You’ve heard of privacy concerns.
Now think about what those concerns might be for a home battery that’s storing a large amount of energy.
The energy stored in batteries is usually kept within a certain volume.
But how much of that energy can be stored safely and safely stored?
That’s a tricky question, and not just because battery companies and the utilities they supply are competing for a portion of the market.
For years, a team of engineers from the National Renewable Energy Laboratory (NREL) has been working on ways to figure out how much energy batteries can safely store.
It’s called energy storage with large volumes of energy, or ESMET.
And the results are coming fast and furious.
“We have now a lot of different batteries, with different volumes, that have different energy storage capabilities,” says Andrew Ellington, the NREL’s director of energy storage.
“There’s a range of different types of batteries and different capacities.”
There are several different kinds of batteries, including the lithium ion, lithium polymer, and nickel-hydroxide batteries.
These batteries have varying storage capacities, with the largest capacity being around 250 kWh.
That’s about one-fifth of what a battery can store for a typical home.
But they’re all made from materials that are both expensive and scarce.
And those materials tend to be made in different places.
For example, the lithium polymer batteries used in home batteries are made in China, but the lithium-ion batteries made by the batteries used by electric cars are made elsewhere.
And that means batteries that are designed for use in homes are not necessarily the same batteries used to make batteries in cars.
So, while a home batteries company might be able to make a battery with the same capacity and range as one made for use on the road, they might not be able make a cell with the exact same capacity.
“The reason we have different capacities is because the materials used for those cells are more expensive, and they are limited in their design,” Ellingon says.
So how much storage is appropriate for a single-family home?
To answer that question, Ellingson says the NREL is developing a battery technology that uses materials that can store up to 250 kWh per battery, which is similar to what batteries used on electric vehicles do.
“If we have a 250 kWh cell, and the cell is made of materials that cost less than that, that would be a very reasonable battery,” he says.
But if that 250 kWh is being used in a car, the battery would need to be designed to store that much energy.
That could be expensive and time consuming, and Ellingons lab is looking at a variety of options for how that can be done.
One idea is to use “self-powered batteries,” which use a computer-controlled circuit to charge a battery and then discharge it when the battery is not needed.
Ellingtons lab has already designed a self-powered battery that has a maximum capacity of 250 kWh, but that’s only possible if the cells are designed to use energy from solar panels on the roof.
“I think a self powered battery is a good idea,” he notes.
But there’s a catch.
“Self-powered cells don’t always work well for homes,” Elledons notes.
“So there’s always going to be some tradeoffs between what you can do with the energy storage you can put into a cell and what the energy you can store with that cell is,” he explains.
So while it’s an important area of research, it’s not without its challenges.
Elleds lab has not yet worked out how to make these self-driven batteries commercially viable.
“It’s going to take a lot more work,” he admits.
Still, it might be worth trying, even if you’re not convinced that a self driven cell is the way to go.
“As long as the energy we’re storing is in the battery, and we can get the battery to work reliably, then it’s probably not a bad idea,” Ellerton says.
“We’re not there yet.
But we’re moving fast and we’re looking forward to seeing what happens.”
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