Researchers have developed a water-based battery to store solar and wind energy

[isoprophlex]

This is really brilliant. They cycle between two chemical species that are thermodynamically very stable in our atmosphere, solid MnO2 and Mn2+. This is very smart as a starting point because you don't need to worry about the electrodes slowly rusting away (compare: related work with exotic/expensive/unstable rare earth oxides)

Also this redox couple charges at 1.6 V so oxygen production (which is bad in a cell that also evolves hydrogen) does not really happen (this takes 2.0 V or so)

Really exciting stuff.

[raverbashing]

Makes me wonder why they didn't think of this before or what challenges have they overcome this time.

[svantana]

>Cui estimated that, given the water-based battery’s expected lifespan, it would cost a penny to store enough electricity to power a 100-watt lightbulb for twelve hours.

Oh dear, I hate university news "journalism" with a passion. For the life of me I cannot understand why they feel the need to dumb down parts of the content while other parts remain decidedly technical. Is it to have something that laymen can quote? In this example, it's not clear how long the storage would be, but presumably overnight? It would make much more sense to compare the expected price to existing solutions, and/or the current price of electricity.

[DennisP]

Well that'd be 1.2 kWh, stored for a penny. Average electricity price in the U.S. is 10 cents/kWh.

I've often criticized people for ignoring the cost of storage when talking about wind/solar prices, but at a penny per kWh it's pretty insignificant.

[timb07]

"Excess electrons bubbled off as hydrogen gas, thus storing that energy for future use."

Just wow.

[josecyc]

I don't know about this. Countless times researchers discover the next battery so much better than the current state-of-the-art being deployed, only to find out they just can't scale it. New battery technology is really hard.

[Animats]

Yes. Surface chemistry ("nanotechnology") seems to attract this sort of hype.

"The prototype manganese-hydrogen battery, reported April 30 in Nature Energy, stands just three inches tall and generates a mere 20 milliwatt hours of electricity ... The researchers are confident they can scale up this table-top technology..."

That is a really puny battery. It's 1/10th the energy capacity of a typical watch/hearing aid battery, which is about as small as you can buy retail. And it's 3 inches tall. So system energy density is currently something like 0.001 of commercial batteries.

They should have scaled it up a bit more before turning on the hype machine. It's embarrassing to see this out of Stanford.

[sitkack]

How about starting with the goal of making a warehouse scale battery and starting backwards?

[fernly]

Could someone ELI5 how the recharge cycle works? On charging it evolves H2 gas; how does that get put back on recharge?

This is very much NOT explained by the paragraph,

> The researchers did this by re-attaching their power source to the depleted prototype, this time with the goal of inducing the manganese dioxide particles clinging to the electrode to combine with water, replenishing the manganese sulfate salt. Once this salt was restored, incoming electrons became surplus, and excess power could bubble off as hydrogen gas, in a process that can be repeated again and again and again.

[hedora]

In the modern sense of the word, this is not a battery. It is a device that cracks water into hydrogen, which can then be fed into a fuel cell. Presumably, it consumes distilled water, which is why it is targeting utility scale storage and not home installations.

The work sounds interesting, but the article is painfully written.

Lead acid batteries produce hydrogen too. I think the insight is that this can’t produce electricity directly, so the chemistry can be much more stable.

[xelxebar]

Just in case anyone's interested, I think this is the primary paper being discussed:

https://doi.org/10.1038/s41560-018-0147-7

which redirects to the Nature Energy page and so is behind a paywall. I'm not sure how Sci-Hub is viewed here, but this links directly to the pdf:

https://sci-hub.tw/10.1038/s41560-018-0147-7

[ecma]

This puzzled me also. Perhaps it's been kicked down the road as an engineering problem and we'd end up with a hydrogen extraction system which is responsible for that part. We'd probably need to feed protons back in though...

[haZard_OS]

I worked on a similar system when I was finishing my degree. I suspect that, in the next 5-10 years, there will be several versions of this of various sizes ready for deployment.

[konschubert]

> To mimic how a wind or solar source might feed power into the battery, the researchers attached a power source to the prototype.

So, they charged the battery? Why doesn't the article just say that? Does the intended audience of the article not know what "charging a battery" is?

[thefifthsetpin]

My guess is that the researchers designed their power source to mimic the behavior of solar and wind farms. The researchers were probably rather specific about these behaviors, but it was too verbose or technical for a news article. Some editor tried to summarize that part of the paper, and that editor failed which is how we got this ridiculous sentence.

[EdCoffey]

There's some more detail on the construction, and what becomes of the hydrogen (it will be stored in large pressurized steel tanks) here: https://cen.acs.org/energy/energy-storage-/New-battery-serve...

[8bitsrule]

"the researchers are confident they can scale up this table-top technology to an industrial-grade system"

Oh dear.

[apsec112]

Unfortunately, history shows that new battery chemistries are a dime a dozen. It's commercialization and manufacturing at scale that's the real bottleneck. Look at what happened to Aquion, which raised $190 million for their salt water battery:

https://www.greentechmedia.com/articles/read/Aquion-the-Bill...

[wpietri]

Ouch. And they later sold for $9.2 million. I sure have some questions about what they spent the money on.

[tzahola]

K...Keep me posted!

I’ve learned not to get too excited by battery research. It was all vaporware in the past 20 years.

[weaksauce]

I wonder how safe this will be with hydrogen gas being a part of it. Sounds promising but you’d want it extra safe considering a mini Hindenburg would be attached to your house. Edit. I suppose I read it incorrectly as this is being invented for the utility scale.

[kbenson]

Well, any vehicles you park in your garage or in your driveway probably have a lot of stored potential energy that can be released catastrophically under the wrong circumstances too. (this goes for whether it's ICE or electric).

The fact that we generally consider those safe to sleep next to is a testament to safety engineering (and possibly a bit of self delusion).

[isoprophlex]

With adequate seals this is no more dangerous than existing chemical energy storage, such as gasoline and natural gas.

The researchers state (in the paper itself) that they carefully control the charging voltage to avoid oxygen production in the same cell. Oxygen and hydrogen in the same device is dangerous, only hydrogen not so much.

[freeone3000]

We currently put high-temperature, charged lithium in our pants pockets. The technology this is replacing uses lead and sulfuric acid. Hydrogen is probably fine.

[walshemj]

One of the major complaints when they trialed fuel cell buses in London years ago was that people though the fueling station would blow up ala hindenberg.

[Tade0]

Sound great, but somebody else might have already stolen their lunch:

https://eosenergystorage.com/

This product is, of course, more expensive but at least it's already being deployed.

[lm2s]

Unrelated: this reminds me of the “2-tier” water dams that also store energy in the form of water from whatever production source connected to them.

[syntaxing]

I was always under the impression that water has an extremely low energy density (in 2H2 + O2 form) relative to existing technology?

[d--b]

Can anyone comment about the size of these? How much hydrogen do you need to store a KWh? And how much manganese solution do you need?

[Tepix]

> it would cost a penny to store enough electricity to power a 100-watt lightbulb for twelve hours

Ha, 100 watt lightbulbs do not exist! /s

[protomyth]

They still do because some folks need to heat/light the chicken coop or compressor. /s not withstanding

[Tepix]

Given that this battery stores energy as H2, doesn't Hydrogen tend to diffuse and escape from the battery after a while?