By the time that Hurricane Helene made its way hundreds of miles inland on September 27, it had been downgraded to a tropical storm. But Helene remained unusually expansive and strong, fueled by the warm waters in the Gulf of Mexico. The storm brought high winds and catastrophic flooding, knocking out power for more than 2 million Duke Energy customers in the Carolinas, and tearing through a region of the country that wasn’t widely seen as vulnerable to hurricane damage: the Mountain South. Asheville, North Carolina, the city hardest hit, had even appeared on lists of “climate havens” considered comparatively safe from the natural disasters whose impacts are intensified by global warming.
Over the course of the following week, more than 50,000 utility workers, with crews from 41 U.S. states and Canada, set about the heroic work to restore power. In some areas, they even transported power poles by helicopter where roads remained impassable. By Saturday, service had been restored to more than 90 percent of the customers who lost power. But some of the remaining outages may prove harder to repair, because they require the complete replacement of technically complex power infrastructure equipment. These repairs “will take potentially many weeks,” said Jeff Brooks, a Duke Energy spokesperson.
The unprecedented devastation has brought renewed attention to the problem of ensuring the resilience of America’s power grids in the face of climate change, and to the massive transformation that decarbonization, electrification, and a projected growth in electricity demand bring. Global shortages of crucial electrical equipment like transformers and circuit breakers don’t make that question any easier to figure out.
Electrical equipment and water don’t mix, so heavy flooding presents a serious threat to power grids that aren’t prepared for it. “There has been a dramatic miscalculation of risk factors here,” said Tyler Norris, a Duke University doctoral fellow and former special advisor at the Department of Energy. “So this event is going to have to prompt a wide range of new analysis on the vulnerability of various parts of the power system.”
Among the challenges that western North Carolina will face in rebuilding its grid are its geographic differences from the regions where various solutions have been tested. Norris described the region as “a mountainous area that still has a relatively decent population density.” In low-lying coastal areas that are more accustomed to hurricanes, for instance, some utility companies have begun moving power lines underground to avoid the problems that hurricane-force winds pose. But in Duke Energy’s service area, “you have this really far-flung set of distribution lines going up into the hills and serving different communities,” Norris continued.
Last week, an early report from North Carolina congressman Chuck Edwards claiming that 360 substations in North Carolina were “out” because of flooding caused a minor panic among grid experts, who worried that there simply weren’t enough transformers in reserve in the U.S. to rebuild that many substations.
Transformers are the pieces of electrical equipment required to shift an electric current from one voltage to another. They are needed at either end of a transmission line — the massive power lines that transmit electricity at a high voltage between power plants and the lower-voltage distribution lines that power homes and businesses. They are housed in substations, the junctions between the transmission and distribution systems.
It turns out that the crisis wasn’t so dire. Of the 360 substations that were reported down, most “were out because of damage to the transmission system that supplies them with power, not necessarily damage to all those substations,” said Brooks, the Duke Energy spokesperson. But even a handful of destroyed substations is no small matter. At least two sites, the utility has trucked in temporary “mobile substations” that will power nearby communities until the equipment can be repaired.
In normal times, said John Wilson, a vice president at the consulting firm Grid Strategies, it takes over a year to build a new substation from scratch, including drawing up a site-specific design and procuring the equipment. Rebuilding can be a significantly shorter process when the designs are already complete, and utilities keep some amount of equipment in reserve. But the depletion of those reserves would only add to the potential supply chain bottleneck for future crises.
Global demand for transformers is growing, in part because the transition to renewable energy will require many more sites of power generation than the old fossil fuel-powered system — and each new power plant requires its own equipment. With few manufacturers of transformers operating in the U.S., utilities must wait an average of 150 weeks for an order to arrive.
While it’s unclear whether the storm recovery will be directly impeded by the transformer shortage, it may breathe life into solutions that have been recently proposed. In September, the president’s National Infrastructure Advisory Council recommended that the federal government create a strategic reserve of transformers to bypass the industry’s long lead times. And in a report published in August, Grid Strategies recommended that utilities band together in a collective procurement organization — ideally with federal loan backing — to make large orders and share the costs. “That would help deal with the construction backlog; right now, manufacturers are hesitant to build new factories to build this equipment in the U.S. or North America because they aren’t confident that the market will be there,” said Wilson.
The reconstruction of the power grid in the areas of Appalachia where it was wrecked by Helene will ultimately offer a chance for the utility industry to rethink how the electricity system should be structured. “??In areas where there could be more extreme weather events like this, it’s going to be more and more difficult to maintain far-flung distribution systems,” Norris said. “And the cost of service is going to rise, and you either have to muddle through that or think about other measures, like undergrounding lines, or trying to bring load into higher degrees of concentration so it isn’t so far-flung, or, obviously, to think more about distributed energy systems and backup power.”
There are ways to build grid resilience that could be implemented on a more local level — although they’re costly. One is the concept of microgrids — local electric grids that are disconnected from the wider power system. Norris said this concept could be extended further by allowing individual homes and businesses to power themselves with rooftop solar when the grid is down. Most solar arrays aren’t configured to produce power when there isn’t a wider grid to feed them into, in order to protect the line workers repairing power lines from a live current. But this can be prevented by a technique called solar islanding, which effectively disconnects the solar array from the grid.
Last week, Duke Energy used one such microgrid, in the flooded resort town of Hot Springs, North Carolina, to keep the lights on downtown for days using only batteries and solar power. For towns like Hot Springs, microgrids could be much more than temporary patches.