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In the days leading up to Hurricane Sandy's destructive march on the East Coast, utilities warned customers to prepare for widespread outages and potentially extensive power failure. The question was not if the grid would fail, but to what extent.
The storm highlighted an already well-known problem: The U.S. power grid is vulnerable to extreme weather. As officials from New York to Venice, Italy, have acknowledged in recent weeks, climate change is likely to increase the prevalence of such weather. And according to analysts and outside groups working on the problem, there is no one-size-fits-all remedy that can insulate the ailing grid against an escalation of the elements.
The conversation over extreme weather and U.S. transmission infrastructure is evolving, due in no small part to extreme weather events like Sandy, last summer's "super derecho" and last year's Hurricane Irene. These events have tested the grid and revealed its weaknesses, but they have also yielded valuable lessons -- lessons that, if successfully implemented, could result in a better-equipped system able to weather the storms of the future.
Smart meters keep operators ahead of the storm
One such lesson has been the success of smart meters in anticipating and responding to large-scale weather events.
When scores of tornadoes spun across the Southeast in 2011, ripping through towns and leaving hundreds of thousands of Georgia Power and Southern Co. customers without electricity, the utilities relied on a widely installed network of smart meters to chart the storm's path, identify high-priority customers like hospitals and fire stations, and deploy response teams to the hardest-hit areas.
In addition to speeding the recovery, the meters saved the utilities time and money. As Ed Carlsen, manager of distribution power systems for Georgia Power, told The Atlanta Journal-Constitution in 2011, "We were able to determine that hundreds of meters were actually on, so that saved us from rolling trucks out there."
Smart meters aid grid resiliency in three primary ways, according to Chris Eisenbrey, director of business information at the Edison Electric Institute (EEI).
First, they act as remote sensors, alerting utilities to outages immediately and eliminating the need for customers to call in to report problems. Second, by providing utilities with a virtual map of outages, they allow response teams to be more efficiently deployed to the areas where they are most needed.
And finally, they allow the grid to be predictive rather than simply reactive -- when a problem begins to occur, operators can shut down or reduce power to troubled sections of the grid, isolating issues before they can spread.
The final point is particularly important given the structure of the U.S. power grid, which some would call antiquated. In a storm or hurricane, the majority of outages occur not because of localized events such as falling tree limbs but due to the cascading impacts of a single outage spreading across a large swath of infrastructure.
"The grid is a radial system. It's like a tree: There are twigs, there are branches, there's a trunk," said John Cooper, a partner at the consulting firm NextWatt Solutions and co-author of the book "The Advanced Smart Grid." "Break a branch, and all the twigs on the branch are gone. Break the trunk, and the whole thing shuts down."
The trick, he said, is to arrest the problem before it can spread from branch to twig.
Smart meters aid in this effort by immediately identifying problem areas. Some utilities, such as Commonwealth Edison, have taken the effort a step further by installing "smart switches" throughout their grid capable of immediately rerouting power away from problems.
"The idea is to limit the damage," Cooper said. "With sensors out there, we can identify and stabilize the problem, like the body does with clotting. Essentially, we contain the damage."
The safest place on the grid is ... off the grid?
Another way of containing the damage, or avoiding it entirely, is to reduce dependency on the grid, Cooper said. Microgrids, or power systems that generate part or all of their own power, are better insulated against the "cascade effects" that plague larger systems, he said.
During Sandy, a housing project in Brooklyn called Co-op City managed to keep its lights on even while the power went dark in the buildings around it, thanks to a 5-megawatt generator and an efficient thermal energy provisioning system, he said.
Not only does self-sufficiency protect the microgrid in question -- it can also lower demand on larger utilities.
"If the microgrid is producing power, they can shift some of that over to relieve pressure on the grid," Cooper said.
"The message I want to get out there is that there is an ecosystem approach that says we can work on this problem from both ends -- both customers and utilities can be working on this issue at once," he said.
EEI's Eisenbrey said that, while self-sufficiency would likely play a role in shaping the future grid, there is still work to be done in policy and planning before such strategies can be widely integrated.
"We as an industry are looking at some customers seeking to become more independent, and we believe there's a real role utilities can play in that," Eisenbrey said. "At the same time, there are regulatory and cost recovery issues we're interested in working through before [microgrids] come into vogue."
"Even if you're on a microgrid, and becoming self-sufficient, you're going to have to depend on your local utility as a backup system," he added. "That raises issues of costs being shifted to other consumers who are essentially paying for that grid as a battery backup."
Stronger doesn't necessarily mean harder
Such solutions, which are broadly grouped under the title "grid resilience," are relatively new to the debate on vulnerability. A more familiar line of debate concerns "grid hardening."
As its name implies, grid hardening aims to shore up the grid before problems occur, rather than shortening response time or containing damages.
The most oft-discussed technique in this vein is the burial of power lines. The practice is widespread in Europe and has contributed to a lower rate of outages in countries like Germany, which buries almost much of its transmission infrastructure.
Invariably, weather events that affect the grid are quickly followed by calls for the United States to follow suit. But as many experts have noted in the fallout from Sandy, much of the grid damage was sustained below ground, as flooded saltwater corroded lines and fuse boxes.
"When responding to natural hazards, you have to be very careful that you do your redesign in an all-hazards way rather than just against one storm," said Joel Gordes, president of the consultancy Environmental Energy Solutions. "Maybe burying power lines would help for one kind of storm, but what about floods in the future? Right now, too much of the time, we're looking at this on a storm-by-storm basis."
Eisenbrey agreed that burying power lines, while useful in some cases, is probably not a universal prescription for the grid.
"Utilities are looking into undergrounding for parts of the system, generally the most vulnerable parts," said Eisenbrey. However, both above-ground and below-ground power lines have advantages and drawbacks, he said. While more resilient to wind and falling trees, subterranean power lines are more vulnerable to flooding and require higher costs and longer periods to repair.
"The more immediate issue is a matter of cost and benefit," he said. "Given the economy we're in, the big concern for utilities and regulators is whether something like [burying lines] would bring about a rate increase."
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