When Hurricane Sandy ripped through the Eastern United States, it took down power lines, sent sea water gushing into substations, and knocked out connections to power plants. Millions of people were without electricity, but more important, dozens of hospitals lost power from both the grid and their secondary and tertiary backup systems. Cleaning up the mess is the first priority, but a close second will be evaluating how the grid could better cope with disasters of this magnitude.
That question comes at an opportune time. We're in the midst of a lengthy and expensive overhaul of our nation's electrical grid, one that heralds a new, "smarter" future. Power generation and delivery haven't changed much since the days of Edison and Tesla, but a new wave of technologies, known collectively as the smart grid, will modernize the industry. Some utility companies have already started down this road, installing smart meters that communicate demand with operators. But could smart grid technologies have helped during Hurricane Sandy, or any other large natural disaster, for that matter? The answer is yes and no, and which part of that answer is right depends on how you define the smart grid.
The smart grid isn't just one technology, but a whole host of new systems which, hopefully, will combine to make our electrical distribution system more robust and efficient. It involves everything from intelligent washing machines, which run only when electricity demand is low, to dynamic power plants, which can quickly spool up in response to spikes in demand.
Much of the smart grid, though, still relies on the same grid we have today. The distribution system may become more responsive, but physically, it won't be much different than it is today. That means when a substation is flooded or a tree knocks down a power line, the juice will stop flowing, just as it does today. And when that happens on a large scale, as it did during Hurricane Sandy, millions of people will still lose power. There's not a lot an intelligent system can do to guard against physical damage.
And when there is widespread physical destruction of the grid, "There's a limited amount the smart grid can do," says Mark McGranaghan, vice president of power delivery and utilization at the Electric Power Research Institute. During smaller disasters, a smart grid could more deftly reroute power around downed lines than a traditional grid, ensuring customers who needn't lose power don't. But that would only work if the alternate routes are still functioning. If they are damaged, you're still out of luck and out of power. The smart grid, McGranaghan says, is no substitute for system hardening.
System hardening is where infrastructure is beefed up to prevent damage from weather or other disasters. It can include things like using cement for telephone poles instead of wood, burying cables underground, or raising substation equipment above the level of flood waters. System hardening is not entirely distinct from smart grid approaches--information relayed by smart technologies can guide hardening efforts--but it can be done independently of "smart" updates.
That's not to say the smart grid won't be useful in the case of disasters. Vermont, for example, has widely deployed smart grid technologies, including smart meters and grid sensors. "When that last hurricane went through the Northeast, they had an easier time getting power restored in Vermont because they could spot the shortages more easily," says Maggie Koerth-Baker, author of Before the Lights Go Out, a book about electricity, infrastructure, and the future of energy. "They were able to actually spot the downed wires through the system." That allowed crews to focus on repairing downed lines rather than searching for them. The same happened after storms swept through the Southeast earlier this year, McGranaghan says. Crews in Chattanooga were able to repair the system in much less time thanks to smart grid technologies.
Many smart grid technologies are better suited to helping a system recover from disaster, but to keep the power flowing during an event, experts are bullish on microgrids. Also considered a member of the smart grid pantheon, microgrids can function autonomously if the larger grid fails, says Alexis Kwasinski, a professor at the University of Texas. They derive their power from a variety of sources, including diesel generators, natural gas-powered microturbines, photovoltaics, and small wind turbines. Microgrids are expensive, though, so they are most commonly used where a continuous power supply is deemed worth the added cost, such as hospitals, telecommunications equipment, and computer server farms, Kwasinski says. (Incidentally, Thomas Edison's first power plant in Manhattan, Pearl Street Station, is considered a microgrid, since it served electricity to only a small section of the city.)
While many smart grid technologies are still being rolled out, microgrids already have a good track record when disasters strike. The continuity of cell phone service is perhaps the most conspicuous example. After the earthquake off the coast of Sendai, Japan, Kwasinski says a microgrid operated by NTT kept power flowing long after the main grid had failed, allowing people to stay in touch. Another in Garden City, New York, operated well after Hurricane Irene in 2011, he adds. And during Sandy, widely deployed microgrids may have helped cell service remain operational long after the grid went down.
Still, even microgrids may not survive powerful or widespread disasters. "We have to look at the capability of the infrastructure to withstand these events," McGranaghan says. During disasters, the smart grid's virtues may not be advantageous because the system is built atop the same, fragile grid as before. System hardening would change that, but like smart grid enhancements, it is not an inexpensive proposition. Fortunately, the smart grid can inform where engineers should focus on hardening the grid. "If we know we can use the smart grid to respond better, maybe that will influence those decisions," he says.
Note: We will be launching a new NOVA Lab on energy, renewables, and the smart grid in the coming weeks. Check the NOVA Labs site soon.