A nine-month, $3.8-billion effort to end the longest blackout in U.S. history has restored power to much of Puerto Rico. Unfortunately though, this year’s Atlantic hurricane season is underway and the still-fragile electrical grid is unlikely to fare any better when the next major storm hits.

As Puerto Rico’s government and state-owned utility company consider their options for a major redesign of the grid’s power generation, transmission and distribution systems over the next decade, many residents see neighborhood microgrids powered by renewable energy sources as their best option for weathering storms in the more immediate future.

Hurricanes Irma and Maria taught Puerto Ricans the importance of energy self-sufficiency when the storms swept across the island last September, leveling a power grid made especially vulnerable by years of neglect. Some of that neglect was the result of Puerto Rico’s massive debt, which prevented equipment maintenance and upgrades. In an attempt to work around its financial woes, its government passed a law on June 20 allowing private companies to own and operate generating stations on the island. Puerto Rico Gov. Ricardo Rosselló claims this move will improve service and promote the use of renewable energy and microgrids. The Puerto Rico Electric Power Authority (PREPA)—responsible for $9 billion of the island’s $72-billion overall public debt—will continue to own the transmission and distribution network, although that might likewise be privatized in the near future.

The Puerto Rico Energy Commission also took a major step toward enabling a degree of island-wide energy independence in May when it adopted a regulation (pdf) allowing homes and small businesses to build microgrids that can deliver electricity, even when the main grid stops working. Homes and residential buildings can now install solar panels to collect energy, batteries to store it—and networks to share that power with neighbors when necessary. “Prior to that law, microgrids were not recognized as a way to legitimately get your energy,” says Agustín Irizarry Rivera, an electrical engineering professor at the University of Puerto Rico–Mayagüez.

Micromanaging Island Energy

Residents throughout the island had already been installing solar panels and batteries over the past several years to cope with the grid’s lack of reliability. “Hurricane Maria really made us think about what’s essential to survive and to have a good life,” says Marcel Castro Sitiriche, another University of Puerto Rico–Mayagüez electrical engineering professor. Many households can survive well on two kilowatts (kW) of generated energy and about 10 kW hours (kWh) of energy stored in a battery, according to Castro Sitiriche. That is enough power to run a small refrigerator and necessary medical devices, to use a washing machine once a day—assuming there is water—and keep cell phones charged. A setup capable of doing all of that, he adds, would require at least six rooftop solar panels and cost about $7,000.

Given Puerto Rico’s average annual income is less than $20,000, “the government would have to offer families a way to finance the equipment through a cooperative, bank or other financial institutions,” Castro Sitiriche says. Until a good form of financing becomes available, a realistic goal might be for one in five houses in a neighborhood to have solar panels and a battery. At the very least that would allow residents to pool their finances to keep medicine refrigerated and medical devices running—an arrangement that likely would have reduced the number of storm-related deaths in the months following Irma and Maria, he says.

The Casa Pueblo environmental watchdog organization based in Adjuntas, a small mountainside town about 120 kilometers southwest of the capital, San Juan, offers a glimpse of what microgrid-based self-sufficiency might look like. The group has retrofitted 10 homes with photovoltaic panels. Since Hurricane Maria, Casa Pueblo members have also distributed 54 small, solar-powered refrigerators to people requiring temperature-controlled medications. The University of Michigan’s Graham Sustainability Institute in May recognized the watchdog’s work, awarding $200,000 to a joint sustainability research project with Casa Pueblo. The project will, among other things, design and build four microgrids that get electricity from a combination of biomass gasification (using food waste) and solar power. “The main idea of the gasification units is to supplement some of the solar panels Casa Pueblo had already established to provide limited power,” says Ivette Perfecto, the University of Michigan environment and sustainability professor leading the project that also involves several University of Puerto Rico researchers. “There are going to be more hurricanes. You have to build a resilient system.”

As more communities have begun working together to install renewable energy equipment, Irizarry Rivera says he and his University of Puerto Rico colleagues have been hosting workshops to train local electricians in installing solar panels and batteries. “We get a lot of requests from people who want more information on setting up their own solar panels, and they have very specific questions that suggest they are very serious about using the technology,” says Irizarry Rivera, who first installed a solar panel on his own home in 2009 and has since added battery storage.

Grid Upgrades

Regardless of how many residents adopt microgrids and other renewable energy systems, Puerto Rico’s manufacturing companies will always need the main grid because they cannot afford to have intermittent power, says José Antonio Santiváñez, a professor of industrial management engineering at the island’s University of Turabo. Manufacturing—of pharmaceuticals and medical devices, in particular—is one of the largest contributors to the local economy.

Most major manufacturing plants are in the northeastern part of the island, yet much of the grid’s generating power is in its south—an area highly vulnerable to hurricanes (pdf). The transmission lines connecting these regions traverse mountainous terrain and thick vegetation, and are subject to high winds and torrential rains. Few of the lines were designed to survive a category 4 hurricane (Maria was category 5), and repairs funded by the U.S. Federal Emergency Management Agency (FEMA) are limited by law to restoring the grid as it was before the storm. There has already been cause to question the repaired grid’s resilience—it experienced two major blackouts in April alone.

Several research groups are investigating how smart-grid software—which enables utilities to dynamically adjust power generation, transmission and distribution based on customers’ energy needs—might help PREPA. The software would also enable PREPA to remotely diagnose grid problems, bid for prices in energy markets and forecast energy consumption. The New York State Smart Grid Consortium is working with PREPA and Atlanta-based software start-up ProsumerGrid to create a program that can simulate how generating systems distributed throughout the island can share the main grid with community microgrids, and with individual households that generate their own energy using solar panels. ProsumerGrid is funded by the U.S. Department of Energy’s Advanced Research Projects Agency–Energy (ARPA–E).


PREPA, Puerto Rico’s sole provider of electricity services, currently owns six fossil fuel and seven hydroelectric generation sites that provide most of the island’s power. Over the next few months legislators will decide how the energy commission will sell off those assets. Some see privatization as a way to move away from petroleum, natural gas and coal—which account for 98 percent of the electricity generated. The government says its goal is to eventually get 30 percent of the island’s energy from renewable sources. The governor’s privatization decision “points Puerto Rico in the right direction toward building a modern, resilient grid,” Santiváñez says. “If the island rebuilds the grid the same as before, people living here can expect the same results in terms of service, maintenance and storm recovery.”

Still, others question whether privatizing generation will improve service as promised. “Simply handing a responsibility over to the private sector doesn’t inherently mean service will improve,” Irizarry Rivera says. “Puerto Rico wants to sell the responsibility for electrical service to private companies, but the government has no experience regulating electric service providers, and they don’t have an appetite to strengthen regulations.” Another concern is the impact privatization will have on the cost of electricity for residents. Fossil fuel–derived energy on Puerto Rico costs about 24 cents per kWh for residential customers—about twice what households pay in the mainland U.S. “There’s no reason homes should be using oil, gas or coal in Puerto Rico in the future, especially when the cost of solar panels and batteries here is approaching grid parity with fossil fuels,” he says. It remains to be seen whether the companies that buy up parts of the grid will feel the same way and offer more energy from renewable sources.

Hurricane season is one of the few constants as Puerto Rico plans the largest overhaul of its grid since PREPA was formed in 1941. Fortunately, the most recent forecasts predict this year will be less active than normal, with only one major hurricane of category 3 or higher expected—a welcome reprieve for an island of 3.3 million people considering their energy options after months of darkness.