Flatiron Energy closes $850 million in financing for 1,200 MWh Boston area battery project

A large battery storage project in Chelsea, Massachusetts, just got about $850 million in financing to move forward. The Energizar project, built by Flatiron Energy, will store 1,200 megawatt-hours of electricity, making it the largest standalone battery system on the East Coast and one of the biggest urban battery installations anywhere. It's set to start operating in the fourth quarter of 2027.

For homeowners in the Boston area, this means more backup capacity for the regional power grid. Battery storage like this helps utilities meet spikes in electricity demand without turning to fossil-fuel power plants, which can mean a more reliable grid and, over time, less reliance on dirtier energy sources during peak hours.

The financing itself is a complex mix of construction loans, equity investments, and a tax credit transfer, arranged by a group of banks and financial firms. None of this changes anything homeowners need to do right now, but it's a sign that large-scale battery storage is expanding in the region, which could support a grid that's better able to handle growing electricity demand, including from things like electric vehicles and electric heating. As more projects like this come online, they may factor into how stable and clean the power running to your house becomes in the coming years.