Energy

MIT discovery resurrects potential of molten salt batteries for grid level power storage

MIT discovery resurrects poten...
A new steel-based membrane could ressurect a 50-year-old battery technology, leading to cheap grid-level power storage and an increase in renewable energy use
A new steel-based membrane could ressurect a 50-year-old battery technology, leading to cheap grid-level power storage and an increase in renewable energy use
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A new steel-based membrane could ressurect a 50-year-old battery technology, leading to cheap grid-level power storage and an increase in renewable energy use
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A new steel-based membrane could ressurect a 50-year-old battery technology, leading to cheap grid-level power storage and an increase in renewable energy use

One of the primary problems with renewable energy, particularly wind and solar, is that power gets generated when the wind or sun is available, rather than when it's most needed. This problem would more or less disappear if the world could come up with a massive, cheap, long-lasting battery design that could be used to store power at grid-scale levels and feed it back out when required.

Lithium batteries are the current darlings (heh heh) of the electric vehicle and consumer electronics industries, due to their high performance, power density and light weight. But lithium is way too expensive a material for grid-scale storage, and when you're talking about making batteries for a whole city, size and weight are far less important than making something super cheap, safe and reliable that will last for as long as possible. All the better if it can be made out of common and easily available materials.

Good news, then, from MIT on this front, as a team of researchers has found a cheap, effective and durable way of resurrecting an old battery idea first documented 50 years ago.

The discovery centers around molten salt batteries such as sodium/sulfur or sodium/nickel chloride designs in which electrodes are kept at high temperatures to keep them in a molten state and allow charge to transfer between them.

Typically, the electrodes need to be kept separate by a special type of membrane that allows certain molecules through and keeps others separate. This has been successfully done in the past with a thin beta-alumina ceramic layer, but commercial use of these batteries has been limited by how fragile and brittle this ceramic layer is, and its tendency to shatter. Not the kind of thing you want to bet your city's power supply on.

The MIT team has discovered a different way of separating the electrodes, using a regular steel mesh coated with titanium nitride. Where the ceramic layer sorts molecules according to their physical size, using the size of holes in the porous ceramic material, the steel mesh uses its electrical properties instead to achieve the same result. And it's much more durable.

The steel mesh technique is applicable to a number of different molten-electrode battery chemistries, and while it doesn't help with small, lightweight battery designs like you'd see in an electric car or mobile phone, the researchers believe it could be a game changer for large-scale, low-cost, fixed-location energy storage.

Such an advance could allow cities to safely and easily ramp up the amount of renewables in its energy mix – and that's good news for everyone.

Source: MIT

8 comments
MartinVoelker
This type of battery would be ideal for utility-scale load leveling. Such batteries can replace so-called “peaker plants” which cost billions each but may only run for a few hours per year (!!) at times of extreme demand, and do so cheaper than existing lithium solutions. Considering that MIT’s discovery can build on previous efforts on that type of battery there’s hope it won’t take a decade to come to industrial applications.
Sisko
Doesn't the power required to keep the salt molten, drain the battery of it's energy? How does this leave enough energy in storage, to be of any practical use?
Catweazle
I'm surprised no-one has rediscovered the old nickel-iron-alkali battery. Cheap compared to Li batteries, manufactured from readily available, recyclable materials, very long life in excess of 20 years, robust - can stand to be overcharged or short circuited, holds its charge practically indefinitely, can be continuously trickle charged on standby, doesn't mind standing flat and doesn't rely on any fancy technology like molten salt, weird membranes or electrode trickery and can be utilised to create hydrogen. Disadvantages are size, weight and poor fast charge/discharge capability, none of which matter for a large static location.
Craig Jennings
Seems like everyday there is another horse to back.... I wonder if the world is so awash with money that it doesn't matter as they're all getting plenty of backing or the opposite is true and no idea is really getting backed as they seem to be springing up every 5 minutes and nobody wants to back the wrong horse! I thought redox flow batteries were the business, they have remarkable properties and only seem to have "oh the density" as the main bugbear, sure they won't power your car or phone but China is building some large ones for grid support. There is a neat one out of Australia but they're pricey (Redflow) if you can get a price out of them at all. Surely something is "good enough" to run with already?
Jim B
You can also store the heat output of a 4th gen nuclear reactor as heat in a molten salt. Due to the economies of scale with storing heat from gigawatt scale reactors vs 10s or 100s of megawatts, renewables don't stand a chance. Or if you hate nuclear, then you'll be storing the heat from a gigawatt gas power station, not renewables. Another advantage Scott points to is the SSR's potential to be used with heat storage. He notes that, for concentrated solar power (CSP) technology, the only "glimmer of hope of making that technology economic is the fact that they can store the heat in molten salt heat stores. So they can sell the electricity when it makes the most money for them, which might make them economically viable, but they're not there yet. However, the technology they use to store the heat, which is a molten salt heat store system, will work with nuclear energy provided the nuclear reactor has an output temp of around 600˚C. See Ian Scott's comments: http://www.powerengineeringint.com/articles/print/volume-24/issue-9/features/a-reactor-worth-its-salt.html "This is unusable with a PWR or a boiling water reactor, or any of the current generation," he says, as their output temperatures are too low. But "some MSRs, including ours, do have output temperatures that high. That gives us the ability to use an energy storage system. We can store heat output for as much as eight hours, produce no electricity at all, then for eight hours we can use both the reactor's output and the stored heat to produce 2 GW on a 1 GW output."
dougspair
...50 years old technology?.......I'm 70, and remember this from my High-School days...Popular Mechanics had articles about how every home would have a couple of 'Deep Freezer' sized batteries in the basement.....I don't remember all the details, but they'd be using 'Molten Salts'.....
noteugene
Another would, could, shoulda, might work someday battery technological solution. Uh-huh. I have a novel idea. Build the battery. Test it, then report the findings.
erik
well there is already functional salt storages out there. And it doesnt need to be in liquid state http://saltxtechnology.com/ https://www.youtube.com/watch?v=7Z3zhpJXwfM&t=83s