A rolling blackout, also referred to as rotational load shedding or feeder rotation, is an intentionally engineered electrical power shutdown where 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. They are a type of demand response for 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 of planning 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. Rolling blackouts are also used as a response strategy to cope with reduced output beyond reserve capacity from power stations taken offline unexpectedly such as through an extreme weather event.
Australia
In South Australia, in February 2017, following heatwave conditions, SA Power Networks used load shedding to cope with demand for 30 minutes. The Australian Energy Market Operator (AEMO) had instructed SA Power Networks to commence 100 MW rotational load-shedding via a government-agreed list due to lack of available generation supply in South Australia.
The Heywood Interconnector between South Australia and Victoria was recently expanded to allow greater power capacity (600 MW) to avoid lack of capacity, however an increased proportion of that generation is from intermittent renewable sources like wind and solar. In 2016, South Australia closed its only coal-fired power plant located at Port Augusta.
Canada
In January 2014, the Canadian province of Newfoundland & Labrador renewed rolling blackouts to compensate for the cascading failure of the Holyrood generating station after a fire at the Sunnyside substation on Jan 4 following a blizzard. The rolling blackouts started before the storm on the 4th, rather were caused by extreme cold weather and a high demand for power at the time.
On 9 July 2012, the Alberta Electric System Operator ordered power companies in the province of Alberta to institute rolling blackouts during a heat wave as six generating plants failed during peak demand in the heat of the afternoon. Because the shortage increased the amount consumers paid to generators, Members of the Alberta Legislative Assembly voiced concerns that price manipulation might have been involved.
In both cases the blackouts were rolled fairly rapidly, so that no area had to spend more than one hour without power.
Egypt
Summer blackouts have been common in Egypt since 2010 but became more severe and widespread after the 2011 revolution. In April 2014, the Minister of Electricity and Renewable Energy said that the problem would take a few years to resolve. The government is blaming the unrest the country is experiencing for the blackouts. However, blame between different ministries reveals their poor organization. Some also point to the fact that the infrastructure is old and lacks maintenance.
Ghana
In Ghana, rolling blackouts occurred in 2007-2008 and again after 2012. At the beginning of 2015, the dumsor schedule went from 24 hours with electricity and 12 without to 12 hours with electricity and 24 without.
Italy
After the great 2003 blackout in Italy, a rolling blackout program PESSE (Piano di Emergenza per la Sicurezza del Sistema Electrico, Emergency plan for national grid safety) was issued. It has 5 degrees of severity, any controlled blackout can't exceed 90 minutes.
India
Due to a chronic shortage of electricity, power-cuts are common throughout India, adversely affecting the country's potential for economic growth. Even in the country's capital of New Delhi, rolling blackouts are common, especially during the hot summer season when demand far outstrips supply capacity. Rural areas are the most severely affected; it is common for the 14% of rural households having access to electricity to lose power for more than 2 hours each day. The states periodically and chronically affected by load-shedding are Delhi, Uttar Pradesh, Tamil Nadu, Bihar, Odisha, Assam, Maharashtra, Karnataka and Madhya Pradesh. The states of Punjab, Goa, Gujarat and Kerala are largely free of any load-shedding due to surplus power.
Japan
Japan instituted rolling blackouts starting on 14 March 2011 due to power shortages caused by the 2011 TÅhoku earthquake and tsunami. The Tokyo Electric Power Company, which normally provides approximately 40,000 MW of electricity, announced that it could only provide about 30,000 MW, a shortfall of 25 percent. This is because 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 affected the Tokyo, Kanagawa, Shizuoka, Yamanashi, Chiba, Ibaraki, Saitama, Tochigi, and Gunma prefectures.
Pakistan
Rolling blackouts began nationwide in Pakistan in early 2008 with the resurgence of democracy and presently continue in 2015. It intensifies in the long summers, with many places around the country having no electricity for 6 hours per day. According to Pakistan Electric Power Company (PEPCO), Pakistan's electricity shortfall is normally 2,500 Megawatts (MW) but reaches around 6,000 MW or more during the summer season. The country's electricity problems are so severe that violent riots sometimes take place in some regions, including Punjab, the country's most populous province.
Poland
During the period of soviet-controlled People's Republic of Poland rolling blackouts begun in 1976 due to economic crisis Poland was suffering then. The point of rolling blackouts was to spare the energy for key industry sectors, which were hoped to help the economy. However, due to poor management (which contributed to the crisis in the first place) the planned outages were barely synchronised with the industry requirements, therefore most of the effort was in fact wasted. With decreasing frequency, the rolling blackouts were performed till the half of 1980s. Since then Polish economy improved as well as the capability of the national grid.
Rolling blackouts have occurred unexpectedly in late July 2015 due to extremely hot weather which made the power stations to reduce their output. There is possibility that rolling blackouts may occur in the following summers for the same reason. However, contrary to 1970/80s outages, in these emergency blackouts the industry is cut off first, the power flow to the houses is usually uninterrupted.
South Africa
Since 2007, there have been multiple episodes of loadshedding in South Africa. In South Africa the major producer and distributor of electricity is Eskom, 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.
Country-wide blackouts 2007â€"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 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.
Country-wide blackouts 2014-2015
Load shedding was reintroduced in early November 2014. The Majuba power plant lost its capacity to generate power after a collapse of one of its coal storage silos on 1 November 2014. The Majuba power plant delivered approximately 10% of the country's entire capacity and the collapse halted the delivery of coal to the plant. A second silo developed a major crack on 20 November causing the shut down of the plant again. This was after temporary measures were instated to deliver coal to the plant.
On 5 December, Eskom launched a major stage three load shedding in South Africa after the shut down of two power plants on Thursday 4 November 2014 due to diesel shortages. It was also reported that the Palmiet and Drakenburg stations were also experiencing difficulties due to a depletion of water reserve to the Hydro plants. On Thursday 4 November, Eskom fell 4,000MW short of the electricity countries demand of 28,000MW. The power utility has the ability to produce 45,583MW, but could only supply 24,000MW due to "planned and unplanned" maintenance. One turbine at Eskom’s Duvha Power Station is also currently out of commission due to an "unexplained incident" in March 2014.
Tajikistan
In January 2008 Tajikistan faced its coldest winter in 50 years, and the country's energy grid began to fail. By February 2008 Tajikistan'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.
Ukraine
Lack of coal for Ukraine's coal-fired power stations due to the War in Donbass and a shut down one of the six reactors of the Zaporizhia Nuclear Power Plant lead to rolling blackouts throughout Ukraine from early till late December 2014.
United States
Texas
In February 2011, North, Central, and Southeast Texas experienced rolling blackouts due to 50 power plants tripping offline. Temperatures ranged between 8 and 19 °F (âˆ'13 and âˆ'7 °C), the coldest in 15 years. The time of the power outages ranged from twenty minutes to over eight hours. Areas affected included Bell, Bexar, Blanco, 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.
California
Though the term did not enter popular use in the U.S. until the California electricity crisis 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 to raise energy prices.
On 13 December 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 17 January 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.