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Thread: Hydrogen engines

  1. #121
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    Quote Originally Posted by profloater View Post
    Photosynthesis might be a red leaved herring, indeed, but the use of hydrogen in engines remains interesting. I was focussed on future H ships as a prime example. I never meant to imply photosynthesis would be a route. That belongs in a carbon capture thread.
    Okay, what is it about ships that makes it particularly desirable?

    Disadvantages:
    Low volumetric energy density. Ships are frequently volume-limited as it is.
    Very low cryogenic temperatures, or very high pressure tanks...lots of big ones.
    Leak prone substance that causes embrittlement of common steels.
    Very high cost per unit power output of fuel cells, in an application that demands a relatively constant power output (preventing you from using a battery buffer to cover high power demands).

    Advantages:
    High specific energy density. Might be helpful for aircraft, but mass isn't a big problem for ships.
    ???

  2. #122
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    Quote Originally Posted by cjameshuff View Post
    Okay, what is it about ships that makes it particularly desirable?

    Disadvantages:
    Low volumetric energy density. Ships are frequently volume-limited as it is.
    Very low cryogenic temperatures, or very high pressure tanks...lots of big ones.
    Leak prone substance that causes embrittlement of common steels.
    Very high cost per unit power output of fuel cells, in an application that demands a relatively constant power output (preventing you from using a battery buffer to cover high power demands).

    Advantages:
    High specific energy density. Might be helpful for aircraft, but mass isn't a big problem for ships.
    ???
    I would say it’s the low carbon footprint, zero if solar is used to supply the hydrogen. Yes there are those challenges but Lithium batteries at large scale use rare elements as well as having waste heat issues. Battery aircraft are coming along for short distances but Hydrogen might be the answer for eventual long haul. I guess biofuels are easier to get carbon neutral if the target is just to stop using fossil fuels. And as I mentioned earlier, water vapour contrails are greenhouse gases.
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  3. #123
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    Quote Originally Posted by profloater View Post
    I would say it’s the low carbon footprint, zero if solar is used to supply the hydrogen.
    How much carbon is used to manufacture a PV cell, and how often do they need to be replaced? AFAIK they've just now got the prototypes to break even on that account, it hasn't hit the market yet. How much to make the tankage, the pipes and the pumps?
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  4. #124
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    Quote Originally Posted by profloater View Post
    I would say it’s the low carbon footprint, zero if solar is used to supply the hydrogen. Yes there are those challenges but Lithium batteries at large scale use rare elements as well as having waste heat issues. Battery aircraft are coming along for short distances but Hydrogen might be the answer for eventual long haul. I guess biofuels are easier to get carbon neutral if the target is just to stop using fossil fuels. And as I mentioned earlier, water vapour contrails are greenhouse gases.
    Hydrogen has thermal issues as well. You can't compress or expand the gas without changing its temperature, and the liquid has to be kept around 20 K and has potential to produce a vastly greater volume of gas if it rises much above that. And in certain leaks it can counterintuitively heat up enough to ignite itself.

    And the rare elements used in batteries are not nearly as rare as those used in fuel cells.

  5. #125
    You need energy to generate hydrogen in the first place, where do you get the energy from. It might be a good way to store the energy,like using solar panels to generate the electricity and split the hydrogen from something and store the hydrogen but then you get to store it safely with reacting with the oxygen in the atmosphere. Everyone could possibly generate it but then there is storage and does everyone have enough space to store it. If do generate it and store it in big refineries or factories how to get around without big booms happening. Plus how about people who need to travel get distances to get around. People around where I live need to travel up to 100 km one way to get to work, I don't really know about hydrogen storage but as far as I know there isn't a way to store enough hydrogen for such long trips. Place there are people who have vehicles like tractors which never leave the property so you need a fuel that you can store and transfer without the need for pumps and such. I don't really like the gas engine but the competitors need to come to solutions to these problems. I have a feeling there will multiple solutions to the problems, some people who have short commutes will probably use electric cars or public transit, people who drive long distances will probably use some kind of hybrid, and they will be some who will still just gas engines.
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  6. #126
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    Quote Originally Posted by The Backroad Astronomer View Post
    You need energy to generate hydrogen in the first place, where do you get the energy from. It might be a good way to store the energy,like using solar panels to generate the electricity and split the hydrogen from something and store the hydrogen but then you get to store it safely with reacting with the oxygen in the atmosphere. Everyone could possibly generate it but then there is storage and does everyone have enough space to store it. If do generate it and store it in big refineries or factories how to get around without big booms happening. Plus how about people who need to travel get distances to get around. People around where I live need to travel up to 100 km one way to get to work, I don't really know about hydrogen storage but as far as I know there isn't a way to store enough hydrogen for such long trips. Place there are people who have vehicles like tractors which never leave the property so you need a fuel that you can store and transfer without the need for pumps and such. I don't really like the gas engine but the competitors need to come to solutions to these problems. I have a feeling there will multiple solutions to the problems, some people who have short commutes will probably use electric cars or public transit, people who drive long distances will probably use some kind of hybrid, and they will be some who will still just gas engines.
    I would think hydrogen would work great for farms. The tank weight for a tractor would not be an issue. Most of the energy for a tractor goes into the tremendous work it does, not related to accelerating to highway speeds.
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  7. #127
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    Quote Originally Posted by Copernicus View Post
    I would think hydrogen would work great for farms. The tank weight for a tractor would not be an issue. Most of the energy for a tractor goes into the tremendous work it does, not related to accelerating to highway speeds.
    Except as The Backroad Astronomer said, they infrequently leave the property. You'll prefer a fuel that can easily be transferred to them on-site. You can walk up to a tractor with a can of diesel in your hands. Hydrogen...you'll need to install a filling station connected to a large tank and have trucks come to keep that full. And if you do maintenance that requires emptying the hydrogen tank, you're going to be stuck venting it, because you're not emptying it into the higher-pressure filling station tank. CNG tractors do exist and share many of the same problems, but they've not made a great deal of progress, and hydrogen has additional problems...every one of those setups as well as every tractor with fuel in it is going to be a significant source of hydrogen losses, for one. Required tank pressures are another.

    You've found a use case where one of the downsides of hydrogen is somewhat reduced. That doesn't make it a superior or even a basically suitable approach.

  8. #128
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    Quote Originally Posted by cjameshuff View Post
    Hydrogen has thermal issues as well. You can't compress or expand the gas without changing its temperature, and the liquid has to be kept around 20 K and has potential to produce a vastly greater volume of gas if it rises much above that. And in certain leaks it can counterintuitively heat up enough to ignite itself.

    And the rare elements used in batteries are not nearly as rare as those used in fuel cells.
    I refer back to my post 111 with link to ships using H fuel cells.
    sicut vis videre esto
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  9. #129
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    Because we brought up this subject here, here is a group of scientists from Waterloo able to replicate photosynthesis artificially:
    https://www.captain-planet.net/scien...-clean-energy/


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  10. #130
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    Quote Originally Posted by Copernicus View Post
    I would think hydrogen would work great for farms. The tank weight for a tractor would not be an issue. Most of the energy for a tractor goes into the tremendous work it does, not related to accelerating to highway speeds.
    Surely methane would be the go-to choice on a farm?

  11. #131
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    Quote Originally Posted by kzb View Post
    Surely methane would be the go-to choice on a farm?
    I thought the stated or implied point of this thread is to speculate on zero carbon prime movers in order to reduce CO2 emission? Farms around me are opting for fields of PV and this a productive farm area, so it must pay well. Methane is a natural product of decay so it has been used as fuel in both small and medium installations over many years.
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

  12. #132
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    Quote Originally Posted by kzb View Post
    Surely methane would be the go-to choice on a farm?
    Methane would be obvious too. Chemists will eventually figure out ways to convert hydrogen, methane, propane, to more transportable items. When I say we should value our engineers more, I include, scientists, like chemists, and technicians in this group, because they all contribute so greatly to success. Chemists, I think, will be the greatest contributors of solving the problems of finding energy that can replace the ones that cause more carbon dioxide levels to increase. I would like to say we could have fusion, but I still see no progress. I think fusion might work if somebody combines something like hydrogen and nickel or some such other element that might make the process more controllable.
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  13. #133
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    Quote Originally Posted by Copernicus View Post
    Methane would be obvious too. Chemists will eventually figure out ways to convert hydrogen, methane, propane, to more transportable items. When I say we should value our engineers more, I include, scientists, like chemists, and technicians in this group, because they all contribute so greatly to success. Chemists, I think, will be the greatest contributors of solving the problems of finding energy that can replace the ones that cause more carbon dioxide levels to increase. I would like to say we could have fusion, but I still see no progress. I think fusion might work if somebody combines something like hydrogen and nickel or some such other element that might make the process more controllable.
    I think you are being overtaken by developments. There are several brands of hydrogen powered cars and hydrogen filling stations in existence! The storage vessels for the hydrogen use multiple layers to reduce the risk of explosion and the development of these is bound to continue towards Standardised international sizes suitable for the various modes of transport. It is happening!
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

  14. #134
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    Quote Originally Posted by profloater View Post
    It is happening!
    Just to add to that thought and to repeat something I've said several times in this thread....

    There seems to be a lot of posts in this thread where there is a search for some "magic" technology that someone will invent that will solve all our energy needs and stop global warming. While searching for new technologies and solutions is a worthwhile endeavor, I think this way of thinking is the completely wrong approach. As has been quoted several times in this thread "perfect is the enemy of good".

    First, we already have good technologies to greatly reduce our emissions of CO2 and other greenhouse gases. There is no single technology that will do that, but this includes multiple types of alternative energy production, increased energy efficiency (including more efficient energy production and distribution), CO2 capture (including land use practices, tree planting, etc.), etc. All this technology currently exists, we just have to have the will as individuals, companies, and nations, to employ them.

    I also fear that if we advocate that the solution to global warming is some yet-to-be-invented technology, that those who do not wish to work on this problem and are happy with the status quo, will use this as an excuse for inaction, along the lines of "we need to study this more" excuse for inaction.

    Second, even if one does come up with some "magic" technology, whether it is a new hydrogen engine or way to produce hydrogen, or vastly improved photovoltaic systems, or whatever, there is still the huge problems of scaling up that technology to the industrial/commercial/consumer scale, and doing so at an affordable price, and for many of these technologies (like hydrogen), putting in all the other things (like infrastructure) to support them. I think these issues are being too casually dismissed.

    Third, I think there is a lack of appreciation of how much research in these fields has happened in the last 40 or 50 years, and how much continues to go on, and how difficult these problems are. It would not be an exaggeration to say hundreds to thousands of papers are published on these fields every year. But one over-hyped paper gets some mention in the popular press and people act like it is the new salvation. It seems to indicate a lack of critical review.
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  15. #135
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    Quote Originally Posted by Swift View Post
    Just to add to that thought and to repeat something I've said several times in this thread....

    There seems to be a lot of posts in this thread where there is a search for some "magic" technology that someone will invent that will solve all our energy needs and stop global warming. While searching for new technologies and solutions is a worthwhile endeavor, I think this way of thinking is the completely wrong approach. As has been quoted several times in this thread "perfect is the enemy of good".

    First, we already have good technologies to greatly reduce our emissions of CO2 and other greenhouse gases. There is no single technology that will do that, but this includes multiple types of alternative energy production, increased energy efficiency (including more efficient energy production and distribution), CO2 capture (including land use practices, tree planting, etc.), etc. All this technology currently exists, we just have to have the will as individuals, companies, and nations, to employ them.

    I also fear that if we advocate that the solution to global warming is some yet-to-be-invented technology, that those who do not wish to work on this problem and are happy with the status quo, will use this as an excuse for inaction, along the lines of "we need to study this more" excuse for inaction.

    Second, even if one does come up with some "magic" technology, whether it is a new hydrogen engine or way to produce hydrogen, or vastly improved photovoltaic systems, or whatever, there is still the huge problems of scaling up that technology to the industrial/commercial/consumer scale, and doing so at an affordable price, and for many of these technologies (like hydrogen), putting in all the other things (like infrastructure) to support them. I think these issues are being too casually dismissed.

    Third, I think there is a lack of appreciation of how much research in these fields has happened in the last 40 or 50 years, and how much continues to go on, and how difficult these problems are. It would not be an exaggeration to say hundreds to thousands of papers are published on these fields every year. But one over-hyped paper gets some mention in the popular press and people act like it is the new salvation. It seems to indicate a lack of critical review.
    I agree but the public sector is one side of the medal that is “bottom up”. The other side being the private sector which will tell us what is profitable and which is “top down”.

    Therefore we all need to work together...


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  16. #136
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    Quote Originally Posted by kzb View Post
    Surely methane would be the go-to choice on a farm?
    There's a lot of choices. Know what they call a farmer who relies on just one way of doing things?

    Unemployed.
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  17. #137
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    Quote Originally Posted by Copernicus View Post
    Methane would be obvious too. Chemists will eventually figure out ways to convert hydrogen, methane, propane, to more transportable items. When I say we should value our engineers more, I include, scientists, like chemists, and technicians in this group, because they all contribute so greatly to success. Chemists, I think, will be the greatest contributors of solving the problems of finding energy that can replace the ones that cause more carbon dioxide levels to increase. I would like to say we could have fusion, but I still see no progress. I think fusion might work if somebody combines something like hydrogen and nickel or some such other element that might make the process more controllable.
    Just to say, there is a roadmap to fusion you know:

    https://en.wikipedia.org/wiki/ITER

    https://en.wikipedia.org/wiki/DEMOns..._Power_Station

    https://en.wikipedia.org/wiki/PROTO_(fusion_reactor)

    We won't live to see it !

  18. #138
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    Quote Originally Posted by kzb View Post
    well if we have a sweepstake on Hydrogen vs fusion for cars, planes and ships, I will back Hydrogen and the hybrids of the future, I think, will be hydrogen fuel cells plus batteries to provide surges of power, and that's for all three transports.
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

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