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Photocatalyst splits water into H and O2 at quantum efficiency near 100% (fuelcellsworks.com)
570 points by bookofjoe 61 days ago | hide | past | favorite | 284 comments

From the original paper

>> SrTiO3 is a suitable photocatalytic material for the assessment of this possibility. This compound is a well characterized photocatalyst with a bandgap energy of 3.2 eV (ref. 11–14), and its EQE for overall water splitting has been improved by up to 69% over the past years using various refinements.

Here, we increased the EQE to its upper limit by constructing highly active HER and OER cocatalysts on SrTiO3:Al particles site-selectively. This was accomplished by using a stepwise photodeposition method instead of an impregnation process, which results in random dispersion of the cocatalysts.

The abstract of the paper makes it sound good:

>Overall water splitting, evolving hydrogen and oxygen in a 2:1 stoichiometric ratio, using particulate photocatalysts is a potential means of achieving scalable and economically viable solar hydrogen production. To obtain high solar energy conversion efficiency, the quantum efficiency of the photocatalytic reaction must be increased over a wide range of wavelengths and semiconductors with narrow bandgaps need to be designed. However, the quantum efficiency associated with overall water splitting using existing photocatalysts is typically lower than ten per cent1,2. Thus, whether a particulate photocatalyst can enable a quantum efficiency of 100 per cent for the greatly endergonic water-splitting reaction remains an open question. Here we demonstrate overall water splitting at an external quantum efficiency of up to 96 per cent at wavelengths between 350 and 360 nanometres, which is equivalent to an internal quantum efficiency of almost unity, using a modified aluminium-doped strontium titanate (SrTiO3:Al) photocatalyst3,4. By selectively photodepositing the cocatalysts Rh/Cr2O3 (ref. 5) and CoOOH (refs. 3,6) for the hydrogen and oxygen evolution reactions, respectively, on different crystal facets of the semiconductor particles using anisotropic charge transport, the hydrogen and oxygen evolution reactions could be promoted separately. This enabled multiple consecutive forward charge transfers without backward charge transfer, reaching the upper limit of quantum efficiency for overall water splitting. Our work demonstrates the feasibility of overall water splitting free from charge recombination losses and introduces an ideal cocatalyst/photocatalyst structure for efficient water splitting.

Not so sure about the fuelcellsworks article clickbaiting up the 'quantum' bit when all it means is one photon splitting one H2O.

People are focusing on the direct (STH - solar-to-hydrogen) efficiency) which is low.

Instead, this paper introduces a materials engineering advance in a prototype UV-absorbing catalyst, that pushes EQE values to maximum, and suggests similar can be done to an existing visible-absorbing catalyst, to give an STH of 10%, which is very high for these durable, cheap catalysts. I got this from a quick reading of this paper and related papers.

Relevant section:

Recently, Ta3N5 and Y2Ti2O5S2 have been reported to split water into hydrogen and oxygen under visible light. These materials absorb visible light with wavelengths of up to 600 nm and 640 nm, respectively, and the STH efficiency can reach 10% once the EQE is improved to a level similar to that of SrTiO3:Al. The suitable photocatalyst design presented here should provide impetus to the development of particulate semiconductor photocatalysts for practical solar hydrogen production from water.

“Quantum efficiency” is a specific and long-used term, even though the word “quantum” (like “exponential”) gets abused for clicks: https://en.m.wikipedia.org/wiki/Quantum_efficiency


To be fair, exponential growth can have a rather large time-constant and it still is exponential. Most valuation/inflation/stock market/house market plots that span more than a decade or two are indeed logarithmic plots because much of these curves indeed follow exponentials.

To be also fair, exponential growth basically does not exist in nature; if you think you have exponential growth, you actually have truncated logistic growth.

Exponential growth is not necessarily fast growth. If r is .00000001 and the period is one year, then the curve would look flat on any human timescale.

> all it means is one photon splitting one H2O

It's not one H20. I read the graphic as:

110 H30+ + 100 OH- -- 350-360nm UV light + Al-doped SrTiO3 selectively coloaded with Rh/Cr2O3 + CoOOH --> 210 H20 + 5 H2

That looks like if it were paired with a cathode, you could take water and produce H2 more efficiently, but you'd need to keep the H+ sufficiently high or continue to supply it with more water, otherwise you develop higher OH- and H2O2 elsewhere in the solution from the H+ depletion, and that'll probably create some O2, but not at the rate you would with electrolysis, because the catalyzed reaction above would itself create a higher H+ environment, which feeds into itself from the H3O, but the H2 gas is escaping, depleting the H2 from the solution whereas the O2 is not gathering and escaping like that as much.

So, you could efficiently turn H2O into H2 source for a fuel cell.

But, you could also use this to make water more basic.

More detail:

Water is naturally a solution of H2, O2, H+, OH-, O--, H20, and H3O+, H2O2--. Except for H+ and O--, those are splitting and recombining most of the time while in liquid state, because the various ions in water and larger structures, etc. act as catalysts to the various reactions.

With light and the catalysts, the reaction above would seem to continue for quite a while, since the reaction produces H+ which will combine with surrounding H2O to product H3O.

Eventually, you're left with a greater concentration of OH- elsewhere in the solution (though surface of the catalyst near the reaction and the area above it that the H2 flows through would be more acidic). The reaction could stop if the availability of H3O and H2O would become too low, and at that point, the water would be more basic, because you wouldn't have sufficient free H+.

Splitting H20 also means a free floating oxygen atom which will eventually form O2 and produce waste heat.

The quantum efficiency is therefore likely a meaningless number in practice. Though it’s handy from a scientific perspective.

Also handy from a PR perspective. Although meaningless.

The caveat is that the portion of solar energy between 350 and 360 nm is very little.

They only tested in the range from 350 to 380nm [1]. With wave lengths under 370nm the efficiencies are quite high; at 380nm it falls to 33,6%. That could either mean that the catalyst works well with light at small wavelengths or that it only works at this specific range.

[1] https://www.nature.com/articles/s41586-020-2278-9

It's probably the same as with solar cells, where you need to match portions of the spectrum with appropriately doped silicon.

Looks like the paper referenced is from May, if you have a subscription to Nature: https://www.nature.com/articles/s41586-020-2278-9

If you do not have a subscription to Nature: https://sci-hub.se/https://www.nature.com/articles/s41586-02...

Nice, it appears that my parent's ISP is doing DPI and a MiTM attack to block Sci-Hub (and I do have a subscription to Nature).

Use the Telegram bot @scihubot, that will probably evade the DPI trap. Just send the DOI or the full article name to this bot and you'l either get a PDF back or a message about the article not yet being in the database.

my ISP's DNS resolver just returns NXDOMAIN for that.

     $ dig @ sci-hub.se. +short

what happens if you try the .st TLD?

.se is Sweden, I was surprised to see that they haven't taken down sci-hub.

sci-hub.st works here (Telekom in Germany).

Is it possible they are simply blocking DNS or the IP(s)?

MiTM should be impossible on HTTPS - if they somehow obtained legitimate certs for sci-hub , you should really announce someone at Mozilla and/or Google.

They appear to do deep packet inspection looking at the SNI and insert an invalid certificate from Allot, redirecting the connection to a very short "Vodafone can't show you this" website: https://pastebin.com/RHwPWBug

It appears to work with ESNI activated in Firefox. Interesting to see these techniques in use...

> Por causas ajenas a Vodafone, esta web no esta disponible

"Due to causes independent on Vodafone, this website is not available".

How so? This is plain false. I bet they do not even inform their customers that the connectivity service they sell is endangered by Deep Packet Inspection.

Virgin Media give you a message for blocked porn, but not the VPNs they stop you accessing.

It's quite insidious - the VPN blocks are textbook government overreach.

If we ever have a written constitution in the UK we need rules stopping the government fucking about with this stuff (As it seems to be the entropic end-state of all policy to protect the children)

That just means the decision to block the site was made by someone outside of Vodafone. Assuming they face meaningful penalties for noncompliance, I wouldn't consider it false. But it would be nice if these kinds of messages identified who is to blame.

Sometimes people use the phrase mitm loosely to mean sniffing SNI and then blocking the connection in some fashion.

Apologies if the usage is incorrect. They appear to indeed sniff the SNI and then inject a one-line website with a self-signed certificate: https://pastebin.com/RHwPWBug

Its still possible that instead they are just hijacking the ip space. You could probably distinguish by running traceroute. Or doing something like curl --header "host: sci-hub.se" -k (which should not send an SNI that can be sniffed but still send the corect host header inside the encrypted http stream so the connection would work minus a cert failure, but DPI by the isp wouldnt be able to detect. If that curl fails they are probably doing ip address hijacking. If domain-fronting request works then they are probably sniffing SNI)

Good idea! I tried the domain-fronting curl request and it works, so they seem to be indeed sniffing the SNI...

Thanks both for taking the time to acknowledge and explain the subtlety. Helps somebody like me who’s casually following along to better understand both scenarios.

That isn't true except for the case of cert pinning. This sort of MiTM (or redirection at the very least) reglarly happens from employers, isps, and many others.

ISPs can't deeply inspect TLS traffic. Employers of course can, because they can insert their own trusted certificates on their own boxes.

Now, if by 'inspect' or MITM in this case you are talking about inspecting the TLS headers, that's possible, and based on the other comments it is exactly what this ISP was doing - checking the SNI of the TLS requests and blocking based on those.

But an ISP that hasn't somehow broken TLS isn't in a position to check the encrypted contents of your packets (e.g. HTTP headers, bodies etc). Your employer can very well have installed a TLS MITM device that is trusted by your company-issued device to actually inspect the contents of your encrypted packets (by acting as a proxy - you actually have a TLS tunnel with the MITM device, and it has a separate tunnel with the TLS server).

Certificate pinning can block even these types of employer MITM inspection, and it can also protect from rogue CAs issuing ilicit certs. But if your ISP is in possession of PKI certs for google.com and outlook.com, then the CA that issued them will soon be removed from the trusted list.

You didn't read my comment that is right next to yours. Or the one that you replied to, where I mentioned cert pinning. You are repeating my comments back to me.

The device does not always need to have a special trust relationship with the client browser, since a trust relationship can already exist with FTU.

I'm amazed that my comment was downvoted on a tech board, where presumably people are informed about these things.

Of course TLS connections are regularly inspected. A simple google search will show you edge boxes you can purchased to perform this on your network. IT people know all about this. No, this does not mean that the cryptography used by TLS has been broken.

Which ISP do you use?

It's Vodafone Spain.

And the accompanying overview/summary: https://www.nature.com/articles/d41586-020-01455-w

Interesting news, but it should be noted that quantum efficiency is only a part of overall efficiency. 100% quantum efficiency means that for 1 photon of sufficient energy you get 1 split H_2O. But it doesn't take into account which part of sunlight would be usable (there will be an energy cutoff) and what efficiency at channeling sunlight photons onto the catalyst your setup will have.

Also, I'm missing the environmental conditions. If the process only works at >9000MPa and >9000K, it will be useless...

Other readers should not be discouraged by the above comment. Although it's disappointing to see this lazy skepticism as the top and longest lived comment.

For a serious paper and a serious forum, I think a comment owes it to that seriousness and its readers to carefully investigate before displaying contempt.

Under Methods:

Photocatalytic reactions

Photocatalytic reactions were carried out in an overhead-irradiation-type glass vessel connected to a closed gas circulation system. Prior to each reaction, all air was evacuated from the reaction system and filled with Ar (about 1 kPa unless otherwise noted). The suspension was subsequently irradiated using a Xe lamp (300 W, full arc). Evolved gases accumulated in the closed gas circulation system were analysed by gas chromatography (GC-8A, Shimadzu Co., thermal conductivity detector, Ar carrier gas, molecular sieve 5 Å column). The STH efficiency was measured under simulated sunlight irradiation (AM1.5G, 9 cm2 illuminated area, solar simulator HAL-320, Asahi Spectra Co.). The STH efficiency was determined according to the following equation

We can clearly see it is 1 atmosphere, and reasonably assume it's "ambient temperature" plus 300 W Xe lamp irradiation. And it mentions nothing about "sunlight" but we can get consider the light spectra from the lamp. Comments should in future refrain from being inaccurate and lazily put together like the above. I think this goes doubly so for revolutionary and energy type tech that can be radically transformative. Good comments should push brave new science into the light, not drag it down into the dark of existing confirmation bias.

Actually that comment was justified, because the article says that while the quantum efficiency is around 96%, the water splitting worked with ultraviolet light having wavelengths between 350 nm and 360 nm.

Only a very small fraction of the solar light is ultraviolet light, so the usable efficiency of such a device is quite low.

While this research result is very interesting as a demonstration of what can be done, it is very unlikely that this is a path that can lead to the best way of capturing solar energy.

Either multijunction photovoltaic cells or thermal devices can capture around half of the total solar energy.

If splitting water is desired, that problem can be solved separately, using electrical or thermal energy, and it should be able to reach similarly high efficiencies as with these photocatalysts.

The combined efficiency of the 2 processes should be still far greater than the efficiency of direct water splitting, which is constrained by the lack of enough ultraviolet light in the solar spectrum.

Is the wavelength restriction a blocker though? There's already use of quantum dot film to shift light wavelengths into spectrums more suitable for growing plants[1]. Theoretically shouldn't this be able to be used to shift a larger percentage of the light spectrum into the 350-360nm range, resulting in a far higher actual yield?

[1] https://ubigro.com/

Your example converts high-energy light (ultraviolet or blue) to low energy light (red). This process is easy and it can be done with quantum dots, as you say.

The reverse process of converting red light to ultraviolet light, as it would be needed for this water splitting, is far more difficult and it has much lower efficiencies, especially when the input light has a low intensity. (The common green-light pointers convert infrared to green, but that works because the input is a laser beam with high intensity, so that optical media can behave non-linearly, and it still has a low efficiency).

So no, wavelength conversion would not work.

The only thing that would work would be to replace their semiconductor crystal with one having a much lower bandgap, like the silicon, gallium arsenide or cadmium telluride that are used in photovoltaic devices.

However any such non-oxide semiconductors would be chemically unstable in contact with the nascent oxygen, so that would still not work.

I'm definitely going to reply, but right now I'm incapacitated thanks to beer.

Actually that comment [focusing on efficiency, asserting lack of environmental conditions, and saying it would be useless under hyperbolic conditions] was justified...While this research result is very interesting as a demonstration of what can be done, it is very unlikely that this is a path that can lead to the best way of capturing solar energy.

I think it wasn't justified, because of its 3 complaints, 2 were incorrect (the paper did include reasonable environmental conditions, and the process is useful), and the third omitted that the key to the paper was not its solar to hydrogen efficiency but a novel process that could show how to increase STH in more viable catalysts.

So in the contrary i think my description of the comment as lazy and skeptical was both justified and totally correct.

I have been chastised (rightly so) by dang for name-calling when referring to someone's pedantry. I resisted at first because I did not call the person pedantic, merely referenced their pedantry.

In this same way I see your wording as calling the GP "lazy" even though you did not use the specific grammatical form.

If your post is not too old by the time you see this, I suggest finding another way to word your message to get the same point across.

I think deleting the word lazy, deleting the 2nd paragraph, and deleting the 2nd part of the last paragraph would get the same point across.

I will certainly respond to this, however, I'm unable right now as I'm drinking a beer.

Okay, let me try your edit (deleting the word lazy, deleting the 2nd paragraph, and deleting the 2nd part of the last paragraph), and discuss below:

Other readers should not be discouraged by the above comment. Although it's disappointing to see this skepticism as the top and longest lived comment.

Under Methods:

Photocatalytic reactions

Photocatalytic reactions were carried out in an overhead-irradiation-type glass vessel connected to a closed gas circulation system. Prior to each reaction, all air was evacuated from the reaction system and filled with Ar (about 1 kPa unless otherwise noted). The suspension was subsequently irradiated using a Xe lamp (300 W, full arc). Evolved gases accumulated in the closed gas circulation system were analysed by gas chromatography (GC-8A, Shimadzu Co., thermal conductivity detector, Ar carrier gas, molecular sieve 5 Å column). The STH efficiency was measured under simulated sunlight irradiation (AM1.5G, 9 cm2 illuminated area, solar simulator HAL-320, Asahi Spectra Co.). The STH efficiency was determined according to the following equation

We can clearly see it is 1 atmosphere, and reasonably assume it's "ambient temperature" plus 300 W Xe lamp irradiation. And it mentions nothing about "sunlight" but we can get consider the light spectra from the lamp.

It's still very good, I grant you that. But i don't think it's as excellent as the original.

The reasons are i think it's important to point out what good comments should do and to point out the damage done by laziness of making authoritative sounding comments that don't accurately reflect and in fact misrepresent the subject of their commentary, and to accurately locate the comment in its proper context in this case and accurately describe what the comment is doing which is showing contempt.

I think these extra bits of information add to the accurate description of such types of comments, help people see the reasons why such comments are unhelpful to readers, are unworthy of their subject, and have no place on a serious forum. So i think the original is better suited to accomplish these various purposes than you edits.

I'll definitely make a reply here, but right now I cannot as I'm drinking some beer.

In this same way I see your wording as calling the GP "lazy" even though you did not use the specific grammatical form.

I get if you see this as the same, and, burned by your chastisement by someone, world like to see the same inflicted upon another to give you a sense of fairness or let you feel your weren't singled out. That makes sense, even tho I disagree.

So while I can't vouch for or against the views of others who would chastise, I get if you see this as the same as what you were alleged to have done, but it's not because I'm not calling anyone lazy, or skeptical. And i have no set opinion on whether the commenter is lazy or skeptical. Tho i don't think they are. However, i know very definitely how i feel about the comment, and that it just as i have said, and that is it's lazy skeptical.

If your post is not too old by the time you see this, I suggest finding another way to word your message to get the same point across.

No. I find the way i choose here is already the best to convey my meaning, which is why i choose it. So i think perhaps you have not grasped the meaning there, which is okay, because everyone will for their own interpretation as a function of who they are at that moment. As an aside, possibly one thing in your way of seeing the meaning, and the correct form for that, is your previous experience, which you have narrated as negative, of being chastised.

So while I appreciate your suggestion which I see merely as trying to improve as you see it the tone of commentary on this forum, I have to reject your suggestion. And I hope you can respect that. Ultimately i think we're both trying I think to do the same thing.

Thank you for sharing some of the environmental conditions of the test.

I do remain curious how this might generalize to real-world efficiency...

Sorry the "1 atmosphere" should be "1 kPa" which is about 0.01 atmosphere. I didn't remember my chemistry units. Still, something you can get to with a normal vacuum pump in a lab.

Where did we get 1 atmosphere/101kPa from?

The comment you replied to did not "display contempt." It pointed out a caveat for quantum efficiency, and that the linked article did not mention the environmental conditions.

You could have contributed constructively, but you chose instead to bring down the tone. It is your comment that is not appropriate to a "serious forum."

But the linked article did mention environmental conditions, justifying the "lazy" criticism.

But you did bring down the tone in an otherwise excellent comment. Assume good faith, please.

I assume it was in good faith and that he didn't read the article. Lazy and good fatih aren't in odd.

Commenting on another commenters comments as "bringing down the tone" in regards to their comments about another commenters comments "displaying contempt" is what really "brings down the tone" for me.

Thing is I at least didn’t see the top post as bringing down the tone. They posited questions as folks here do and added to the topic. I for one would not have even known what to ask without the top comment.

You assumed a lot of negativity and bad intent from the person and what they wrote that I didn’t see.

HN isn’t meant to be a cheer squad for anything new, IMO. It’s meant to be a forum for folks to discuss and people will have differing reactions but so long as they add something interesting, the comments are welcome, again IMO.

Your comment is childish.

I would love to reply but I'm not capable right now, just relaxing and having some beers. I'll definitely get back to you tho!

I think you need to look up the meaning of contempt, because the comment clearly displayed that. First by failing to investigate and accurately represent the subject, then by positing it to be useless under supposed and inaccurate hyperbolic conditions.

Unfortunately for you in this case your claim is not supported by the facts.

But i can say i felt it was pretty funny.

I mean ..Wow. I wasn't attacking you, I was attacking the comment. And you could have acknowledged the mistake of the original lazy and skeptical comment, or owned your own inaccurate description, but instead you choose to doubled down and tried, and failed, to attack me. And others. Well played.

The "I can't stand being wrong. Ever" look is not great for credibility. Just FYI.

And you do so, while pretending you are good and see something bad, while I attack comments and not people.

You could have contributed constructively, but you chose instead to bring down the tone. It is your comment that is not appropriate to a "serious forum."

Unfortunately for you, this is not the case. I contributed constructively. Your choice was to project your own intense unresolved issues of feeling criticised onto this unrelated discussion, and are blind to my excellence of my contributions because of that.

So, it's funny that, it's you, not i, who brings down the tone. Your trying to attack people without justification, and make this thread some twisted outlet for your unresolved mess, are your contributions.

It is clearly your comments, not mine, that are grossly inappropriate, both for this serious forum, and for any good interaction between people. For 2021, please reform yourself instead of pretending others are bad and trying to attack them as an excuse to avoid facing your own issues. That will be the best thing for your path and your karma i think. Try to make 2021 the best, not the worst, year of your life.

It appears to be good science, but lousy engineering. To be fair to the original, the whole 'this research will save the planet shtick' is pretty much boilerplate for any paper[0].

Photocatalytic H2 production will never be practical vs even boring old solar->electricity->Water-splitting. Literal acres of catalyst and transparent plumbing are not cheap or maintenance free, never mind that a hydrogen 'farm' producing mixed hydrogen and oxygen will make the Hindenburg look like a tea candle in comparison.

re the conditions: the energy cutoff appears to be at around 370nm, so it essentially operates under UV light only, at atmospheric to a few bar pressure and close enough to room temperature.

[0]e.g. Every nanotechnology paper is going to claim to all but revolutionize one or more of: drug delivery, cancer treatment, materials science, or my favorite, lithium batteries. Nine times out of ten though they are just taking <insert metal> and making <insert shape>: something which is useful to know how to do, but not typically revolutionary.

Too add: In materials research the term quantum efficiency, QE, implies that there are other efficiencies to consider.

E.g. in the OELD space, it is talked about that the materials developed have near 100% QE. This is useful terminology because researchers know that there are other efficiency losses that need to be improved on, and that this one can now be considered ‘finished’ (although, some even look at other effects to try to go above efficiency ‘maximums’ that appear fixed at first glance: https://news.mit.edu/2019/increase-solar-cell-output-photon-...).

Note: For OLEDs, although the QE is high, the light output efficiency is not very high due to internal light guiding effects.

As it stands, I don't see how hydrogen proponents in either vehicles or energy distribution can recoup the head start of pure electric. The best electrolysis + fuel cell cycles commercially available are maybe 35-40% efficient (electric-electric). Maybe someday, 20 years from now, some quantum catalyst gizmo will push that to 90%. For vehicles you then need another step of compression to force the hydrogen inside a very high pressure tank - by the laws of thermodynamics this can only cost you energy regardless of any technological advancement.

Meanwhile, electric batteries today are over 90% eficient on the whole charge-delivery cycle, the industry is rapidly gaining momentum, charge networks are built, the cost of components only goes down. Compared to hydrogen, battery electrics are today where internal combustion cars were compared with electrics 100 years ago: the market has spoken and the massive economies of scale of the winner will relegate the competitor to very specialized niches.

And once you lose the hydrogen vehicles, the whole distribution network becomes a very dubious business proposition. Why build H2 pipes that need expensive and inefficient electric conversion endpoints, when you can rely on and extend the existing electric distribution networks? Indeed, you can store hydrogen, but what advantage do you have by storing it closer to the consumption point, instead of a grid connected hydrogen battery that generates, stores and consumes hydrogen as requested by the smart grid? In that scenario, hydrogen becomes just one of multiple competing energy storage technologies, together with pumped storage, grid connected batteries etc., all together helping to regulate intermittent renewables.

Real Engineering did a video about this and committed the same fallacy. Engineers nearly always overlook practicality and chase perfection.

Heres the thing: It's not about efficiency, it's about convenience. Transferring 2700 megajoules of energy to an f150 via gasoline in a few minutes is very convenient, something that would take a Tesla a few hours. If consumers were concerned with efficiency the same way engineers were, we'd all be driving electric hummers and cybertrucks.

Hydrogen isn't aiming to be as efficient as batteries. It's assuming to be as convenient as gasoline, but with little environmental impact.

Except that as we keep trying to point out, 90% of EV charging occurs overnight at home, or at work during the day. Yes, that does not cover all cases for all people, but it covers a large part and the scenario people keep bringing up is the exception to the rule that would only take place if people were on road trips or there was no charging at their residence or work.

Obsessively talking about charging times is a frame of reference influenced by decades of driving ICE vehicles. And frankly the hydrogen vehicle thing also seems like it is heavily influenced by this mindset as well.

I can't make or fill gasoline (or hydrogen) at home. After years of "refueling" my Volt this way, I'd have a hard time giving up my "gas butler" that gives me a full "tank" every time I leave my house, and having to return to going to gas stations sounds highly unpleasant and very inconvenient.

> Except that as we keep trying to point out, 90% of EV charging occurs overnight at home, or at work during the day.

This isn't a good comparison at all. You're looking at the set of people who looked at the operational requirements for EVs and said "yes, this works for my needs" and then looking at how those needs are met. What you would really want to do is compare the operational requirements for EVs and the general usage of motor vehicles to see what proportion of the general usage of motor vehicles can be replaced by EVs and their operational requirements.

EDIT: Even further, you would really want to know about the value of different modes of usage as well. So, for example, it is possible that users value edge case usage (such as very long trips) much, much higher than they do day-to-day usage and so still you could meet 90% of general motor vehicle usage with EVs at the same convenience but if the remaining 10% was far more valuable to end users and the inconvenience too high, it might still not be reasonable.

People don't know what they want. The fact is, the infrastructure for renting gas vehicles for long drives is already in place, and 99% of driving is short and local.

Thinking about "how much users value x" based on the CURRENT PARADIGM is a constraint to progress, and doesn't help predict very much at all. Consumer habits change.

> The fact is, the infrastructure for renting gas vehicles for long drives is already in place, and 99% of driving is short and local.


If you are going on a long trip, renting or renting plus flying is likely best. If you are traveling 1200 miles, do you really want to drive for 20 hours solid? I've done it and it mostly sucks.

Except now your back to using fossil fuels again.

This is the big problem pro-BEV people are missing. If your goal is to reach 100% green transportation, batteries will never get you there.

> If your goal is to reach 100% green transportation, batteries will never get you there.

When you pose every problem as an absolute, it's impossible to come up with a solution for anything.

I'm not one to make perfect be the enemy of good. If 99% of driving is EV and 1% is ICE then we have a much smaller problem to deal with.

Not long ago, people predicted EVs would never get to the point they are now. The picture will be entirely different in 10 more years. By the time we've replaced the first 90% of ICE vehicles, the solutions to the last 10% will become more obvious than they are now.

The problem is that fuel cell cars really can take you to 100% green transportation. This is a problem that can be avoided entirely.

Nobody seriously expects to get to 100% green anything. Getting to 95% provides all the benefit anyone rationally hopes for. Squeezing out the remaining few percent is not worth the extra cost, much as getting the last bit of toothpaste out of the tube is not worth the bother (unless you are indulging obsessiveness).

People seriously expect fuel cell cars to allow for 100% green transport. Only from a BEV context do you talk about figuring out the last 10% or whatever.

I’m significantly more interested in saving the planet for my child than I am in driving a car with a specific powertrain. I’m pro-BEV because it seems to be a good way to move in the right direction. I drive an ICE VW but will move as soon as it makes sense to.

When I need a 4x4, I rent one.

Are pro-BEV people actually missing this? At least for now, the goal is only to remove some of the more significant sources of pollution. Vehicles for personal transport are a reasonable place to start. Obsessing about perfection is only going to hold us back.

I think the point made here is that those very requirements are tailored around a ICE world. If, say, your city bus network is designed so that each driver can make a 5 minute stop at terminus and fill up when required, of course pushing an electric bus into that will create 1-2h gaps in service and be "not fit to operational requirements". But it's a simple exercise to shift things around so that all recharging is done in low demand periods and all your fleet is online during rush hour.

The bottom line: electrics are quickly overcoming the 1000Km/charge barrier, in the next 10 years it will probably become the norm. That's a charge level that can last you a full day in almost any conceivable usage mode, so it can cover 99% of real world tasks.

Sure, there will still be very specialized tasks where 2 hours of downtime per day is unacceptable, or some fresh produce delivery route that requires 36 hours non stop driving by a shift of truckers. But that would be negligible in the grand scheme of things.

The other possible option to work around range issues with electric vehicles is to electrify our major highways so that battery capacity is no longer a concern. That would require expensive infrastructure upgrades and new standards for how to charge a moving vehicle, but it would mean vehicles could be substantially lighter and less expensive.

>36 hours non stop driving by a shift of truckers. But that would be negligible in the grand scheme of things.

Can you elaborate on why you’d consider trucking to be a negligible edge case? What I could find online shows it’s over 40% of commercial miles and over 60% of transport for delivered goods.

You left out this important qualifier in your quote: "[...] some fresh produce delivery route that requires 36 hours [...]". yholio was talking about a particular niche case, not about trucking in general.

Ahh, ok, I read it as two separate cases (produce delivery and long haul trucking). Thank you for clarifying

Trucking is 40% of commercial miles. Most trucks are parked for hours/ day so the driver can sleep. It'll be interesting seeing how this changes as autonomous driving becomes more common.

Some trucking companies are using a “local” model where a driver will drive 4 hours one way, drop off the trailer to another driver for the next leg, and pick up a trailer to drive back home to be more efficient

> So, for example, it is possible that users value edge case usage (such as very long trips) much, much higher than they do day-to-day usage and so still you could meet 90% of general motor vehicle usage with EVs at the same convenience but if the remaining 10% was far more valuable to end users and the inconvenience too high, it might still not be reasonable.

How much do you weigh the inconvenience of being 10 minutes late for an appointment because you had to make an unplanned fuel stop?

How much do you value 100s of unneeded fuel stops interrupting your life?

Fortunately, it's not necessarily an either/ or. You can buy an EV for 99% of driving and just rent an ICE car when you need to road-trip.

Totally. I’m not taking a side here. I think it’s a really complicated issue. I’m excited for EVs and optimistic about their future but we have to be real about trade offs when considering other possibilities.

> This isn't a good comparison at all. You're looking at the set of people who looked at the operational requirements for EVs and said "yes, this works for my needs" and then looking at how those needs are met. What you would really want to do is compare the operational requirements for EVs and the general usage of motor vehicles to see what proportion of the general usage of motor vehicles can be replaced by EVs and their operational requirements.

The vast majority of journeys and days overnight charging of a tesla style car is fine. The average driver

1) Spends 55 minutes a day behind the wheel

2) Drives 29 miles a day


"93% of all vehicle-days show a total distance below 100 miles. It is important to note that only vehicle-days are included where the cars were used that day"

A car with a 300 mile range covers almost all drivers for almost all uses.

So you're down to whether the downsides of owning and operating a gas-fueled car outweighs the downsides of an electric car (having to hire a gas one for occasional long trips)

As more and more people move to electric, there are fewer and fewer customers for gas stations, reducing the number around, and reducing the utility of a gas car even more. The costs of repair become higher, and the cost of the car in the first place will increase as economies of scale tip the other way.

> A car with a 300 mile range covers almost all drivers for almost all uses.

Depends on charging options. If you can charge overnight at home or at the office, then yes. If your only option is spending a long time at a charging station away from home / office, an EV suddenly requires planning.

Thankfully there's more and more public chargers in or near residential areas around here.

> What you would really want to do is compare the operational requirements for EVs and the general usage of motor vehicles to see what proportion of the general usage of motor vehicles can be replaced by EVs and their operational requirements.

Okay, has this been done by anyone? Something that shows current limitations of the infrastructure and projected mitigation of those?

A quick Google search doesn’t find anything official from NREL or similar DoE labs, but I’m mobile so my search is quick and not comprehensive.

The average American round trip commute is under 40 miles. Longer commutes can be accommodated with financial incentives and legal requirements for employers to provider EV chargers on prem (with pass through billing for the power, or providing it for free). Anything beyond that (high daily mileage outliers) are served by long range EVs and Fast DC charge networks.

I could see an interesting appeal in focusing on getting to a 1-hour or 30-minute charge time. because that allows for some structural changes to an entrenched business model.

The current gas-station/convenience-mart ecosystem is designed around a 5-minute or so petrol fueling cycle. There's nothing they offer that will keep you productively occupied for a hours-long charge cycle.

A 30-minute or hour charge cycle, in contrast, is long enough to perform errands-- I could see a large number of supermarkets, strip malls, big-box shops, and restaurants interested in offering 1-hour charging stations. You can offer cross-promotions (spend $100 in store and your charge is free) and you have captive customers who are likely to wander the aisles a bit longer/order an extra coffee or dessert if they know they need to wait another 10 minutes for their charge to complete. Maybe the no-garage apartment dweller does his charging when he goes for his weekly grocery run.

Love it. The same for motels, roadside attractions etc. Once a sizable fraction of motorists require it, businesses will bend over backwards to provide it subsidized, to acquire customers for their main cash vector.

And electric is intrinsically democratic, if you have civilization you have electric power around. Some upgrades will be required but from a single business' point of view, the investment is much lower than building underground fuel storage tanks, obtaining the necessary environmental and zoning permits etc. Literally anyone can enter the charging market.

Fast charging is also arguably the least environmentally concious way to charge any electric vehicle.

A) fast charging causes battery degradation at least 3-5x as fast as charging at or below the nominal "C" rating of a given cell or amortized individual cell rating. This means, in the next 10 years, more batteries have to be produced, more lithium has to be mined and more Tesla parts have to be shipped on diesel powered vehicles. [0][1]

B) it uses more power and places more demand on the grid, hence you're burning more coal in order to meet the demand curve and incur a larger transitional period in production which means more fossil fuels burned, more energy lost to conversion and at the end of the day more Co2 in the air. [2]

0 - https://cleantechnica.com/2017/07/09/tesla-limiting-supercha...

1 - https://cleantechnica.com/2020/01/12/is-it-true-that-a-tesla...

2 - https://afdc.energy.gov/files/u/publication/ev_emissions_imp...

Yes, EVs are a great 99% solution. The problem is people aren't willing to own a second car to take care of the other 1%, so they need their car to be a 100% solution. Most of my friends take weekend road trips to camp or visit friends in other cities, and EVs just aren't capable of those use cases yet.

No car ever made is a 100% solution, and many people do own multiple cars already.

Most people with two cars actually drive both cars every weekday. If one of them is gasoline, then you're replacing half of their gasoline consumption instead of all of it.

What those people will not do is buy two electric cars plus a gasoline car for their 1% needs. Many people also would rather not hassle with rentals on a regular basis.

But in fairness, it'd be great progress just to get to the point where most two-car families choose electric for one of them, and by the time that happens, batteries will probably be a lot better anyway.

Yeah, I think EV adoption will stall out for a long time at around 50%. Families will have one EV and one gas vehicle. That covers all their needs; two EVs won't. And the gas-burner will get used just as much, since both parents need a vehicle.

The idea that people will rent vehicles for those longer trips is a bit untethered from reality.

By your reasoning they only need the rental 1 percent of the time. A lot of people use Uber more than that.

My own car is only a 20 percent solution. The rest is walking, biking, and public transit.

Uber is very convenient. Going down to the Enterprise office and filling out paperwork to take a drive out of state, not so much.

Obviously I'm not actually claiming any particular percentage, since that varies by person.

I'm surprised nobody does a product that's an EV lease plus some prepaid credit every month for a rental service, so for the one day a month you need a conventional petrol car, it's already budgeted for.

Hell, you could generalize it to small petrol cars too. I suspect most of us "overbuy" larger and more capable vehicles for the one day a month we need something bigger than a Mirage.

This is 100% false and hasn't been true for a long time.

A Tesla can easily take a road trip the same as any ICE vehicle. I've personally driven one across the country. Supercharging along the way now takes the same amount of time as any normal stop for gas.

EVs are already better than a 100% solution because electricity is far cheaper than gas and you can fill up at home.

Maybe a Tesla can make a trip in the same time as an ICE, but only if you normally stop frequently. I'm a "drive straight thru" kind of person, and road trips in my Telsa frustrate me.

A few times a year, I make a ~950mi drive in my 2017 MX 100D (~295mi rated, ~220 maybe at 75 mph). In an ICE car its 13.5 hours of driving, and about 4.5 hours of charging. I frequently find myself wishing I owned an ICE car when I'm on the trip. Especially when the weather is cold, and I'm debating the range impact of turning the heat on vs 12 more hours of not being able to feel my toes. Or when the supercharger is busy and it ends up taking 2x as long to get from 5% to 45% because I'm sharing... or the anxiety of trying to make it one more charger to be able to save time by charging 2% -> 55% rather than 12% -> 65% (to avoid charging past the taper..)

I'm hoping the new models coming with 500 or 600 miles of range improve this. I'd probably only need to charge 3 times.

You need to develop a relationship with a car rental agency. And maybe an airline or rail carrier. You are putting a lot of miles on your car, reducing its value unnecessarily.

That seems unlikely to work out in their favor, if for no other reason than that car rentals turn a profit on top of depreciation and a ton of other overhead, and the cheapest rental cars are only a few times less expensive new than their Tesla.

As a ballpark estimate, each such trip would cost at least $50 after taxes and fees for a budget car rental (ignoring gas vs supercharging or any other fees that would be incurred in both situations, assuming there aren't one-way fees, etc). After 100 such trips you'd have paid $50k in rental fees, vs simply having a Tesla with an extra 100k miles. Resale value is a nonlinear function of a lot of variables, but linearizing a few portions of the parameter space for the current market an extra 100k miles would only devalue the car by at most $16k (less if they intended to hold on to it for a few extra years instead of selling it immediately while the mileage depreciation matters the most).

What they said was "a few times a year". Rounding up, that would be 25 years. In a few years, there will be plenty of electric rental cars and charger stations, and the batteries will be much better.

Right now, the most expensive wear in a Tesla is battery cycles.

The point wasn't that it works out in their favor if they make a ton of trips but not if they make a smaller number. Those figures were approximately a best-case cost for the rental and worst-case cost for mileage-induced depreciation at any point in the depreciation parameter space. If they only added 10k miles then they'd incur $5k or more in rental fees and $1.7k or less in mileage-induced depreciation by the above math.

I did misplace a zero though for what it's worth. A budget rental would only cost $500 or so over 10k miles, not $5k, if they're making the entire trip in a single day and returning it to the same place they picked it up. If that's the case the budget rental would probably be worth it financially (unless they were planning to hold the Tesla for awhile so that it hits a more favorable point in the depreciation curve), and if not then the extra rental fees are likely such that especially counting gas vs supercharging it's approximately a wash one way or the other.

I’ve owned three Teslas and I can tell you that road tripping isn’t at all as convenient in a Tesla as an ICE.

I agree, though I'd concede that we enjoy taking the Tesla on road trips because our kids are young. Stopping at the McDonalds next to the supercharger for a restroom break, sometimes lunch, or a romp in the play area for half an hour works really well for us. If our definition of roadtripping was drive-pee-drive-pee-drive-pee-drive with no real rest stops, it would definitely be faster to take our pickup (the only gas vehicle we have left).

I can tell you quite definitively that a tesla with the maximum range possible will still not be able to get you to and from a great deal of small cities and camp grounds in the US, especially if you live outside California.

If you can afford a Tesla, renting a car for 1 week a year isn't a big burden.

Yet another reason EVs aren't the dominant market yet.

Likely the single biggest reason.

I'd suspect the fact that not everyone has a convenient place to plug in overnight would be a pretty major factor. A good percentage of city dwellers in particular park their cars on the street, away from their home.

>Except that as we keep trying to point out, 90% of EV charging occurs overnight at home

Most people don't buy vehicles for 90% of the use-cases. They buy something that does everything they normally expect a car to do, which includes a long road trip every year or so. Maybe driving to a favorite campground 200 miles away, etc.

The reason people keep bringing these scenarios up is due to the fact that electric cars are terrible for these cases. Nobody is suggesting they can't be used for daily commutes.

Right now electric cars are for people who can afford to also own an ICE or rent an ICE for road trips (or who don't like road trips at all).

Just look at the number of pickup trucks there are, with empty (even pristine) beds. Nobody is hauling stuff most of the time, but they got a vehicle that can.

I think EVs make a great second car. I drive a Tesla, my wife drives a Bolt, and we have an F250 for towing the travel trailer, hauling household stuff around, or going somewhere that charging infrastructure is going to be inadequate (haven't really run into that yet, but the pickup is our catch-all). I can't see going back to ICE cars as daily drivers, but it'll be quite a while before we don't have at least one in our household. Especially as long as we continue to own the RV.

so, to save the environment, everyone get two cars.

Or, rather: a small enthusiast minority gets two cars, generates the critical mass required to build charging infrastructure etc., then everybody can switch directly to an electric when it becomes convenient for them.

I would use a lot more fossil fuel if I used the pickup as a daily driver. Getting an EV as a second car is the sensible choice.

It's an emotional decision, but even with that - well under 20% of vehicles sold in the US in 2019 are trucks


Yep, well, this is why I drive a Volt and not a Tesla. The EV portion of it covers 90% of my use cases, and then I have the ICE to fall back on if I need it, which I do once in a while, mostly for ski or camping trips to places that will probably only ever get charging infrastructure in like... 20 yeras.

Too bad GM killed it from their line-up.

The Honda Clarity plugs the hole left by the Volt pretty nicely. And last I checked it's still eligible for the full federal phev rebate.

But there are a few caveats:

- The power to charge the EV is drawn from the grid

- Batteries are heavy, so you cannot scale up batteries for range

- These batteries require a lot of lithium mining

Given these, I would definitely prefer the hydrogen solution.

- The grid where I am is 90% non-CO2 emitting; nuclear and hydroelectricity with natural gas supplimenting it. We phased out the last of the coal plants 15 years ago. More places should, the air quality in the whole province improved markedly after.

- I drive a car with a small 14kWh battery, and a backup ICE for when I need it. 90% of my miles are electric. I don't understand why this model isn't more popular. I see no need to drag around a 60kWh battery "just in case" I need that extra range.

- Lithium isn't the huge environment/social problem really. Basically big evaporation ponds in desert areas. There's even some work being done to pull lithium out of abandoned oil wells in some locations. Some of the other components are a problem, such as Cobalt in some formulations. But all these formulations can be played with. And they are one-time for the whole vehicle, rather than requiring continual extraction. And can be recycled. Can't recycle petroleum or hydrogen.

Meanwhile the only practical sources for producing hydrogen require fossil fuels, typically natural gas, and end up emitting CO2. Emitting CO2 is not necessary for EV usage. But most practical sources of hydrogen do. And the efficiency is far lower.

There is no fundamental physics reason to use lithium, it's just the current best technological node. There are many technologies that are very promising in the lab, like carbon nanotubes, iron and sodium ion, aluminum-air etc. There is massive research in this area and if none of these technologies turn out to be economically superior to Li-ion in the near future, then they will certainly be available if, for environmental reasons, lithium becomes expensive.


It’s times like these that people should realize that fuel cells are a type of battery. You can call them hydrogen-air batteries.

That's not really accurate since the "electrolyte" changes phase requiring external storage (H2O -> gaseous H2) and the re-oxygenation step cannot be performed (yet) in the same device as the electrolysis.

It's not an electrochemical battery but I can agree with seeing it in a general sense as the an energy storage device, in the same way a dam is a "gravitational battery".

You can perform both steps in the same device. It's just more efficiency to have a dedicated electrolyzer doing that elsewhere.

Problem 1) Many people don't live in houses. Problem 2) Free charging at work or elsewhere ends once a significant share of people utilize it Problem 3) electric grid can't handle the amount of capacity needed, not by a long shot.

If petroleum didn't already exist we'd be trying to create it.

There are quite a few urban areas with single occupant houses but without driveways. Most people wouldn’t want to install a charger out in their parking strip, on general principle - too exposed. Running high current wires out into the front yard and under the sidewalk would also be a mess.

And that’s all ignoring the fact that the city owns the parking strip, not you, and I don’t think they’re going to be interested in having that kind of equipment in their space.

> I don’t think they’re going to be interested in having that kind of equipment in their space.

Aren't some cities (LA comes to mind) installing level 2 chargers along the street?

That's a good point. I think it's qualitatively different for a city to decide to build charging stations on 'their' property versus a private citizen.

There's also no guarantee they'll put it in front of my house. Or if long-term that's what I want (now I get home from work late and some other EV is parked in front of my house? How do I feel about that if I have an early meeting tomorrow?)

> If petroleum didn't already exist we'd be trying to create it.

You are forgetting about the power of NIMBY!

If gasoline weren't already a vital piece of infrastructure, nobody would allow a gas station to be built in their neighborhood. Any time someone tried to build one, the pile of litigation would bury the prospective builder. This is already an issue and our society has largely taken the risks of having (literal) toxic waste at the end of their block.

NIMBY like that is only a problem in a specific environment. My gas station is 5min drive away, which in practice means out of town. Even bigger cities around here have more industrial/commercial areas. It have the gas stations attached to shopping centres. So I don't think NIMBY would affect the introduction of petrol.

> that would take a Tesla a few hours

Even with "version 2" superchargers, this is not true. With 250kW (v3) charging, you can get to a sufficiently high state of charge (>80%) in under 30 minutes. And the thing is, given how efficient an EV is, you don't need 2700 mega-joules (20 gallons of gas or 750 kWh) to go ~500 miles. The Cybertruck will do that range to with ~100-150 kWh of battery and charge up in under an hour. This will probably get faster over the coming year as charging rates go up.

And like another comment pointed out, majority of charging happens overnight or during the day when the car sits idle. I own a Model 3 myself and I have not been to a supercharger in several months.

20 gallons of gas still only takes 5 minutes to fill. If I can get 125 KwH in 30 minutes with your v3 charging that's still a 6x multiplier, not really something you can ignore.

Now you need bigger charging stations because people are spending longer at the pump or else you'll have longer lines. Adding to that, I sure as hell am not spending half an hour at a pump on an already long road trip.

The lack of population density in the US, especially in the middle of the country, makes electric vehicles not a great choice for many people. I'm guessing this is why we see higher adoption in Europe on a consumer and infrastructure level.

I live in Iowa. It's about as "middle-of-the-country" as it gets. Lines at charger stations are really a California problem as of now. I have never encountered it driving throughout the midwest and I have gone on some long road-trips.

As for taking 30 minutes to charge, what people usually do is to make sure their charging stops line up with food/bathroom breaks. Realistically, if I drive 10-12 hours in a day, I would stop about 3-4 times for food/bathroom breaks, if not more. This lines up perfectly with the range in my Model 3 AWD. In many cases, I have ended up having to get up and go get my car to avoid idle-rates because it finished charging while we were still eating.

On these trips, I usually pick a hotel/B&B with destination charging so that I can get going in the morning the next day with a full battery.

The "6x" is a number to ignore, because it's focused on one tiny part of the trip. If you can drive all day long with 1 stop, then the extra 25 minutes only makes you a few percent slower.

This is a point that needs to driven home.

Yes, filling up gasoline delivers energy at an insanely high rate due to its density but the vast majority of that is wasted and not converted to miles driven.

The real comparison is miles of range delivered per minute of fueling. And a Tesla supercharger is already competitive with gasoline by this metric. If hydrogen takes longer than gas to fill up a tank for a similar range then its already behind just charging directly.

> Hydrogen isn't aiming to be as efficient as batteries. It's assuming to be as convenient as gasoline

And it won't be. H2 is terrible for convenience of handling compared to gasoline. Handling liquid H2 is a nonstarter, it liquefies at 21 K at atmospheric pressure; cryogenics like that are not convenient at all. Gaseous H2 will escape through every tiny gap in whatever containment setup you choose, plus it's highly flammable, much easier to ignite inadvertently than gasoline.

And to top it all off, at the end of the day, its available chemical energy per unit mass is only two to three times that of liquid hydrocarbons. That's simply not enough of an advantage to overcome all the downsides.

What H2 can be used for is to make liquid hydrocarbons, through various chemical processes.

Hydrogen is also notoriously low density, even in liquid form. It embritles metals on contact. Hydrogen fires are invisible during the day (if you see rocket engineers walking around with broom pointed forward in front of them, that's why).

Personally I count on hydrogen for high energy space propulsion (either chemical with oxygen or alone in a NERVA for NTR) as otherwise it's IMHO too much of a headache to work with in practice.

It doesn't just escape through tiny gaps. It's small enough to permeate through any material we use to contain it.

Using electricity usually is even more convenient, since you can do that at home, and very few of us have gas station in the garage.

I charge my electric Hyundai with a normal power outlet, and every once in a while I fast-charge it. 99% of the time that‘s good enough already. If we‘re going by convenience, plugging in at home is probably more comfortable than driving to a gas station, waiting 5 minutes, paying, and driving back.

> Heres the thing: It's not about efficiency, it's about convenience. Transferring 2700 megajoules of energy to an f150 via gasoline in a few minutes is very convenient, something that would take a Tesla a few hours. If consumers were concerned with efficiency the same way engineers were, we'd all be driving electric hummers and cybertrucks.

There are 2 types of convenience.

- Being able to fuel up quickly on a long trip

- Having your fuel tank full at the beginning of every single trip.

Hydrogen fuel cells (and combustion engines in general) are better only for the former case. Since most people drive less than 300 miles most of the time, it's hard to argue a car optimized for longer trips is more convenient for most drivers.

75 kWh doesn't take a few hours with a supercharger. Doing similar with hydrogen is probably a similar level of infrastructure.

> Transferring 2700 megajoules of energy to an f150 via gasoline in a few minutes is very convenient, something that would take a Tesla a few hours.

A 75% charge can happen in ~20 minutes on something like a 250kw Telsa super charger. Battery tech and battery charging tech will only get better/faster. Also the vast majority miles driven on the road aren't "road trip" miles in which you would see the drive-to-fuel/energy exhaustion over and over for days on end scenario. When a Tesla plugs in at home and charges over night, that's actually more convenient than having to go to a gas station.

and economics. If I can make an H2 vehicle for less than it cost me to make a gas or electric vehicle, it's worth my time and money to push into or even create a market that'll buy them.

>Heres the thing: It's not about efficiency, it's about convenience.

>Hydrogen isn't aiming to be as efficient as batteries. It's assuming to be as convenient as gasoline, but with little environmental impact.

Energy conversion efficiency is pretty important for that "little environmental impact" part.

Also, it’s not just an option for passenger vehicles. Natural gas can be replaced with hydrogen in the existing pipeline network, providing distribution of heating gas at extremely low cost and with a very minimal investment in retooling of existing furnaces.

Aside from blending small amounts on hydrogen in existing methane feeds, no one will do this. Pure hydrogen is a dangerous gas that burns much hotter than methane, can seep trough the tiniest of cracks that methane/propane cannot and can even penetrate the crystal lattice of common metals such as steel, leading to embrittlement and catastrophic failure under normal use. By the time you upgrade the methane infrastructure to handle it, you will build a whole network all together.

And there is also an economic argument: methane/propane work because they are pure energy coming from the ground, you can only burn them to recover it. To produce Hidrogen, you need electric energy, or some very hot source that could be turn to electricity at a high efficiency. It makes zero sense to generate hidrogen in order to burn it for domestic heating, when the equivalent electric energy could give 3-5 more heat using electric heat pumps.

It looks like you can blend something in the neighborhood of 10-15% hydrogen into the existing natural gas infrastructure without negative consequence. That's not game changing, but it's a significant environmental improvement if you're using renewables to produce it. It's a fine way to utilize daily or even seasonal renewables overproduction in a useful way without blowing up tons of existing infrastructure. Many diverse steps - some small, some large - are needed to get ourselves to a carbon negative lifestyle.

> Aside from blending small amounts on hydrogen in existing methane feeds

What's "small"?

20% hydrogen on existing grid in place now: https://www.theguardian.com/environment/2020/jan/24/hydrogen...

100% hydrogen trial over next few years: https://www.msn.com/en-us/news/technology/scottish-homes-wil...

Hydrogen has suddenly skyrocketed up the agenda in Europe this year. There is a pressure group called Hydrogen Europe (which oddly doesn't even have a wikipedia page) which comprises companies like BP, Shell, Total, Equinor, Repsol, Engie, OMV, PKN Orlen, Hellenic Petroleum, and many more. At the same time almost 100% of hydrogen used in europe comes from oil.

It concerns me how much government subsidy (both cash and regulations) is being pushed into hydrogen.


"Hydrogen companies were given a boost this week after the Prime Minister vowed to inject £500million to 'turn water into energy' as part of a 10-point plan for Britain's green recovery.

However, critics say the targets are nowhere near enough compared to Germany's and France's respective plans to invest €9billion and €7billion in hydrogen."

Everything has gotten subsidies in the past. Coal got it in Germany, Spain, Rusia,Poland, Norway and of course England. Places like current Bangladesh supported coal mines in England.

Certainly oil got it later, but few places in Europe had it compared to coal. Refineries grew costing lots of billions.

Then natural gas got it with the investment of big gasoducts.

Then it was renewables. Hydrogen is just the next step, because it is the cornerstone of the chemical synthesis process, not just transportation.

Hydrogen and electricity are just "vectors". They let you use coal,gas,nuclear, hydro or Eolic power to power your cars and trucks with much less dependency on US controlled oil for industry and transportation.

> Aside from blending small amounts on hydrogen in existing methane feeds, no one will do this.

The province of Alberta, Canada has put hydrogen at the core of its energy development strategy. The idea is to use existing natural gas pipelines to transfer hydrogen.

It’s true that a small fraction of hydrogen will permeate the pipes and leak; however, that leakage is not economically significant:

“... this theoretical distribution main leakage rate (43 million ft3/yr) would be 0.0002% of the 24.13 trillion cubic feet of natural gas consumed in 2010.” [1]

Hydrogen can be blended with natural gas (the above calculation was made assuming a 20% blend) or it can be sent down the line exclusively. As for how the hydrogen is produced, there are several ways:

1. It can be cracked from natural gas, after which the carbon is captured and stored back underground. Or,

2. It can be produced from electrolysis of water using energy from a renewable source such as wind or solar, effectively storing the energy for later use.

Either way, the point is that hydrogen is a useful fuel that can be transported over existing infrastructure and then used in a variety of ways that may help with the transition to a zero carbon system. Just to give one example, hydrogen can be combined with carbon dioxide to create jet fuel. [2]

[1] https://www.energy.gov/sites/prod/files/2014/03/f11/blending...

[2] https://www.nature.com/articles/s41467-020-20214-z

>>To produce Hidrogen, you need electric energy, or some very hot source that could be turn to electricity at a high efficiency.

This is not a true statement... Aluminum alloys readily liberate H2 from H20 at room temperarure (an exothermic reaction generating roughly equal parts thermal and chemical potential energy - both of which of course can be used for work) [1].

The oxidized aluminum is environmentally benign and can be recycled by applying more energy to deoxydize the product. The 'purification' process is ultimately where the useful energy comes from. The energy to power the purification can come from any number of sources - but as good stewards, we opt for clean energy sources. Al smelting historically produced a lot of carbon, but thanks to R&D by Apple, there are new carbon-free alternatives for this process [2].

At my company we are researching application of this energy infrastructure loop for powering ships (where source water is abundant). Essentalially, the Al+ is your fuel (battery), and from a volumetric energy density perspective (important for ships), you can store about 2X as much as gasoline/diesel - and way better than liquified or compressed H2 storage. However, on a mass energy density perspective (important for automobiles), it is a bit worse (heavier) than hydrocarbon fuels. Again though, each application has it's own constraints when considering an energy storage medium.

The automotive or civil sectors aren't the only use-cases for hydrogen fuel cells. One needs to take a look at all sectors to really grasp the global impact. A large part of my job is to explore this big-picutre aspect, because we need to understand the long term infrastructure stability/availability of potential "clean" energy supply chains, and it's VERY complex when you consider process efficiencies over the entire supply chain, raw material abundance and regeneration potential/economics/environmental impacts/speed, geopolitical forces affecting supply chains, the list goes on and on (and on).

H2 is an interesting "energy storage" option and it will certainly continue to be researched and applied broadly.

1. PDF - https://www.google.com/url?sa=t&source=web&rct=j&url=https:/...

2. https://www.apple.com/newsroom/2018/05/apple-paves-the-way-f...

100% of aluminium is made with electrical energy...

Actually, Al+ is purified by smelting, which is powered by applying thermal energy to a sample. As I alluded in my comment above, you can generate the thermal energy by any number of modes of energy transmission (electrical, chemical, RF radiation such as concentrated solar, nuclear, etc.).

The primary point of the above comment was that you need electrical energy to produce H2. That's a false statement. Al+ can generate H2 without electricity.

The important point is that the energy efficiency of any cyclic energy carrier system (batteries/chemical, mechanical, intertial, etc.) is only one, albeit important, factor. Other factors include mass and volumetric energy density, motion/environmental stability, cost, and so forth. The importance of each of these factors is weighted differently based on the application (e.g. automobiles, ships, trains, aircraft, domestic use, etc.).

Hydrogen pipelines with probably never be a thing. It's safer and more convenient to just produce h2 at the distribution point. The oil refinery/pipeline model exists because of the difficulty in synthesizing hydrocarbons, whereas h2 is (relatively speaking) far easier to create.

I believe OP is thinking more municipal pipes that feed individual buildings rather than a distribution pipeline like Keystone XL.

1. Hydrogen distribution might be able to use/share natural gas infrastructure (not high yield so embridlement isn't as big an issue)

2. Hydrogen is used for chemical processes (refining/ammonia) that can serve as a first step even if use for energy storage never becomes feasible.

3.Hydrogen is cheaper to store (<$10) per kWh than basically anything else (>$50).

But it basically won't be relevant until we have 12 hours of storage and zero marginal cost electricity 50+% of the year. Then it may be cheaper than overbuilding renewables or capturing gas emissions to cover the last 10-20 percent

If there's abundant pure hydrogen, synthesizing methane gets a lot easier, and we can use natural gas infra with no modifications.

One of the cases I think about for Hydrogen is moving energy around globally. The Sahara has tons of energy potential, but nobody lives there. How can we move that energy around efficiently, even across continents? Definitely not "batteries on boats"

A project has been announced to move energy from the Australian outback to Singapore, a distance of over 3000km mostly underwater.

I would like to see a cost comparison from true start to finish. What is the manufacturing/resource cost of making batteries? What is the efficiency or cost of producing the electricity to charge the batteries? How does this compare to making the photocatalyst and compressing and/or distributing the hydrogen compare? I remember seeing a breakdown of making batteries, distributing them, and charging them, compared with oil resource procurement, refining, and distribution. I'll take a look again, but does anyone have such a table reference? Thanks!

I think we're going to see a diversification in energy storage and power delivery systems for different applications. There's lots of uses for hydrogen beyond running your passenger car. It's a feedstock into a lot of chemistry (hydrogenating food, making fertilizer, reducing ores) as well as various high temperature processes.

It looks like you can blend it at some modest proportion into existing natural gas infrastructure to lighten its environmental burden somewhat.

Closer to my personal sphere, I'd be interested in using it for longer-term energy storage. It'd be amazing to be able to have some onsite high pressure or even cryogenic storage of hydrogen to be able to store a summer solar surplus for use in the winter. And yes, that's in addition to batteries to handle short term (hours up to maybe a week) of generation/load mismatches. I'd probably want to turn some back into electricity, but I'd be happy to simply burn a bunch too.

>Closer to my personal sphere, I'd be interested in using it for longer-term energy storage. It'd be amazing to be able to have some onsite high pressure or even cryogenic storage of hydrogen to be able to store a summer solar surplus for use in the winter.

Hydrogen really doesn't like to be stored though. It also ruins any storage vessel it is kept in long term.

You see Hydrogen is the smallest atom, small enough to fit between atoms of other materiel. and it will work its way through materials and sometimes bonding with the material sometimes just escaping, this creates a spoilage of the materiel the holding vessel is made of resulting in hydrogen embrittlement, creation of cracks and voids inside the metal,

About the only materiel we believe to be immune are carbon fullerenes and graphene. Which we have had problems producing at scale.

as for cryonic storing it you are just adding another energy cost to they system because you are spending more energy still to chill the hydrogen

>It looks like you can blend it at some modest proportion into existing natural gas infrastructure to lighten its environmental burden somewhat.

and this makes less since.

You have to spend more energy to make the H_2 by splitting the H2O than you get out of burning the H_2, so adding it to natural gas to make it more environmentally efficient doesn't make since as you are increasing the net energy cost of the system than just burning the natural gas.

> Hydrogen really doesn't like to be stored though. It also ruins any storage vessel it is kept in long term.

It's true that it's the smallest atom, but it's not the smallest molecule. Helium is more prone to escapement since it's not diatomic. Doing a bit of research it looks like aluminum is actually a fine container for pressurized hydrogen (low permeation rates, low embrittlement). You do need to reinforce it (e.g., composite wrapping) if you want to go to high pressures.

>and this makes less since.

FYI, s/since/sense

I think you're over-indexing on efficiency. That's not the only metric that influences success. Suppose that we have an overabundance of intermittent sources of electricity (e.g., wind and solar). Right now there's not much you can do to store it. Batteries are great for smoothing demand over hours or days, but they're quite far from smoothing demand over weeks or months.

So if you're able to cheaply overproduce electricity, it doesn't really matter if your storage process is not particularly efficient. Even at fairly low efficiencies, it's more useful than throwing it away so long as the capital cost of the conversion equipment is low enough to tolerate the intermittency.

As for the cryogenic storage adding an additional efficiency hit - yes, correct. But there's an intercept of marginal cost, storage density, and efficiency where it will be economical to do it. The technology question is if we can deliver that intercept at a lower total cost than other alternatives.

One thing that's really attractive about hydrogen is that the costs are not the processed media. Batteries are full of expensive to mine and refine materials and their storage capacity is more-or-less directly tied to the quantities of used materials. With hydrogen production the media are water and space, both of which are almost free in many contexts. Vehicles aren't really one of them because volume is precious, but for stationary applications it's a completely different story.

>and this makes less since.

>You have to spend more energy to make the H_2 by splitting the H2O than you get out of burning the H_2, so adding it to natural gas to make it more environmentally efficient doesn't make since as you are increasing the net energy cost of the system than just burning the natural gas.

I think you are missing something or are lacking in creativity. By this logic we shouldn't use batteries either because the energy you get out of the batteries is always less than the energy you put in. Also, where are you introducing additional natural gas? It's merely meant to be used as a temporary storage technology to allow a greater renewable share.

To be more blunt. Investments into storage technologies allow more renewables to be introduced into an electric grid. Nobody cares about the efficiency because that was never the goal in the first place. The goal is reducing the usage of fossil fuels to an absolute minimum and that means using less natural gas, despite the inefficiency.

So, you don't see how EV could take over from gasoline? Because you're describing the exact same "the infra's not there, and the tech's not good enough" situation as before.

If hydrogen extraction can be be made efficient enough to economically make more sense than batteries, that's the only necessary criterium. If it can, the rest is a matter of time. If even with this approach it can't, then it won't happen. It's really just economics.

1.) There is already a 240 km hydrogen pipeline network in Germany (and probably in other countries as well) [1]. It connects chemical plants in the rhein-ruhr region. So there is already a huge market for hydrogen. These chemical plants will need hydrogen in the future. If we want to get away from using oil and gas and become CO2 neutral, we need a solution for those industries.

2.) I don't see air travel happening with batteries (except really short distances or really small planes). Weight is just too much of a factor in air travel and the energy density is just too far off with batteries. Hydrogen would maybe be a solution or some fuel that is synthesised from hydrogen.

[1] https://industrie.airliquide.de/wasserstoffanlagen

There are some applications where energy density is far more important than energy efficiency. Airplanes come to mind. You would accept the pumping losses when it comes to filling a 737 with hydrogen, because you literally can’t make that plane work with batteries at this point in time.

Glad to find this in the responses.

Air transport is quite possibly the best use case for hydrogen fuel that I can think of, and likely the only way we'll get sustainable air travel in the near future.

Wouldn't it be easier to just work on efficient synthesis of jet fuel? Then we could just keep the rest of the infrastructure the same.

Sometimes I wonder if that would end up being a solution for cars, too. It would certainly solve a few difficult edge cases that electrification will have a hard time overcoming.

> Wouldn't it be easier to just work on efficient synthesis of jet fuel?

Some synthetic fuel production processes require hydrogen, so a cheap hydrogen source would still be useful.

> when it comes to filling a 737

That brings up an interesting point. I wonder how much of a factor fuel is in dictating the preferred size for an airliner. Maybe if the fuel economics and physics change, we'll see an evolution towards larger numbers of smaller point-to-point airliners.

The efficiency argument is brought up a lot, but it ignores that

Energy is cheap, Storage is expensive.

If storing a KWh of power costs 50 Cent in a battery and 5 Cent in a fuel cell, then it doesn’t matter if you pay 10 or 20 Cent per KWh of fuel.

Of course this is an example with made up numbers, but the point is valid.

The problem with electric is the specific energy of batteries (how much energy per weight). Current batteries used in cars top out at around 300 Wh/kg. That's 1.08 MJ/kg. Gasoline has a specific energy of 46.4 MJ/kg. Hydrogen has even higher specific energy, but with hydrogen you need a lot of weight for safety reasons. Hydrogen probably isn't going to give you much note than gasoline in specific energy. That's still 40 times better than batteries though.

As an aside, body fat has a specific energy of 38 MJ/kg.

This is a disingenuous comparison.

The specific energy of gasoline does not matter unless put into context with the efficiency of the mechanism extracting it into useful work.

The mechanism in this case is an internal combustion engine and its efficiency is around 10%.

The mechanism for extracting useful work from a battery is an electric motor, and it achieves ~98% efficiency.

Which means gas is only ~4X more dense in terms of actual useful energy. So a battery pack weighing 4x more than full gas tank to get the same range is not unreasonable at all and is basically what a Tesla is.

Also ICE engines themselves are pretty heavy compared to electric motors and require heavy gearboxes and shafts.

My back of the envelope calcs say that if batteries energy density increases by 30-50% the weight penalty for electric cars disappears. It's a fuzzy line because it depends on the cars range.

Difference between electric and gasoline cars. With a gas car the marginal cost of extra range is low. With electric it's high. With gas cars the marginal cost of extra HP is high where with electric it's low.

For hydrogen, the mass of the gas itself is negligible compared to the weight of the tank used to store it in compressed form:

  Therefore, an advanced composite container holding 5.7 kg of CH, would provide a range of 300 miles in a hydrogen vehicle, but will require a storage space of 260 liters (69 gallons) and weigh about 230 lb (104 kg). This will then be about nine times bulkier and three times heavier than a typical 7.5-gallon gasoline tank. (https://www.fsec.ucf.edu/en/consumer/hydrogen/basics/documents/task2_gaseous_h2.pdf )
So what you get overall is on par with the best batteries that are becoming available - which however have much better volumetric energy density. This is especially important at higher speeds: the energy required to accelerate a large mass can by recovered with a high efficiency using regenerative braking, while the friction of a bulky vehicle with air is lost (alternatively, passengers will drive a larger vehicle than required since the internal space is insuficient).

Electric engines convert those Megajoules to actual motion much more efficiently than combustion engines.

I’m not going to pretend to be as well researched on this point as yourself but one thing you hadn’t mentioned is the environmental impact of disposing batteries. Isn’t that the biggest complaint against electric cars (in much the same way that fission reactors are criticised for the radioactive matter that needs to be disposed of — albeit the timescales involved are different by orders of magnitude).

> the environmental impact of disposing batteries

Why would anyone want to discard these batteries with precious minerals?

1. Their lifetime is measured in decades (first in EVs and then in grid-storage) as compared to single-use for gas.

2. They (at least the various types of Li-Ion cells) are 100% recyclable. Battery production will probably switch to "urban mining" once enough has been manufactured to supply the global fleet.

Tesla recently mentioned during their battery day presentation that they plan to do exactly this. Re-manufacturing batteries will be far cheaper than mining fresh raw materials once enough EoL batteries are available.

That’s interesting. I wasn’t aware that was now possible with battery tech.

Thanks for the explanation.

check out https://www.redwoodmaterials.com/

All EV batteries are 100% recyclable and this company was founded by the original CTO of Tesla to do just that.

if anything it's the environmental and social impact of the mining of the minerals vs the disposal.

I think you're correct as far as you go, but hydrogen has other uses, as an input to chemicals such as Ammonia that are currently produced and/or used in ways that release CO2.

Just Ammonia for fertilizer alone generates 2% of annual CO2 emmisions, so that alone is a market worth targetting in both environmental and business sense. As soon as the inevitable policy response kicks in there will be a massive market for green ammonia (and therefore hydrogen).

Ammonia has a decent shot at being a shipping or aviation fuel too, but many of its alternatives need the same input of green hydrogen anyway so can share costs and scale with Ammonia production.

As for intermittent renewables, we're approaching the point where we shift from mostly underproduced and only occasionally overprovisioned to them being near permanently overprovisioned and needing to find uses for that electricity that can be rarely halted to help the grid a few times a year.

Hydrogen production fits the cost profile for long-term/seasonal storage that no lithium battery can hit, even if they drop in price even more than currebtly predicted.

Electric still has some major disadvantages particularly around refuel times. That’s the one major area I see, and the distribution story is better for electric but also still evolving. For example the 6 chargers at the mall aren’t really enough, and scaling to a few hundred isn’t easy or viable.

> scaling to a few hundred isn’t easy or viable

That seems wrong to me. I mean, objectively I'd expect the construction expense of a gasoline fueling station to be much higher than just running more electrical distribution lines to a major shopping area.

I think you're making the mistake of comparing the "cost" of new construction to the sunk cost of existing infrastructure. Those gas stations don't last forever and the cost to disassemble and rebuild them needs to be part of your analysis.

It scales faster than building out a whole new infrastructure especially since it gets to piggyback off of existing electrical distribution networks, and any one with a driveway/garage can charge there own vehicle by plugging it into the wall albeit slower than at a purpose built charger. many of those will have a personal charger though so even that will be faster. also batteries are less prone to explosive decompression in a accident than storage tanks of highly compressed explosive gas.

Hydrogen may be cheaper as energy storage for meeting peak load on a mostly-renewable electrical grid. In the short term (20 years) the loss of thermodynamic efficiency isn't much compared to the ability to re-use existing steam turbines from natural gas plants. Water and carbon fiber is much more widely available than the precursors to batteries and so the working medium is more accessible world-wide.

If there's a place for hydrogen in the electrical grid then there will be cheap hydrogen available for other potential uses and the market will likely find some niches. Long-haul transport is a big one; instead of electrifying all freight rails in a country use locomotives with hydrogen fuel cells.

Yours is a very good post, I’m just curious of you could elaborate on

>electric batteries today are over 90% eficient on the whole charge-delivery cycle

Isn’t the most common electrical delivery via natural gas power plants which are generally 40%-50% efficient? Meaning the 90% is a downstream measure from the source and not really “whole cycle”? It would be interesting to see comparisons of the true life-cycle efficiency of different modes of energy delivery and storage.

Transportation aside hydrogen storage is great for its energy density. Storing it locally probably as a hydride.

I'm picturing home use replacing oil or gas with hydrogen combined with a fuel cell.

It would be great for high demand situations where solar plus a battery setup capacity was too low. For example winter little sun (low on the horizon too) and a long cold spell.

It should be pointed out that stationary systems can easily exceed 40% if we really wanted to. By combining heat and power generation you could push net efficiency out to 60% or higher. You also don't need to worry about compression or mobile storage saving you some more efficiency there too.

Simple counterargument: you can't make a large electric plane. The energy density of a battery is too low.

Nor can you make a hydrogen plane with current (compressed hidrogen) technology, its tanks would be much too bulky and heavy. Unless you are proposing to transform planes into some sort of foam-covered Space Shuttle external tanks storing liquid hidrogen, our best bet for carbon neutral flight is some sort of fuel synth or biofuel.

Electric cars are at the sweet spot. If you look at larger vehicles e.g. Semi-trailer truck, battery doesn't make sense. To have a good range you would need 5 tons of batteries which limits your cargo and it's not economic. Then you have electric ships and planes.

I don't think hydrogen powered vehicles are viable. But what if solar-splitting of water followed by electricity generation with a fuel cell turned out the be more efficient than the best solar cells? I doubt it, but it seems like a maybe.

How should we obtain enough electric generation to offset the lost of hydrocarbons?

Less pollution in the future and less need for lithium?

So maybe that’s a better trade off for the planet.

How about e.g. aeronautical applications where energy density is valuable?

most of the universe is hydrogen. it's easier for a base on some other planet to find hydrogen than set up a battery factory.

Hydrogen is abundant in gas clouds, in Stars, and gas giants.

But unbound molecular hydrogen (H2) is basically nonexistent on terrestrial planets since their gravity is insufficient to hold onto it.

Hydrogen has an energy density of 120 MJ/kg. Gasoline has an energy density of 46.4 MJ/kg. Lithium ion batteries at 2.5. They’re not even in the same ballpark.

> Hydrogen has an energy density of 120 MJ/kg.

Divide that by 15 to get real world densities of compressed hydrogen composite storage tanks, you need a 104 Kg tank to store 7.5 Kg of hydrogen, for a total of 111.5 kg when full.

Only aircraft care, though. Fuel weight in other applications is basically a non-issue except for really niche gadgets.

As long as we have coal plants powering our electrical grid we should seek alternatives that would replace or reduce reliance on them.

This is entirely false. It's called the long tailpipe theory.

Every study that suggests this conclusion was published by Oil companies in the 90s to shut down California's effort to switch to electric cars by the year 2000.

No actual study has ever found this conclusion and in fact all find the opposite. Even with the worse polluting power generating plants, charging an EV directly off of the massive grid power generation is far more efficient in terms of pollution than burning gas inside your car.

Another researcher I was following along these lines, and it faded away:

https://en.wikipedia.org/wiki/Daniel_G._Nocera --- "Sun Catalytix, a startup for development of the artificial leaf. The company was bought by Lockheed Martin in 2014" ---- "In 2009, Nocera formed Sun Catalytix, a startup to develop a prototype design for a system to convert sunlight into storable hydrogen which could be used to produce electricity"

Do you mean talk of the tech faded away or the organization got consumed by the bigger firms R&D and you didn’t hear much about it?

Edit: found a good article on the topic

> The hardest part of innovation often comes after you make the discovery, as Nocera learned.


The lab is still active: http://nocera.harvard.edu/Publications2020

Publications from 2020 include "Practical challenges in the development of photoelectrochemical solar fuels production (Sustainable Energy Fuels)"

I'm long hydrogen vehicles due to the convenience factor. Convenience trumps efficiency.

EVs are great if you own a house with a driveway and get to charge overnight. Outside of USA, how common is that really? Most people live in apartments in cities, where a parking spot is hard to find.

> EVs are great if you own a house with a driveway and get to charge overnight.

I think denser cities will eventually have battery-swapping stations, where you just get a new battery whenever you're running low. They then fast-charge your depleted battery and give it to a new customer later.

The big obstacles are compatibility and preventing people from abusing the system to get batteries in better condition for free, but I think countries with more central planning (like China) could force those issues.

You could also use regulations to standardize battery design and performance criteria right here in the US. Just like we have regulations that dictate what can and can’t be “gasoline”. Make batteries a commodity.

I can see charging being built directly into parking buildings/apartment carparks and factored into the parking cost. Would be pretty convenient always being fully charged when setting out.

At this stage parking buildings have maybe 4 chargers but 1 is out of order and the other 3 are in use. But that's a scaling issue.

Will be interesting when parking buildings start drawing megawatts overnight though.

You also have the problem of range with an EV, which can only go a few hundred miles. You would need to swap out the batteries to have an instant charge. With hydrogen, you could have ubiquitous automated solar powered gas stations.

Garages are also not very common in non US countries. As the population urbanized further into denser cities this will make this problem even more acute. We absolutely need a better solution.

There has been a noticeable uptick of hydrogen articles peppering tech, car, and similar sites in the last three months.

Is there some inflection point in policy coming to a head for this, or a bunch of startups trying to push mindshare?

The hydrogen economy seems 5-10 years from mainstream even with huge investment, and that's the same problem that nuclear has:

Solar / EV / battery is improving double digits every year on cost. The hydrogen "economy" will be a niche at best, maybe for air transport or long haul shipping.

Is anyone familiar enough with the chemistry of creating synthetic hydrocarbons to comment on whatever bottleneck is preventing it from being mainstream?

It seems like synthetic gasoline and synthetic propane would be ideal energy sources (and that cheap hydrolysis would be the starting point), so I figure there must be a reason that people don't often talk about it.

It's not sexy and the cost is usually too high relative to fossil fuels.

I personally think it would make a lot of sense to develop further. Conventional fuels are very convenient, and if you produce them synthetically without extracting resources from underground deposits, there's a lot less climate impact. It wouldn't eliminate tailpipe emissions, but it might significantly reduce sulfur emissions for example.

Long distance transportation is always going to be a challenge for EVs, that synthetic fuels could handle if they're economical to produce and sell.

The processing plant that could be built with a certain investment would usually make more money processing crude or surplus petroleum than it would synthetic hydrocarbons.

The price of crude can be adjusted to maintain this situation.

Some biodiesel made from surplus edible oils can co-produce common gasoline-range hydrocarbons along with the biodiesel.

You have to figure those that are doing this are making money, they are just making less money from the same equipment than a traditional oil company would.

To some extent it's just a matter of what you want to invest in for the future compared to what has cumulatively been invested in over the past.

There should be opportunity for renewable gases, autofuels, and oils to share infrastructure with established petroleum and make money for shareholders as reliably as a traditional oil company. There simply needs to be ambition to accept a lower percent dividend per barrel in the same market, with the tradeoff/tradeup that the environmental impact per barrel is dramatically lesser by a much greater percentage.

So you make money as reliably as an oil company, only less of it but it's still possible for everybody to win.

Depends on what you are committed to.

OTOH whether it's photosynthetic, photocatalytic, photovoltaic or direct radiant solar, efficiency is not as much of a show-stopper as it would seem. Any net gain is free energy.

It has been scaled up. https://en.m.wikipedia.org/wiki/Sabatier_reaction

The first commercial synthetic gas plant opened in 1984 and is the Great Plains Synfuel plant in Beulah, North Dakota.[9] It is still operational and produces 1500 MW worth of SNG using coal as the carbon source. In the years since its opening, other commercial facilities have been opened using other carbon sources such as wood chips.

Glad to know it's more popular than I thought. Seems like a good thing to put near a windmill (or a fusion plant if we ever get there) so we can use existing infrastructure and switch from pumping billion-year-old carbon into to atmosphere to just pumping last-decade carbon into the atmosphere.

The wood chips thing is interesting. In the last five weeks I've filled as many trash totes with leaves from the neighbor's tree. I wonder how that mass of carbon compares with the gas I've burned for heat this winter.

We don't have an overabundance of low carbon energy that would justify the investments. There is also the problem that capturing CO2 is only economic at a point source. The fundamental problem is that the concentration of CO2 in the atmosphere is too low for direct air carbon capture.

So will this produce hydrogen and oxygen gas separately or a 2:1 mix of the two (i.e. oxyhydrogen)?

Any idea what the real world efficiency is? It sounds like it’s limited to a narrow UV spectrum.

I wonder if it’s even vaguely competitive (in theory) with commercially available hydrogen crackers that use electricity from solar panels.

That's some very impressive news. Hope this will make hydrogen cheap.

I am excited because hydrogen can be used in steelmaking for a much more carbon friendly process than burning coals. Cheap hydrogen will be a game changer for emissions regardless of if anyone uses it to power vehicles.

The real application here is power plants. Use hydrogen to heat water to turn a turbine to turn a genset to produce electricity, in the same way that we've been doing for ages now.

The real question is, say you have a natural gas power plant that's been retooled (minimally) to run on hydrogen that they create on site. Now you're producing a ton of water vapor and tossing it into the air. If all power plants run this way, that water vapor is going to be problematic as water vapor is an excellent greenhouse gas, so, if you'd like to avoid that, you'll need to recondense the water and put it back into the cycle, which will harm efficiency if done in a 100% closed cycle.

That's probably not a huge obstacle to overcome, because the water will likely have to be pure anyway in order to be usable, so, you could likely recapture waste heat and use it to distill water to a high purity and because your exhaust is likely full of higher purity water than you could otherwise get, it makes sense to recapture it.

Additionally, you could solve in part, the main issue with renewables, which is energy storage, by converting excess capacity to hydrogen made by electrolysis that you can then burn in traditional power plants. Sure it's 70-80% efficient, and burning hydrogen is likely not going to beat ~62% efficient in a combined cycle plant (the current record for natural gas), it's much better to take that efficiency hit than it is to waste power, or further complicate the grid, and you'll get to keep ~40% of that energy based on my napkin math, which is better than 0% and you can put it anywhere, likely on the solar farm directly.

Whilst a greenhouse gas H20 does have the difference that it comes back down relatively quickly, potentially even right away. I also think we would only be using hydrogen plants to stabalize renewables like we do now with natural gas turbines. I wonder if there is any research into the lifecycle of emitted water vapour?

Pipe dreaming now, but I wonder if there is a potential cycle that could help drought stricken areas, even if perhaps supplemented with renewables for desalination.

Desalination of coastal water > hydrogen production > power generation with hydrogen > captured purified water.

Thinking about this now my state is in the perfect position and often effected by drought. We have green hydrogen production, a gas turbine supplemented solar grid, and a desalination plant the government put in to safeguard drinking water supplies. This may come about as a natural evolution of the market.

Can’t you just release the hot steam into a nearby river/large water body?

That's what my dad said. Personally i like the vehicles too. I think there will continue to be a sizeable market for petrol vehicles as long as bevs are difficult to charge. Hydrogen would be more easy to refill. Hydrogen could fill that market in time.

I am doubtful, but if true and if this can be deployed on a large scale hydrogen cars could be a viable alternative to battery powered EVs.

I find it amazing (in a bad way) that whenever you talk about hydrogen someone comes up and wants to talk about cars.

There's a number of use cases where clean hydrogen will be desperately needed. This starts with areas where hydrogen is already used today - but it's hydrogen made from fossil fuels - like ammonia production and includes areas like steel production where hydrogen really is the only game in town for a low-carbon production.

We'll need all the clean hydrogen we can get, and probably more than that. There's no plausible scenario where we'll have excess hydrogen that we can waste in an area where it's just vastly less efficient than the available alternative.

> I find it amazing (in a bad way) that whenever you talk about hydrogen someone comes up and wants to talk about cars.

It would solve the battery charging problem that electric cars have (for long trips) while not polluting like conventional cars.

Any solution that is applied to massively produced product (a car) will get massive funding, research grants and it will only improve over time. This way it can be distributed to other areas quicker and at lower cost. So yes, implementing hydrogen in cars is a massive success to other industries.

On the specific case of steel production, it's way more likely that people will settle on synthetic carbon based fuels.

Of course, producing those uses hydrogen too, so no big change.

Yeah, I really don't see a case where large amounts of hydrogen are being transported commercially. Anything you don't need on site makes much more sense to convert to synfuel.

Why would that make any sense?

(Synfuels are really, really inefficient, you basically only want them in places where you need the high energy density and can't avoid them, like aviation.)

Because the carbon has an important role on the chemistry of making steel.

Unfortunately, splitting water into hydrogen and oxygen are only a part of the process. A lot of energy is wasted when the hydrogen has to be compressed for transport, storage and in the car. That makes hydrogen less attractive than batteries, even if we solve the inefficiencies of the hydrogen production.

However, it would be great news for many other fields. One way to make hydrogen more storable is to produce methane. And of course use hydrogen directly for industrial applications, like steel production.

For transportation, hydrogen can be absorbed by a carrier oil. That way it is basically inert, doesn't even count as dangerous goods for transportation purposes. No compression needed. In cars it is different, so.

What’s the density of hydrogen using this method versus compression?

I'd have to look up the numbers. Cost wise, a pure hydrogen pipeline is cheaper for sure. At scale at least. Until that scale is reached, using carrier oil is much cheaper, but still competitive enough to get it going.

EDIT: The oil is called marlotherm something, if memory serves well.

It would be specially interesting for aviation, since the energy density of batteries is still too low for commercial aircraft. Airbus is pushing for zero emissions H2-powered planes: https://www.airbus.com/innovation/zero-emission/hydrogen/zer...

What makes hydrogen interesting in aviation is that it is possible to convert existing engine designs to burn hydrogen apparently. There have been a few tests with this recently.

Mid term, hydrogen is the obvious way to clean up the aviation industry. Basically as soon as hydrogen prices drop below kerosene prices, companies will start doing this by themselves because it makes economical sense. Right now it's more of an investment for the long term. Airbus is clearly betting that this is going to happen in the next two decades or so. If you look at clean energy cost dropping over time, they might be right about that.

Battery powered planes also make sense; just not for the bigger planes any time soon. But with another decade of battery improvements, GA planes & battery is going to be a no brainer-solution for a lot of use cases. Basically, this will be driven by cost. At some point battery powered is going to be cheap and good enough that the added advantage of low energy cost and vastly simpler/cheaper maintenance is going to be a killer argument. E.g. flight schools are already switching because it makes economical sense.

If you look at the R&D pipelines of companies in this space, ten years could solve a lot of issues. Think double/triple the range of current electrical planes at half the cost. Small planes are expensive to operate currently and fuel & maintenance are big factors here.

Completely correct, H2 either in fuel cells or burnt in turbines and battery-powered hybridization are two of the pillars of the EU's Clean Aviation R&D programme: https://clean-aviation.eu/files/Clean%20Aviation%20-%20Share...

It is going to be very costly (energy and capital investment) to convert steel making to use hydrogen. A blast furnace is a well balanced chemical reaction where the coke serves two purposes; a source of carbon monoxide for turning ore in iron (Fe2O3(s) + 3 CO(g) => 2 Fe(s) + 3 CO2(g), very exothermic, good for turning the iron / steel into a liquid alloy), and a source of carbon for turning the iron into steel. All in one vessel and in one process no less. I guess you could do the first step using peroxide to strip the oxygen from the iron, but the second step in the same vessel at the same time?

Fe2o3 + 3H2O2 => 2 Fe + 3 H2O, somewhat exothermic (if my rusty memory of enthalpy calculations are correct), not sure of the activation energy or need for catalysts).

[EDIT] also forgot the peroxide reaction would probably require external heat to over come the latent energy required to turn the H2O into super heated steam so that you could melt the iron / steel. This would probably boil off a large chunk of the peroxide as well, so it might need to be done in a contained pressure vessel, which would probably affect the speed of the iron ore reduction.

The biggest steel mill in my state is switching to locally sourced green hydrogen. Written out, that sounds pretty funny. But it's produced with local solar energy farms, so it's pretty accurate.

This is one area where carbon taxes are the obvious solution. Cost and availability is the biggest driving factor for industry. Furnace coal is available and cheap, but if you tax it heavily for it's emissions enough it won't be. Will steel become extinct? Of course not, the mills will switch to the next alternative, which is hydrogen. It will be ripe with opportunity, with solar farms and hydrogen plants popping up around steel mills.

Already we are seeing coal plants written off as unprofitable and future mining projects are becoming less attractive to investors in an unpredictable future. Even without a carbon tax, we could see the cost of coal go up enough to make a local hydrogen industry make more sense. But we can speed the whole process up with smart carbon taxes.

Look here: https://www.hybritdevelopment.com/

Particularly the "Downloads" section, they have quite a bit of info reasonably easy to digest for interested lay people.

It may be expensive, but it's pretty much the only game in town. The only possible alternative is direct electrolysis, but that's even less developed. The hydrogen path is from what I understand technically not that much different from direct reduced iron with natural gas, which is something that already is in use for a significant chunk of steel production.

Thanks, it's a good source. Also on the financial front of how they organised finance and created a route to market.

The "Just have a think" youtube channel did a nice episode on this topic last week: https://www.youtube.com/watch?v=ywHJt88H5YQ

Apparently there are several viable ways to make clean energy work in this space. And there are some companies starting to do some of this already. Carbon prices is short term going to be needed to cover the price difference.

But the cool thing is that it boils down to cost per MWH of energy per tonne of steel. As that goes down, it becomes more viable and eventually cheaper.

There is a steel mill that uses hydrogen, but it appears to be a recycling kind, rather than one that makes iron from ore with a blast furnace.


Yes, I suspect this is much easier as you don't need to alloy as the steel is already alloyed with carbon.

Fe2o3 + 3H2O2 => 2 Fe + 3 H2O

This is not balanced correctly. There are 9 oxygen atoms on the left hand and only 3 oxygen atoms on the right hand.

Hydrogen peroxide can act as a reducing agent relative to some things, like permanganate anions, but it's an oxidizing agent relative to metallic iron. Hydrogen peroxide cannot substitute for coal or hydrogen in steel production.

Yup, you're right, rusty chemistry on my part.

I am not a steel expert, but the steel industry is constantly talking about converting to hydrogen. Your sum formula has a bit lot of oxygen, shouldn't it be Fe2O3+3H2 => 2 Fe + 2 H2O? In any case, they could use additional hydrogen for heating and burning it with ambient air.

I suggested using peroxide not hydrogen, as the peroxide reaction is more exothermic. Either way I suspect that you'd need to burn a lot of extra hydrogen to overcome the latent heat of water and create sufficient heat to melt the ore / alloy.

A quick back of the envelope calculation would be at least 1 million litres of H2 per ton of steel. So maybe 2~3 million litres of H2 per manufactured car just for the steel alone?

[EDIT] Peroxide also has the added benefit of being a liquid at room temperature.

I am reminded of the classic article "things I Won't Work With" by chemist Derek Lowe on the subject of Peroxides


they don't sound safe

Yes, peroxide being liquid certainly is nice, being a light gas is certainly one major obstacle in using H2. However I am surprised that the peroxide reaction would be more exothermic, as you would have to break the hydrogen from the peroxide first. 1 million litres of H2 are just 90kg though, that isn't that much for a ton of steel.

It is only a bit more exothermic, about 20% more (again from my rusty enthalpy calculations). The downside of course is making the peroxide in the first place.

Also, peroxide is relatively safe (compared to gaseous hydrogen) to handle up to ~150C.

When there is wind or sun, it's not entirely impossible to produce hydrogen on site - within limits of course. Then the question is what kind of energy storage is more cost efficient on the long run.

If there is sun why not skip the middle man and use an array of mirrors for direct heating?

Oh come on. Anyway, the sun doesn't shine at night. In the winter, the situation is difficult too. You need storage but you don't necessarily have to move the storage across countries.

The idea is to use water as the fuel and convert to hydrogen just in time for combustion.

No, it's not :)

Where would you get the energy to split the water? Why not just use that energy directly :).

The idea is to use the water as an energy carrier. You split the water into H2, than use that to power a car producing water as the only output.

>Where would you get the energy to split the water?

From a battery.

If cars produce water as exhaust, will there be constant rain showers on congested roads?

Watch a YouTube of a hydrogen car review. They produce maybe a cup of water for a consider amount of driving. It’d evaporate relatively quickly.

They already produce plenty of water in the exhaust.

Right, I did a simple calculation, for the same distance driven, both gasonine and fuel cell cars produce pretty much the same amount of water, about 100ml/km. Only difference is, with gasoline that water is mostly vapour, so it doesn't get on the road so much, fuel cell cars have small tanks not to wet the road constantly.

How would that work? That sounds like a perpetual motion machine.

Like how a gun works, essentially a battery for the initial motion, using the subsequent motion storing some for the next initial motion.

Guns work by having chemical explosives in them. Which is also how gasoline powered cars work.

They definitely do not work by using a depleted battery to charge a second battery to create energy out of nothing.

gasoline cars also use a battery to initiate the engine.

Yes. However they don't use it to both power the car and charge the battery. Kickstarting the engine with a battery is very different from only having a battery and also using that battery to charge itself and the car at the same time.

The original poster was proposing a closed system where you would turn water into hydrogen (a very energy intensive process) and then turn it back into water (an energy releasing process) inside the car to provide all the energy. This is not how physics works. You cannot use your energy source to create more of your energy source without an external energy source. It just doesn't work that way.

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