By 31 December, a half-dozen 1-megawatt lithium-ion batteries could be in place, helping to support Puerto Rico’s electric power grid, which was almost entirely destroyed by Hurricane Maria.
Independent power producer AES is working with the Puerto Rico Electric Power Authority (PREPA) to site and deploy the batteries. Most likely, says Chris Shelton, chief technology officer of the Virginia-based company, the batteries—which AES is donating—will support the still-fragile grid by enhancing both power quality and grid stability.
“We are not looking for commercial applications,” Shelton says. “We are focused on putting them to work to help.”
Storage batteries are gaining credibility as a reliable and rapidly deployable technology. A pair of crises thousands of miles apart illustrates how the technology can bolster grids when they face difficult challenges.
The first crisis struck in October 2015 when the Aliso Canyon natural gas storage facility in southern California began leaking. The accident shut the facility for months and threatened gas supplies to electric power generating facilities providing 10,000 megawatts of capacity to the region. Also at risk were dozens of industrial facilities and public buildings like schools and hospitals.
State regulators in May 2016 approved deployment of more than 100 MW of battery-based energy storage systems. Among the systems was the 20-MW/80 megawatt-hour (MWh) Mira Loma Battery Storage Facility, installed by Tesla in less than three months.
And at a utility substation in Escondido, Calif., a 30-MW, four-hour-duration lithium-ion Advancion battery array was installed by AES Energy Storage. At the time, it was one of the world’s largest such deployments.
The Aliso Canyon response showed that developers could design, build, and commission significant amounts of energy storage in a short amount of time. Installing an equal amount of natural gas-fired generation likely would have required years rather than months.
The second crisis occurred this past September, when Hurricane Irma buffeted the Dominican Republic. Just three months earlier, AES’s local business unit had installed a pair of 10-MW, 30-minute-duration battery energy storage arrays. As the Category 4 hurricane churned through the Caribbean toward the island, the grid operator asked AES to keep those units online for grid support.
“The grid moved all over the place” during Irma, says Shelton, and pushed the arrays beyond their normal operating range of +5 MW to -9.8 MW. For 12 hours, the operating range varied from +9.8 MW to -10 MW as the batteries provided rapid support.
But no battery can prevent the kind of devastation that Puerto Rico suffered when Maria hit two weeks after Irma. PREPA reported that around 1.57 million customers—fully 100 percent of the island—lost power. By contrast, Irma knocked out power to around 1 million customers, most of whom had their service restored by the time Maria struck.
Hurricane Maria did more than knock down power lines: it destroyed the island’s transmission backbone, which connected power plants along the island’s south side with load centers on the north.
Shelton says that AES’s power generating assets rode out the storm well. That included a 524-MW circulating fluidized bed boiler power plant and a 24-MW solar photovoltaic installation.
“We built the solar farm to withstand a Category 4 storm,” says Shelton. The array’s reinforced structure helped it emerge 90 percent intact. By contrast, a 5-MW solar facility on the Virgin Islands (an AES acquisition) sustained “material damage,” according to the company in early October.
From Holy Grail to Viable Option
What seems clear from these two crises is that energy storage—long considered the holy grail of electric power—is emerging as a viable option for utilities that need to strengthen and modernize their grid. And storm response isn’t the only application. The technology can support large amounts of energy from intermittent renewable generating resources like wind and solar.
For example, rather than rebuild more than 30 kilometers of transmission and distribution poles and wires, Arizona Public Service (APS) is installing two 4-MWh Advancion battery storage systems from AES. The investment makes APS one of the first U.S. utilities to install batteries in place of traditional infrastructure.
Meanwhile, Florida Power & Light plans to add 30 MW of battery storage alongside a 160-MW solar farm. The project would be among the largest in the United States to combine solar with energy storage. The Florida utility says the combination approaches what a fossil-fueled power plant might deliver.
“Putting solar together with a battery allows you to have a resilient system,” Shelton says.
And just as the price of solar energy has dropped over the past decade—for example, a mid-November auction in Mexico for new generating capacity resulted in prices that approached $20/MWh—so, too, has the price of storage. It has fallen by as much as 80 percent since 2010.
“There’s a psychological trap” when it comes to thinking of energy storage as prohibitively expensive, Shelton says. Its downward price trajectory is a “function of how innovation works.”
Innovation, coupled with the industry’s ability to rapidly deploy capacity in times of crisis, may position battery energy storage to deliver its full potential.