Microgrids, Storage Could Make Puerto Rico Grid More Resilient

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By Rebecca Kern

The Energy Department is looking into how microgrids and energy storage could transform Puerto Rico’s electric grid to make it more resilient to hurricanes.

But first the island has to have its electric grid up and running. Hurricane Maria almost completely wiped it out on Sept. 20, and only about 65 percent of the generation is back online. The Energy Department has been working with other agencies and Puerto Rico to restore power, but also is collaborating on plans for more long-range grid improvements.

Bruce Walker, the new head of the Energy Department’s Office of Electricity Delivery and Energy Reliability, went to Puerto Rico a few days after he was sworn in on Oct. 16 to work there for several weeks.

Walker said he has met with Energy Department research and development personnel “to look at a number of opportunities that we have in storage technologies to find what we could actually take and put into [the Puerto Rico Electric Power Authority’s] system in a prioritized way.”

“We’re trying to make it more resilient and look at where the real opportunities are,” he added.

Soot-covered rocks sit on a beach near the Puerto Rico Electric Power Authority (PREPA) Palo Seco plant in Palo Seco, Toa Baja, Puerto Rico, on Saturday, Oct. 21, 2017.
Photographer: Xavier Garcia/Bloomberg
Potential for Microgrids

Walker said microgrids would make it easier for Puerto Rico to recover after another hurricane.

“There are industrial corridors where putting a microgrid might make sense,” he said. The Energy Department has identified these places in the northern part of the island, where 70 percent of the electricity demand is located. The areas include facilities such as water treatment plants and hospitals.

Microgrids involve electricity generators and possibly energy storage systems interconnected to a distribution network that supplies electricity to a localized group of customers. Having the generation sources close to demand centers means they don’t have to rely on a transmission system that can be vulnerable to hurricanes and other natural disasters. The department has identified 200 potential locations for microgrids on the island near key industrial centers and hospitals.

“You can coordinate those microgrids so that collectively they best serve the emergency response needs in that area,” said Carl Imhoff, manager of the electric infrastructure market sector of Pacific Northwest National Laboratory. Imhoff has been working with DOE headquarters on plans for Puerto Rico’s future grid.

He also is the chair of the Grid Modernization Laboratory Consortium of 13 national labs that was formed in 2014 to help the Energy Department create an integrated grid strategy across the country.

Workers repair power lines in Puerto Rico.
Photographer: Xavier Garcia/Bloomberg

Walker is coordinating a plan for the future of Puerto Rico’s electric grid with the Grid Modernization Laboratory Consortium, the New York Power Authority, the office of Puerto Rico Governor Ricardo Rossello, the Federal Emergency Management Agency and the Financial Oversight and Management Board for Puerto Rico, which was created by Congress to help the territory recover from its $74 billion debt.

He said all of the groups are working on individual plans and will meet in December to select the best ones.

Then Congress must decide whether to provide funds for any improvements.

“If it doesn’t get funded, then we still have a plan to hand to the Puerto Rico Energy Commission as a road map for them to move forward,” Walker said.

Walker knows a thing or two about electric grid emergency restoration and planning. He has spent his entire career working in the electric utility space, including 18 years at Consolidated Edison Inc., New York City’s investor-owned utility company, eventually becoming director of corporate emergency management.

ConEd is part of a contingent of U.S. utilities that have sent crews to help with electricity recovery along with PREPA—the island’s power authority—and Army Corps of Engineers contractors. The Corps estimates 95 percent of electric grid will be restored by the end of February.

For now, the DOE and Army Corps of Engineers have installed about 750 diesel generators totaling 200 megawatts mostly in the northern part of the island, where 70 percent of electricity demand is located near San Juan. The temporary generators are necessary because the majority of the older generation sources, such as natural gas and coal plants, are located on the southern end of the island, and the transmission lines connecting the north and south were largely destroyed.

Planning Grid of the Future

Walker also said DOE and the Army Corps are evaluating how to build new renewable generation resources, such as solar and wind facilities, on the island.

Currently only 2 percent of the island’s electricity comes from renewables, half of that coming from two wind farms. Otherwise, the island relies on oil for 47 percent of its power, liquefied natural gas for 34 percent, and coal imports for 17 percent, according to the Energy Information Administration.

Walker said they’re doing analysis on how to rebuild solar and wind farms where they won’t be destroyed by future hurricanes.

“So we’re not wed to any particular one [generation source], just looking at the possibility of making it more resilient,” he said.

Additionally, the Energy Department is working with the National Oceanic and Atmospheric Administration and the National Hurricane Center to use wind and tsunami studies to make sure electricity towers don’t get rebuilt on flood plains.

The timeline of when more renewables will be integrated into the grid will depend on the U.S. federal government, the Puerto Rico government, and PREPA all coming on board.

“The regulatory and financial framework that’s in place makes it near impossible to do this in a drastic shift on a dime,” Morten Lund, an energy attorney at Stoel Rives LLP in San Diego, told Bloomberg Environment.

“Physically there are not obstacles, but there are structural obstacles: societal, financial, and regulatory,” he said. “Our whole system is set up to make change difficult, and this would be a big change really fast.”

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