A look at why an island-wide blackout hit Puerto Rico and what caused it

SAN JUAN, Puerto Rico — An island-wide blackout hit Puerto Rico this week, leaving 1.4 million customers without power and more than 400,000 without water.

It was the second massive outage to hit Puerto Rico since New Year's Eve, when a blackout left 90% of clients without power.

Crews on Thursday scrambled to restore power as a growing number of Puerto Ricans called on the governor to cancel the contracts of two companies that oversee the generation, transmission and distribution of power on the U.S. territory of 3.2 million residents.

When did the blackout start?

At 12:38 p.m. on Wednesday, massive generating plants began to shut down across Puerto Rico after a transmission line failed. Refrigerators stopped humming, air conditioners fell silent and traffic lights went dark.

People started realizing the magnitude of the outage when they began calling friends and family that live on the other side of the island who said that they, too, were without power.

Hundreds of businesses closed, including the biggest mall in the Caribbean. Hospitals and the main international airport began running on generators while dozens of passengers using a rapid transit system that serves the capital, San Juan, were forced to walk on an overpass next to the train's rails to evacuate.

Incredulous, Puerto Ricans began demanding answers from the government as crews scrambled to find out what happened. ''When are we going to do something?'' reggaeton superstar Bad Bunny wrote on X, reflecting people's collective outrage.

Anger grew as people began posting pictures of those affected by the blackout, including one of a woman who had plugged a small machine into the outlet of a grocery store to give herself medical treatment for a lung condition.

Why did it happen?

Authorities are still investigating the causes of the blackout, which could include whether several breakers failed to open or exploded. González said.

Another possibility is that overgrown vegetation may have affected the grid and caused a transmission line to fail, officials said.

Luma Energy, the company responsible for overseeing transmission and distribution of power in Puerto Rico, is supposed to do frequent air patrols over certain lines to ensure they remain free of vegetation.

Pedro Meléndez, a Luma engineer, said at a news conference Thursday that the line where the failure occurred was inspected last week as part of regular air patrols to check on more than 2,500 miles of transmission lines across the island.

''No imminent risk was identified,'' he said.

Josué Colón, the island's energy czar and former executive director of Puerto Rico's Electric Power Authority, said Luma also needs to explain why all the generators shut down after there was a failure in the transmission system, when only one was supposed to go into protective mode.

It will likely take weeks to find a precise reason for the blackout, although Gov. Jenniffer González said on Thursday that she expects to have a very preliminary report within three days.

Officials also warned of potential setbacks. On Thursday afternoon, a power plant failed twice, leaving 200,000 clients without power again.

Why is Puerto Rico's power grid in such bad shape?

For decades, Puerto Rico's Electric Power Authority did not carry out the maintenance and investments the grid required.

It began crumbling over the years, and then on Sept. 20, 2017, Hurricane Maria hit the U.S. territory as a powerful Category 4 storm. It snapped power lines, toppled transmission towers and broke flimsy wooden light posts, leaving some people without power for nearly a year.

In the months that followed, crews focused on emergency repairs. It wasn't until a couple years after the hurricane that actual reconstruction began.

In June 2021, the Electric Power Authority contracted Luma as it struggled to restructure its more than $9 billion debt, with negotiations still ongoing.

In January 2023, the authority contracted Genera PR to oversee power generation on the island as part of another public-private partnership.

Puerto Rico has been plagued by chronic power outages since Maria, with photographs and videos of transmission lines on fire becoming increasingly common.

González has said that providing consistent energy is a priority and distanced herself from renewable energy goals set by the previous governor. Her administration recently extended the operations of Puerto Rico's lone coal-fired plant.

Meanwhile, with a poverty rate exceeding 40%, many on the island cannot afford solar panels or generators.

Roughly 117,000 homes and businesses on the island have solar rooftops. Petroleum-fired power plants provide 62% of Puerto Rico's power, natural gas 24%, coal 8% and renewables 7%, according to the U.S. Energy Information Administration.

What are officials doing to improve the grid?

A growing number of Puerto Ricans have demanded that the governor cancel Luma's contract, and she has pledged to do so.

''People must be fed up with us having such a mediocre system. If it's not the transmission, it's the generation,'' González said. ''Of course there will be consequences.''

However, she noted that canceling the contract and finding a new company takes time.

Officials also previously warned that there would not be sufficient power generation come summer, when demand peaks.

Given that concern, González said the government is seeking to contract a company that can provide more than 800 megawatts of energy in the upcoming months. The request-for-proposal process began on March 25 and ends this month. Sixty companies have submitted proposals.

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