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Scientists at Stanford develop water splitter that runs on ordinary AAA battery

news.stanford.edu

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Re: Scientists at Stanford develop water splitter that runs on ordinary AAA battery

#41

Post by digikata »

lutorm wrote: post #6

... and not a single word about how the necessary electricity needed to make this "zero emission fuel" is supposed to be produced. Plus, all I know about hydrogen points to it not being anything close to "an ideal fuel for powering vehicles, buildings and storing renewable energy". It has very low density, requires cryogenic storage or very heavy pressure vessels, migrates through materials, and is explosive when mix…

I'm skeptical of hydrogen infrastructure using direct hydrogen too, and assume you need some other way to store and release the hydrogen. http://en.wikipedia.org/wiki/Hydrogen_storage I would think it would be more interesting to electrolyze directly into some storage material. But then, I'm just a casual observer in this topic area...

Re: Scientists at Stanford develop water splitter that runs on ordinary AAA battery

#42

Post by kazinator »

alex_duf wrote: post #18
nardi wrote: post #12

I'm amazed at the ignorance in these comments. First, yes this is cool new science. No one imagined nickel would work as a water-splitting electrocatalyst. This is very surprising, and awesome. Second, the point of water-splitting is obviously not power generation . It's power storage , just like a battery, but with better transport and storage characteristics.

right, but using a AAA battery which is already storing energy doesn't serve any purpose. But I agree with you, efficient-cheap catalyst is needed indeed. I'd like to know the efficiency of the system though...

Even if we imagine ourselves in a crazy world in which banks of actual AAA batteries are used for water splitting (not only to demonstrate the low voltage) there can still be an advantage.

A cylinder full of compressed hydrogen weighs less than a trunk full of AAA batteries, which cuts into economy.

The clunky bank of AAA batteries can be stationary in some water-splitting plant, whereas the hydrogen is light and portable.

Re: Scientists at Stanford develop water splitter that runs on ordinary AAA battery

#44

Post by kazinator »

sirdogealot wrote: post #9

This isn't news. "The researchers also plan to develop a water splitter than runs on electricity produced by solar energy." Unfortunately that approach would be less efficient that simply transferring the electrical energy to an electric motor. Light > Electricity > Hydrogen > Electricity > Electric Motor is longer than Light > Electricity > Electric Motor

Efficiency isn't everything. If you want to transfer solar energy directly to a mobile motor, such as one which moves a car, the solar cells to do that have to be mounted on that car, oops! How big is that?

Using non-mobile solar cells to produce an energy-dense fuel which is portable makes sense, even if there is an efficiency hit.

Cars themselves are not efficient no matter how they are powered, because utmost efficiency in a car means lying on your back in a narrow, feather-weight, fragile aerodynamic tube with wheels, going about 25 mph max, and taking minutes to get to that speed. Forget niceties like air conditioning.

Re: Scientists at Stanford develop water splitter that runs on ordinary AAA battery

#45

Post by lutorm »

nardi wrote: post #28
lutorm wrote: post #24

Earlier quoted context omitted.

Well, if they claimed that using batteries was "emissions free", I would complain about that, too. With hydrogen, the issue issue is that (at least to my understanding) if you have electricity, we already have a far more efficient solution: put the electricity directly into a battery and use it to power a motor. Going the route over electrolysis->hydrogen storage->fuel cell imposes such efficiency penalties that it w…

Hey, I like chemical batteries too, but they're not capacitors. You don't put electricity into them. You drive an electrochemical reaction with them, which is subject to its own inefficiencies, as well as wear and tear on the battery, which isn't a problem with hydrogen fuel cells. Hydrogen fuel cells also tend to be highly efficient.

Sure. Are you saying the fuel cell cycle is actually more efficient than the battery cycle?

The long-term performance question is interesting, though. Any idea how long the time scale would have to be before the fuel cell wins?

Re: Scientists at Stanford develop water splitter that runs on ordinary AAA battery

#46

Post by keenerd »

nardi wrote: post #23
crististm wrote: post #21

Earlier quoted context omitted.

I don't know about ignorance, but basically, the energy you get from splitting the water molecule (in the form of H2 and O2) is lower than the energy consumed to make the split. For storage you will also have to deeply freeze the gases unless you want to have huge tanks for storage So what makes a hydrogen exposed freezing tank better suited for transport and storage than a chemical battery?

This is just pessimism. Yes, there are other hurdles to overcome for hydrogen. But this is a major advance in one of the primary pieces necessary for a hydrogen economy. What makes you think advances in other areas are impossible? And to answer your question, much better energy density by mass .

Who cares about mass except NASA? H2 is terrible by volume, a liter of gasoline has more hydrogen in it than a liter of liquid H2 and the gasoline is a lot more safe.

Some little PDFs about the hurdles of hydrogen from one of my favorite tech writers:

http://www.tinaja.com/glib/resbn88.pdf

http://www.tinaja.com/glib/energfun.pdf

A hydrogen economy might be possible one day, but not until we find a natural H2 source that is as "free" as crude oil. Man made hydrogen will not work on a large scale. Electrolysis is one of the worst ways to make hydrogen, though it does have the highest "gee-whiz!" factor.

If we did have unlimited hydrogen spewing out of the ground people would seriously consider first cracking the H2 into hydrocarbons to make it easier to transport.

Re: Scientists at Stanford develop water splitter that runs on ordinary AAA battery

#47

Post by lutorm »

jacquesm wrote: post #36
justin66 wrote: post #25

Earlier quoted context omitted.

> ... and not a single word about how the necessary electricity needed to make this "zero emission fuel" is supposed to be produced. At some point you have to trust the reader to understand things that are completely obvious. That's a necessary quality of good writing, even if you're adhering to the newspaper standard of targeting someone at the 8th grade reading level.

But in the case of Hydrogen such 'completely obvious' things are actually not all that obvious to the target audience. So it's ok to spell it out to avoid the risk of overselling a new technology and thus create a situation where it will fail to deliver due to unrealistic expectations. Hydrogen is not exactly the easiest compound to work with and how it is generated is a huge part of equation.

Exactly. If you haven't come across people who think hydrogen is "the solution to global warming", you need to talk to more people.

Re: Scientists at Stanford develop water splitter that runs on ordinary AAA battery

#48

Post by epistasis »

lutorm wrote: post #38
epistasis wrote: post #31

Earlier quoted context omitted.

Using the batteries is emissions free. Claiming anything else is just bringing emotional baggage and irrationality to the situation.

It is anything but. It's like saying "gasoline is emissions free, it's the burning of it that's the problem." If we're going to have a rational discussion about various forms of emission, we need to talk about total fuel cycle emissions, otherwise it's meaningless. Touting one small section of a fuel cycle as emissions free is at best confusing, at worst misleading.

You're still being incredibly dishonest, and if you're willing to talk like that, you should really worry about how much it hurts your personal credibility.

With gasoline, the use of stored energy requires emissions.

With batteries, the use of stored energy does not require emissions.

You are creating false equivalencies, the only purpose of which is to drag down the discussion and stop the discussion.

You want to talk about fuel cycle, talk about the fuel cycle, don't say things that are blatantly false.

Re: Scientists at Stanford develop water splitter that runs on ordinary AAA battery

#49

Post by dang »

lutorm wrote: post #39
nardi wrote: post #12

I'm amazed at the ignorance in these comments. First, yes this is cool new science. No one imagined nickel would work as a water-splitting electrocatalyst. This is very surprising, and awesome. Second, the point of water-splitting is obviously not power generation . It's power storage , just like a battery, but with better transport and storage characteristics.

Give me a break. Did you read the article? Although touted as zero-emissions vehicles, most of the cars will run on hydrogen made from natural gas, a fossil fuel that contributes to global warming. Now scientists at Stanford University have developed a low-cost, emissions-free device that uses an ordinary AAA battery to produce hydrogen by water electrolysis. You don't agree the juxtaposition gives the impression tha…

> Give me a break. Did you read the article?

Please don't be personally rude on Hacker News. This comment would be fine without the first two sentences.

Re: Scientists at Stanford develop water splitter that runs on ordinary AAA battery

#50

Post by digikata »

crististm wrote: post #21
nardi wrote: post #12

I'm amazed at the ignorance in these comments. First, yes this is cool new science. No one imagined nickel would work as a water-splitting electrocatalyst. This is very surprising, and awesome. Second, the point of water-splitting is obviously not power generation . It's power storage , just like a battery, but with better transport and storage characteristics.

I don't know about ignorance, but basically, the energy you get from splitting the water molecule (in the form of H2 and O2) is lower than the energy consumed to make the split. For storage you will also have to deeply freeze the gases unless you want to have huge tanks for storage So what makes a hydrogen exposed freezing tank better suited for transport and storage than a chemical battery?

It's not, but it might be interesting for electrical storage of excess renewable energy, especially in concert with a less reactive storage material. http://en.wikipedia.org/wiki/Hydrogen_storage Though many places seem to want to solve the issue for cars, while to me it makes more sense to solve it for buildings before making it portable enough for cars.
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