An average of once every one hundred
years the sun takes aim at earth and launches a ginormous coronal mass
ejection(CME). Less than a day later, it arrives as a cloud of charged
particles and hits the earth’s magnetic field. It has a southern polarity and,
therefore, “couples” with the earth’s magnetosphere, creating swirling
“electrojets” of charged particles 100km above the earth. These produce
geomagnetically-induced currents (GIC) in the earth itself. These currents flow
into the grounding mechanisms of large Extra High Voltage (EHV) transmission
towers. The current then flows through the transmission lines and into the EHV
transformers in the system. This quasi-DC current (in an AC system) produces
“half cycle saturation” that overheats and permanently damages those $5-10
million boxcar-sized transformers. The current also produces harmonics that can
damage or trick other components in the system, resulting in a collapse of the
grid. The most important EHV transformers are the Generator Step Up (GSU) units
located at nuclear or equally large coal generating plants. When these
transformers fail, there is no way to get power from the plant to the grid. The
icing on this cake is that it takes about a year to order, manufacture, and
install a replacement EHV transformer (when the grid is up everywhere).
In 2008 a leading geomagnetic storm
researcher developed a model to simulate the effects of another 100-year storm
on the modern electric grid. The study, “Severe Space Weather Events;
Understanding Societal and Economic Impacts” done by Metatech, an electric
industry consultant (working for the Congressional EMP Commission and FEMA, not
the Sierra Club), predicted that in a geomagnetic storm equivalent to the 1921
“100-year storm” approximately 365 EHV transformers would fail. The grid could
not compensate for that many failures, leading to collapse east of a line from
Chicago to Memphis to Jacksonville, FL and in the Pacific Northwest. The
estimate for full recovery is four to ten years at a cost of trillions of
dollars. The above is not the worst case scenario. The modeled storm is
centered over southern Canada. If it is farther south, the predicted damage is
over 600 EHV transformers. The model only examines transformers down to 345kV.
Many 230kV transformers will fail, too. Also, storms larger than the 100-year
storm have struck us in the past.
This vulnerability was first documented
with the 1989 Quebec Hydro storm. A moderate-sized storm took Quebec and part
of the Northeast grid offline in 92 seconds, put six million people in the
dark, and immediately damaged two EHV transformers in Quebec and one in the
U.S. The two Quebec transformers were not damaged directly by the GIC but by
“the uncontrolled operation of circuit breakers in rapid succession” causing
overloads as the grid collapsed. [Kappenman, Meta-R-319 p.2-12, 2010.] Also
noteworthy is that 11 nuclear power plant GSU transformers needed to be
replaced over the next two years, indicating that even if GIC doesn’t
immediately kill a transformer, it can greatly shorten its life. The cost of
this storm has been estimated at $360-645 million [Tsurutani, et al, Journal of
Geophysical Research, 3July2003 online]. In the “Halloween Storms” of Oct-Nov
2003, a series of storms destroyed 14 EHV transformers in South Africa [NERC,
HILF, 2009]. These storms produced lower GICs, but they lasted for several
days. The transformers failed over a period of 10 months following the storms,
so there was no massive blackout during the storm. Instead, there were
brownouts and rolling blackouts as transformers failed. This storm was also
important because previously these latitudes from the magnetic poles
(equivalent to southern California and Florida) were thought to be safe from
damaging GICs.
Another important event occurred in
2003. A high voltage line touched a tree and precipitated a collapse of the
grid from Ohio to New York City. This put 50 million people in the dark. It was
important, since it showed that even 14 years after the 1989 storm we could not
prevent cascading collapses of the grid. The minimum cost estimate for the
blackout is $6 billion [CENTRA, 2011]. Later, we will see that blackouts cost
much more than hardening the grid to prevent grid damage and collapses.
There have been other more powerful
storms, but they pre-date a modern electrical grid. The 1921 “Railroad Storm”
is named for the impacts to railroad signaling and switching devices, as well
as the trans-Atlantic cable and telegraph systems. It has been estimated to
have been ten times the intensity of the 1989 Quebec Hydro storm [Meta R-322 p.
7-5]. It is considered the “100-year” geomagnetic storm and is the basis of the
Metatech modeling from 2008 and 2010.
The largest recorded geomagnetic
storm was the “Carrington event”. The name is from the astronomer who was
actually looking (indirectly) at the sun in 1859 when the CME erupted. Nitrates
are produced in the atmosphere above the poles by geomagnetic storms and settle
to the polar ice. Measurements from ice core samples from 1561 to 1994 show
that the 1859 storm was the most intense in that 433 year time span [McCracken,
2001].
EHV transformers are large, custom designed,
and very expensive, so there are few spares. A representative of one, large,
electrical provider estimated its number of spare EHV transformers “would be a
single digit percentage” [comment of Mr. Heyeck of American Electric Power at
the FERC Technical Staff Conference, April 30, 2012]. By 2009, almost no EHV
transformers were made in the U.S. However, because 70% of our “fleet” of 2148
EHV transformers is at least 25 years old and 50% is at or beyond its 40-year
design lifetime, demand has been increasing since 2002 [Kappenman, Meta-R-319,
2010]. This means that around 1074 new vulnerable transformers, an investment
of over $5 billion, will be installed shortly. So, four new EHV/HV transformer
plants have been constructed in the U.S. since 2010.
In 2010 the U.S. Department of
Energy’s (DOE) Office of Electricity Delivery and Energy Reliability issued
“Large Transformers and the U.S. Electric Grid” that stated there were six
plants producing large transformers in the U.S. Those plants satisfied only 15%
of domestic demand. The other 85% was imported. From 2007-2011 an average of
500 Large Power Transformers (LPTs) were imported each year.
Even with four new transformer
plants, we still have limited production capability in the U.S. If 365 EHV
transformers go down, as the modeling suggests, many will stay down a long
time. Although the normal lead time for an EHV transformer is about 12 months,
it can be 20 months in some cases [DOE, 2012]. Will they even be able to
produce replacement transformers with large parts of the grid down? How long
will it take under those conditions?
Ramping up production is seriously
impacted by the raw materials for EHV transformers. Even when produced here,
many of the materials come from overseas. Copper and “electrical steel” will
become very sought after, and not just in the U.S. There were only 13
manufacturers in the world of electrical steel and only a handful of them
capable of producing the high-permeability core steel used in LPT cores. Only
one is in the U.S. [DOE, 2014]. If the storm affects the whole northern
hemisphere, or even the world, know that even though China is a huge
transformer producer, it still has to import transformers. Now try to envision
the competition for imported transformers. One study suggested that long waits
would ensue and “prioritizing delivery to customers would become a politically
charged issue” [CENTRA, 2011, p 30]. Also, “If you don’t invest in [hardening]
it’s hard to argue you should be first in line for replacement transformers.”
[FEMA, Feb. 2010 workshop - Managing Critical Disasters in the Transatlantic
Domain - the Case of the Geomagnetic Storm]
So, why has the grid become so
vulnerable? First, nobody is responsible for the grid. The grid is really just
a bunch of contracts and agreements between competing companies to move
electricity among them. The system has three components– the generating plants,
EHV and HV transmission lines, and the lower voltage lines that step down
voltages and distribute the juice from the transmission lines to local
customers. To move electricity most efficiently, transmission voltages are high
to minimize resistance. The low resistance increases vulnerability to GICs. A
765kV line permits GICs ten times higher than a 115kV line [NERC, “HILF Event Risk
to the North American Bulk Power System“, 2009]. The cost considerations also
result in a preponderance of single phase and autotransformers, instead of the
more durable 3-phase transformers. Finally, the desire to buy inexpensive power
a long way away means there are more and more miles of EHV transmission lines.
These lines are like antennae; the longer they are, the more current they
collect. The age of the transformer fleet also increases its vulnerability.
In 2011 CENTRA Technology, Inc., on
behalf of the Office of Risk Management, U.S. Department of Homeland Security,
looked at likely consequences of power outages in 20 industries during the
storm, one week later, and one month later. During the storm, there are
widespread impacts due to the loss of power. Gas stations are unable to refuel
vehicles, including freight haulers. Lack of power prevents people from getting
their money or spending it. Dark traffic signals impede highway transportation.
As backup generators come online, the impacts are reduced for services, such as
hospitals, public water and sewer utilities, and emergency services.
The CENTRA report notes that, “…most
continuity plans suffice for a period of days, not weeks”. After one week (or
less) backup generators begin to run out of fuel. Nuclear power plants have
backup power for “…up to 7 days, depending on location and circumstances”
[Singh Matharu, NRC, in comments at the FERC Staff Technical Conference on GMD,
April 30, 2012]. After that, how do they pump cooling water to the spent rod
storage pools? The CENTRA report summarizes, “The concerns as time progresses
after the storm grow from economic losses to major health and safety issues”
(page 32). When I asked the director of a metropolitan utility how much fuel he
had onsite for pumps for the water system, the answer was “about two days”. The
answer was the same for chemicals for water and sewage treatment. Our economy
is based more and more on “just in time” delivery.
From the Survival Blog
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