Tesla’s Powerwall and other home batteries are part of a bigger movement

It seems as though everyone is talking about electric vehicle batteries lately. Automakers are racing to make these batteries more powerful so they can convince more people to buy EVs, and the Biden administration is spending billions to make the United States a manufacturing hub for next-generation battery technology. But even as EV batteries soak up the spotlight, another kind of battery is gaining momentum: home batteries.

The concept of a home battery is simple. In the same way that a laptop battery powers a laptop when it’s not plugged into an outlet, a home battery powers a home when it’s not receiving power from the grid or a renewable energy source. Hundreds of thousands of people have already installed Tesla Powerwalls, solar-powered home battery packs that provide a few hours of backup power. And as extreme weather events, like last year’s devastating winter storm in Texas, have stretched the power grid to its limits, even more consumers have started buying these and other types of home batteries.

The government is throwing its support behind similar kinds of upgrades to the power grid. On Tuesday, the Energy Department said that it would spend more than $3 billion from the Bipartisan Infrastructure Law on EV batteries as well as batteries meant for long-term energy storage, including batteries that could one day power people’s homes and businesses. This money will fund projects focused on boosting the US’s supply of key battery components, as well as developing the country’s overall battery manufacturing capacity. The hope is that these investments will help the US build more batteries that could then be installed not only in people’s homes but also in neighborhoods and throughout the grid, playing a critical role in easing the growing pressure on the country’s aging energy infrastructure — and making it more resilient.

“We have to build clean homes and start with clean homes that are fully electrified, which use batteries to stabilize their load and be part of a clean grid,” Ryan Brown, the CEO of the small battery startup Salient, told Recode. “Otherwise, there’s just not a really good prospect for solving climate change.”

This week, Salient announced a partnership with a Texas-based sustainable homebuilder, Horton World Solutions, to demonstrate its new zinc-ion battery technology. If all goes according to plan, the companies will install these batteries in more than 200,000 homes over the next decade.

Home batteries vary in size and energy storage capacity, and while many are based on familiar lithium-ion technology, some take advantage of being stationary to use more abundant materials, like zinc. Each battery — some people install multiple for more storage — is usually about as big as a television and typically costs at least a few thousand dollars. Beyond Tesla, there are a few large electronics companies like LG Chem and Panasonic — both of which are in the EV battery business — that sell home battery packs, as well as lesser-known battery makers like Salient, Generac, and Enphase.

Bigger batteries or large battery banks could power many homes simultaneously. While these giant battery systems wouldn’t fit into a single residential building, they could be connected directly to the power grid or to microgrids that power an entire apartment building or neighborhood. Compared to a home battery in a single-family home, this sort of setup would allow entire communities of people to access electricity when power is unavailable or extra-expensive — this is why some experts say they’re a much more equitable approach to the future of energy.

Regardless of their scale, home batteries and other types of stationary batteries have become a critical part of the effort to increase the world’s supply of renewable energy in the fight against climate change. The reason is straightforward: Because the sun isn’t always around to power solar panels and there isn’t always wind to power turbines, utility companies and individuals alike need batteries to store their renewable energy to ensure that it’s available when people actually need it. Stationary batteries ultimately expand the overall capacity of the grid, which is especially important as we move to electrify things that are currently powered by fossil fuels.

“We also see potential increased adoption of electric vehicles and even heat pumps for replacing gas furnaces,” Dharik Mallapragada, a research scientist at MIT’s Energy Initiative, told Recode. “Batteries can come in handy there because they can basically shift consumption … in terms of how much you’re drawing from the grid.”

In addition to his administration’s latest investment in battery technology, President Joe Biden in March used the Defense Production Act to order production of critical materials needed for stationary storage, which he called “essential to the national defense.” Some state governments, along with utilities, have also started offering financial incentives for people to buy home batteries as well as commercial battery banks. California has even updated its state energy code to require that all new commercial and high-rise multifamily buildings install batteries, as well as solar panels.

“Within the next few years, everybody will realize that they will need a battery,” Jehu Garcia, a battery reseller who runs a DIY YouTube channel about batteries, told Recode. “Right now it’s kind of up for grabs: Who’s gonna make the move first? Is it going to be the homeowners, or is it going to be the utilities? But it’s going to happen either way.”

Even the EV industry is investing in the stationary battery business. In addition to offering its Powerwall batteries to individuals, Tesla recently finished building one of the world’s largest batteries for PG&E in Northern California, and has also started work on another utility-scale battery outside Houston that could power 20,000 homes. CATL, a Chinese company that’s arguably the world’s largest EV battery manufacturer, last month announced plans to produce 900 battery systems for a Texas-based renewable energy company that will support the state’s beleaguered power grid. Meanwhile, GM is designing its Ultium batteries so that they could eventually be repurposed to provide long-term energy storage, and Nissan announced earlier this year that it would test a similar idea using its EV batteries at a power plant in Spain.

All this represents progress, but it also serves as a reminder that we may need all the batteries we can get. The International Energy Association estimates that in order to reach net zero carbon emissions by 2050, the world will need to boost the world’s battery storage capacity from the 17 gigawatts we had in 2020 to 585 gigawatts by the end of the decade. That means that batteries may need to be ubiquitous — inside people’s cars, in the basement of apartment buildings, and on site at power plants. As intimidating as this task seems, it’s just one piece of the very complicated puzzle of figuring out how to combat climate change.

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