(John Kemp is a Reuters market analyst. The views expressed are
By John Kemp
LONDON Aug 12 Exactly ten years ago, at 15:05
Eastern Time on August 14, 2003, an overhead power line came
into contact with an overgrown tree near Cleveland, Ohio.
What happened next is a frightening case study of how
vulnerable modern economies are to even a small disruption in
vital and highly interconnected systems.
Little more than an hour later, a cascading power failure
had blacked out most of the Northeast United States and
neighbouring parts of Canada -- leaving 50 million people
without power, some for up to four days.
By 16:13 Eastern Time, parts of Ohio, Michigan,
Pennsylvania, New York, Vermont, Massachusetts, Connecticut, New
Jersey and the Canadian province of Ontario had been sent back
in time more than 100 years to a pre-electrical age.
"How did we become so vulnerable?" Amory and Hunter Lovins
asked in a report entitled "Brittle Power: Energy Strategy for
National Security," for the U.S. government.
The Lovinses could have been writing after the 2003
blackout. In fact, the report had been written more than two
decades earlier, in 1982, for the Federal Emergency Management
Agency, which even then was concerned about emerging threats to
the nation's critical infrastructure.
Amory and Hunter Lovins worried " a few people could
probably blackout most of the country." They cited the risk of
terrorism, sabotage or a hydrogen bomb, in what would come to be
seen as an eerily prescient warning about the risks to critical
infrastructure after the attacks on the World Trade Center on
September 11, 2001.
Terrorism was quickly ruled out as a cause of the August
2003 blackout. But the Lovinses had prophetically identified the
weakness in North America's electricity network.
"America's energy vulnerability is an unintended side effect
of the nature and organisation of highly centralised
technologies. Complex energy devices were built and linked
together one by one without considering how vulnerable a system
this was creating," they wrote.
"Americans' most basic functions depend ... on a continuous
supply of electricity," the co-authors explained.
"Without it, subways and elevators stall, factories and
offices grind to a halt, electric locks jam, intercoms and
televisions stand mute, and we huddle without light, heat or
ventilation. A brief faltering of our energy pulse can reveal
... the hidden brittleness of our interdependent, urbanised
The blackout concentrated minds in the electricity industry
and on Capitol Hill. In the ten years since August 2003, the
North American power industry has invested billions of dollars
upgrading computer systems, training control room staff, and
cutting down vegetation along power lines.
Reliability standards which were once voluntary have become
mandatory. New synchrophasors are being rolled that will provide
updates about the state of the grid several times a second,
giving control room staff more situational awareness.
Lessons have been learned. The precise failures which led to
the 2003 blackout are unlikely ever to be repeated.
But every blackout results from a unique cocktail of causes.
In a complex systems, it is not possible to reduce the risk of
catastrophic failure to zero.
The 2003 blackout was not the first. There had been earlier
mass blackouts in 1965 (affecting 30 million people in the
Northeast), 1977 (9 million people in New York), 1982 (5 million
people on the West Coast), 1996 (two big blackouts on the West
Coast) and 1998 (152,000 people in Minnesota and neighbouring
It will not be the last. In 2011, a blackout cut power to
2.7 million people across southern California and Arizona. In
2012, the two biggest blackouts in history rolled across India's
power grid, cutting power to states containing half of the
country's 1.2 billion people.
While some aspects of reliability have improved enormously,
other vulnerabilities are increasing.
The risk of cyber-attacks by terrorist groups or hostile
states has increased, ironically because the United States
itself has demonstrated the power of cyber-operations with its
Stuxnet attack on Iran's nuclear programme.
Integrating more unpredictable sources of power like wind
and solar into the electricity network is also increasing the
reliability challenges for grid coordinators.
The trend towards linking up local and regional networks
into super-grids, connecting entire countries or continents in
China, India, Europe and Latin America, is increasing the very
interconnectedness that lay at the heart of the 2003 power
Despite all the precautions, it could and will happen again.
AN ORDINARY DAY
August 14, 2003, was a typical summer day in Ohio. Power
consumption was high as a result of airconditioning demand, but
well below the peaks recorded at the same time in previous
years. The grid had coped with much worse.
"Peak load conditions on a less than peak load day," is how
managers from First Energy, which managed the local grid,
described it to investigators from a joint U.S. and Canadian
government task force set to up to establish the causes of the
Several generating units were undergoing maintenance and
were unavailable. At 13:31 the East Lake 5 generating unit,
which produced almost 600 megawatts of power, unexpectedly
tripped off and was no longer available. Without East Lake 5,
the region became dangerously dependent on the nearby Perry
nuclear power plant to keep meeting demand.
The Cleveland-Akron region, on the southern shore of Lake
Erie, had been identified as a "transmission constrained area"
with limited links to the rest of the Eastern Interconnection,
the giant power network that services the eastern two-thirds of
the United States.
The potential for problems was well-known to grid operators
because Cleveland-Akron had suffered severe power shortages and
transmission congestion in 1994 and 2002. Two power lines had
already failed that afternoon, increasing pressure on the grid.
Nonetheless, none of these factors was responsible for the
rolling blackout which occurred later that afternoon. Subsequent
modelling by task force investigators established that the
condition of the electricity grid was vulnerable but stable
before a tree contact caused the third, Harding-Chamberlin,
power line to trip at 15:05.
"The central organising principle of electricity reliability
management is to plan for the unexpected," the task force
explained. "The unique characteristics of electricity mean that
problems, when they arise, can spread and escalate very quickly
if proper safeguards are not in place."
No matter what happens, how many generating units and
transmission lines are unavailable, the grid must be operated at
all times to ensure it will remain in a safe condition.
Operators must assess the worst case scenario, usually the
loss of the largest generator or transmission line on the
system, and plan how to meet it (the "N-1 criterion"). If it
happens, they must be able to bring the system back into a safe
operating condition within no more than 30 minutes, and start
planning to meet the next worst-case scenario.
To cope with emergencies, area controllers can order more
generation to come on line or seek help from neighbouring areas
by requesting transmission loading relief.
Grid managers can cut power supplies to customers with
interruptible power supplies and request voluntary conservation.
But if all else fails, controllers are expected to start
disconnecting blocks of customers to protect the rest. From a
reliability perspective, it is better for a few customers to
suffer a power cut than risk a cascading power failure across
COMPUTERS AND TREES
When the Harding-Chamberlin power line came into contact
with a tree, the failure of Perry nuclear plant became the N-1
contingency. Grid controllers should have disconnected 1,500
megawatts of load to safeguard the system. It would have blacked
out much of Cleveland-Akron but the rest of the Eastern
Interconnection would have been safe.
Unfortunately, the FE control room was unaware of the danger
because several critical computer systems were not operating
properly, including the automatic alarm systems. It did not help
that reliability and transmission operators were situated in
different rooms, or that unusually the control room did not have
a visual display of the topology of the grid, its generating
assets and transmission lines.
The first indication that something was wrong came only at
15:42, more than half an hour after the critical tree contact.
"Nothing seems to be updating on the computers," operators
at First Energy's control room, who were responsible for
controlling the grid in northern Ohio, told their IT staff.
"We've had people calling and reporting trips and nothing
seems to be updating on the event summary ... I think we've got
something seriously sick."
Around the same time, an operator from Perry nuclear power
station telephoned the control room to warn that the plant
risked an automatic shutdown for safety reasons: "I'm still
getting a lot of voltage spikes and swings on the generator ...
I don't know how much longer we're going to survive."
Four minutes later, the Perry operator telephoned again:
"It's not looking good .. We ain't going to be here much longer
and you're going to have a bigger problem."
By that time, it was almost too late. Less than 24 minutes
later Cleveland-Akron was blacked out. Much worse was to follow.
A rolling power failure had begun that would shut down 265 power
plants, with 508 generating units, including 10 nuclear power
stations, within the next 8 minutes.
As each power line failed, the remaining lines became more
and more congested, heating up and sagging closer and closer to
trees and other vegetation. Two additional power lines failed
between 15:05 and 15:39, and then 16 more by 16:08, as the
situation around Cleveland became critical.
Perhaps if the grid controllers had initiated disconnections
in Cleveland a full-blown crisis could have been averted. But it
was the failure of another power line, Sammis-Star, at 16:05
that turned a local problem into a regional disaster. The
Sammis-Star outage was the critical event leading to widespread
cascading, investigators concluded.
"The collapse of FE's transmission system induced unplanned
shifts of power across the region," according to the task force.
"With paths cut from the west, a massive power surge flowed
(from Pennsylvania, New Jersey and Maryland) into New York and
Ontario in a counter-clockwise flow around Lake Erie to serve
the load still connected in eastern Michigan and northern Ohio".
Protective relays monitoring power lines interpreted the
surge as a fault and triggered the circuit breakers to protect
the equipment. What followed was a high-speed race, in which
power surged along the few remaining pathways on the grid, and
the relays and circuit breakers rushed to disconnect more and
more transmission lines.
First the Northeast U.S. power network and Ontario were
disconnected from the rest of the United States and Canada.
Seconds later this giant electrical island broke apart into
dozens of smaller fragments.
As voltage and frequency started to fluctuate wildly within
each island, protective relays shutdown almost all of the
remaining transmission lines and generators to protect them from
damage. By 16:13 the Northeast was dark.
In its final report on the causes of the blackout, the
U.S.-Canada Power System Outage Task Force identified poor
vegetation management, computer failures, inadequate training
and lack of real-time situational awareness of grid conditions
as the main factors behind the disaster.
First Energy was harshly criticised, but the task force
identified institutional failures across the industry,
particularly in setting and enforcing reliability standards, and
coordinating across the grid. No fewer than 46 recommendations
were made to prevent the blackout recurring ("Final Report on
the August 14, 2003 Blackout" April 2004).
As usual, a major blackout spurred the industry and Congress
to enact long-stalled reforms. The North American Electric
Reliability Council became the North American Electric
Reliability Corporation (NERC). Under Title XII of the 2005
Energy Policy Act, NERC was given power to set mandatory rather
than voluntary standards across the industry.
Although the 2003 blackout was not caused by a cyber-attack,
NERC has stepped up efforts to strengthen the grid from
malicious activity caused by hackers, terrorists and foreign
powers, through its Critical Infrastructure Protection
Despite all this work, could massive blackouts happen again?
Yes. The subsequent mass blackouts in California-Arizona and
India point to the continuing risk.
Eight years after the August 2003 blackout, NERC found the
California blackout in September 2011 happened because "the
system was not being operated in a secure N-1 state. The failure
stemmed primarily from weaknesses in ... operations planning and
real-time situational awareness," which is similar to what
happened in Ohio.
The risk of cascading failure is inherent in complex
interconnected systems, as the Lovinses realised. It can be
reduced via careful systems analysis and contingency planning,
but will never be reduced to zero.
(Editing by Anthony Barker)