Some background and context from someone tangentially related to the field:
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.
Beyond the expensive of the metals another problem is duty cycles. Most transition metal catalysis is oxygen sensitive, and it seems like for some reason the first step of splitting water is creating oxygen. Plants go through great lengths to separate oxygen synthesis (photosystem II) from electron consumption. Most hydrogen production in lower organisms (like e coli) occurs entirely in anoxic conditions. Engineered systems for generating hydrogen via algae typically are temporally segregated (harvest light during day, produce hydrogen at night) which defeats the purpose and is also chemically steppy (carbohydrate intermediates).
can you compare storing an intermittent energy source by means of a chemical fuel, hydrogen and oxygen, as compared with in a battery? Just compare and contrast every aspect that matters. Just to be clear, this is (in effect) a battery, right? So what are its characteristics as compared with, say, lithium ion batteries. (I am particularly interested in weight and in number of duty cycles, which sounds like it's "unlimited" as opposed to lithium ion which is really not that many cycles, right?) I'm also far outside the field, just interested. Thanks!
I emailed Jeannie and she sent me the paper. I'm an idiot about finding a place to post it or host it (or find it), but the title of the paper is:
"Highly active catalyst derived from a 3D foam of Fe(PO3)2/Ni2P for extremely efficient water oxidation"
As a former chemist in another but related field, this phrase is telling and part of why it is not in a higher impact journal: "We find that this catalyst, which may be associated with the in situ generated nickel–iron oxide/hydroxide and iron oxyhydroxide catalysts at the surface". This is generally code for "we're getting some sort of nano surface effect we're not 100% sure we understand or can replicate." I can't access the full paper, but the downfall of catalysts are usually: cost, durability, or unreproduciblity\creation cost. Getting nano surfaces to grow properly at industrial (10s of grams scale as one researcher said to me) is still more of an art than a science, with maybe one guy in a 10 person group able to get the substrate to perform.
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.
"Primary energy source" is a term with a specific meaning. I'm not talking about 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.
And then in the very next sentence he says “Water could be the most abundant source of hydrogen if one could separate the hydrogen from its strong bond with oxygen in the water by using a catalyst.”
"Sensationalism and poor science communication" is not the half of it. He's lying outright.
I am (was) a chemist but I find this research area somewhat puzzling. Electrolytic hydrogen production has been industrialized for more than a century. Put nickel electrodes in an aqueous solution of potassium hydroxide. Separate anode and cathode with a porous diaphragm. Run direct current through it. Get pure hydrogen. "Simple" alkaline electrolysis is only ~50% efficient, but that means there's only a factor of two efficiency gain possible no matter how good your catalyst. Large commercial electrolyzers from a decade ago reached ~70%. Why so much research on further marginal efficiency gains from new catalysts? Are there other costs that fall faster-than-linearly with improved efficiency?
Large commercial electrolyzers from a decade ago reached ~70% (efficiency)."
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.
That was actually the data source I was thinking of. It's reviewing units commercially available by the end of 2003. More time had passed than I thought.
I agree that the efficiency is already pretty good and even a "perfect" system would not drastically lower energy inputs further.
>“Cost-wise, it is much lower and performance-wise, much better,”
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.
I agree that cheap-but-intermittent renewable electricity calls for differently optimized electrolyzer designs. Optimize for "cheap to manufacture and maintain" so you can afford to use them at a low duty cycle. If that is the underlying objective for this research, it's great, but doesn't come through clearly in the linked report. They mention efficiency in the headline, efficiency 7 times more in the body, and cost only twice, only in the body.
Does the electrolysis of water in the presence of the currently-used catalysts gradually corrode the anode/cathode, reducing efficiency and requiring eventual maintenance? If so, this could simply be a Total-Cost-of-Ownership thing: reducing maintenance costs or extending cycle time by decreasing corrosion.
The general goal of the research grants is to create a technology stack that takes sunlight as input and provides hydrogen as output. Such a thing would allow production of storable energy in the open ocean, immediately making the rest of the planet inhabitable by people.
> That would solve one of the primary hurdles remaining in using water to produce hydrogen, one of the most promising sources of clean energy.
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.
Yeah, this doesn't make sense. Also the problem isn't getting hydrogen, its to burn the hydrogen for energy efficiently and safely, which we currently have not found a way to do ... yet.
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?)
So, uh, do catalysts like this reduce the waste heat you get when electrolyzing water with a cruder setup? Because there's nothing but a specific minimum energy input that's going to break the bonds between hydrogen and oxygen.
Readit News
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.
good laugh on that :)
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.
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
"Sensationalism and poor science communication" is not the half of it. He's lying outright.
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.
[1] http://www.nrel.gov/docs/fy04osti/36705.pdf
I agree that the efficiency is already pretty good and even a "perfect" system would not drastically lower energy inputs further.
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.
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.
Deleted Comment
https://ssl.toyota.com/mirai/fcv.html
There are also house scale fuel cells (that reform natural gas).
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.