A worker repairs damaged lines in Yulee, Fla., restoring power to residents who had suffered outages for six days in the aftermath of Hurricane Irma. Photo: FEMA/J.T. Blatty
Backgrounder: As Power Goes Out, Time To Design a More Resilient Grid?
By Joseph A. Davis
After Hurricane Irma blew through Florida earlier this month, some 6.5 million homes and businesses were without electricity in that state alone, and there were more without power in nearby states. Then Maria hit Puerto Rico, and initial reports were that 100% of the island’s power was gone.
Does our electric grid need to be so vulnerable?
Perhaps the outages were a rare event, or a sign of aging infrastructure. But either way the power loss matters. Lack of power and the subsequent loss of air conditioning, for instance, was fatal for nine seniors in a Hollywood, Fla., nursing home.
A Florida Power & Light spokesman spoke at the time of a “total rebuild” of the state’s grid. Whether that happens or not, it is a good time to look at improving grid resiliency not just in Florida, but across the nation.
The immediate villain in many storm-related outages
is the system of wires strung on power poles
throughout much of the United States.
Here are some key considerations in tracking this issue:
Power poles can fall
The immediate villain in many storm-related outages, to be sure, is the system of wires strung on power poles throughout much of the United States. High winds blow down trees, which fall on the lines and interrupt power. Ice and other weather hazards can do it, too. Crews cannot work on the lines until the most hazardous weather has passed.
When the damage is widespread, it takes time for even the largest army of crews to restore power. While utilities generally work as fast as they can, it took more than a week to restore power for some customers after Irma. This makes people mad. In some places, stronger concrete and even steel poles could replace traditional treated wood poles, improving reliability.
Trees need trimming
Trees are the enemies of power lines. Line crews trying to restore downed lines and poles can not work until branches and trees causing the problem have been cleared away. Sometimes separate tree crews do this work. A good utility will work with tree-trimmers during non-storm periods to do preventive trimming of trees that threaten the lines. Sometimes customers will object.
Underground lines have pros, cons
In some places, typically urbanized business districts, power lines are laid under ground. This prevents disruption by trees, but is much more expensive than lines strung on poles. Underground lines have their own perils: such as water damage and the buildup of heat. These things can cause spectacular failures as manhole covers to underground vaults are blown into the air. Underground lines may not be more “resilient” if water issues are not well managed and controlled.
|A worker installs a new smart meter at a residence in Portland, Ore. Photo: Portland General Electric|
Transformers can be knocked out
Electric power going into local distribution networks goes through transformers, which step it down from higher voltages to the voltages used for household service. Newscasters during Irma were fond of commenting on the bright blue-green flashes they would see as the storm knocked out transformers. Experts say many of these flashes are actually not transformer explosions, but more likely some other arcing. Nonetheless, failed transformers often must be replaced after a storm. A good utility has them in stock and ready.
Substations need backup hardware
The substations are intermediate nodes in the distribution system that include larger transformers, switching and circuit protection equipment. They may also be specific to industrial facilities that use large amounts of power. Substations get their power from even bigger transmission lines and divvy it up for distribution to smaller parts of the system. Having backup hardware to repair or replace at substations is critical. Without that, whole areas may remain without power.
Transmission lines less likely to fail
The lines that transmit power from generating stations to the many substations out in the grid run on much higher voltages than your household system. This is because less power is lost in transmission when the voltage is higher. These much larger lines are strung on well-engineered pylons, at considerable height, along rights-of-way that are usually completely cleared of trees. They are less likely to fail in a major storm or weather event.
Smart meters, smart grids provide real-time data
Many electric customers today have “smart meters.” At their simplest, smart meters monitor power usage and patterns and transmit such information back to the utility. Power lines can transmit data as well as power (sometimes it is wireless).
Not only can utilities save on meter-reader wages, but they can get a precise real-time view of just when demand is highest, so they can supply power to match demand. Customers can get price breaks for lowering their demand during peak hours. Conservation is encouraged, and a grid that adapts demand to generation can better avoid expensive “peaking” power — and offer more reliable service.
When smart meters are linked to computerized control equipment at the centralized utility, the system is called a smart grid.
Communication between utilities and customers matters immensely during a crisis. Actually, it matters before and after a crisis, too. Utilities need to know when a customer’s power is out (hot lines and smart meters help). Customers need to know when the power will go back on.
Market shifts encouraged diverse sources
After decades of being structured as a government-regulated monopoly, where the companies that generated the power were also the ones that delivered it to consumers, the system changed. In 1978 Congress passed PURPA (the Public Utility Regulatory Policy Act) in response to the “energy crisis” as well as deregulatory fervor. PURPA decoupled the wholesale and retail power markets.
Now, some companies just generate power wholesale. This is what allows retail customers to choose to buy electric power from renewable sources. By encouraging diversity and efficiency, PURPA improved grid resiliency. But it must also be said that many big utilities are still working hard to block feed-in tariffs and similar mechanisms, which allow homes with solar roofs to sell excess energy back to the grid.
Reliability standards can prevent blackouts
Remember the great Northeast Blackout of 2003? Parts of eight states and Ontario went dark, some for days, because of a fault in the grid-control system that caused a cascade of outages. It was possibly the worst, but hardly the first, regional blackout. It is a hard, complex job to coordinate the national grid, which consists of eight regional grids. It takes split-second precision and is far too technical to explain here.
The technical failures that cause blackouts can be partly prevented by setting and following an array of technical standards. NERC, the North American Electric Reliability Corporation, was given beefed up regulatory powers to set and enforce those standards by Congress in 2006.
One design feature of the existing grid
that makes it vulnerable is centralization.
When a major plant or transmission facility goes down,
the outage may be region-wide and recovery may be slow.
Security, sabotage and terrorism are worries
Electrical facilities are often vulnerable to physical and technical attack — although such attacks in the United States have been pretty rare. Nuclear plants, which could present a high hazard, are hardened and defended (although it’s important to ask, “is it enough?”).
Right now, the biggest worry seems to be cyber-attack on the remotely controlled switching and dispatching networks which run the grid. Blake Sobczak and Peter Behr have done a great running series of articles on this in ClimateWire (subscription required).
Generating stations’ reliability is key
The reliability and resilience of power-generating facilities is key to the whole system. This varies much according to the energy source. Coal and gas are usually pretty stable. Coal can be stockpiled. Gas arrives via a network (usually fairly hardened) of distribution pipelines, and it can be stored onsite, too.
Nuclear can be both reliable and unreliable. Nuclear plants can, and often do, produce a steady baseload of power for long periods. But when they go down (which they do for various reasons), power must be supplied from elsewhere in the grid. As Irma approached Florida in September, the two nuclear plants there actually went into planned shutdown as a precautionary measure.
Renewable energy offers (uncertain) reliability
Renewable sources of energy (wind, solar, geothermal, wave) may promise greater resilience than some of the older fuels and sources. But that promise depends on some uncertainties.
Wind turbines are actually engineered to shut down and protect themselves during the highest of winds — but that also means depriving the grid of their power. And it remains to be seen whether they can handle the worst hurricanes and tornadoes. Just as turbines only generate when the wind is blowing, solar panels only generate when the sun is shining.
The intermittent nature of renewable energy is perhaps more of a political issue than an engineering issue. A recent grid study commissioned by Trump Energy Secretary Rick Perry was expected to say renewables were a threat to the reliability of the grid (a conclusion that would please the administration’s fossil-industry and nuclear clients). But it didn’t.
In the end, the study’s credibility was questioned, especially by environmentalists, for predictable anti-regulatory conclusions — but it did not say renewables harmed the resilience of the grid (subscription required). This hypothesis was put to another test during the August 21, 2017, solar eclipse. Would a temporary lack of sun cause disaster? Turns out the grid did just fine. Intelligent switching among diversified power sources is something utilities have done well for a long time.
But utility-scale storage would make a grid based on intermittent renewables perform even better. This is Tesla mogul Elon Musk’s big idea — though the idea is not his alone. He is just one of the first to develop and produce such storage. To be sure, Musk’s Nevada “gigafactory” is largely focused on car batteries. But China’s battery industry is trying to leave him in the dust. Once the technology is developed, large and affordable storage capacity would allow utilities to generate when the sun shines (or wind blows) and then deliver the power when customers need it.
Microgrids mark a “soft energy path”
One design feature of the existing grid that makes it vulnerable is centralization. When a major plant or transmission facility goes down, the outage may be region-wide and recovery may be slow. As early as 1976, visionary physicist Amory Lovins coined the term “soft energy path” to describe a decentralized system based on renewables and conservation. Utilities struggled against it for decades, but it is catching on.
Today, many envision “microgrids” mostly unconnected to the larger centralized grid. They are supposed to be small, autonomous and based on appropriate and renewable power technologies. Today, big technology companies are selling equipment that helps manage and control microgrids. Microgrids may make a lot of sense in remote areas and the developing world.
Joseph A. Davis is director of SEJ’s WatchDog Project, and writes SEJournal Online’s Backgrounders and TipSheet columns.
* From the weekly news magazine SEJournal Online, Vol. 2, No. 36. Content from each new issue of SEJournal Online is available to the public via the SEJournal Online main page. Subscribe to the e-newsletter here. And see past issues of the SEJournal archived here.