(John Kemp is a Reuters market analyst. The views expressed are
By John Kemp
LONDON Feb 18 U.S. electricity regulators have
begun drafting new reliability standards to protect the power
grid from a repeat of severe geomagnetic storms like those that
crippled the U.S. telegraph service in 1859 and blacked out
Quebec in 1989.
Experts remain divided about just how much damage the grid
would sustain in the event of another big solar storm, but
regulators are taking a safety-first approach, ordering
reliability coordinators and transmission operators to start
According to the North American Electric Reliability
Corporation (NERC), the organisation which is responsible for
grid reliability in the United States and Canada, the most
likely consequence would be "voltage instability and subsequent
Power could be restored to customers in a matter of hours
("Special Reliability Assessment Interim Report: Effects of
Geomagnetic Disturbances on the Bulk Power System" 2012).
But modelling by the U.S. Department of Energy's Oak Ridge
National Laboratory indicates a 1-in-100 year solar storm, such
as those that struck the United States in 1859 and again in
1921, would cause as many as 300 high-voltage transformers to
fail and suffer permanent damage.
With only very limited stocks of spare high-voltage
transformers, and a lengthy lead time for ordering and
manufacturing new ones, customers could be left without power
for weeks or even months.
Ironically, the sun is unusually quiet at present. But the
consequences of a big solar storm, if and when it arrives, would
probably be much worse than a physical attack on the power
network by criminals, terrorists or foreign agents
"Should a storm of similar magnitude (to 1859 or 1921)
strike today, it could interrupt power to as many as 130 million
people in the United States alone, requiring several years to
recover," Oak Ridge warned ("Electromagnetic Pulse: Effects on
the U.S. Power Grid" 2010).
Geomagnetic storms are a classic example of a high-impact
low-frequency risk. The threat on any given day may be remote,
but if it occurred, the results could be catastrophic. If a
solar storm struck the planet at the wrong time of day, North
America could be thrown back over a century into the
And it could happen surprisingly fast. The worst geomagnetic
storms are caused by coronal mass ejections (CMEs) in which
billions of tonnes of highly charged particles are flung from
the sun's surface out into space in the direction of Earth and
then interact with the planet's own magnetic field.
The full fury of the storm would reach Earth in between 14
and 96 hours, according to scientists, leaving hours or at most
a few days to prepare after a coronal mass ejection has been
detected by satellites close to the sun ("Research on Historical
Records of Geomagnetic Storms" 2005).
The National Aeronautic and Space Administration's Advanced
Composition Explorer (ACE) satellite, positioned a million miles
from Earth, can give indications of an incoming storm's
potential severity but might give just 30 minutes warning,
according to NERC.
Both the United States and Canada have specialist space
weather forecasting centres, which use satellite data to issue
forecasts, warnings and alerts about incoming solar radiation
and solar storms, including to power grid operators
Once the storm hits, power networks can be damaged almost
instantly. The 1989 solar storm brought down the whole
Quebec-Hydro power system in just 92 seconds, leaving six
million customers without power, according to Oak Ridge.
The same storm also triggered hundreds of incidents across
the United States and burned out a major transformer at the
Salem No 1 nuclear power plant in New Jersey.
As a solar storm interacts with the Earth's own magnetic
field, it produces strong geomagnetically induced currents
(GICs) on the planet's surface, which can enter the power grid
at transformer stations and travel along power lines, disrupting
the normal operation of the network.
NERC reckons the most likely impact would be wild
fluctuations in voltage across the system. But those could still
result in a cascading power failure as relays race to isolate
vulnerable equipment and power plants shut down automatically.
The result might look a lot like the August 2003 blackout in
the Northeast United States and neighbouring parts of Canada,
when extreme swings in voltage led to the automatic shutdown of
more than 500 generating units and cut power to 50 million
people in five minutes.
Some customers were left without power for as much as four
days as grid operators attempted to perform a "black start" on
However, in the case of a geomagnetic storm, the
consequences could be much more widespread, because a really
large storm would hit power supplies across the entire of North
The biggest risk would arise if current flows and voltage
swings caused high voltage transformers to become overloaded and
overheat, resulting in failure or permanent damage.
NERC admits some transformers based on older designs and
nearing the end of their service lives could be vulnerable to
burn out, especially if they are already heavily loaded at the
time the storm hits.
The Salem No 1 transformer was of this type. When it was
inspected a week later the internal windings showed signs of
High-voltage transformers are not simple to replace. The
power industry keeps limited spares, which are pooled among
transmission operators and utilities through NERC's Spare
Equipment Database (SED) programme.
But in the event of a storm that took out dozens, or even
hundreds, of high-voltage transformers, there would simply not
be enough spares to go around.
The general manager of Pennsylvania Transformer, one of
several manufacturers in the United States, recently told the
Wall Street Journal: "I can only build 10 units a month."
Following a really big solar storm, it might take over a
year to replace all the burned out transformers.
FERC ORDER 779
While the industry remains divided on the extent of the
danger, the U.S. Federal Energy Regulatory Commission (FERC) has
ordered it to start making preparations anyway.
Order 779, issued in May 2013, instructed NERC to initiate a
two-stage planning process. In the first phase, NERC was ordered
to develop reliability standards that would require owners and
operators of the transmission system to develop operational
procedures to mitigate the impact of solar storms.
NERC has now submitted a three-point standard and submitted
it to FERC for approval. Each of the regional reliability
coordinators in the United States will be required to develop a
geomagnetic storm operating plan and disseminate space weather
forecasts to utilities and transmission operators. Transmission
operators, too, will be required to develop an operating plan to
show how they will respond to an incoming storm.
In some instances, that may mean cutting power supplies and
reducing the loading on vulnerable equipment to reduce the risk
In the second stage, which is more controversial, NERC must
develop standards requiring transmission owners and operators to
conduct initial and ongoing assessments of how a solar storm
would affect their equipment.
According to FERC, stage two will "require owners and
operators to develop a plan so that instability, uncontrolled
separation or cascading failures of the bulk power system,
caused by damage to critical or vulnerable equipment ... will
not occur as a result of a (solar storm)".
Transmission owners will not be allowed to rely on operating
procedures alone. They must also develop strategies for
protecting the grid "based on factors such as the age,
condition, technical specifications or location of specific
Such strategies could include "automatically blocking
geomagnetically induced currents from entering the bulk power
system, instituting new requirements for new equipment,
inventory management, and isolating certain equipment that is
not effective to retrofit."
The industry worries that some of these measures might not
be cost effective, given the uncertain danger posed to
transformers, but FERC has overruled these concerns, ordering
the industry to start planning for the big one.
(Editing by Veronica Brown)