Three monster storms in just the last month have pummeled the United States and Puerto Rico, killing more than 100 people, destroying thousands of homes and inflicting economic losses in the hundreds of billions.

Predictably, millions of homes lost power. All of Puerto Rico is in the dark following Hurricane Maria. Not even half of Florida residents had power after Hurricane Irma. In Texas, Hurricane Harvey took 10,000 MW offline.

For all the talk of grid hardening and resiliency, keeping the lights on in a major hurricane — Category 3, 4 or 5 — may just be impossible. The triple-digit wind speeds are more than most infrastructure can handle, and debris and flooding are lethal for an electric grid. But utility efforts are paying dividends — on the recovery side.

Focus on recovery

"Really, what you're seeing from storm hardening investment isn't stopping outages entirely. Anyone who saw the sheer magnitude of Irma, the size, scale and intensity of a storm hitting every county in Florida, knows you simply can't invest enough to stop a blackout," said Scott Aaronson, who leads Edison Electric Institute's security and business continuity team.

Leaving aside areas where major damage has been done, recovery efforts have been significantly sped up compared with past storms. Part of that is massive restoration crews marshaled for the clean up: Florida Power & Light at one point had 28,000 linemen in the state, working on recovery after Irma. But system improvements, automation and grid hardening, are all also coming to bear.

"It's what we said all along about the investments in infrastructure: it is not that they will prevent outages, but they help us restore faster," said Peter Robbins, a spokesman for the utility.

The largest utility in the Sunshine State, FPL clocked about 5 million customer outages following Irma. That's significantly more than it faced after Hurricane Wilma, just over a decade ago.

But according to the U.S. Energy Information Administration, recovery has been faster. The agency said five days after Irma’s landfall, the share of customers without power had fallen from a peak of 64% to 18%, a recovery rate of about 9% of customers per day. Power outages during Wilma declined from 36% of customers to 16% by the fifth day after landfall, an average recovery rate of about 4% of customers per day.

System hardening

About 40% of the Florida Power & Light system has been hardened, with traditional wooden utility poles replaced by either a composite or concrete and some power lines buried underground. In addition, flood monitoring equipment has been installed in substations, allowing them to be de-energized as waters rise, avoiding ruining equipment.

"The flood monitoring can give us the ability to proactively de-energize some equipment. Electricity and water don't mix," said Robbins. The stations then need to be only reconnected and re-energized after the storm, rather than FPL having to replace ruined electrical components. "We can bring it back online much faster after the storm."

In Hurricane Wilma, FPL had about 12,000 utility poles damaged. Assessments are still ongoing, but Robbins said the number is significantly lower following Irma, possibly a 90% reduction.

"The grid hardening has definitely paid dividends," said Robbins.

Flood monitoring and hardening of utility poles are two of the biggest system improvements that utilities have made, Aaronson agreed.

He also touted the benefits of de-energizing substations as floodwaters rise while noting that "it's a lot easier to restring lines than to reset a utility pole. It all makes for a much more efficient restoration process."

Opportunity in Puerto Rico

Puerto Rico was devastated by Hurricane Maria — it could be months before some residents get power. Its system was already weakened by Hurricane Irma, but Maria's direct hit this week means the grid will need to be rebuilt. 

Now, a week after Maria hit the island, electricity still remains out for most of the territory. Reuters on Monday reported 80% of the island's power lines are down, and the island is on the brink of a humanitarian crisis.

“The situation in Puerto Rico in the wake of this hurricane is horrible," said Tom Sanzillo, finance director at the Institute for Energy Economics and Financial Analysis. But "attached to it is an opportunity to rebuild for a better future,"  he added.

Puerto Rico is now largely reliant on oil and gas for electricity generation, but Sanzillo said that if it maintains that mix "it will be to the hindrance of its economy." Acccording to the U.S. Energy Information Administration, last year almost half of Puerto Rico’s electricity came from petroleum, more than a third from natural gas, and 17% from coal. Just 2% came from renewable energy.  

Modernization has been difficult, as the utility has struggled to manage billions in debt.

"A far more sensible approach — and one that will help the commonwealth recover from its broader financial and fiscal problems while modernizing its costly and outdated electricity system — would be for Puerto Rico to embrace the potential in its abundant solar resources," said Sanzillo. "Solar energy is cheaper and more resilient. It is a natural fit for a sunny island, and it offers a level of energy security to the commonwealth that it has historically lacked.”

Distributed resources no panacea 

"Hardening the grid is important, but we need to do much more than that," said Steve Clemmer, director of energy research for the Union of Concerned Scientists.

Beyond stronger poles and flood monitoring, Clemmer said states need policies that will help reduce emissions and the impacts of climate change. And investments need to do double-duty, providing returns not just in the event of a storm.

"We also need to invest in clean energy solutions and microgrids that not only protect communities when the centralized grid goes down, but also helps reduce global warming emissions from the electric system," Clemmer said. "It's critical that we protect critical infrastructure and vulnerable populations so they're not left in the dark when these storm hit."

Clemmer said many states have undertaken grid hardening efforts, particularly in the wake of large disruptive storms. Florida’s SunSmart E-Shelters Program supported the installation of solar+storage systems at schools, allowing them to act as emergency shelters. Massachusetts' Community Clean Energy Resiliency Initiative and New Jersey’s Renewable Electric Storage Initiative are both looking to better support critical resources. Following Hurricane Sandy in 2012, the New York State Public Service Commission directed Consolidated Edison to study its system's vulnerability to climate change.

"A lot of these technologies, processes or solutions, were developed following previous storms," said Aaronson. "The storm that was perhaps best teacher, in recent memory, was Sandy. And a lot of things you're seeing from a grid hardening perspective were investments made not long after the devastation from that storm."

But microgrids, particularly solar generation linked with storage, are unlikely to be a quick fix for areas most significantly impacted by storms. Clemmer said their value will more likely show up in areas with standalone microgrids that are developed alongside the traditional grid.

"In areas that are directly hit by these storms, where there is a lot of devastation and buildings destroyed, it's unlikely you'll be able to provide power to those places," Clemmer said. "But where they will be beneficial is in areas affected by the outages that are nearby — not sustaining as much damage, but because the broader grid is down these systems can provide a lot of value."

Customers seek backup diesel

One solution many customers look to, from residential to industrial and large commercial users, is backup diesel generation. But Clemmer said during Sandy, those systems had failure rates in excess of 50%, the units can face fuel supply issues, and they're polluting. 

That was the case on Ocracoke Island over the summer, where a 3 MW diesel generator that is part of the community's microgrid failed during an outage.

"Microgrids also provide value when there is not an emergency," Clemmer said. "Solar PV provides value year-round, even when there is not a catastrophic event. Diesel generators are typically just used when there is an emergency."

But Aaronson cautioned that distributed resources alone would not provide a solution to storm outages.

"A lot of those distributed resources are held up to be some sort of panacea ... I'd caution that distributed resources play a part in resilience, but by themselves are not inherently resilient," he said.

Utilities in Georgia and Florida brought a combined workforce of 60,000 to restore power to almost 8 million customers, he noted.

"You see the value of the grid itself, as a backbone for all of these other technologies," said Aaronson. "And then if you layer some of these technologies, whether its storage or distributed generation or microgrids, you then see their value to supporting the broader ecosystem. But they are not a panacea in their own right."