UH Researchers Report New, More Efficient Catalyst for Water Splitting
uh.edu
uh.edu
1. The overall idea here is to take an intermittent energy source (e.g. solar power) and "store" it as chemical fuel, in this case hydrogen and oxygen. This is what plants do, and we can also view fossil fuels as resulting from the "storage" of millions of years of solar energy. Note also that you get the water back when you burn the hydrogen, so there is no net consumption of water, it's just a carrier.
2. While you can split water without a catalyst, most of the energy gets wasted as heat, so this is not a great way to go if you're trying to do energy storage.
3. Efficient catalysts exist for this reaction, but they are based on rare and expensive metals, typically Pd, Pt, and Ir. As a result, there has been a search for catalysts involving "first-row" metals such as Fe, Co, Ni, etc.
4. There are variety of metrics for an electrocatalyst (efficiency, stability, cost, etc), but it's a fair bet that if this were significantly better than state-of-the-art, it would be in Science or Nature rather than PNAS.
https://en.wikipedia.org/wiki/Power_to_gas
Lithium ion batteries for grid storage typically use an NMC chemistry, and standard warranties are for 10 years of daily cycling.
of course, I appreciate your reply too. epistasis, why do you say "cycles don't make sense" -- is it because it's "infinite" or because it can't be run as a fuel cell immediately in the same place? Like you can't go back and forth immediately?
I read most of the article you linked (which had a couple of occurrences of the term 'fuel cell' - not many - therefore leading me to be confused as to why you said what you just said).
I am talking about using it as a fuel cell, same as a battery. If daily cycling means 1 cycle per day, then 10 years means 3650 cycles. How does "power to gas" compare? Infinite cycles?
OP was talking about burning the hydrogen, as was I. Burning is not typically the term used with what goes on in fuel cells.
A battery has a fixed capacity attached to it, it has a fixed power to energy ratio. The component that stores the energy is directly attached to the part that discharges the energy. This is what makes "cycles" make sense.
With power to gas, or using fuel cells to consume energy from the process described in the article, the component that stores energy is not directly connected to the part that consumes energy. It's not necessary that they even have a fixed fuel stores attached to them, they could just be hooked up to a pipeline. The rate at which parts wear out would better be described in terms of total energy stored or consumed.
That's why I mentioned the cost estimates (€0.10/kWh for hydrogen in that article), because it's perhaps the best way to compare. The rapid drop of lithium ion grid storage has put it at $250/kWh capacity with 3650 cycles, which is ~$0.07/kWh before accounting for taxes, maintenance, siting, etc., which may or may not be included in that above estimate for hydrogen.
Both of these numbers blow me away by how small they are. We're in for a wild ride on tech changes over the next few years...
By the end of one year, would it be totally depleted?
Please note that I did not want to name the application, so don't worry about the specifics of my illustrative example, it's totally made-up and I see the problems with it - just about the timing.
Additionally I am interested in the size and weight as compared with other rechargeable battery types.
I am sorry that I seem to be asking really strange questions. If they are not well-defined could you reply with your questions about my question?
Thank you so much for taking the time to understand my question and and reply. Basically, I'm asking if the effect you describe applies to hundreds of thousands, millions, tens of millions, hundreds of millions, or billions of charge/discharge cycles. Is it a tiny little effect or rather more significant than that?
I want you to really think out of the box, please, so just to expand your mind (as an "anchor"), even though it is not relevant to my application, consider:
>Modern automobile engines are typically operated around 2000–3000 rpm (33–50 Hz) when cruising, with a minimum (idle) speed around 750–900 rpm (12.5–15 Hz), and an upper limit anywhere from 4500 to 10,000 rpm (75–166 Hz) for a road car or nearly 20,000 rpm for racing engines such as those in Formula 1 cars (currently limited to 15,000 rpm)
So if the ctypical cruising speed is 2000 RPM, then in an hour of cruising, a piston would go through 120,000 cycles. If an hour of driving gets you, say, 100 miles (obviously higher than average) then 100,000 miles is 1,000 hours (likely actually more), so that we are at 120 million cycles per 100,000 miles. Obviously this is pretty crazy and I don't envision anything that does anything like that, plus it would need an electric generator, but I just wanted to expand your mind as to why in certain, as-yet unspecified, applications, hundreds of millions, billions, or tens of billions of duty cycles might well be completely reasonable to talk about, and therefore whether the answer to my questions is "tens of thousands" or "infinite" is by no means an equivalent answer!
Please note that both the heart-valve driven pacemaker, and the hybrid engine with per-cycle electric recovery, are not the domains I'm talking about. So I'm interested in a more pure or abstract description of the possible specifications here.
By the way if you happen to know off-hand of other kinds of energy storage (example: graphene supercapacitor; flywheel) that you happen to know are good for the mentioned hundreds of millions of cycles, then you could mention this as well. However, in this thread I was primarily asking about the number of duty cycles (and, to a lesser extent, the possible weight) of a reversible fuel cell - whether via water splitting or some other mechanism.
This is kind of out-there, but it also sounds like you are saying the catalyst may be thought of as an additional "fuel" to be added over time. Like, for the engine made-up example, someone might think of topping up their engine with both petrol and catalyst-fuel, every time they top up. So in this case it would matter how much in quantity we are talking about - if the catalyst is thought of as a consumable that gets used over time and adding some more is part of operations. If it gets used exceedingly slowly, this is no greater a burden than engine oil changes, which are already used regularly.
Thank you so much for your time. I hope I've been clear about my questions.
If all this is pretty crazy, then please just name the number of duty cycles until the catalyst is 50% depleted. (And please name a definition for what 50% depleted means.) Or, any other alternative measure you can think of, as long as it's well-defined. I would just like to know within 1-2 orders of magnitude! Thank you!
good laugh on that :)
What is that OH? Is it hydroxide radical? Hydroxide? Hydroxyl radical? Where does it go? Does it recombine to make hydrogen peroxide?
Btw... To make oxygen from water the first part of the first step is to split it into H and HO. You can't really break two bonds simultaneously, or anyways it's equivalent to doing them stepwise by the principle of microscopic reversibility.
Searched for that and got this: http://www.pnas.org/content/early/2017/05/10/1701562114.abst...
Not super aimed at this particular paper, but those are probably the reasons you don't see fireworks going off over inorganic labs around the country about this paper.
"Hydrogen is the cleanest primary energy source we have on earth,” said Paul C. W. Chu, TLL Temple Chair of Science and founding director and chief scientist of the Texas Center for Superconductivity at UH.
This seems like sensationalism and poor science communication to me. Hydrogen isn't a primary energy source.
It has nothing to do with market share
Primary energy sources do not require any type of conversion. Fossil fuels, nuclear, wind, and solar are all primary energy sources. Free hydrogen isn't found in nature. It can be made by splitting water using energy from a primary source. The catalyst described in this press release makes that process more efficient, but it still takes energy from a primary source to create hydrogen.
Reference: https://en.wikipedia.org/wiki/Primary_energy
Sure it is; you just have to go kind of far out of the solar system before you'll start running into it. Molecular clouds of hydrogen are what makes those pretty Hubble pictures of nebulae. :)
"Sensationalism and poor science communication" is not the half of it. He's lying outright.
Having lower catalyst costs may allow for more installations that are used only intermittently. I know very little about the research in this particular field, but am not surprised that it's seeing more attention.
As intermittent renewable electricity generation continues to get cheaper and replace fossil fuel sources, there's going to be a massive interest in using the large amounts of curtailed energy in someway. California is currently curtailing GWh per day of solar, and there's still a fairly low amount of renewable penetration. The question isn't necessarily about storing hours of energy, but perhaps weeks or maybe even months.
Power to gas to electricity is currently only about 1/3 efficient, but depending on the cost curve of various battery technologies, there could be a big case for generating and storing a few months worth of methane mixed with hydrogen for winter months in the northern hemisphere.
I bet there are likely to be far more research into combining electrolysis with methanation (perhaps with CO2 that's already dissolved in the water) or even chains of carbon.
CNG automobiles, fueled with methane made from surplus renewable energy, might be a way for natural gas to be used in the future. We'll see if its ever economical, but there may be some great use cases for it.
That's good to know. No "breakthrough" can improve the process by more than another 30%. NREL says the best commercial systems are at 73% today.[1] There's also an additional energy cost for compressing the hydrogen.
That's pretty good. Getting any chemical or electrochemical process up to 73% efficiency is a good result.
I agree that the efficiency is already pretty good and even a "perfect" system would not drastically lower energy inputs further.
Missouri U: http://onlinelibrary.wiley.com/doi/10.1002/cssc.201601631/ab...
Stanford: http://science.sciencemag.org/content/353/6303/1011.full
Lots and lots and lots of research going on in this space. So far nothing that can be used to produce hydrogen at scale.
What? No. Hydrogen is not a source of energy, it's a storage format. A more efficient catalyst will certainly help with losses when storing the energy, but there's no net gain.
https://ssl.toyota.com/mirai/fcv.html
There are also house scale fuel cells (that reform natural gas).
Hydrogen fuel cells have a sweat spot at around 30% efficiency lasting for several years, and another at around 50% efficiency lasting for a few months. I have never seen anybody get a different set of numbers.
(and for a heated house you'd get better effective efficiency because the waste heat can be utilized)
If you go and generate the hydrogen from natural gas (so you have a natgas powered car, not much gain) you'll have to multiply those by a 40% to 50% conversion efficiency. If you generate it from water and electricity, your equivalent battery will have that 30% efficiency multiplied by another ~30% efficiency of electrolysis.
Could this also be used in desalination? Turn into hydrogen, burn to convert back to water, feed it catalyst material like a fuel? (I'm not really sure how these catalysts work, do you like push water through them? and out comes gases?)
The water will also contain lye from the leftover sodium.
Sure it's easier than other forms, but it's my understanding that there are some significant challenges in storing hydrogen?
there are only 3 significant problems with hydrogen as an energy carrier to solve before it becomes ubiquitous: 1. how to make it 2. how to store it & transport it 3. how to use it
IMO there was a time in the late 80s, early 90s when there was a chance it could be useful but the battery tech development over the last 25 years has nailed the coffin shut - hydrogen research persists because people with jobs know how to research hydrogen production.
There are a lot of processes that use methane for the hydrogen though.
So far the process to do this involves a lot of messy intermediate steps, like hundreds of millions of years and enormous pressure in the mantle of the Earth.
http://www.audi.com/corporate/en/corporate-responsibility/we...
(mentioned on https://en.wikipedia.org/wiki/Sabatier_reaction)
Who knows what the economics really are, but they don't sound dire.
We need energy in portable forms (and have other uses for hydrocarbons). Getting that energy from clean sources and storing it with atmospheric CO2 is better than burning fossil sources of energy.
But to be cost-competitive with fracked methane, I'm pretty sure we're going to need some heavily genetically-engineered strains of algae, growing in artificial forests of pipes.
The irony is that algae can be used to clean up fracking wastewater, so it makes methane production cheaper as it competes.
The promise of syntetic fossil fuels from things like water and CO2 is that you don't need a lot of land, you just need energy, and that energy can be renewable.
There's a lot of overlap between these in some areas like home heating and BBQs, but each application requires some engineering to make it work with any particular fuel.
The energy storage density of hydrocarbons make them more practical as a fuel in situations where portability is a concern. For example: You could have a hydrogen BBQ, but the tank would probably have to be much larger for the same amount of burn time.
Isn't the opposite true? I mean, hydrogen at 700 bar has a specific energy of 142 MJ/kg while hydrocarbons in general have less than 60 MJ/kg.
So the question is what is that source of energy, and whether we could simply connect the source directly to where the energy is needed and cut out the middleman H2.
For example you can transports natural gas in plastic pipelines - can't do that with hydrogen since it will leak right out.
Homes often have cast iron pipes for natural gas - can't put hydrogen in those because you will make the metal brittle.
There are metals that can handle it, but it would be unrealistic to replace everything.
Long term it makes it more viable to replace oil and other hydrocarbons used in industrial processes with energy, air and water.
It would also be essential for mining fuel from asteroids or gas giant's moons as ice is not so rare, improving the sustainability of space operations. Hydrogen itself has a pretty big specific impulse, it's just not used more often than Kerosene for rockets due to safety issues.
If you could achieve Metallic Hydrogen [1][2] then you would have the perfect fuel for navigating the solar system.
[0]: https://en.wikipedia.org/wiki/Hydrogen_vehicle
[1]: https://en.wikipedia.org/wiki/Metallic_hydrogen
[2]: http://iopscience.iop.org/article/10.1088/1742-6596/215/1/01...
http://pubs.rsc.org/en/content/articlepdf/2016/ta/c6ta02876d
Highly active and durable self-standing WS2/graphene hybrid catalysts for the hydrogen evolution reaction
Direct PDF link: https://www.researchgate.net/profile/Zhenhuan_Zhao/publicati...
Abstract: A variety of catalysts have recently been developed for electrocatalytic oxygen evolution, but very few of them can be readily integrated with semiconducting light absorbers for photoelectrochemical or photocatalytic water splitting. Here, we demonstrate an efficient core/shell photoanode with a highly active oxygen evolution electrocatalyst shell (FeMnP) and semiconductor core (rutile TiO2) for photoelectrochemical oxygen evolution reaction. Metal−organic chemical vapor deposition from a singlesource precursor was used to ensure good contact between the FeMnP and the TiO2. The TiO2/FeMnP core/shell photoanode reaches the theoretical photocurrent density for rutile TiO2 of 1.8 mA cm−2 at 1.23 V vs reversible hydrogen electrode under simulated 100 mW cm−2 (1 sun) irradiation. The dramatic enhancement is a result of the synergistic effects of the high oxygen evolution reaction activity of FeMnP (delivering an overpotential of 300 mV with a Tafel slope of 65 mV dec−1 in 1 M KOH) and the conductive interlayer between the surface active sites and semiconductor core which boosts the interfacial charge transfer and photocarrier collection. The facile fabrication of the TiO2/FeMnP core/shell nanorod array photoanode offers a compelling strategy for preparing highly efficient photoelectrochemical solar energy conversion devices.
But the original title is : "UH Researchers Report New, More Efficient Catalyst for Water Splitting"
catalyst for water splitting aren't new. the article even says it :
>The catalyst, composed of ferrous metaphosphate grown on a conductive nickel foam platform, is far more efficient than previous catalysts, as well as less expensive to produce.
Submitters: please don't rewrite titles unless they are misleading or linkbait. This is in the site rules: https://news.ycombinator.com/newsguidelines.html.
HN has an 80 character limit for titles so I had to cut it down drastically from that.
Still today, over 10% of the world population don't have access to clean water. I'm also curious on how clean the water needs to be to be used with this catalyst. AFAIK, most catalyst conversion need pretty pure water, in which case, we would not only use water, but use _clean_ water, which is even more scare than "dirty" water...
Sea Water (H2O + sea junk) -> H2
Then later when generating electricity:
2 * (H2) + O2 -> H2O (fresh) + energy
Naturally, the resultant H2O can be moved and recycled. I think a catalyst that splits water points towards a potential where we have more fresh water, not less.
If you are worried about water shortages, the place to fight that is water intensive farming, on luxury crops.
Dan Nocera ( http://nocera.harvard.edu ) is very prominent in the water splitting field and has done a calculation in which a volume of an olympic sized pool would need to be split every second to replace all power sources on earth ( https://poptech.org/blog/daniel_nocera_on_personalized_energ... ).
It seems like a lot, but it would presumably be decentralized across many many locations. Additionally, you don't need 24 * 60 * 60 * olympic pool volumes -- you can cycle the same amount of water into/out of a fuel cell in a closed system.
The inland reservoir here is 100 billion liters:
https://www.google.com/maps/@43.8937611,-86.4337261,8900m/da...
It's not very much water.
Hydrogen has a specific energy of 142 MJ/kg [0].
1 water molecule has 2 Hydrogen molecules and 1 Oxygen molcule. Hydrogen has a molecular weight of 1, while Oxygen has a weight of 16 [1][2]. This means that, by weight, water is about 1/9th hydrogen. So 9kg of water should give us 142 MJ worth of Hyrdogen.
Gasoline is about 46 MJ/kg [0], so 3kg of water should give us the equivelent of 1kg gasoline.
Gas has a density of .77 kg/L [3], water has a density of 1kg/L [4]. So 3L of water, should be about 2.31L worth of Gas.
Also, if we keep the water that results from burning hydrogen we may be able to avoid needing to re-purify it.
[0] https://en.wikipedia.org/wiki/Energy_density [1] https://www.google.com/search?q=water+molecular+weight&oq=wa... [2] https://www.google.com/search?q=hyrdogen+molecular+weight&oq... [3] https://www.google.com/search?q=gasoline+density&oq=gasoline... [4]https://www.google.com/search?q=gasoline+density&oq=gasoline...
(Unless you're "burning" the hydrogen in a fusion reactor. But that takes much less hydrogen...)