11 ms·

Hydrogen production from the air

102 points by sohkamyung 4y ago

r0ckarong 4y ago
Wait till thunderf00t sees this one.
- ncmncm 4y ago
  Only if he misses the point.
derriz 4y ago
I barely got through the introduction before giving up. The opening line - "Hydrogen is the ultimate clean energy." - is a vague, meaningless, scientifically vacuous claim. I'm not sure that hydrogen can even be considered "clean" - potentially clean maybe? Hydrogen leaked into the atmosphere is 6-16 times more potent than CO2 as a greenhouse gas[1]. Hydrogen combustion (for heating, transport or driving turbines) releases 6 times as much NOx as burning methane (natural gas)[2]. The same opening paragraph contains the dubious claim: "H2 produced by water electrolysis using renewable energy, namely, the green hydrogen, represents the most promising energy carrier of the low-carbon economy". The most promising energy carrier of the low-carbon economy is and has been electricity. Hydrogen as an energy carrier has contributed almost nothing to lowering carbon emissions despite decades, if not a century, of research and effort. [1] https://www.rechargenews.com/energy-transition/hydrogen-twice-as-powerful-a-greenhouse-gas-as-previously-thought-uk-government-study/2-1-1200115 https://www.rechargenews.com/energy-transition/hydrogen-twic... [2] https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/798243/H2_Emission_Potential_Report_BEIS_E4tech.pdf https://assets.publishing.service.gov.uk/government/uploads/...
- u320 4y ago
  For fixed infrastructure, nothing beats power lines. For mobile applications, hydrogen has numerous problems. There are other options, like batteries, ammonia, synthetic hydrocarbons etc that should be explored further. Hydrogen doesn't even come close to deserving the title "the ultimate clean energy".
  - ncmncm 4y ago
    That wholly misses the point. We need hydrogen production in unlimited amounts for myriad processes. Want synthetic ammonia? Need hydrogen. Methane? Hydrogen. Kerosene? Hydrogen. Green steel production? Hydrogen. Furthermore, liquified hydrogen is the future of aviation. So a tech that produces hydrogen efficiently anywhere there is air is intrinsically important.
    - eru 4y ago
      > Furthermore, liquified hydrogen is the future of aviation. What makes you think so? Why not eg methane? Or other synthetic carbohydrates?
      - ncmncm 4y ago
        LH2's extreme mass-energy density will make other aircraft unable to compete, because the weight savings may be sold as additional paying cargo capacity. That presumes a joule of LH2 is the same price as of kerosene. But LH2 may end up much cheaper, increasing the gap.
        eru 4y ago
        One would suppose mass energy density is even more important for rockets. In practice, only some rockets use LH2. Many rockets use souped up kerosene (RP1) or, more recently, methane. Compare https://en.wikipedia.org/wiki/Liquid_rocket_propellant#Hydrogen https://en.wikipedia.org/wiki/Liquid_rocket_propellant#Hydro... and https://en.wikipedia.org/wiki/Hydrogen-powered_aircraft https://en.wikipedia.org/wiki/Hydrogen-powered_aircraft Also: > With materials available in the 2020s, the mass of tanks strong enough to withstand this kind of high pressure will greatly outweigh the hydrogen fuel itself, largely negating the weight to energy advantage of hydrogen fuel over hydrocarbon fuels. Hydrogen has a severe volumetric disadvantage relative to hydrocarbon fuels, but future blended wing body aircraft designs might be able to accommodate this extra volume without greatly expanding the wetted area. From https://en.wikipedia.org/wiki/Aviation_fuel https://en.wikipedia.org/wiki/Aviation_fuel
- aydyn 4y ago
  Those are just buzzwords thrown in to make their article sound more impactful and progressive. Every author does this (yes, literally every author). Who cares. What about their tech?
  - ncmncm 4y ago
    Yes. The tech seems very interesting. The key observation seems to be that atmospheric water vapor is massively purer than any terrestrial water source. And, production directly from vapor avoids efficiency and fouling problems seen when working in liquid. I don't know what they mean by "faradaic efficiency".
- csdvrx 4y ago
  > Hydrogen leaked into the atmosphere is 6-16 times more potent than CO2 as a greenhouse gas Which is a problem considering how small the H2 molecule is: we can't reuse our existing LNG pipelines. Personally, I believe aerochemistry will "work out" in the long term by generating short to medium length aliphatic compounds from CO2 and H2O: we'll eventually figure out the catalyzation from sunlight. We can then have access to lots of energy, with a negative carbon balance, using always sunny surfaces like the Sahara desert - which sits conveniently close to Europe! This could help with the European energy problems if only France would stop thinking short term and try to protect and extend the commercial life of its ailing nuclear energy business (50% of which is currently closed down to being unsafe/uncoolable etc) by shooting down initiatives to build LNG pipelines from North Africa to Europe. Yes, they are doing that, even now that they (and Germany, and the rest of Europe...) are facing a winter without Russian gas: https://www.archyde.com/gas-spain-criticizes-frances-opposition-to-the-midcat-gas-pipeline-project/ https://www.archyde.com/gas-spain-criticizes-frances-opposit... Unfortunately, France stands in the way between the shortest route from North Africa to continental Europe through Gibraltar. If a pipeline can't be build from Spain to Germany by going through France, the next best would be from Italy.
  - ncmncm 4y ago
    It is vastly more cost effective to build electric transmission lines instead of gas pipelines, and crack hydrogen at the point of use. Furthermore, the desert is a lousy place to put solar panels. They get hot and dusty, making them inefficient and shortening their life. The best places are floating on water, and sharing pasture and crop land. Spain, Italy, and Greece have plenty of room for such solar. Portugal, too, and former Yugoslavia, Albania and Bulgaria. Nukes will shortly be unable to produce competitive power, and will be mothballed except where taxpayers are forced to subsidize them.
    - csdvrx 4y ago
      > It is vastly more cost effective to build electric transmission lines instead of gas pipelines, and crack hydrogen at the point of use No it's not. You are building in your assumption that I talk about solar panels for electricity generation. I don't. I'm talking about direct aerochemistry, without separate solar panels, to avoid tackling up the conversion rate of solar to electricty on top of the conversion rate of the chemical reaction that would create the hydrocarbons. There is gas in North Africa. This gas can be directly burnt to generate heat. It can also be used to generate electricity. That's short term. In the long term, we'll be able to make similar compounds from energy (sunlight or heat) + CO2 + H2O. Inbetween, there's a window of opportunity for nuclear and solar, but both are extremely polluting due to the metals used: we should avoid getting locked in this bad situation. Also, I think the lack of nuclear accident in Western Europe so far has just been luck. With the dense population, it's a catastrophe waiting to happen. > Furthermore, the desert is a lousy place to put solar panels I don't think you understand, as I don't suggest at all the use of solar panels. Using solar panels to generate energy is nice, but it's at best carbon neutral. I'm talking about the future: being carbon negative: extracting CO2 from the atmosphere and generating a usable from of energy.
- harg 4y ago
  H2 may well be a more potent GHG when compared to CO2, but it's tendency to remain in the atmosphere for a long time is a factor than shouldn't be ignored and doesn't seem to be mentioned by your first citation. I.e. H2 may be 16x more potent than CO2 but if it reacts away within hours/days/[<16th of the time that CO2 stays around] then its overall contribution to warming will be less than CO2. (I don't know what this figure is, but I believe Hydrogen is pretty reactive so doesn't tend to stick around that long) From your second citation: > The evidence base relating to non-GHG emissions from end-use in heating applications is almost non-existent It then says that a single study: > suggests there is potential for up to six times higher point NOx emissions compared with natural gas". and that it could be significantly reduced with catalytic converters. The points you raise are not nearly as unequivocal as you make them out to be. I also don't feel like Hydrogen is going to solve all of our problems - it has many problems that needs to be overcome. But it could well play a role in certain areas when it comes to getting off fossil fuels, so studies into more efficient production of it will surely be valuable.
  - CorrectHorseBat 4y ago
    >H2 may well be a more potent GHG when compared to CO2, but it's tendency to remain in the atmosphere for a long time is a factor than shouldn't be ignored and doesn't seem to be mentioned by your first citation. I.e. H2 may be 16x more potent than CO2 but if it reacts away within hours/days/[<16th of the time that CO2 stays around] then its overall contribution to warming will be less than CO2. (I don't know what this figure is, but I believe Hydrogen is pretty reactive so doesn't tend to stick around that long) Usually these numbers take that in consideration and the two are compared over a certain number of years, i.e. 100 years. A quick Google seems to confirm this, H2 is ~10 more potent than CO2 over 100 years.
    - audunw 4y ago
      Good point Still.. we're talking about unintentional leaks here. With the alternatives, CO2-emissions is an unavoidable by-product (in theory it can be managed with CCS, but not for transportation) We should use batteries whenever we can, but seems to me like hydrogen is an essential component of a green, fully carbon neutral economy. Though I agree with the comment above that it's a bit... misleading.. to call hydrogen the ultimate clean energy. Green hydrogen (do differentiate from hydrogen made from natural gas) is a very good clean energy carrier. That'd be more precise to say.
- ZeroGravitas 4y ago
  Green Hydrogen is going to be big. You are correct that if you are burning it then you have taken a wrong turn, or at least haven't got to the final destination. Mostly it will be a sink of energy and a chemical feedstock. That is still massive, size of the oil industry scale big.
  - rvbissell 4y ago
    The prioritization that you propose will make the oceans saltier. Whereas, burning H2 is water-neutral.
- jbu 4y ago
  Were you thinking of methane instead of hydrogen? But the paper does seem hypy. H2 will have its place, but wire transfers electrons better than hydrogen.
  - ncmncm 4y ago
    You miss the meat of the article. Highly efficient production not subject to fouling makes hydrogen generated at point of use practical. H2 has myriad uses, and is gaining more at breakneck pace.
- ajnin 4y ago
  > "Hydrogen is the ultimate clean energy." This is a lie pushed by oil companies. First it is incorrect because hydrogen is not a natural energy source, it is a way to store energy. But above all, currently the vast majority of hydrogen is made by steam cracking methane or other hydrocarbons, which is a process that releases CO2. You can think of hydrogen production + hydrogen use as a combustion with additional steps. And since the hydrogen supply chain is very inefficient (hydrogen is very light so you need to compress it a lot to store it, it is a very small molecule so it leaks very easily, and when you use it you need to decompress it so you get more losses due to thermodynamic effects) it turns out as quite bad from the point of view of CO2 emissions. It is just a way to sell more oil.
  - ncmncm 4y ago
    You seem to have read only the introductory paragraphs. There is little need to store or transport hydrogen that may be produced right where and when it is needed.
    - wongarsu 4y ago
      If I read the abstract correct it's doing electrolysis of moisture in the air. That's a process that inherently uses more energy then you get back out of the hydrogen. After all burning hydrogen just turns it back into water, and we can't have more than 100% round-trip efficiency. I could imagine it as a viable storage technology, e.g. if you want to install a solar farm in a remote location you could have it produce hydrogen from the air and sell that.
      - ncmncm 4y ago
        Obviously all conversions involve losses. If you have electric power but need hydrogen, you have to make the hydrogen, whatever the loss. This method has lower loss than others. Probably ammonia will be a better transport medium than hydrogen, but you need hydrogen to make ammonia.
        saalweachter 4y ago
- marcosdumay 4y ago
  With higher NOx emissions, come higher generator efficiency. Anyway, you can control both on your combustion chamber, so the claim for open fires does really not apply.
deleted 4y ago
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ZeroGravitas 4y ago
I guess the trick is the purity of the water combined with the location independence. Similarly e-fuels made from hydrogen can be both purer than standard jet fuel, and obtained from a wider range of places. Both of those things help tilt the cost towards e-fuels.
- criddell 4y ago
  Would the water have minerals? If not, can you add them? I'm not sure I want to be drinking pure water.
  - ZeroGravitas 4y ago
    The similar devices for drinking water do add minerals, but for hydrogen production the lack of them is a benefit. https://en.m.wikipedia.org/wiki/Atmospheric_water_generator https://en.m.wikipedia.org/wiki/Atmospheric_water_generator
raverbashing 4y ago
It's an interesting paper but I think most of the limitations in H2 production are in electricity supply, not in water supply
- ncmncm 4y ago
  Electricity supply cost is plummeting. Water is plentiful, but pure enough water not to foul electrolysers has not been, and efficiency has been low. Avoiding liquid phase bypasses all the difficulties of existing electrolysis.
  - deleted 4y ago
    [deleted]
  - s1artibartfast 4y ago
    Source? From what I've seen Electricity wholesale costs increasing for the last 8 years. Yes there are times of the year where the spot price is low, but the average cost continues to go up.
    - ncmncm 4y ago
      Cost is still dominated by natural gas price. As solar and wind build-out saturates in coming decades, mined gas will become unable to compete with renewables and hot storage, most places.
      - s1artibartfast 4y ago
        Your parent post was present tense, not future. Prices today nor the last several years have been plummeting.
        ncmncm 4y ago
        If you built a solar farm last year, build another today, and another one next year, the cost for those will be seen on a sharp downslope. There would be no need ever to pay spot market price: you operate when you have power to operate. You could put up wind turbines too if you wanted to operate more regularly. In any case you can't buy these things yet. All costs are necessarily referred to a time when they are available off the shelf.
pydry 4y ago
Not sure what the obsession with hydrogen is about. It's inefficient to produce and difficult to store.
- ncmncm 4y ago
  The article is specifically about an efficient process to produce it at point of use, so it need not be stored.
  - pydry 4y ago
    The first paragraph contradicts you: >is the most promising energy carrier of the low-carbon economy. ^_ energy carrier != production at the point of use. The article seems to be about dealing with a supposed shortage of fresh water to make the hydrogen from. If this is solved it changes nothing.
    - ncmncm 4y ago
      The authors' speculations on how hydrogen may be used are irrelevant to the substantive content of the article. There is no shadow of doubt about whether hydrogen production will be massively important in the immediate future, so better ways to make it are equally as important.
  - dang 4y ago
    Please edit swipes out of your comments here. This comment would be just fine without that last bit. Edit: We've had to ask you this kind of thing many times before. Would you please review https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html and stick to the rules when posting here? I don't want to ban you, because your substantive comments are great, but this is not ok: https://news.ycombinator.com/item?id=30890352 https://news.ycombinator.com/item?id=30890352 (April 2022) https://news.ycombinator.com/item?id=26290876 https://news.ycombinator.com/item?id=26290876 (Feb 2021) https://news.ycombinator.com/item?id=22199357 https://news.ycombinator.com/item?id=22199357 (Jan 2020) https://news.ycombinator.com/item?id=22087086 https://news.ycombinator.com/item?id=22087086 (Jan 2020) https://news.ycombinator.com/item?id=21799929 https://news.ycombinator.com/item?id=21799929 (Dec 2019) https://news.ycombinator.com/item?id=21709427 https://news.ycombinator.com/item?id=21709427 (Dec 2019) https://news.ycombinator.com/item?id=21667970 https://news.ycombinator.com/item?id=21667970 (Nov 2019) https://news.ycombinator.com/item?id=20257959 https://news.ycombinator.com/item?id=20257959 (June 2019) https://news.ycombinator.com/item?id=20188474 https://news.ycombinator.com/item?id=20188474 (June 2019) https://news.ycombinator.com/item?id=20112003 https://news.ycombinator.com/item?id=20112003 (June 2019) https://news.ycombinator.com/item?id=19945156 https://news.ycombinator.com/item?id=19945156 (May 2019) https://news.ycombinator.com/item?id=19334737 https://news.ycombinator.com/item?id=19334737 (March 2019) https://news.ycombinator.com/item?id=19334734 https://news.ycombinator.com/item?id=19334734 (March 2019)
Rygian 4y ago
I really enjoyed reading the top comment of this /r/AskEngineers post [1]. The gist of it is "use electricity directly whenever possible, and otherwise go for e-fuels [2]." [1] https://www.reddit.com/r/AskEngineers/comments/wrv59o/what_are_your_thoughts_on_the_hydrogen_industry/ https://www.reddit.com/r/AskEngineers/comments/wrv59o/what_a... [2] https://en.wikipedia.org/wiki/Electrofuel https://en.wikipedia.org/wiki/Electrofuel
- raverbashing 4y ago
  Thanks, that's very insightful. But still, it is an engineering response If you go to the e-fuel page he links it says: "They are manufactured using captured carbon dioxide or carbon monoxide, together with hydrogen obtained from sustainable electricity sources" (and what's the efficiency in that process? less than making only H2 for certain) Electrolysis efficiency can go up. Safety issues exists, but fossil fuels are only safe today due to major engineering work. I think most investment in H2 is betting on it "just in case".
  - Rygian 4y ago
    > (and what's the efficiency in that process? less than making only H2 for certain) On the contrary, it will be more efficient overall because you skip the transporting/distributing that hydrogen to a destination. Assume that you can deliver e-fuels over existing pipelines.
    - raverbashing 4y ago
      True if you count delivery, but the production efficiency is smaller In the end, it all depends how those numbers compare
  - deleted 4y ago
    [deleted]
- jbu 4y ago
  Indeed. I found this useful: https://www.linkedin.com/pulse/clean-hydrogen-ladder-v40-michael-liebreich https://www.linkedin.com/pulse/clean-hydrogen-ladder-v40-mic...
boringg 4y ago
Stop with the media induced hydrogen vs electric vehicle debate. They have different use cases and value propositions. Hydrogen is a fuel that can be transported which has its own merits (there are always trade offs). Also it is a rocket fuel and used in a variety of crucial industrial practices. If we produce hydrogen through crack natural gas, that is a loss for us on the planet as a species. However if we use the newer cleaner mechanisms (waste reuse, electrolysis) there is value from it. Also if oil and gas majors dont reap the benefits is important as they have been bad corporate citizens over the decades. We need all technologies to move us forward in the energy future on this planet or elsewhere. Also remember that were midway through a tech tree, who knows where the other tech will come along to facilitate our research and development.
- photochemsyn 4y ago
  There are two main in-situ uses of hydrogen that come to mind that don't require problematic long-distance transport and storage: nitrogen fertilizer production, and hydrogen-based direct iron reduction. For example: (2021) "Green Ammonia and the Electrification of the Haber-Bosch Process Reduce Carbon Emissions" https://guidehouseinsights.com/news-and-views/green-ammonia-and-the-electrification-of-the-haber-bosch-process-reduce-carbon-emissions https://guidehouseinsights.com/news-and-views/green-ammonia-... (2022) "Hierarchical nature of hydrogen-based direct reduction of iron oxides" https://www.sciencedirect.com/science/article/pii/S1359646222000720 https://www.sciencedirect.com/science/article/pii/S135964622...
  - bobthepanda 4y ago
    Well, there‘s also the issue that batteries for boats or airplanes result in either a massive capacity cut, or something too big to fly, float, or fit through the Suez and Panama Canals.
    - AtlasBarfed 4y ago
      Long range shipping is more solvable than your sky-is-falling astroturfing implies: https://cleantechnica.com/2022/03/18/fleetzeros-container-ship-battery-swapping-scheme-may-help-electrify-shipping/ https://cleantechnica.com/2022/03/18/fleetzeros-container-sh... Much like 90% of BEV trips not needing 300 miles of range, most shipping routes actually don't need 1000s of miles of range, they can hopscotch between ports and swap batteries quickly at the ports with some shipping conatiner sized battery that sits on the top of the ship (presumably with some rapid swap equipment that wouldn't require docking). Hydrogen will probably rule the skies though, I'll grant you that, for any long range flights. But fuel costs dominate aviation, and if shorter ranges can be addressed with batteries and some fundamental power cost advantages, then BEVs can be applied to aviation, where appropriate.
huntertwo 4y ago
Interesting, but most places with low water supplies have electricity transport already built out, no? You can burn hydrogen in Seattle and transport electricity to California.
- bobthepanda 4y ago
  I think removing a requirement for freshwater would be good for islands (which import fuel at great expense, and no one is building a submarine power cable thousands of kms to Hawaii) or military bases in hostile areas (the Navy was looking into syngas synthesis from the air)
nintendo1889 4y ago
I remember Nikola Tesla was working on generating "electricity out of thin air" and someone on youtube even has a working model of it. It hovered around 48 volts, so you'd need some kind of voltage regulator in front of it.
- aaaaaaaaaaab 4y ago
  Lol, sure! And the solution for the greenhouse gases from cattle farming is replacing them with organically raised bigfoot herds.
- xani_ 4y ago
  Yeah at what amperes ? Of course you can get voltage out of it, now try to get useful power from it!
- arbitrandomuser 4y ago
  Electric fields in the earth's surface can reach 100V/m you can take two large sheets of metal place them a meter apart vertically and a multimeter between them will read around 100 volts . I have never read up much on Tesla , sure he was a brilliant inventor , but some of the claims seem to far fetched , did he really understand the theory well enough or were most of his "experiments" let's toss this stuff together and see what's happens and make grand claims of free electricity , efficient turbines and long distance wireless transmission
  - JoeCortopassi 4y ago
    For anyone more curious about this: https://www.feynmanlectures.caltech.edu/II_09.html https://www.feynmanlectures.caltech.edu/II_09.html
  - mandeepj 4y ago
    > did he really understand the theory well enough or were most of his "experiments" let's toss this stuff together and see what's happens At least, you can show some respect to him and read a bit to understand his inventions. He developed the alternating-current power system that provides electricity for homes and buildings, so without you may not have typed your comment.

102 points by sohkamyung 4y ago

r0ckarong 4y ago

Wait till thunderf00t sees this one.

ncmncm 4y ago
Only if he misses the point.

derriz 4y ago

I barely got through the introduction before giving up. The opening line - "Hydrogen is the ultimate clean energy." - is a vague, meaningless, scientifically vacuous claim. I'm not sure that hydrogen can even be considered "clean" - potentially clean maybe? Hydrogen leaked into the atmosphere is 6-16 times more potent than CO2 as a greenhouse gas[1]. Hydrogen combustion (for heating, transport or driving turbines) releases 6 times as much NOx as burning methane (natural gas)[2]. The same opening paragraph contains the dubious claim: "H2 produced by water electrolysis using renewable energy, namely, the green hydrogen, represents the most promising energy carrier of the low-carbon economy". The most promising energy carrier of the low-carbon economy is and has been electricity. Hydrogen as an energy carrier has contributed almost nothing to lowering carbon emissions despite decades, if not a century, of research and effort. [1] https://www.rechargenews.com/energy-transition/hydrogen-twice-as-powerful-a-greenhouse-gas-as-previously-thought-uk-government-study/2-1-1200115 https://www.rechargenews.com/energy-transition/hydrogen-twic... [2] https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/798243/H2_Emission_Potential_Report_BEIS_E4tech.pdf https://assets.publishing.service.gov.uk/government/uploads/...

u320 4y ago
For fixed infrastructure, nothing beats power lines. For mobile applications, hydrogen has numerous problems. There are other options, like batteries, ammonia, synthetic hydrocarbons etc that should be explored further. Hydrogen doesn't even come close to deserving the title "the ultimate clean energy".
- ncmncm 4y ago
  That wholly misses the point. We need hydrogen production in unlimited amounts for myriad processes. Want synthetic ammonia? Need hydrogen. Methane? Hydrogen. Kerosene? Hydrogen. Green steel production? Hydrogen. Furthermore, liquified hydrogen is the future of aviation. So a tech that produces hydrogen efficiently anywhere there is air is intrinsically important.
  - eru 4y ago
    > Furthermore, liquified hydrogen is the future of aviation. What makes you think so? Why not eg methane? Or other synthetic carbohydrates?
    - ncmncm 4y ago
      LH2's extreme mass-energy density will make other aircraft unable to compete, because the weight savings may be sold as additional paying cargo capacity. That presumes a joule of LH2 is the same price as of kerosene. But LH2 may end up much cheaper, increasing the gap.
      - eru 4y ago
        One would suppose mass energy density is even more important for rockets. In practice, only some rockets use LH2. Many rockets use souped up kerosene (RP1) or, more recently, methane. Compare https://en.wikipedia.org/wiki/Liquid_rocket_propellant#Hydrogen https://en.wikipedia.org/wiki/Liquid_rocket_propellant#Hydro... and https://en.wikipedia.org/wiki/Hydrogen-powered_aircraft https://en.wikipedia.org/wiki/Hydrogen-powered_aircraft Also: > With materials available in the 2020s, the mass of tanks strong enough to withstand this kind of high pressure will greatly outweigh the hydrogen fuel itself, largely negating the weight to energy advantage of hydrogen fuel over hydrocarbon fuels. Hydrogen has a severe volumetric disadvantage relative to hydrocarbon fuels, but future blended wing body aircraft designs might be able to accommodate this extra volume without greatly expanding the wetted area. From https://en.wikipedia.org/wiki/Aviation_fuel https://en.wikipedia.org/wiki/Aviation_fuel
aydyn 4y ago
Those are just buzzwords thrown in to make their article sound more impactful and progressive. Every author does this (yes, literally every author). Who cares. What about their tech?
- ncmncm 4y ago
  Yes. The tech seems very interesting. The key observation seems to be that atmospheric water vapor is massively purer than any terrestrial water source. And, production directly from vapor avoids efficiency and fouling problems seen when working in liquid. I don't know what they mean by "faradaic efficiency".
csdvrx 4y ago
> Hydrogen leaked into the atmosphere is 6-16 times more potent than CO2 as a greenhouse gas Which is a problem considering how small the H2 molecule is: we can't reuse our existing LNG pipelines. Personally, I believe aerochemistry will "work out" in the long term by generating short to medium length aliphatic compounds from CO2 and H2O: we'll eventually figure out the catalyzation from sunlight. We can then have access to lots of energy, with a negative carbon balance, using always sunny surfaces like the Sahara desert - which sits conveniently close to Europe! This could help with the European energy problems if only France would stop thinking short term and try to protect and extend the commercial life of its ailing nuclear energy business (50% of which is currently closed down to being unsafe/uncoolable etc) by shooting down initiatives to build LNG pipelines from North Africa to Europe. Yes, they are doing that, even now that they (and Germany, and the rest of Europe...) are facing a winter without Russian gas: https://www.archyde.com/gas-spain-criticizes-frances-opposition-to-the-midcat-gas-pipeline-project/ https://www.archyde.com/gas-spain-criticizes-frances-opposit... Unfortunately, France stands in the way between the shortest route from North Africa to continental Europe through Gibraltar. If a pipeline can't be build from Spain to Germany by going through France, the next best would be from Italy.
- ncmncm 4y ago
  It is vastly more cost effective to build electric transmission lines instead of gas pipelines, and crack hydrogen at the point of use. Furthermore, the desert is a lousy place to put solar panels. They get hot and dusty, making them inefficient and shortening their life. The best places are floating on water, and sharing pasture and crop land. Spain, Italy, and Greece have plenty of room for such solar. Portugal, too, and former Yugoslavia, Albania and Bulgaria. Nukes will shortly be unable to produce competitive power, and will be mothballed except where taxpayers are forced to subsidize them.
  - csdvrx 4y ago
    > It is vastly more cost effective to build electric transmission lines instead of gas pipelines, and crack hydrogen at the point of use No it's not. You are building in your assumption that I talk about solar panels for electricity generation. I don't. I'm talking about direct aerochemistry, without separate solar panels, to avoid tackling up the conversion rate of solar to electricty on top of the conversion rate of the chemical reaction that would create the hydrocarbons. There is gas in North Africa. This gas can be directly burnt to generate heat. It can also be used to generate electricity. That's short term. In the long term, we'll be able to make similar compounds from energy (sunlight or heat) + CO2 + H2O. Inbetween, there's a window of opportunity for nuclear and solar, but both are extremely polluting due to the metals used: we should avoid getting locked in this bad situation. Also, I think the lack of nuclear accident in Western Europe so far has just been luck. With the dense population, it's a catastrophe waiting to happen. > Furthermore, the desert is a lousy place to put solar panels I don't think you understand, as I don't suggest at all the use of solar panels. Using solar panels to generate energy is nice, but it's at best carbon neutral. I'm talking about the future: being carbon negative: extracting CO2 from the atmosphere and generating a usable from of energy.
harg 4y ago
H2 may well be a more potent GHG when compared to CO2, but it's tendency to remain in the atmosphere for a long time is a factor than shouldn't be ignored and doesn't seem to be mentioned by your first citation. I.e. H2 may be 16x more potent than CO2 but if it reacts away within hours/days/[<16th of the time that CO2 stays around] then its overall contribution to warming will be less than CO2. (I don't know what this figure is, but I believe Hydrogen is pretty reactive so doesn't tend to stick around that long) From your second citation: > The evidence base relating to non-GHG emissions from end-use in heating applications is almost non-existent It then says that a single study: > suggests there is potential for up to six times higher point NOx emissions compared with natural gas". and that it could be significantly reduced with catalytic converters. The points you raise are not nearly as unequivocal as you make them out to be. I also don't feel like Hydrogen is going to solve all of our problems - it has many problems that needs to be overcome. But it could well play a role in certain areas when it comes to getting off fossil fuels, so studies into more efficient production of it will surely be valuable.
- CorrectHorseBat 4y ago
  >H2 may well be a more potent GHG when compared to CO2, but it's tendency to remain in the atmosphere for a long time is a factor than shouldn't be ignored and doesn't seem to be mentioned by your first citation. I.e. H2 may be 16x more potent than CO2 but if it reacts away within hours/days/[<16th of the time that CO2 stays around] then its overall contribution to warming will be less than CO2. (I don't know what this figure is, but I believe Hydrogen is pretty reactive so doesn't tend to stick around that long) Usually these numbers take that in consideration and the two are compared over a certain number of years, i.e. 100 years. A quick Google seems to confirm this, H2 is ~10 more potent than CO2 over 100 years.
  - audunw 4y ago
    Good point Still.. we're talking about unintentional leaks here. With the alternatives, CO2-emissions is an unavoidable by-product (in theory it can be managed with CCS, but not for transportation) We should use batteries whenever we can, but seems to me like hydrogen is an essential component of a green, fully carbon neutral economy. Though I agree with the comment above that it's a bit... misleading.. to call hydrogen the ultimate clean energy. Green hydrogen (do differentiate from hydrogen made from natural gas) is a very good clean energy carrier. That'd be more precise to say.
ZeroGravitas 4y ago
Green Hydrogen is going to be big. You are correct that if you are burning it then you have taken a wrong turn, or at least haven't got to the final destination. Mostly it will be a sink of energy and a chemical feedstock. That is still massive, size of the oil industry scale big.
- rvbissell 4y ago
  The prioritization that you propose will make the oceans saltier. Whereas, burning H2 is water-neutral.
jbu 4y ago
Were you thinking of methane instead of hydrogen? But the paper does seem hypy. H2 will have its place, but wire transfers electrons better than hydrogen.
- ncmncm 4y ago
  You miss the meat of the article. Highly efficient production not subject to fouling makes hydrogen generated at point of use practical. H2 has myriad uses, and is gaining more at breakneck pace.
ajnin 4y ago
> "Hydrogen is the ultimate clean energy." This is a lie pushed by oil companies. First it is incorrect because hydrogen is not a natural energy source, it is a way to store energy. But above all, currently the vast majority of hydrogen is made by steam cracking methane or other hydrocarbons, which is a process that releases CO2. You can think of hydrogen production + hydrogen use as a combustion with additional steps. And since the hydrogen supply chain is very inefficient (hydrogen is very light so you need to compress it a lot to store it, it is a very small molecule so it leaks very easily, and when you use it you need to decompress it so you get more losses due to thermodynamic effects) it turns out as quite bad from the point of view of CO2 emissions. It is just a way to sell more oil.
- ncmncm 4y ago
  You seem to have read only the introductory paragraphs. There is little need to store or transport hydrogen that may be produced right where and when it is needed.
  - wongarsu 4y ago
    If I read the abstract correct it's doing electrolysis of moisture in the air. That's a process that inherently uses more energy then you get back out of the hydrogen. After all burning hydrogen just turns it back into water, and we can't have more than 100% round-trip efficiency. I could imagine it as a viable storage technology, e.g. if you want to install a solar farm in a remote location you could have it produce hydrogen from the air and sell that.
    - ncmncm 4y ago
      Obviously all conversions involve losses. If you have electric power but need hydrogen, you have to make the hydrogen, whatever the loss. This method has lower loss than others. Probably ammonia will be a better transport medium than hydrogen, but you need hydrogen to make ammonia.
      - saalweachter 4y ago
marcosdumay 4y ago
With higher NOx emissions, come higher generator efficiency. Anyway, you can control both on your combustion chamber, so the claim for open fires does really not apply.

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ZeroGravitas 4y ago

I guess the trick is the purity of the water combined with the location independence. Similarly e-fuels made from hydrogen can be both purer than standard jet fuel, and obtained from a wider range of places. Both of those things help tilt the cost towards e-fuels.

criddell 4y ago
Would the water have minerals? If not, can you add them? I'm not sure I want to be drinking pure water.
- ZeroGravitas 4y ago
  The similar devices for drinking water do add minerals, but for hydrogen production the lack of them is a benefit. https://en.m.wikipedia.org/wiki/Atmospheric_water_generator https://en.m.wikipedia.org/wiki/Atmospheric_water_generator

raverbashing 4y ago

It's an interesting paper but I think most of the limitations in H2 production are in electricity supply, not in water supply

ncmncm 4y ago
Electricity supply cost is plummeting. Water is plentiful, but pure enough water not to foul electrolysers has not been, and efficiency has been low. Avoiding liquid phase bypasses all the difficulties of existing electrolysis.
- deleted 4y ago
  [deleted]
- s1artibartfast 4y ago
  Source? From what I've seen Electricity wholesale costs increasing for the last 8 years. Yes there are times of the year where the spot price is low, but the average cost continues to go up.
  - ncmncm 4y ago
    Cost is still dominated by natural gas price. As solar and wind build-out saturates in coming decades, mined gas will become unable to compete with renewables and hot storage, most places.
    - s1artibartfast 4y ago
      Your parent post was present tense, not future. Prices today nor the last several years have been plummeting.
      - ncmncm 4y ago
        If you built a solar farm last year, build another today, and another one next year, the cost for those will be seen on a sharp downslope. There would be no need ever to pay spot market price: you operate when you have power to operate. You could put up wind turbines too if you wanted to operate more regularly. In any case you can't buy these things yet. All costs are necessarily referred to a time when they are available off the shelf.

pydry 4y ago

Not sure what the obsession with hydrogen is about. It's inefficient to produce and difficult to store.

ncmncm 4y ago
The article is specifically about an efficient process to produce it at point of use, so it need not be stored.
- pydry 4y ago
  The first paragraph contradicts you: >is the most promising energy carrier of the low-carbon economy. ^_ energy carrier != production at the point of use. The article seems to be about dealing with a supposed shortage of fresh water to make the hydrogen from. If this is solved it changes nothing.
  - ncmncm 4y ago
    The authors' speculations on how hydrogen may be used are irrelevant to the substantive content of the article. There is no shadow of doubt about whether hydrogen production will be massively important in the immediate future, so better ways to make it are equally as important.
- dang 4y ago
  Please edit swipes out of your comments here. This comment would be just fine without that last bit. Edit: We've had to ask you this kind of thing many times before. Would you please review https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html and stick to the rules when posting here? I don't want to ban you, because your substantive comments are great, but this is not ok: https://news.ycombinator.com/item?id=30890352 https://news.ycombinator.com/item?id=30890352 (April 2022) https://news.ycombinator.com/item?id=26290876 https://news.ycombinator.com/item?id=26290876 (Feb 2021) https://news.ycombinator.com/item?id=22199357 https://news.ycombinator.com/item?id=22199357 (Jan 2020) https://news.ycombinator.com/item?id=22087086 https://news.ycombinator.com/item?id=22087086 (Jan 2020) https://news.ycombinator.com/item?id=21799929 https://news.ycombinator.com/item?id=21799929 (Dec 2019) https://news.ycombinator.com/item?id=21709427 https://news.ycombinator.com/item?id=21709427 (Dec 2019) https://news.ycombinator.com/item?id=21667970 https://news.ycombinator.com/item?id=21667970 (Nov 2019) https://news.ycombinator.com/item?id=20257959 https://news.ycombinator.com/item?id=20257959 (June 2019) https://news.ycombinator.com/item?id=20188474 https://news.ycombinator.com/item?id=20188474 (June 2019) https://news.ycombinator.com/item?id=20112003 https://news.ycombinator.com/item?id=20112003 (June 2019) https://news.ycombinator.com/item?id=19945156 https://news.ycombinator.com/item?id=19945156 (May 2019) https://news.ycombinator.com/item?id=19334737 https://news.ycombinator.com/item?id=19334737 (March 2019) https://news.ycombinator.com/item?id=19334734 https://news.ycombinator.com/item?id=19334734 (March 2019)

Rygian 4y ago

I really enjoyed reading the top comment of this /r/AskEngineers post [1]. The gist of it is "use electricity directly whenever possible, and otherwise go for e-fuels [2]." [1] https://www.reddit.com/r/AskEngineers/comments/wrv59o/what_are_your_thoughts_on_the_hydrogen_industry/ https://www.reddit.com/r/AskEngineers/comments/wrv59o/what_a... [2] https://en.wikipedia.org/wiki/Electrofuel https://en.wikipedia.org/wiki/Electrofuel

raverbashing 4y ago
Thanks, that's very insightful. But still, it is an engineering response If you go to the e-fuel page he links it says: "They are manufactured using captured carbon dioxide or carbon monoxide, together with hydrogen obtained from sustainable electricity sources" (and what's the efficiency in that process? less than making only H2 for certain) Electrolysis efficiency can go up. Safety issues exists, but fossil fuels are only safe today due to major engineering work. I think most investment in H2 is betting on it "just in case".
- Rygian 4y ago
  > (and what's the efficiency in that process? less than making only H2 for certain) On the contrary, it will be more efficient overall because you skip the transporting/distributing that hydrogen to a destination. Assume that you can deliver e-fuels over existing pipelines.
  - raverbashing 4y ago
    True if you count delivery, but the production efficiency is smaller In the end, it all depends how those numbers compare
- deleted 4y ago
  [deleted]
jbu 4y ago
Indeed. I found this useful: https://www.linkedin.com/pulse/clean-hydrogen-ladder-v40-michael-liebreich https://www.linkedin.com/pulse/clean-hydrogen-ladder-v40-mic...

boringg 4y ago

Stop with the media induced hydrogen vs electric vehicle debate. They have different use cases and value propositions. Hydrogen is a fuel that can be transported which has its own merits (there are always trade offs). Also it is a rocket fuel and used in a variety of crucial industrial practices. If we produce hydrogen through crack natural gas, that is a loss for us on the planet as a species. However if we use the newer cleaner mechanisms (waste reuse, electrolysis) there is value from it. Also if oil and gas majors dont reap the benefits is important as they have been bad corporate citizens over the decades. We need all technologies to move us forward in the energy future on this planet or elsewhere. Also remember that were midway through a tech tree, who knows where the other tech will come along to facilitate our research and development.

photochemsyn 4y ago
There are two main in-situ uses of hydrogen that come to mind that don't require problematic long-distance transport and storage: nitrogen fertilizer production, and hydrogen-based direct iron reduction. For example: (2021) "Green Ammonia and the Electrification of the Haber-Bosch Process Reduce Carbon Emissions" https://guidehouseinsights.com/news-and-views/green-ammonia-and-the-electrification-of-the-haber-bosch-process-reduce-carbon-emissions https://guidehouseinsights.com/news-and-views/green-ammonia-... (2022) "Hierarchical nature of hydrogen-based direct reduction of iron oxides" https://www.sciencedirect.com/science/article/pii/S1359646222000720 https://www.sciencedirect.com/science/article/pii/S135964622...
- bobthepanda 4y ago
  Well, there‘s also the issue that batteries for boats or airplanes result in either a massive capacity cut, or something too big to fly, float, or fit through the Suez and Panama Canals.
  - AtlasBarfed 4y ago
    Long range shipping is more solvable than your sky-is-falling astroturfing implies: https://cleantechnica.com/2022/03/18/fleetzeros-container-ship-battery-swapping-scheme-may-help-electrify-shipping/ https://cleantechnica.com/2022/03/18/fleetzeros-container-sh... Much like 90% of BEV trips not needing 300 miles of range, most shipping routes actually don't need 1000s of miles of range, they can hopscotch between ports and swap batteries quickly at the ports with some shipping conatiner sized battery that sits on the top of the ship (presumably with some rapid swap equipment that wouldn't require docking). Hydrogen will probably rule the skies though, I'll grant you that, for any long range flights. But fuel costs dominate aviation, and if shorter ranges can be addressed with batteries and some fundamental power cost advantages, then BEVs can be applied to aviation, where appropriate.

huntertwo 4y ago

Interesting, but most places with low water supplies have electricity transport already built out, no? You can burn hydrogen in Seattle and transport electricity to California.

bobthepanda 4y ago
I think removing a requirement for freshwater would be good for islands (which import fuel at great expense, and no one is building a submarine power cable thousands of kms to Hawaii) or military bases in hostile areas (the Navy was looking into syngas synthesis from the air)

nintendo1889 4y ago

I remember Nikola Tesla was working on generating "electricity out of thin air" and someone on youtube even has a working model of it. It hovered around 48 volts, so you'd need some kind of voltage regulator in front of it.

aaaaaaaaaaab 4y ago
Lol, sure! And the solution for the greenhouse gases from cattle farming is replacing them with organically raised bigfoot herds.
xani_ 4y ago
Yeah at what amperes ? Of course you can get voltage out of it, now try to get useful power from it!
arbitrandomuser 4y ago
Electric fields in the earth's surface can reach 100V/m you can take two large sheets of metal place them a meter apart vertically and a multimeter between them will read around 100 volts . I have never read up much on Tesla , sure he was a brilliant inventor , but some of the claims seem to far fetched , did he really understand the theory well enough or were most of his "experiments" let's toss this stuff together and see what's happens and make grand claims of free electricity , efficient turbines and long distance wireless transmission
- JoeCortopassi 4y ago
  For anyone more curious about this: https://www.feynmanlectures.caltech.edu/II_09.html https://www.feynmanlectures.caltech.edu/II_09.html
- mandeepj 4y ago
  > did he really understand the theory well enough or were most of his "experiments" let's toss this stuff together and see what's happens At least, you can show some respect to him and read a bit to understand his inventions. He developed the alternating-current power system that provides electricity for homes and buildings, so without you may not have typed your comment.