UKH

Interested in any papers/research/info on how “green” Green Hydrogen actually is and how useful it will be in the future.

Any info/opinions much appreciated, especially stuff that’s not just propaganda/a press puff piece for Ineos etc.

Hydrogen has 'narrow shoulders' I.e. it's a small molecule that can 'bleed through' steel containers. A Dewar vessel that is robust enough to survive, for example a road crash is very difficult but not impossible to make.

At the moment most industrial hydrogen production is via 'decomposing' (actually reforming) natural gas with super-hot steam. I.e. it relies on fossil fuels.

The hope is that electrolysis using electricity from renewables can replace the above method. but at the moment it's triple the cost.

In my opinion it's a dead-end and represents the last hope (gasp!) of the internal combustion engine; it's only justification might be to improve air quality in inner-city areas in the short to medium term, replacing diesel powered road haulage.

It depends on what the source of the power is or where the hydrogen comes from if not electrolysis and then on what it's used for afterwards. There's no simple answer. For example in our biogas plant we actually spend a fair sum to NOT produce hydrogen.

https://e360.yale.edu/features/green-hydrogen-could-it-be-key-to-a-carbon-f...

I’m specifically interested in “green hydrogen”, i.e. from electrolysis using renewable power.

I’m specifically interested in “green hydrogen”, i.e. from electrolysis using renewable power. There seems to be a big drive for it in Europe with a lot of investment.

Is it an actual solution, or just the next “hyped up” technology being pushed by the oil and gas sector to remain relevant as fossil fuels get sidelined?

Certified road tanks are an off-the-shelf item, either with an aluminium or dense  polymer liner and whatever outside. The standard spun-cast steel cylinders you can buy in any industrial gas dealer are plastic lined. You can even buy the stuff from Amazon!

The use of hydrogen in i.c. engines is effectively a dead issue due to the thermodynamics, all the production vehicles (and there's a fair few out there) use fuel cells and electric traction. For heavy work batteries will never make it until they are maybe 100 times better so hydrogen is coming (or bio/sythetic fuels of some kind). For some applications hydrogen is the clear leader as an alternative (steelmaking for example).

Cheers Mike. I’ll give that a proper read this evening.

It's the obvious solution if you have random surplus renewable energy and problems distributing this over long distances, you just put it in a tank and take it somwhere useful. As the grid supply becomes more and more imbalanced it will become the standard.

Sorry this is very tangential, but as a fun science experiment... Hot water on steel in absence of oxygen can very very very slowly produce hydrogen in small quantities. If you have no rust inhibitor in central heating and haven't introduced fresh water for a couple of years, when you bleed the radiators...  that's not air. Try lighting the gas that comes out with a lighter. If you are as stupid as I was when I was a kid, you can try it and see... 

Hydrogen does have a potential future use for electricity storage, recombining in a fuel cell. Some things like wind farms don't produce matching demand and one approach might be converting surplus power to hydrogen. The technology still has a way to go.

Looks like they might make it sooner than you think, certainly to businesses who have control of charging infrastructure (supermarkets, couriers):-

https://www.bbc.co.uk/news/science-environment-56678669

I suspect the gulf states are thinking of using the massive solar resource they have, but sourcing the raw water might be the bigger problem!

Puff pieces from universities have been around since fusion power or sunshine electricity. Since hydrogen fuelled trucks are on the roads and for example the Coop in Switzerland have a fleet I'll wait on speculative solutions.

 I think the challenge will be where are you going to put all these wind and solar farms to generate the green hydrogen? Once the intermittency of wind and sun are taken into account, the power per unit area that can be generated is low, meaning that impractically large areas of land are required. There just isn't enough land available. I know offshore wind is an option, and the power density is better, but it is still low. 

I bet some some clever person on here could calculate how much land is needed to generate one kg of hydrogen. I think the answer would reveal the scale of the problem. 

Surely we have to find ways to reduce our energy use, trying to find ways of meeting ever increasing demand is coming at things the wrong way. 

It feels a bit like we're clutching at straws with hydrogen to me. 

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I think as aluminium ion batteries hopefully move from R&D to industrial production over the next 20 years, the number of corner cases where gaseous H2 has an advantage over battery tech is going to shrink and shrink.  We could eventually have >10x the present energy density in batteries, and no rare Earth or lithium dependencies.  

Cryogenic liquid H2 might have a special role in aviation and particularly hypersonic aviation.

The much mooted introduction of some H2 in to natural gas grids is a sop measure; we should be replacing housing stock with passive stock that doesn’t need heating in the first place.

I’m still far from convinced of the merits of gaseous H2 as a significant part of a green future.

The green nature of hydrogen is more about how the hydrogen fuel is produced, rather than the tail-pipe when used. The industry is beginning to label and differentiated hydrogen, three phrases are used to describe, but not universally adopted.

Green hydrogen - Hydrogen generated from electrolysis using renewable energy. How 'green depends' on the renewable energy, hydro-dams take lots of concrete which is C02 emitter, wind-turbines are made from metals needing power to mine, extract, process, refine, smelt and mould resulting in C02 emissions. C02 savings from fossil fuels from renewables is large however. 

Grey Hydrogen - Formed from cracking methane. Not particularly environmentally friendly, and the most common source at present, better would be;

Blue hydrogen - formed from cracking methane, or using traditional power sources for electrolysis but the C02 generated is scrubbed, transported and then injected into a underground carbon capture and storage facility.  Obviously this route is question by anti-fossil fuel groups.

The benefit of going down a hydrogen combustion engine route is avoiding huge mining operations for lithium and other rare earth elements to go in batteries for electric cars, do a web search to see some photo's.  In the West these are out of sight and mind. Though as wintree suggests other battery forms may emerge.

However lithium brines have been commonly found in produced waters in geothermal wells, the question is can we concentrate it in an environmentally and economically sound way. If we can it would help immensely both reducing the mining damage, but also making geothermal electricity generation more economic.

There is the potential to use high temperature nuclear reactors for hydrogen generation however these sorts of reactors are mainly research or pilot reactors rather than commercial operations. If the demand for hydrogen was high enough then using nuclear power would be amongst the most viable large scale options.

https://www.sciencedirect.com/science/article/abs/pii/S0360319916308710

I’d not heard of that; fascinating.  Some pretty awful stuff in the water when they tried drilling in Eastgate apparently.

Yes I hadn't mentioned nuclear as it is normally considered to be low carbon rather than truly renewable. 

www.withouthotair.com might be a good place to start

"the power per unit area of wind farm is about 2 W/m"

can anyone supply the power requirements of hydrogen production?

A puff piece to get you started.

https://www.thinkgeoenergy.com/geothermal-lithium-its-extraction-and-impact...

The problem is it is in ppm abundance, that not only causes problems once you have got it top-side for concentration, but also from an exploration perspective how do you efficiently identify if it is present down hole, in what abundance, and then delineate which zones/fracture systems its coming from to maximise production, and start understanding geologically so you can improve exploration/development success. At present you cannae get a mass spectrometer down an 8.5" diameter borehole, even if you could rate one for 200 DegC!  Obviously you can grab formation fluid samples down-hole but you would be initially grabbing samples at differing depths blindly, and geothermal operators are generally cash poor, and not in the business of increasing costs on a prayer and the hope they might have lithium.

Something I've mentioned before on here is the possibility of space based solar power (SBS).  The phenomenal drop in £/kg to orbit represented by the SpaceX Starship program opens the possibility of commercially viable SBS.  This would take the form of large orbital arrays in geostationary orbit that do not have intermittency (no weather, no night-time occlusion by the planetary shadow), and that beam power to receiving arrays on the surface of the Earth.   

The primary barrier to these for the last 20 years has been launch costs.  Every component of the technology for on-orbit and Earth-side operation is mature.

Sim City 2000 gave the technology a bad rep through microwave beams going off-target and destroying parts of the city, but in practice this was solved decades ago though use of a ground-based pilot beam which is amplified and phase conjugated by the space based array, providing a system that is fail safe in that the system can only beam-form on to the pilot array coming from the Earthside rectanna farm.

I think the US military in particular will be all over this as an early adopter; they have significant logistics hassles shipping vast quantities of fuel in to the desert for their electrical power, air conditioning and vehicle fuel needs.  They're investing in systems to turn electricity and foot waste + human excrement in to biofuel for vehicles, and space based power delivery is the missing part of the equation.  A single orbital array can serve customers over a vast area.  

The rectanna farms that will receive power on the ground can receive power concentrated to a far higher area density than the solar - pushing the large area from Earth in to space.  They can also be integrated with some other land uses.

Exciting stuff.  Even large ocean going vessels could receive power this way.

Off note is that with Starlink, SpaceX are suddenly on the leading edge of phased array microwave systems, and they've been sighted installing a Starlink phased array (communications) antenna on the latest Starship prototype, as well as submitting FCC paperwork for permission to use it during launch.  Attempting to established and maintain a satellite to rocket link through a phased array antennae is bonkers.  I'd imagine they're starting to scope out space based solar power given the confluence of interests and competencies under the Musk umbrella.  Creating another customer for SpaceX after Starlink is right up his approach to these things.

I thought Hydrogen was colourless.

This prompts me to muse, in an entirely uninformed way, whether, say, Iceland might potentially be a prime spot for making and exporting hydrogen - basically infinite amounts of geothermal energy, plus famously surrounded by water. And ideally placed to serve two big markets

Surely you get round this quite easily with packer testing, the hydrocarbons industry do this sort of thing and I understand exploration wells for lithium brines in Cornwall have good depth control for sampling. That being said I don't deny there are many pretty huge barriers to combined geothermal / mineral extraction! Allthough on the face of it it sounds like a great idea.

Interesting uptheread how it was mooted Al batteries could be an environmental friendly alternative to Li, aluminium production is not the most environmentally friendly process, indeed the EU mine waste directive was pretty much in response to bauxite tailings ponds spills.

It's all a matter of proportion.  

Some crude numerical estimates and other gross simplifications ahead...

Aluminium is mined at about 250x the annual rate of Lithium and should be required in 1/3rd of the mass per mile of range as Lithium given the chemistry.

Current lithium mining is enough to support production perhaps of 3 million cars / year with a 300 mile range.  

Current aluminium mining is enough to support production perhaps of 2 billion cars / year once battery technology gets there.

With lithium, to replace the global fleet over a decade we'd have to increase Lithium mining rates by about 500x over that period 

To replace the global fleet over a decade, we'd need to increase aluminium production by about 1.15x over that period.

That's ignoring the extensive supply of recycled aluminium, a resource that doesn't exist for Lithium in any real quantity.

Aluminium mining is dirty because of the sheer scale of the operation; Aluminium ion EVs wouldn't represent a massive change to the scale of that.  Lithium mining is dirty because the abundance is something like 1/8000th that of aluminium.  Scaling that up to global EV demand would be a disaster if met through mining.

Good numbers there, I think an interesting think about any of these battery technologies is that they will require vast amounts of raw materials, and we need to make sure we obtain these with the minimum impact. Which is hard and somthing that isnt yet factored into many supply chains.  I'm constantly reading the apples and bmws of this world sourcing strategies which often state how the can be super sustainable via recycling but as you say for lithium you cant recycle what doesn't exist! The statement last week from various car manufacturers about the perils of deep see mining made me laugh, they currently get supplies from child labour in DRC! hardly the model of responsible sourcing! 

Anyway I'm going massively off topic, the op may find this analysis of uk potential supply chains of use (although 2 years old) https://www.google.com/url?sa=t&source=web&rct=j&url=https://as...

All very interesting, I just have don't have the knowledge to judge how viable any of that is. One thought- I don't think there is much space junk at geostationary altitudes at present, but could it become a problem for large structures in the future?

Yet Scania's doubling down on electric batteries

https://www.rechargenews.com/transition/blow-to-clean-hydrogen-sector-as-ma...

What about for aviation? I know electric planes are being trialled as we speak, but I can't help think they are not going to be viable for international mass travel.

If we don't have a civilisation wide setback (global war, worse pandemic) it's a question of when, not if IMO.  In space terms I'd say the technology readiness level is very high for most of space based solar power, apart from the required launch costs, and the TRL of that is getting better almost by the week.

I'd hope not; GEO space is vast compared to LEO, and it's hard to see many junk generating situations up there; the bigger threat is getting stuff to GEO through ever expanding LEO junk.  With cost to LEO set to plummet, clearing up space junk becomes more possible, and there's a lot of R&D going on in to other ways of dealing with it - for example using high power lasers to micro-ablate the surface of junk, which creates an ablation based rocket engine changing the orbit of the junk, this can be used in a way that encourages faster orbital decay.  I see no other applications for such a laser system...

In reply to ByEeek:

Unless something like aluminium ion batteries at close to their theoretical energy density can be made, it's an awfully long way from competing with modern airliners.  The renewable future of civil aviation looks like a mix of bio-fuels and renewable energy created synthetic stuff for bog-standard travel and liquid hydrogen air breathing "SABRE" style hypersonic for the well heeled.  

I'm always surprised that more effort isn't spent on tidal energy as a renewable, there's loads of it - especially around the UK and it's pretty predictably and reliably there - I mean how many times has anyone found a tide to have gone missing - unlike wind and solar power (at these latitudes).

So if you need energy and water to get hydrogen, why not use tidal energy which is usually near some water.

have a look at these two british companies who are leaders in this field, AFC  and ITM.

 Ok, I'll have a go at this. Wikipedia says 50kWhrs is needed to produce 1kg of hydrogen by electrolysis.

1 square metre of windfarm will produce 48Whrs of electricity per day (at 2W/m). Let's round that up to 50Whrs per day.

So we need 1000 square metres of wind farm to produce 1kg of hydrogen per day.

Hmmm. Sounds like we need country sized wind farms. And we haven't compressed the hydrogen yet and let some of it leak away as we transport it.

Scotland is better. It's got massive won't and tidal potential, and there's an existing large network of disused oilfields and pipelines that can be used to store the hydrogen and distribute it.

Lots of the people where I work have bought AFC shares. As usual the first ones have done very well, the later ones, not so great yet but they haven't lost anything.

Of course investments can go down, turn into cream teas or indeed be deported or something like that.  As you can tell, I am not a financial advisor. 

Not at all green. It's colourless.

In seriousness though, using hydrogen as a source of power will almost certainly one day (still a couple of decades away) basically solve all our power problems. We are on the cusp of making it work with the ITER plant, you can see the timeline for that here:

https://www.iter.org/proj/ITERMilestones

First attempts at firing it up are 2025 according to that timeline. Basically the ITER will, in theory, produce more power than it uses and be a final proof-of-concept that we can make nuclear fusion work effectively. The next generation of plant after that will be the first to produce electricity though so it is still a while away.

Widespread fusion power is going to be too far away to rely on as a solution to global warming so although it probably will work and be very green, it's not close enough on the time horizon that people should factor it into the solutions for global warming imo.

You need tritium for a fusion reactor though, not basic hydrogen. I think most fusion designs envisage breeding tritium by neutron irradiation of lithium in a blanket around the reactor. Funny how the same elements keep coming up, best hope there is some lithium left over from the battery factories...

When we eventually get viable power from nuclear fusion, I very, very, very much doubt it's going come from a large Tokomak device like ITER.

We really, really aren't on the cusp of making it work as a viable energy source with ITER.  ITER is making it astoundingly clear how self defeatingly difficult it is to make fusion work with a giant reactor given the cubed/squared relation between radius, volumetric power generation and area based power extraction.  It's making it astoundingly clear how insanely expensive it is to project manage and build something of that physical scale.

ITER is a plasma and nuclear physics experiment, not a prototype power plant.  The follow on project, DEMO, is a prototype power plant.  It's decades in to the future. 

It seems very clear to me that whatever succeeds has to be a more compact device.  For multiple reasons - physics, finance, project and complexity management. 

Leading contenders would appear to be compact tokomak/spheromak devices with minimal resemblance to the giant money pit that is ITER, using superconducting magnets to produce much more concentrated confinement fields, radically shifting the volume/area problem and reaping the benefits of changes in ELM behaviour in a high Beta confinement mode.... ?  I notice we've had another entrance in to the compact tokomak field just this week.  

My favourite contender is General Fusion, because their approach involves hitting a giant ball of swirling, molten lead with many steam driven pistons.

Stellarators represent such a massive step over ITER-like Tokamaks in terms of confinement quality that they allow another route to smaller, faster to test and integrate, affordable and better volume/area ratio devices than Tokamaks.   The Wendelstein 7-X is very exciting indeed.

Also, to be pedantic, bog standard Hydrogen doesn't feature in to any of the power generation plans based on these reactors, it's deuterium and tritium.  Muons might be making a dark horse appearance if we're lucky. 

Yeah, deuterium and tritium mixture is the most promising fusion reaction everyone is concentrating on but it's all just hydrogen.

I don't think I'd worry to much about using the lithium up this way, quantities would be absolutely tiny in comparison to any of its other uses (although you definitely don't get to recycle it afterwards ).

The pipe dream is a proton-boron 11 reactor.  For this, 99% of the energy comes out as charged alpha particles.  These can be caught to give 99% efficient conversion of fusion energy to HVDC. 

Whereas any deuterium/tritium reactor has to catch and thermalise the high energy neutrons and then suffer the ignominy of loosing half that thermal energy to the steam turbines.  Some of the most cutting edge physics bolted on to steam machinery....

A recent independent study seems to have put the Polywell idea to bed which is a shame, as that was the least impossible looking route to H₁-B₁₁ fusion. 

True. But the prototype is always the hardest one to make because it's the prototype. As technology progresses, the next model always gets more efficient, cheaper and easier to make. I think you'd really have to search to find something that path of progress didn't apply to.

I did say all this, I just didn't remember the name of the DEMO plant.

I don't agree. The "more compact device" argument doesn't hold up for any of the ways we have now of making electricity which is added to the national grid so it seem illogical that fusion would suddenly buck the trend of "larger device = more efficiency".

I love their idea but I'm very susicious of its ability to actually work without needing to replace parts of the machine every 10 seconds, controlled nuclear fusion is very difficult and they were making it sound pretty easy last time I checked. I liken this project to the WW1 supergun that fired shells 100 miles but needed the barrel replaced constantly. 10/10 for cool factor, quite a bit lower for ability-to-convince-me factor.

Not looked at stellarators before.

both deuterium and tritium are hydrogen. Personally I think hydrogen doesn't deserve 3 names when none of the other elements get more than 1, so I choose not to stoke its ego :P

I fundamentally disagree.  It's the materials physics of the pressure vessel wall and the power and radiation loads, combined with the plasma diverter physics.  Intuition developed on other forms of power generation just doesn't translate to fusion at all.  When you make a device larger, the radiation damage and heat flux the pressure vessel walls have to deal with increases more than linearly with device size.  Much more than linearly.  Many of the major problems limiting the translation of a big tokomak in to a power plant are to do with the materials physics off the reactor wall, and occurs as a direct result of the device being very large.  ITER was made very large as a result of limitations in achievable field strength and curvature related losses that have both since been surpassed.  Subsidiary problems revolve around "big" for a tokomak being a couple of orders of magnitude above "big" for a combustion + turbo-machinery based power plant and the concomitant financing and project management burden involved in such a gigaproject.  

That's the whole point of their device.  The part that interacts with the fusion is the molten lead, and that is literally continuously replaced as it's pumped out to the heat exchangers and returned to the form the molten vortex that is the pressure vessel lining.  It can be subject to continuous purification; not that - as I understand it - lead is as bothered as most materials by the neutron flux.

IMO, the concerns you raise apply far, far more to ITER style reactors where the pressure vessel lining is not molten and constantly replenished, but fixed and subject to constant and harsh degradation from the fusion neutrons.  General Fusion's approach solves one of the most difficult - and critical - problems of conventional fusion reactor designs.  It has many other barriers ahead of it but I think you've missed their USP here.  Their fusion facing components are orders of magnitude replaceable than those of other designs - further, they're lead and not fancy pants materials, the problem with the later being their tendency to outages their constituent elements in to the vacuum chamber under neutron bombardment, poisoning the plasma.

Interestingly that's not really the case.  With hydrogen being the lightest element in the periodic table, the difference between its isotopes seeps through in to chemical and physical properties way more than for other elements.  Drink enough deuterated water and you are going to die - not from radiological issues (which could kill you from many other isotopes) but from the fact it behaves measurably and significantly differently to hydrogen in chemical reactions.  Drink just the right amount and its greater density counteracts the lower density of ethanol and so maintains overall fluid density in the inner ear balance organs in the presence of high ethanol content, allowing a very, very drunk person to maintain balance.  Purportedely.

It’s the difference between scaling up and scaling smart.  They’re a bit like SpaceX’s Falcon 9 rocket - redefining a stagnant sector by going back to first principles but with all the power of modern computer aided design and manufacture at their disposal.  When the bones of ITERs designs were set - as has to be done for a gigaproject to progress - the CAD/CAM situation was very different.  

SpaceX have done “scaling smart” and now they’re scaling *that* up.  In space terms, ITER is more likely the Sea Dragon rocket - going large on historic designs.  Sea Dragon never flew.  

This thread has been a fun read, I love the diversity we get on UKC.

I just wanted to chime in that a gas safety training course at work cultivated a bit of a fear of the stuff in me.

1. Difficult to contain, per the first reply.
2. Explosive limits 4-75% in air. Lot of other gases quickly become too fuel-rich to burn. e.g. Methane 5-17%, Propane 2-10%.

This does not seem a good combination of features and I really hope all development and adoption of the technology can be done without big disasters!

Yeah, It's going to leak, but that doesn't pose an environmental hazard (assuming it's just slowing seeping from seals and joints and not hosing everywhere, in the latter case it's a problem for any gaseous fuel), unlike methane which is very damaging in a global warming sense.

I think the fire/explosion hazard should really be treated the same way as with any other fuel gas, I'm not convinced hydrogen is much different in that respect. I suppose that to efficiently transport it, you _would_ want to keep it at higher pressure than you would for other gases.

I was talking about the hammers and plates on the outside of the lead that are being smashed together with explosive force.

You know, I was going to write "(yes, I know, the relative isotopic mass difference is far higher in hydrogen and that affects etc. etc.)" but I just didn't think I needed to.

That is not an experiment I'm going to try any time soon thanks very much!

I'll have to read up on them in a few months when I'm not so busy.

As Jim says hydrogen production is a useful way of dealing with excess renewable energy. Orkney is a classic UK example. They are even converting ferries to part run on hydrogen.

https://www.orkney.gov.uk/Service-Directory/Renewable/h2-in-orkney-the-hydr...

You always need engineering to manage the physics, and you always need engineers to manage the physicists (or at least people who can do both)

I think you are both partially right about the fundamental approach to sizing of a power station. What existing nuclear power shows us is certainly that a larger plant can theoretically be made more efficient because you can get more power from building a single plant and this has to hold true regardless of technology. However at least in a capitalist environment without significant state support, the size of project, level of investment and risk associated with the largest plants means they are very difficult to build. A huge % of the cost ends up being interest payments on loans and there are major difficulties in mundane things like building enough accomodation to house all your specialist workers near the build site. That's why the worldwide trend in fission is now back towards smaller reactors (SMRs) - financing and build being much easier. Engineers don't tend to consider things like financing costs when designing concepts so it's taken a long time for that to happen. There is however a balance point in size to be struck and it's difficult to know exactly what is best.

Re: "It's the materials physics of the pressure vessel wall and the power and radiation loads, combined with the plasma diverter physics. Intuition developed on other forms of power generation just doesn't translate to fusion at all. When you make a device larger, the radiation damage and heat flux the pressure vessel walls have to deal with increases more than linearly with device size."  I struggle a bit with what you say here. I'm not that familiar with the details of fusion technology but I know a lot about this in a fission context. Irradiation damage is a function of the neutron flux incident on the material and the time under irradiation. Also the energy spectrum of the neutrons, but let's assume for the moment the designer can't change that for one reason or another.  So if you make a tokamak reactor physically larger, increasing the surface area, but without changing the nuclear power output and you control the plasma field to a similar set of parameters with the magnetic field, then surely the flux at the wall must be reduced. If you allow the plasma field to expand geometrically or run it at a higher nuclear power for a given size then the wall flux will increase. There has to be a trade off, basically for any given physical size of a reactor you need to determine the appropriate power density and power output that is achievable without compromising requirements associated with irradiation damage (among many other things.)

In fission plant design, people have got much better since the 50s at controlling neutron flux shapes to allow for a higher average power density without increasing flux too much in limiting locations. If fusion ever takes off properly, I'm sure the same will happen there.

I confess that each time I see a completely new fusion concept talked about, it makes my heart sink a bit. These things are massively complex pieces of technology and getting the science to work will not be the hard bit. Each time you design a completely new type of fusion concept, you will have to design a completely new reactor around it and have lost all the learning from existing work like JET, or ITER when complete. Newer technologies sound great on paper because they don't have all the same challenges as existing technology, but later on new challenges will undoubtedly be found. I'd be really surprised if one of the newer concepts actually makes it to production use first. The same paradigm exists with advanced fission designs.

PS. Way off the topic of hydrogen, but it's not often I get to write about neutron physics or nuclear design outside of work.

There's a couple of plants around Denmark way to use their excess wind power as well.

Electrolysis of water is pretty grim efficiency wise (though a good way to use spare generating capacity)  but not the only game in town. While water electrolysis needs ca 50kWh to produce 1kg (which contains 33kWh energy) pyrolisis of methane only takes about 8kWh to make 1kg and produces solid carbon as the by product. So running a biogas plant to produce the methane you are carbon capturing at the same time.

The other interesting direction is bacterial production, as it is we have to be careful to stop the bacteria producing hydrogen in bio-reactors as the plant isn't designed for it (we are allowed 2%) but there's plenty of research being done to massively change the proportion and seperate the methane and hydrogen.

Industrially the world production is already ca 80 million tons of the stuff, anyone who thinks handling and storing it is difficult is demented.

The shift to SMRs is a good point re: the problem with large plants in the current environment.   Power plants derived from ITER and DEMO will be much more capital, space and staff intensive than fission plants.

Unfortunately it just doesn’t work like that. The large dimension requirement comes from needing to have a large radius of curvature, as losses from imperfect plasma confinement go up with stronger curvature on the plasma (mostly fixed in a stellerator).  You suggest dialling the power density down to reduce the flux on the containment walls but this isn’t possible; the plasma has to reach “ignition” - the point at which sufficient energy is being produced by fusion to heat the plasma enough to overcome the energy lost.  This requirement for ignition means you can’t dial the power back below some level, and so the power unavoidably increases as volume - R^3 vs the power extraction area of R^2.   This can also be overcome by using much stronger magnetic fields to confine a higher pressure plasma to a smaller volume, giving a lower power, less difficult volume/area ratio. A spinout in Oxford is doing this sort of thing.  But for a tokomak running at “low” fields, it means a very high total power spread over a large volume in order to reduce losses enough to maintain ignition.  This forces the design to something with a pressure vessel 20 meters in size...

ITER will have a way, way higher neutron flux than any existing fission reactor.  There are also issues of ion implantation from the plasma.  It can’t spall under bombardment or it salts the plasma.  It has to be thermally conductive to get the heat out.  Somehow it also has to support breeding tritium.  Some of the most difficult physics in ITER and beyond is in the materials design for the pressure vessel wall, especially in the exhaust area known as the “plasma diverter”.

>  I'd be really surprised if one of the newer concepts actually makes it to production use first. The same paradigm exists with advanced fission designs

Most of them aren’t particularly new concepts, they just haven’t had the same funding bandwagon as giant tokamaks.  Given that giant tokamaks aren’t expected to reach power generation for decades, so there’s a lot of time for a smaller system to come together.

You should read a few online PhD theses from students at the York Fusion DTC.  The introductory chapters should be very accessible to you and the rest can be battled through I’d expect.  I was tangentially involved with some of the plasma diagnostic stuff but a jump to the life sciences, so I don’t get to talk about fusion stuff much these days.

One of the less challenging parts; we’ve been building heat engines based on that sort of thing for a century.  The force of the nuclear explosions is not directly transferred to the whackers; they introduced a spherically convergent compression wave in the molten lead vortex which concentrates as it converges, not unlike the effect of 60 odd shaped charges on a shell of high density metal...

I think the key to it will be the advanced instrumentation on the pistons and the digital filters used to fine then their control to maintain the required precision over time.  That sort of thing is pretty old hat these days.

> You know, I was going to write "(yes, I know, the relative isotopic mass difference is far higher in hydrogen and that affects etc. etc.)" but I just didn't think I needed to.

When protonic water is central to life and deuterated water is highly toxic to most life, it’s kind of a critical distinction and why I don’t mind deuterium being referred to by a different moniker; it’s chemically distinct enough from protonic hydrogen to kill.  

What’s really interesting is if you combine atmospheric CO2 extraction with a Sabatier reactor to turn water and CO2 into methane and oxygen, then follow that on with pyrolysis.  This gives us a viable pathway of sequestering atmospheric carbon into solid carbon; the H2 is then available for use elsewhere or for conversion on-site in to heat and power to reduce the energy requirements of the sequestration.

I suppose I was a bit vague, I was only concerned about fire and explosion hazard rather than any other consequences of a leak. You raise a good point that a leak wouldn't have the same environmental problems as other fuels.

My point being it isn't like other fuel gases. Small leak of air into a low pressure system will be more likely to achieve an explosive mixture. A leak into a confined space is more likely to create an explosive mixture. A release dispersing to atmosphere is more likely to have a larger volume at an explosive mixture.

As it becomes more commercialised, competing manufacturers may look to make savings on maintenence, staff training, supervision. If we have bottles of it in consumer vehicles we introduce the accident mechanisms of cowboys, muppets, and having more of it in less controlled environments.

Of course there are risks with existing fuels, electricity etc.  If its only ever advertised as cleaner, greener, safer, or though of as "another gas fuel, but better" we might be blasé and overlook its unique dangers.  Its another stored energy source, and they all need respect.

I want to see it happen, I'd just like a more sensible species than humans to be the ones in charge of it and I don't really want us to learn any lessons though Darwinism.

Too high-tech, plant stuff and let nature do it's work. Easier to sell to the eco-freaks, it's "natural"

For numpty use (industrially hydrogen isn't a real problem) you can convert hydrogen and magnesium into magnesium hydride, bung in some fillers and you get a paste which you can pack into something like a silicon cartridge. Then mix it with water ( which gets split in the reaction) and away you go. The Frauenhofer Institute is building a pilot production plant at the moment to prove the industrial concept, their demonstrators are things like portable generators. 

I think it's still quite unclear what the medium and longer term role of H2 will be in our energy storage and distribution. Medium term is is (re)creating a market for natural gas so scepticism is justified.

I don't think it'll displace batteries in personal road transport. I'd be surprised if long-term it becomes a major grid-scale energy store/supply, here I think aside from small increases in grid scale storage (pumped hydro, lagoons, mine-shaft gravity stores etc)  we'll end up with a lot of distributed storage and even more virtual storage through smart consumption, mostly using our 'cars' and probably quite a bit integrated into the home (electric and thermal) to create a secondary market for used/degraded automotive traction batteries. That's both useful to a renewable heavy grid and it delays the need to solve the battery recycling issues properly.

With airliners, I suspect in the longer term they'll be switching battery electric for short haul and bio/synthetic hydrocarbons like for like interchangeable with fossil derived with JetA1 for long haul, it's such a conservative field, what they have works and it's built to last. Medium term we may see a little electric-surplus H2 blended into our mains gas, largely as a subsidy farming experiment if the embrittlement issues are avoidable but I'm not sure how realistic that is technically. Personally I'm not convinced we'll see mains H2 boilers and hobs beyond a pilot program or two, it's just too dangerous and I suspect the amount of re-work of homes and grid is too great, electric upgrades seem like the safer and much lower resistance (no pun intended) path. Marine transport is an interesting one, with the improvements we've made in forecasting I'd be surprised if we don't see some significant return to sail power (augmenting oil). Nuclear is an ever present contender here if cost and security concerns are ever solved.

I think there will be a lot of effort put into hydrogen but personally I struggle to see anywhere where it's a stand out technical or practical winner over existing or near-future possibilities, just one with powerful backers. If I was betting, I'd go for road haulage and agricultural power being where it'll find a significant medium term role but even there I'd still hedge.

jk

What do numpties use hydrogen for?

What are the thoughts on this - a positive move?

https://www.bbc.co.uk/news/uk-scotland-scotland-business-56721727

Numpties are capable of using and abusing anything for purposes beyond your wildest dreams. I get a bit nervous about the idea that they may have improved acces to another explosive.

All sorts of things which is why you can buy it online. Stuff like polishing acrylic.

Like petrol, diesel etc? All of which have an auto-ignition temperature well under half that of hydrogen.

It's just another gas that's been readily available for centuries. LPG is cheaper if you want to blow things up.

Natural photosynthesis takes a lot of beating, and it produces useful polymers (e.g., wood) on a grand scale. Pyrolysis of methane would be more attractive if the carbon production could be engineered into a really useful form such as graphene. 

I thought, what rub it with hydrogen? That's not going to work is it. YouTube to the rescue - flame polishing, who knew?!

Pyrolisis doesn’t compete with food and the ever shrinking rainforest however as a way of sequestering carbon.  It also produces a dense, solid, pure carbon which can be thrown in to a mine and safely forgotten about unlike the results of photosynthesis, which take a lot of work to make sure they don’t end up as CO2 or worse yet atmospheric methane.

Like all those things that humans have failed to keep a clean safety record while exploiting. From industrial accidents like oil platform fires, user error like smoking while filling up, or misguided tinkering gone wrong.

I know there are plenty equally and more hazardous things out there already that can/do cause mischief whether accidentally or intentionally.

I was simply expressing my hope that we can adopt this one without too many people or places disappearing with a squeaky pop. At the same time, trying to add to the discussion on what unique challenges it brings.

The information on the paste/generators was interesting, what would be the by-products of the cartridge... magnesium hydroxide?

I was merely pointing out that it would be nice if we could make useful forms of C rather than just a carbon waste product to be chucked down a mine. The solid carbon products of pyrolysis are polyaromatic; I am not sure how easy it is to control the molecular weight, so there might be some risk of toxicity.

Me? It's used medically and in gas mixtures breathed by deep divers as well. And various quack beauty antioxidant therapies. Plenty used industrially, the red cylinders on a truck load of industrial gas are hydrogen.

Magnesium hydroxide as you say which is then reprocessed. The whole thing is a neat process as it's suitable for small scale applications like drones as currently it has ten times the capacity of a battery by weight (about the same power density as petrol) but for bigger stuff a tank is going to be the economic choice.

Drove past my local hydrogen filling station today on my way back from visiting the customs office, it's just another pump in the row in a Agip station. I've filled up at the next door pump before now, looks like a normal lpg pump except you select which pressure to use v

It's sure a bit annoying, we take about 6000 tons of green stuff off every year but when we burn the gas all the carbon goes back into the system, it's carbon neutral but would be better if we could actively be reducing it. And we would be doing it a hell of a lot faster than planting a few trees!

Someone already said that hydrogen is produced and transported in very large quantities already. And explosions from methane/ethane/propane/etc. seem to be pretty rare (in the UK at least), I can't remember the last time I read about one. So I think with these two things coupled together, the risk/hazard matrix of fire/explosion with hydrogen is pretty low (having said that, I don't work with anything more than tiny quantities of it, so while that seems logical, it isn't based on my expertise!).

This guy has some good videos on green energy:

youtube.com/watch?v=0_bTjcjqN6c&

The one that sprung to mind without the help of search engine was Avonmouth in December. Methane is a very likely suspect given it is a sewage treatment plant. Producing, moving and processing sewage in large quantities is something that has been going on for a while now too but it seems that is no guard against accidents

I also did a quick Google for "UK Gas Explosion" and scrolled through the news tab, latest was a house in Walsall that went bang two weeks ago.

A headline on the Independant asking what was the cause of a "spate" of explosions caught my eye too, the article quoted nine in six months Oct 2020 to Feb 2021, mix of natural gas and LPG incidents.

Then I was curious to see what utility strike rates are and found an article that quoted 6,700 strikes on flammable gas pipelines reported to the HSE 2012-17. So about 3 per day that companies owned up to.

My attitude is really only mimicking the chap who gave us the gas safety course, who seemed disturbed by behaviour he had seen with propane and made a very convincing argument about Hydrogen having some scary aspects.

I'm not a fire and explosion expert, but if I'm hitting a pipeline with an excavator, or sitting in a room with leaking pipework system, I can see the logic that says I'd rather it be the gas with the narrower explosive limits, and/or the one that doesn't have the Houdini reputation. I'll take the above point about ignition temperatures as a solid counterpoint.

I'm not suggesting its total risk profile is worse than any alternatives, won't argue against the claims that the existing industry is proven and accetably safe.

Just trying to share that one aspect where the risk profile is a bit different to stuff we are familiar with, in a way that could catch out Joe British Public. I'd like there not to be another Avonmouth in the near future, but I can also see logic that says given accidents will happen, hydrogen releases or combusing to water might be nicer than hydrocarbons or radioactive mess.

I think the sealing and explosive limits might be a reason why we might never (or I would be nervous to) see a national grid of buried hydrogen pilelines as we have natural gas - although I know there are plans to trial that idea. To get back to the OPs questions around limitations.

Good job we don't build cars with half a ton of stuff that explodes and on contact with water produces hydrogen then

Several houses blow up and make the news every year from domestic gas leaks.  They tend to be missing walls and roof tiles when you see them on the news; fuel/air explosions are not good.

Yes, lithium is scary too and like many others I walk around with some of it quite close to my genitals on the daily, regardless. Although I recently decided to clear out the old mobiles in the junk drawer so they can't get up to any mischief.

We don't have to just think up the scariest danger and be complacent about all others, we are allowed to treat them all with some caution or respect as they infiltrate our lives, or at least give them the occasional second thought.

I haven't made up my mind whether I think battery vehicles are better or worse idea on the safety front than ones with fuel tanks. Perhaps the aluminium battery tech mentioned upthread would be a step change in safety?

I'd expect that none of these things trump driving or DIY for injury or fatality figures either.

EVs are less likely to catch fire than FF ones. The problem is that you can't put them out as easily, but when most FF vehicle fires write off the vehicle anyway that doesn't really matter.

You could start down the rabbit hole of pressure vessel linings for large Tokamaks here...

http://etheses.whiterose.ac.uk/13728/

This goes in to the damage mechanisms (it's a plasma facing wall as well as a neutron facing wall) and the research around different materials, including the recent change to an "ITER like" cladding on JET and the improvements that made to the plasma quality. It doesn't go in to the scaling laws and tradeoffs that mean a large Tokomak is going to have way higher neutron fluxes than fission reactors though.

Agree. Burning hydrogen will produce significantly more NOx than natural gas but nobody bothers about NOx any more. It's a greenhouse gas as well as a killer.

Without wanting to sound facetious.. depends if it's green hydrogen or not.

Green = produced using renewable electricity = green

Pink = produced with nuclear electricity = green-ish depending on who you ask

Blue = produced with natural gas with CCS = green if the CCS bit were to work properly

Grey = produced using natural gas = not green

Of course people still care about NOx still, especially AQMAs. And you're absolutely right about it, many times the amount of NOx compared to natural gas for example. It was always thought that it may be a valid alternative to town gas in terms of heating, but it's really a bit of a red herring, another  development that will have had money invested in it. In terms of heating (and I appreciate that this may not be what this thread was concerned around), but also in terms of transport... The absolute best thing we could do is to maintain existing equipment/plant/vehicles for as long as is feasibly possible. This is not an economically attractive option, the world loves selling stuff, but when embodied carbon is taken into account the best option is to repair and retain until replacement is nessesary, and then replace with a lower carbon alternative. The concept that we should just bin off serviceable plant and equipment and vehicles because there is an alternative available that consumes less energy (in terms of fuel) makes no sense when you take into account embodied carbon and realistic economic life factors, however as mentioned, economically, people love selling new shit to people.... 

Edit.... Speliling 😊

You don't have to produce NOx burning hydrogen, it's widely used as a fuel in industry which is also emission controlled and they know how to reduce the NOx to nearly zero.

Speaking of my view of alternatives to giant Tokamak's being more likely to make it....

Tri-Alpha Energy has rebranded as TAE Technologies and has now raised US$ 1Bn for their work on a different approach.  That's a step change in their funding levels and really quite exciting.

It's notable that private funding is steering well clear of giant tokamaks...

https://techcrunch.com/2021/04/08/claiming-a-landmark-in-fusion-energy-tae-...

Tokomak Energy down in Oxford are making progress with their compact Tokamak...

https://www.tokamakenergy.co.uk/tokamak-energy-on-track-to-be-the-first-pri...

... and also making the point that the UK could choose to put more effort in to funding disruptive, commercially driven approaches to fusion, as is happening in the US

https://www.tokamakenergy.co.uk/learning-from-our-mistakes-and-successes-it...

The problem is that there is no 'cost of carbon', thus businesses see the new cheaper running costs, or greener running costs and change, even though it would be greener to maintain their existing plant.