ESS Tech launches 1.2-MWh sodium-ion battery ‘building block’ system

A company called ESS Tech has released a new large-scale battery system built with sodium instead of the lithium used in most batteries today. The system, called ESS Bridge, stores 1.2 megawatt-hours of energy and can be combined with other units to hold up to 4.8 megawatt-hours in a standard shipping-container-sized unit. It's aimed at utilities, businesses, and data centers rather than individual homes.

This isn't a home product, but it's part of a broader shift worth knowing about if you're weighing battery backup for your own house down the road. Sodium-ion batteries are drawing interest because sodium is cheap and widely available, unlike lithium supply chains that depend heavily on China. Sodium batteries are also less prone to overheating and catching fire, a problem that destroyed part of a large lithium battery facility in California last year. They can also run in a wider range of temperatures without needing the liquid cooling systems lithium batteries often require. The tradeoff is that sodium batteries are bulkier for the same amount of stored energy, since sodium is a heavier element than lithium.

Other companies, including Colorado-based Peak Energy, are making similar bets on sodium batteries, including a new manufacturing plant planned in Sacramento. As this technology scales up for grid and commercial use, it could eventually filter down into smaller residential battery products, though nothing like that has been announced yet.