(John Kemp is a Reuters market analyst. The views expressed are
By John Kemp
LONDON Nov 16 The concept of a "super-grid"
capable of moving huge amounts of electricity over long
distances is popular with environmentalists and governments keen
to promote the integration of more renewables into the power
supply, overcome transmission bottlenecks and bring power to
"An electricity super-grid could take green electricity
produced in one country to another through thousands of
kilometres of sub-sea cables. Wind farms built out at sea could
also be connected to a number of countries," Britain's
Department of Energy and Climate Change announced last year.
The super-grid would be "a pan-European transmission network
facilitating the integration of large-scale renewable energy and
the balancing and transportation of electricity, with the aim of
improving the European market", according to the Friends of the
Super-Grid, a lobbying organisation.
It would connect wind farms in northern Europe with solar
power producers in the Mediterranean and North Africa and the
massive power-consuming centres in the centre of the continent.
Policymakers should proceed with caution, however, because
highly interconnected systems are inherently vulnerable.
"Vulnerability is an unintended side effect of the nature
and organisation of highly centralised technologies," Amory and
Hunter Lovins explained in a famous report for the U.S. Federal
Emergency Management Agency.
"Complex energy devices were built and linked together one
by one without considering how vulnerable a system this process
was creating," they wrote in 1982 ("Brittle Power: Energy
Strategy for National Security").
Super-grids will require significant improvements in control
to maintain stability.
Power engineers at ABB recently announced a new generation
of super-fast, high-voltage direct current circuit breakers that
can stop the flow of power within 5 milliseconds.
"The breaker can cut out the faulty line and keep the rest
(of the grid) healthy," according to the company's chief
But the much bigger problem is how to keep the system
balanced in the event of a failure along one of the ultra-high
voltage transmission lines, or if a region exporting power to
the rest of the network suffers some sort of failure that
abruptly halts exports.
The idea of linking up existing regional and national power
networks in a super-grid system is not restricted to Europe.
The United States is backing "Connecting the Americas 2022,"
a programme that aims to bring power to the 31 million citizens
in Central and South America who currently lack access to
reliable, clean and affordable electricity within the next
Connecting the Americas backs more electrical links.
"Electrical interconnection benefits all countries by allowing
those with excess power to export electricity to countries that
have a power deficit," according to the U.S. Department of
"Interconnected power systems allow for greater integration
of renewable energy resources as well as power exchanges among
countries with varying climate and seasonal needs.
Interconnection expands the size of power markets, creating
economies of scale, which can attract private investment, lower
capital costs and reduce electricity costs for consumers."
Grand plans for connecting up entire continents remain at
the conceptual stage, but even without them power networks are
becoming increasingly interconnected.
National grids in Finland and Estonia have been linked by a
high-voltage, direct current (HVDC) sub-sea cable capable of
delivering 350 megawatts (MW) in either direction since 2007
(Estlink 1). Estlink was explicitly intended to link up the
Baltic and Nordic power markets. Another cable is planned to
come into operation by 2014 (Estlink 2).
In Namibia, the Caprivi Link joins the remote northeast part
of the country, which is part of the Zambian grid, with the rest
India's Power Grid Corporation has linked and synchronised
four of the country's massive regional power networks (the
Northern, Eastern, Western and North Eastern grids) in a
super-grid. The final Southern grid will be synchronised by
No country has done more to build a nationwide super-grid
State Grid Corporation is building an enormous
inter-regional transmission system to move power from coal-rich
areas in the northwest and hydropower-rich provinces in the
southwest to the massive consuming centres including Guangdong,
Zhejiang and Shanghai on the east coast.
State Grid has built both alternating current (AC) and
direct current (DC) transmission lines operating at ultra-high
voltage (UHV) to move power over long distances.
The 1 million volt Jindongnan-Nanyang-Jingmen AC line went
live in December 2011, moving electricity from power stations in
coal-rich Shanxi east to Hubei province. The 640 kilometre line
can transport 5 gigawatts, equivalent to 60,000 tonnes of coal
DC links such as Xiangjiaba-Shanghai and Jinping-Sunan have
also gone into operation, connecting the enormous hydro dams in
Sichuan to coastal mega-cities such as Shanghai.
Even more ambitious projects are under construction. In May,
State Grid commenced work on a vast 2,200 km UHV DC line from
Xinjiang in the far west through the provinces of Gansu,
Ningxia, Shaanxi and Shanxi all the way to Henan in the east.
State Grid sees a super-grid as essential to meeting the
country's energy demand while easing pressure on the railroad
In September, however, the Energy Research Institute (ERI)
of China's powerful National Development and Reform Commission
urged the government to apply the brakes.
"The building of large-scale and long-distance UHV
transmission systems should be avoided," ERI warned. "The cost
and power loss of long-distance UHV transmission systems are
"In addition, this kind of system is relatively fragile.
Once an accident happens, widespread power outage and power
surplus will co-exist, causing immense damage to the eastern and
western regions. If all the country's grids are connected by UHV
transmission lines, if the lines broke because of some natural
or human incident, it would result in a nationwide power outage.
The potential hazard is huge."
Stability is a major concern on massive networks, where a
problem in any one part can bring cascading failures across the
India's widespread blackouts on July 30 and 31, which took
out the power supply across the four synchronised regional
grids, were a stark reminder of the fragility that can be
introduced by creating a widespread network.
At a special conference called to examine the Indian
blackouts, China State Grid's power engineers blamed the mass
failure on "lack of unified controls and too many rituals
causing untimely implementation of orders, which grew into a
In contrast to the Energy Research Institute, State Grid
officials said they "consider that the interconnection of power
grids should be further improved. Otherwise, the partial failure
will trigger a chain effect or a considerable drop of power
generation, which would bring on a large-scale blackout because
of weak mutual support."
The stability of super-grids is controversial.
Interconnectedness together with inadequate control systems were
responsible for widespread blackouts in the United States in
August 2003. However, advocates of super-grids claim they can
also be a source of stability.
Much of the controversy focuses upon AC grids, which must be
synchronised. In contrast, DC interconnectors between separate
AC networks can help ensure that failures in one network are not
transmitted to the other.
Siemens, for example, notes that during the August 2003
blackout, power remained on in Quebec because the province was
connected to the rest of the North American network only by DC
lines, which acted as a firebreak even as failures cascaded
across other parts of the Northeast United States and Ontario.
Some super-grid advocates have suggested a mixed system -
with regional and national AC grids linked by DC
interconnectors, providing firebreaks against failure - or a DC
pan-continental grid superimposed over separate AC national
grids. But that may not be enough.
If the dream of super-grids is to be realised and not become
a nightmare, super-transmission will have to be matched with
super-control, which may be doable but has yet to be achieved.
(editing by Jane Baird)