Florida Power & Light Co. (FPL) said it will replace two aging natural gas-fired generation plants with a solar-powered battery system that the utility claims will be the world's largest -- four times the capacity of the current largest solar-powered system.

FPL, which has been shifting from coal and oil to natural gas and solar for nearly two decades, said last week the Manatee Energy Storage Center will have 409 MW of capacity, the equivalent of about 100 million iPhone batteries. The facility is scheduled to begin operations in late 2021 and would be charged by an existing FPL solar power plant in Manatee County, FL.

The utility, a subsidiary of NextEra Energy Inc., said by deploying energy from the batteries when there is higher demand for electricity, it would offset the need to run more costly and polluting power plants, reducing emissions and saving customers money through avoided fuel costs.

FPL officials emphasized that the Manatee facility is part of "an innovative modernization plan" to accelerate the retirement of two, 1970s-era gas generating units at its neighboring power plant, and "replace them with clean and renewable energy."

Beyond Manatee County, FPL is also planning smaller battery installations across the state in conjunction with numerous solar power plants and efficiency upgrades to existing combustion turbines at other power plants to replace the 1,638 MW of generating capacity. The effort is expected to save customers more than $100 million and eliminate more than 1 million tons of carbon dioxide (CO2) emissions, FPL said.

Since 2001, the utility estimates that it has saved customers nearly $10 billion while eliminating more than 130 million tons of CO2 emissions. Part of the modernization program has involved replacing oil-burning plants with highly efficient energy centers that run on natural gas.

"Now, as the price of battery and solar technology continues to decline and FPL has learned how to optimize the technology to best serve customers, the company is taking an innovative approach to modernizing its fleet [again] and tearing down two aging gas-fired units that have dotted the Parrish skyline for nearly 50 years," an FPL spokesperson said.

The utility shut down two coal plants in Jacksonville in 2016 and 2018, respectively, collectively preventing nearly 7 million tons of CO2 emissions annually while saving customers tens of millions of dollars in fuel and operating costs.

According to a 10-year plan filed last year with the Florida Public Service Commission, FPL had 45 generating units at the end of 2017. Of those, 16 were combined-cycle units, nine were simple-cycle combustion turbines and five were photovoltaic facilities. FPL also had four nuclear units, four combustion gas turbines, four fossil steam units and three coal units at the end of 2017.