The tricky thing about generating electricity is that for the most part, you pretty much have to use it or lose it.

This fundamental fact has governed and constrained the development of the world’s largest machine: the $2 trillion US power grid. Massive generators send electrons along a continent-wide network of conductors, transformers, cables, and wires into millions of homes and businesses, delicately balancing supply and demand so that every light switch, computer, television, stove, and charging cable will turn on 99.95 percent of the time.

Making sure there are always enough generators spooled up to send electricity to every single power outlet in the country requires precise coordination. And while the amount of electricity actually used can swing drastically throughout the day and year, the grid is built to meet the brief periods of peak demand, like the hot summer days when air conditioning use can double average electricity consumption. Imagine building a 30-lane highway to make sure no driver ever has to tap their brakes. That’s effectively what those who design and run the grid have had to do.

But what if you could just hold onto electricity for a bit and save it for later? You wouldn’t have to overbuild the grid or spend so much effort keeping power generation in equilibrium with users. You could smooth over the drawbacks of intermittent power sources that don’t emit carbon dioxide, like wind and solar. You could have easy local backup power in emergencies when transmission lines are damaged. You may not even need a giant, centralized power grid at all.

That’s the promise of grid-scale energy storage. And while the US has actually been using a crude form of energy storage called pumped hydroelectric power storage for decades, the country is now experiencing a gargantuan surge in energy storage capacity, this time from a technology that most of us are carrying around in our pockets: lithium-ion batteries. Between 2021 and 2024, grid battery capacity increased fivefold. In 2024, the US installed 12.3 gigawatts of energy storage. This year, new grid battery installations are on track to almost double compared to last year. Battery storage capacity now exceeds pumped hydro capacity, totaling more than 26 gigawatts.

There’s still plenty of room to expand — and a pressing need to do so. The power sector remains the second-largest source of greenhouse gas emissions in the US, and there will be no way to add enough intermittent clean energy to sufficiently decarbonize the grid without cheap and plentiful storage.

The aging US grid is also in dire need of upgrades, and batteries can cushion the shock of adding gigawatts of wind and solar while buying some time to perform more extensive renovations. Some power markets are finally starting to understand all the services batteries can provide — frequency regulation, peak shaving, demand response — creating new lines of business. Batteries are also a key tool in building smaller, localized versions of the power grid. These microgrids can power remote communities with reliable power and one day shift the entire power grid into a more decentralized system that can better withstand disruptions like extreme weather.

If we can get it right, true grid-scale battery storage won’t just be an enabler of clean energy, but a way to upgrade the power system for a new era.

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