An aged transformer in a utility substation blew up this month in the Denver metro area. It sent up a geyser of flame and smoke, knocking out power to 31,000 homes.
Xcel Energy, the utility, was able to reroute electricity and restore power after six hours. It trucked in emergency equipment to keep the lights on temporarily and appealed for customer to conserve power. Meanwhile, it ordered new transformers to replace the two destroyed in the fire that followed the explosion.
But what if 300 or more large transformers had been knocked out simultaneously across the top half of the United States by a once-in-a-century megaburst of radiation from the sun? The result would be a catastrophe of unprecedented dimensions, according to a study released this month by the North American Electric Reliability Corp. (NERC) and the Department of Energy.
As the utility industry embarks on a potential $1 trillion-plus expansion in renewable energy transmission and energy-saving smart grid technologies over the next two decades, it must also confront a new and growing fragility while demands on the grid increase. It must be able to protect the grid against so-called "high-impact, low-frequency" threats to the power system.
Rogue currents created in the nation's transmission lines by a massive geomagnetic solar burst could black out dozens of states for months because of one glaring vulnerability. Denver could find the two transformers it needed within hours. But the hundreds of spare transformers needed to restore power after the solar burst are not readily available, the NERC report states.
Transformers raise voltages for long-distance transmission of power, then step voltages back down for delivery to customers. The grid does not work without them, but they are no longer commercially manufactured in the United States. Although there are some spares, U.S. utilities wait a month or more for new units to be built and delivered from abroad.
In addition to solar flares, parts of the transmission grid potentially could also be devastated by electromagnetic pulses triggered by explosion of a nuclear bomb some 20 miles over North America, according to the NERC report. It also warns against a terrorist attack on strategic sections of the grid using a mobile high-powered generator beaming electromagnetic interference at sensitive grid equipment -- a kind of "death ray" weapon.
'It's got to make you nervous'
Some smart grid and green power strategies could help protect the grid against catastrophic threats, said Bob Gilligan, GE Energy Services' vice president for digital services. "You end up with more distributed generation," he said. Advanced automated controls will be commonplace in time, allowing grid managers to isolate the most vulnerable parts of the network ahead of a solar flare's arrival on Earth, limiting power losses and speeding a recovery. Such protections could be in place within a decade, he said.
On the other hand, the trend toward higher transmission voltages and the use of higher-rated transformers makes the grid more vulnerable to some electromagnetic pulses.
The NERC report concludes that the immediate threat to the grid is posed by cyber attackers seeking to take control of computer systems that manage generators and operations. The risk of a coordinated cyber attack on the North American grid has become "more acute" in the past 15 years because of the increased use of digital communications equipment linking generators, transmission hubs and control centers, the report says. In addition to stronger defenses against cyber attack, the industry needs to design strategies to help the grid survive and recover from attacks, it says.
"Every day there are more and more attacks on everybody's infrastructure," said Gilligan. "We have to be concerned about it." But if the financial networks that handle the nation's wealth can withstand cyber assaults, so can the grid, he said.
"It's got to make you nervous," Federal Energy Regulatory Commission Chairman Jon Wellinghoff told an energy conference yesterday. "I don't see it as a problem we can't overcome. There are lots of problems that are more substantial."
The threats of massive damage from solar storms or deliberate attacks on the grid have a low probability at present, but devastating consequences if they occur, the report says, adding: "[T]he potential extremes of a geomagnetic threat environment may be much greater than previously anticipated."
The Congressional Budget Office noted last month that there currently are no federal standards or policies that address the risks of geomagnetic storms and electromagnetic pulses from weapons. Various proposals to strengthen grid defenses against attack have costs estimated at between a few hundred million dollars and more than $1 billion, CBO said.
The House has passed H.R. 5026, the "Grid Reliability and Infrastructure Defense Act," or "GRID Act," authorizing FERC to order utilities to take emergency measures required to protect bulk power transmission networks and critical defense facilities, if directed to do so by a presidential emergency order.
Power companies owning large transformers would be required to stockpile sufficient spares in order to restore the bulk-power grid following an attack or solar storm, under the legislation, authored by Reps. Ed Markey (D-Mass.) and Fred Upton (R-Mich.).
Is this a job for 'cyber czar'?
No bill has passed the Senate, but as concerns about grid security have grown, so has the number of Senate committees seeking jurisdiction over the threat. The Senate Commerce Committee reported out its version in March, and the Senate Homeland Security Committee has a parallel bill. Both would create a White House cyber czar -- confirmed by the Senate -- to coordinate policy.
The bills also would give the president temporary emergency powers to protect the Internet and other critical infrastructure, a provision that has caused some alarm. Senate Majority Leader Harry Reid (D-Nev.) has the task of seeking common ground among these and competing proposals from other committees.
The base case for the geomagnetic threat is the two-day geomagnetic storm that struck the Hydro Québec electric system on March 13, 1989, cutting off power for nine hours. The cascading blackout was contained in Canada, but impacts on the grid reached into the mid-Atlantic states and the Pacific Northwest.
The surge in electrical current damaged a large transformer at a New Jersey nuclear plant. Until recently, many scientists and utility engineers believed this solar storm represented the extreme threat level, and the industry's defenses have been designed based on that incident, NERC reported.
The report says that a disturbance 10 times as intense as the 1989 incident may have occurred in 1921 -- when the North American power grid was far smaller, simpler and less vulnerable. According to a simulation conducted for the NERC study, a repeat of such a storm today could cause "irreparable damage" to more than 350 transformers. "Such large-scale damage could lead to prolonged restoration and long-term chronic shortages of electricity-supply capability to the impacted regions, arguably for many years."
After 9/11, the Edison Electric Institute began a program to increase stockpiles of transformers, called the Spare Transformer Equipment Program (STEP). Currently, 49 utility transmission system operators covering about 70 percent of the grid have signed voluntary contracts to share spares with neighboring systems that lose transformers because of a terrorist attack. The commitments are updated every year. EEI officials would not disclose the number of spare transformers currently on hand.
"We are in compliance" with program requirements, said Keith Walters, the STEP manager. Neither Walters nor officials at NERC would disclose how many transformers are in reserve. GE's Gilligan said that in a national emergency, spare transformers could be deployed from industrial companies to help the recovery.
The STEP program is not designed to deal with the loss of scores of large transformers from a catastrophic geomagnetic disturbance, however, said David Batz, manager of security, infrastructure and operations at the Edison Electric Institute.
Compounding the problem are the physical challenges of moving large transformers around the country. Their size and weight requires rail transportation, which would prolong the grid's recovery from attack or solar storm. Transformers come in many voltage classes and often are fine-tuned to a particular system's requirements, limiting their use elsewhere on the grid.
One answer is the development of smaller, modular generic transformers that could be moved on highways, said Rich Lordan, technical director for power delivery and utilization at the Electric Power Research Institute in Palo Alto, Calif.
EPRI has designed a prototype -- three smaller transformers that could replace a single large one. The units will be built this year at ABB Group's St. Louis, Mo., plant. "We would have all this equipment on trailers. We would blow the whistle to move from St. Louis and energize it in 96 hours," Lordan said.
Unsolved questions, critical exemptions
At this point, there are no plans to build anything more than a prototype, he said.
Transformers cost from $1 million to $10 million, depending on their size. The total prices of the three EPRI units will be half again as expensive as the top price, Lordan said.
A crucial, unresolved question is assessing the number of transformers that should be stockpiled nationwide to permit recovery from a worst-case solar storm or nuclear weapon pulse. The House bill gives that responsibility to FERC and would allow the commission to establish a means for utilities to recover costs of creating the stockpile.
But cost issues have already surfaced. The House bill exempts the Tennessee Valley Authority and the Bonneville Power Administration from the transformer stockpile requirement for 11 years. "That's nonsensical. The grid is as strong as its weakest link," commented one critic of the provision. The exemption was a political necessity to avoid creating new expense commitments that would have affected the budget, a congressional staff aide explained.
EEI's Batz said the success of the STEP program demonstrates persuasively that the industry can create programs to safeguard grid operations without mandates and regulation. "You need the legislation," countered one industry regulator involved in the issue. "You have to make them do it."
Before utilities would have to stockpile transformers under the House bill, even deeper questions would have to be settled. Any such requirements set by FERC would have to be based on its determination of "the nature and magnitude of the reasonably foreseeable attacks or events" that could create an existential threat to the grid. These are questions that so far lack answers, experts say.