Eskom is a South African electricity public utility, established in 1923 as the Electricity Supply Commission by the government of South Africa in terms of the Electricity Act . It was also known by its Afrikaans name Elektrisiteitsvoorsieningskommissie . The two acronyms were combined in 1986 and...
, which provides over 95% of the country's energy usage. During the 1980s Eskom mothballed three of their coal-fired power stations, as there was an excess of generation
Electricity generation
Electricity generation is the process of generating electric energy from other forms of energy.The fundamental principles of electricity generation were discovered during the 1820s and early 1830s by the British scientist Michael Faraday...
capacity at the time. With the demise of Apartheid in the 1990s came massive investment and economic growth. At the same time the government tried to deregulate the electricity supply industry by inviting the private sector
Private sector
In economics, the private sector is that part of the economy, sometimes referred to as the citizen sector, which is run by private individuals or groups, usually as a means of enterprise for profit, and is not controlled by the state...
to build new power stations to meet the rapidly growing demand for electricity. Eskom was at the time prevented from building new power stations (including de-mothballing the three existing power stations) or from strengthening the transmission network. The transmission network is especially important in delivering power from Mpumalanga
Mpumalanga
Mpumalanga , is a province of South Africa. The name means east or literally "the place where the sun rises" in Swazi, Xhosa, Ndebele and Zulu. Mpumalanga lies in eastern South Africa, north of KwaZulu-Natal and bordering Swaziland and Mozambique. It constitutes 6.5% of South Africa's land area...
, where the majority of the power stations are located, to other parts of the country such as KwaZulu-Natal
KwaZulu-Natal
KwaZulu-Natal is a province of South Africa. Prior to 1994, the territory now known as KwaZulu-Natal was made up of the province of Natal and the homeland of KwaZulu....
and the Western Cape
Western Cape
The Western Cape is a province in the south west of South Africa. The capital is Cape Town. Prior to 1994, the region that now forms the Western Cape was part of the much larger Cape Province...
. With no bidders coming forward to construct new power stations, there was effectively no investment into new generation plants during the early 1990s, which eventually led to the shortage of capacity that was experienced in the 2000s.
In 1998, the Department of Minerals and Energy released a detailed energy review in which it explicitly warned that unless "timely steps were taken to ensure that demand does not exceed available supply capacity", generating capacity would reach its limit by 2007.
Blackouts in Western and Northern Cape 2005–2006
The energy consumed by the Western and Northern CapeNorthern Cape
The Northern Cape is the largest and most sparsely populated province of South Africa. It was created in 1994 when the Cape Province was split up. Its capital is Kimberley. It includes the Kalahari Gemsbok National Park, part of an international park shared with Botswana...
are only partially supplied by Koeberg nuclear power station
Koeberg nuclear power station
Koeberg nuclear power station is the only nuclear power station in South Africa and the entire African continent. It is located 30 km north of Cape Town, near Melkbosstrand on the west coast of South Africa. Koeberg is owned and operated by the country's only national electricity supplier, Eskom...
, with the balance of the energy supplied by the coal-fired power stations in Mpumalanga via the transmission network. In December 2005, a bolt left in Koeberg Unit 1 reactor after maintenance caused extensive damage to the rotor, resulting in it tripping out. Consequently, there was insufficient power to supply the Cape, with the transmission network only partially able to supply the electricity demand. As a result, rolling blackouts were implemented across the two provinces.
The blackouts and the accompanying brouhaha in the media resulted in Eskom and the government announcing a number of plans for new power stations, and Eskom started returning mothballed power stations to service as well as expediting plans to build new gas-fired power stations to support the Western Cape supply.
Country-wide blackouts 2007–2008
With the freeze on any new developments being placed on Eskom during the early 1990s, South Africa was faced with a situation where for the next few years the electricity demand kept rising, without any new power stations being built to keep up the necessary supply. By October 2007 the situation had deteriorated to such an extent that Eskom implemented rolling blackouts throughout the country. Blackouts occurred in most suburbs throughout the country for a period of two hours at a time.The situation came to a head on 24 January 2008 when the national grid was brought to near collapse. Multiple trips at a number of different power stations rapidly reduced the available supply, resulting in Eskom declaring force majeure
Force majeure
Force majeure or vis major "superior force", also known as cas fortuit or casus fortuitus "chance occurrence, unavoidable accident", is a common clause in contracts that essentially frees both parties from liability or obligation when an extraordinary event or circumstance beyond the control of...
and instructing its largest industrial customers (mainly gold and platinum mining companies) to shut down their operations and reduce consumption to "minimal levels", just sufficient to evacuate workers that were still in the mines.
In January 2008, with no short- or medium-term relief available to ease the power shortages, Eskom warned the public that the country's electricity demand would exceed the supply until 2013 (when the first new power stations would be brought online).
Eskom also began recommissioning older power stations which had been mothballed in earlier decades.
Tajikistan
In January 2008 TajikistanTajikistan
Tajikistan , officially the Republic of Tajikistan , is a mountainous landlocked country in Central Asia. Afghanistan borders it to the south, Uzbekistan to the west, Kyrgyzstan to the north, and China to the east....
faced its coldest winter in 50 years, and the country's energy grid began to fail. By February 2008 Tajikstan's energy grid was near collapse and there were blackouts in most of the country. Hospitals throughout the country were on limited electricity use, and nurses and doctors were forced to keep newborn babies warm with hot water bottles. There were reports of newborns freezing to death. The UN reported that with so much energy required to keep warm there was a danger of people starving to death.
United Kingdom
The Three-Day WeekThree-Day Week
The Three-Day Week was one of several measures introduced in the United Kingdom by the Conservative Government 1970–1974 to conserve electricity, the production of which was severely limited due to industrial action by coal miners...
of January to March 1974, introduced to limit electricity consumption, and thus conserve coal supplies which were severely reduced due to industrial action, meant that non-essential commercial users were only allowed to consume electricity for three days each week. Home electricity supplies were also limited in some areas.
Texas
In April 2006, parts of Texas experienced rolling blackouts due to excessive air conditioner use because of unexpectedly high temperatures. The longest power outage lasted for a period of five hours, affecting areas in the Middle to the South of Texas.In February 2011, North and Central Texas experienced rolling blackouts due to 50 power plants tripping offline. Temperatures ranged between 8 °F and 19 °F, the coldest in 15 years. The time of the power outages ranged from 20 minutes to over eight hours. Areas affected included Bell, Bexar, Brazos, Collin, Comal, Dallas, Delta, Denton, El Paso, Fort Bend, Guadalupe, Harris, Hays, Hill, Hidalgo, Hunt, McLennan, Montgomery, Navarro, Palacios, Smith, Tarrant, Travis, Webb and Williamson counties, as well as some counties in New Mexico, Including Doña Ana, Otero, and Eddy Counties.
The 2006 and 2011 blackouts were the only two to occur in two decades. However, the EPA under the Obama administration is to implement rules that will eliminate much of ERCOT's generation capability.
California
Though the term did not enter popular use in the U.S. until the California electricity crisisCalifornia electricity crisis
The California electricity crisis, also known as the Western U.S. Energy Crisis of 2000 and 2001 was a situation in which California had a shortage of electricity caused by market manipulations and illegal shutdowns of pipelines by Texas energy consortiums...
of the early 2000s, outages had indeed occurred previously. The outages were almost always triggered by unusually hot temperatures during the summer, which causes a surge in demand due to heavy use of air conditioning
Air conditioning
An air conditioner is a home appliance, system, or mechanism designed to dehumidify and extract heat from an area. The cooling is done using a simple refrigeration cycle...
. However, in 2004, taped conversations of Enron
Enron
Enron Corporation was an American energy, commodities, and services company based in Houston, Texas. Before its bankruptcy on December 2, 2001, Enron employed approximately 22,000 staff and was one of the world's leading electricity, natural gas, communications, and pulp and paper companies, with...
traders became public, showing that traders were purposely manipulating the supply of electricity, in order to raise energy prices.
On December 13, 2003, shortly before leaving office, Governor Gray Davis
Gray Davis
Joseph Graham "Gray" Davis, Jr. is an American Democratic politician who served as California's 37th Governor from 1999 until being recalled in 2003...
officially brought the energy crisis to an end by issuing a proclamation ending the state of emergency he declared on January 17, 2001. The state of emergency allowed the state to buy electricity for the financially strapped utility companies. The emergency authority allowed Davis to order the California Energy Commission to streamline the application process for new power plants. During that time, California issued licenses to 38 new power plants, amounting to the addition of 14,365 megawatts of electricity production when completed.
Rolling blackouts were again imposed in late August 2005 in Southern California
Southern California
Southern California is a megaregion, or megapolitan area, in the southern area of the U.S. state of California. Large urban areas include Greater Los Angeles and Greater San Diego. The urban area stretches along the coast from Ventura through the Southland and Inland Empire to San Diego...
due to the loss of a key transmission line; the transmission line shut itself off because of a faulty sensor.
Most of California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
is divided into 14 power grids, each containing approximately 7% of electricity customers in the state, creating a total of 98%. The remaining 2% are placed on a separate grid, where users such as hospital
Hospital
A hospital is a health care institution providing patient treatment by specialized staff and equipment. Hospitals often, but not always, provide for inpatient care or longer-term patient stays....
s and police station
Police station
A police station or station house is a building which serves to accommodate police officers and other members of staff. These buildings often contain offices and accommodation for personnel and vehicles, along with locker rooms, temporary holding cells and interview/interrogation rooms.- Facilities...
s are exempt from ever having their power deliberately cut off.
In a Stage 1 emergency only a general call for voluntary conservation is issued, while a Stage 2 emergency results in power being temporarily cut off to certain large users, primarily industrial concerns, who have agreed to this arrangement in exchange for lower rates. When a Stage 3 power emergency is declared, electricity to one of the grids is shut off for a fixed period of time, which can range from 60 minutes to 2½ hours. If after this period of time the Stage 3 emergency still exists, power is restored to this grid but then the next grid in the sequence is blacked out, and so on, until the situation is stabilized — the blackout thus "rolls" from one grid to the next.
In California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, each customer's electric bill includes the number of the power grid (from 1 to 14) that customer belongs to; this gives customers at least some advance notice of when their electricity might be turned off in the event of a Stage 3 emergency. The grids are set up in such a manner as to ensure that a large percentage of customers in the same neighborhood would not be blacked out concurrently, which could invite looting
Looting
Looting —also referred to as sacking, plundering, despoiling, despoliation, and pillaging—is the indiscriminate taking of goods by force as part of a military or political victory, or during a catastrophe, such as during war, natural disaster, or rioting...
and other related problems. Normal electricity customers can fall within the areas reserved for emergency use (if they are near a hospital or other critical infrastructure), in which case their electric bill will indicate a power grid of 99 and they will not be affected by rolling blackouts.
Elsewhere
In many East CoastEast Coast of the United States
The East Coast of the United States, also known as the Eastern Seaboard, refers to the easternmost coastal states in the United States, which touch the Atlantic Ocean and stretch up to Canada. The term includes the U.S...
states (such as New York State and New Jersey
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...
), "brownouts
Brownout (electricity)
A brownout is an intentional drop in voltage in an electrical power supply system used for load reduction in an emergency. The reduction lasts for minutes or hours, as opposed to short-term voltage sag or dip. The term brownout comes from the dimming experienced by lighting when the voltage sags...
" rather than rolling blackouts are implemented during power emergencies. In this scenario, instead of the power being cut off altogether to a certain percentage of customers, the voltage
Voltage
Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...
is reduced by a certain percentage to all customers — the resulting dimming of electric lights being the origin of the term "brownout." Brownouts can cause significant damage to unprotected electronic equipment, but usually have no effect (other than reduced performance) on incandescent lights or some types of motors.