Sourcing Hydrogen Equipment Part 3 — Hydrogen Fuel Storage System
I Lied. Part 3 Isn’t about Batteries at all.
In part 2 describing the Fuel Cell part of the System, I said part 3 would be about the battery backup system necessary to maintain the power from the panels to the electrolyser, the latter being the hydrogen generation component in the solar hydrogen power chain.
But the battery backup unit is such a standalone self documented item, it doesn’t warrant a whole part to itself, and besides, it isn’t itself a hydrogen component. Readers would not be learning much about sourcing hydrogen equipment by reading about the battery backup. Further as explained in part 2, the battery backup is intended as a temporary measure. It is warranted whilst it remains competitive in price, whilst that still matters in the for-profit (Pre-Kardashev Scenario — See part 2 for clarification). Further, battery backup technology and how to apply it is already mature, literature on it is all around us. I only need to reference some of that in the next and final part of the detailed system design, covering the panels selection.
In contrast, the hydrogen storage part of the system, the stuff in this part, part 3, is probably the most controversial, in terms of how it has to work, relative to the other system elements. This is the part of hydrogen technology which seems to me to have suffered most due to misinformation, and subsequent lack of development, preventing it from becoming something directly comparable with fossil fuels in many ways, because actually if we know a little about hydrogen, it potentially trounces fossil fuels on every count.
As for batteries, well the writing has to be on the wall for all the plans to use those massively, when we realise the full potential of hydrogen (Sorry Elon)
So instead of covering the battery battery backup system, here we are going to cover the most controversial part of the hydrogen energy chain, hopefully removing much of the controversy.
Hydrogen Value
The truth is we can’t even see the full potential beneficial value of widespread use of hydrogen. We won’t, and actually can’t, until we move to it.
But we do know some of the benefits, including creation of food (See “Solein”), filtration and circulation of both water and air, and the potential to create bio-friendly plastics. Further it works to directly fuel both internal combustion and electrically powered machines.
What I can see as someone deeply immersed in Engineering technology all my life to date, including in R&D roles, is that the pumping aspect of hydrogen appears to have been something severely underfunded and knee-capped at every turn, since most of the research done on it seems to have been funded and lead by fossil fuel based industries, which if they/we are honest, do not wish to cannibalise their existing business, by activating a fuel which potentially wipes the floor with all benefits that were thought to have been had by fossil fuels.
But in the end, the thing that matters most, as we are seeing, is our planet. Without that in good healthy working order, we are nothing, and money is nothing, because without real sustainable energy in money, there is no working economy. In fact there is not even any life, if we carry on as was. Of course it has to change for our survival, and the survival of all life, if nothing else.
I’ve explained elsewhere why profit directly relates exclusively to extracted energy and temperature rise, so won’t go into too much details again here.
Anyone wishing a quick primer on the fundamental economic argument driving the design should check part 2, it gives a quick rundown with links to futher information of how Kardashev Money, and the “Money-fuel tree” relates to the system under design.
In effect, we are building a money-fuel tree, but without the ability to generate cryptocurrency, though anyone can add that on for free, if banks and money issuers fail to “Step up”, to provide the financial side of the system solution, by failing to issue solar indexed stimulus ^^.
The point is that after construction of this system, all hydrogen generated which is not used by the microgrid is convertible to money, by being exchangeable for money, and the energy that goes into creating all of the hydrogen is for free per Joule / KWhr. The sun never asked anything in return for it, other than maybe we use it wisely (i.e. we should use it to create things, anything other than heat!).
OK now you’ve been given the reasons why, you are forewarned of what can only be called a development starved horror story, and a mess, of what we currently need to do, in the storage system, to put the most development handicapped part of the system to use, despite the handicapping. Remember this is the one part of the system that will, one day very soon in my own opinion, be rapidly developed to produce liquid hydrogen, bottle-able at moderate pressures and room temperature, using minimum non-recoverable energy, thus unlocking all the potential of hydrogen to be used to do far more than we ever did by fossil fuels, all at real benefit to the planet, the more put to use the better, none of it doing any damage.
For now the best trade-off that can be had between fossil fuels replaceability, and energy cost of pressurisation, resulting in still by far the most energy inefficient part of the system due to lack of development to date, is as follows:
Hydrogen Pump
At the input of the hydrogen storage system we need a pump, to pump the hydrogen from the electrolyser / drier combination to a form that is practically storable, and useable by outside parties who might use our excess fuel. This type of pump, approved for pumping hydrogen, as stands is only available in compressed air driven form. I believe this is most likely due to onerous safety standards which we can be sure will have been driven by utilities energy / fossil fueled interests to maximise the perceived safety hazards of hydrogen. I don’t see technical any reason a safety approved hermetically sealed brushless electrical motor driven pump, for example, could not be developed for this.
But we need to work with what is available, regardless of our instinct that here we are losing a lot of valuable energy to heat, unnecessarily. The resulting efficiency figures are horrendous, compared with established battery backup figures, for example.
The hydrogen pump specification selected is for this one, from Alibaba:
The pump at the heart of this rack assembly is described as a reciprocating pump.
More information on those is here:
We need the 700 bar version of the pump found, to fit with current pressure standards commonly in use (More on this when we get to the hydrogen tank specification)
The pump model we need is the highest pressure variant in the Technical paramaters section of that web page, model number GU-GTB-100.
A clip of the Pump Technical Parameters is shown below, GU-GTB-100 is the one in the bottom row.
We can see there the maximum flow rate that the pump can handle is given in NL (“Newton Litres”) per minute. NL is a pressure included flowrate, where the flowrate in Litres is modified by Newtons pressure. This is equivalent to Litres flow at atmospheric pressure, and becomes less volume at higher pressures.
The maximum production rate of the electrolyser is given as 500NL/hr, which is 500/60 = 8.33 NL/minute. So the pump can easily handle this.
When we consider the pump efficiency in more detail, as we have to for the System DMN model, the pump duty cycle, deduced by the relationship between the pump capacity, and the electrolyser output will be most useful.
Though it has to be admitted the need to drive the hydrogen pump by another pump looks like a horror story in terms of efficiency, what we must keep in mind is that every kg of hydrogen stored, is 33KWhrs less energy from the sun that will go to heating the planet, at least until the hydrogen is consumed. Imagine billions of people, all storing a few kg of hydrogen, and every vehicle including every aeroplane (thousands of kg per plane), storing lots more kgs of hydrogen — that is a lot of heat energy removed from the the environment.
This is very different from the heat energy discarded to the environment in all the processes of fossil fuel production, which are actually the opposite processes to above. In the “creation” of fossil fuels, we are actually reversing the process that nature did, over millions of years. This is not creation at all but actually the opposite. Nature converted all the energy captured from the sun, in fossil fuels, into something other than heat. The amount of energy taken from the sun by nature to do this is given by E=MC squared, where M is the mass of materials. We can say this about any materials in nature, they were all created, and continue to be created with the effect of reducing heat. By reversing that that action, inevitably we are releasing the vast majority of the energy used to create the materials back to heat.
The total heat energy returned to the environment by energy extraction is given by ((E=MC squared) minus what we put to use, minus the energy yielded as usable fuel, minus the energy in the pollution materials produced.
This was before we consumed the energy yielded. This has to be added to the unused energy of the heat of the sun, so its a double whammy. When we don’t use the energy of the sun, not only do we miss an opportunity to use energy that results in less heat, but we are forced also to do the work of extraction, which adds to the temperature impulse, because we have to get at least the energy we each need to metabolise, 150 or so Joules per second (150 Watts), 24/7, from somewhere.
Compare that with the case of our creation of hydrogen from solar energy, at any efficiency. We didn’t add any heat whatsoever per KWhr of energy put into hydrogen, which would not have been generated by the eneregy of the sun had it gone unused in any case.
Yes there is an energy cost in the kit we have to install here, but once this is installed, there is only the energy cost of maintenance remaining. Notice much of the resources in this kit are things that will become available from recycling, because if we are honest, this kit will replace a lot of utilities grid infrastructure. An awful lot of those pylons, overhead cables, substations, and of course power stations, will disappear, leaving an awful lot of materials to be recycled.
The mathematically positive energy rule of creation applies, however efficiently we did the conversion. Obviously if we can make improvements to efficiency, then we can accelerate rate of creation, and rate of temperature drop.
But low efficiences of creation are infinitely better than high efficiencies of destruction.
So it isn’t a fair comparison to compare the efficiency of solar energy with any other energy at all. Solar is the only mathematically positive energy, the only one added to Earth, the only one we can actually create with, so actually the only one that is sustainable. This is why we should have formally mathematically signed energy a long time ago, to make this clear, and to begin auditing one against the other.
Again fossil fueled / utilities energy profit driven interests and associated subsequent instruments like Occam’s razor, are most likely responsible for that omission.
But hey-ho, we have to work with what is on the table.
Even if we only get 10% efficiency, every kg of hydrogen created, is still creation, vs the actual destruction done by all the heat energy lost in the physical extraction and processing of fossil fuels. LNG might look good relative to other fossil fuels on paper, due to it having much less processing en route to consumer, but only until we realise that it too is a material, every gram of which when converted to energy has to add to heat impulse. Use of it can never be something that subtracts from heat impulse, like use of solar energy absolutely is.
This matters much more than efficiency, and actually it is this process of creation which creates economic product which is far more valuable than fossil fuels can ever be. Money, when it comes to represent solar energy, as it has to, will have strength never seen before. Inflation will become a thing of the past, when we accept it was always about the effective energy per token money, that was always what mattered, and still matters most to money.
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UPDATE — The following section extension on Pump Selection was added on 23/11/2023. Choice of pump changed, but performance specification is similar. Above information still relevant, reasoning is augmented rather than superseded. Original information is left basically as published.
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On quizzing TEREK about the efficiency of pump GU-GTB-100, they clarified that they would not recommend use of their pump for H2 pressure in excess of 350 bar.
Technically it would work, but they are concerned that the materials used in their pump could not be guaranteed for sustained high pressure H2.
I am glad, and to their credit, they were honest about this.
Risks of hazards of this kind are obviously not worth taking, especially in a potentially domestic environment.
So I had to spend a little (Actually a lot) more time, to search further for a suitable pump with the above experience and lesson learned; about limitations likely with probably most pumps in Alibaba, appearing to be capable of use for H2 at all the pressures listed.
I had to search for a pump that explicitly states in writing, with a guaranteed period of operation, that it is capable of handling hydrogen at 700 bar. The one found is guaranteed for a year’s operation at 1000 bar H2 pressure.
This is the pump found:
It obviously looks a lot different than the effectively racked unit of Terek. This looks more like just the pump within the Terek racked assembly with none of the connecting and manual controls or guages.
The technical details of whether or not it would be best to have this pump incorporated in a rack assembly like the Terek pump are left for later considerations. All we are really interested in right now, for the purposes of System Modeling, is whether or not this pump will do what we need, racked or otherwise.
It does appears to have everything needed, pressure switch etc, for use directly connected between tank and electrolyser. It is again air driven like the Terek pump.
The materials are specifically mentioned in the description of this pump as being suitable for high pressure H2, and separate pressure specifications are given for oxygen, hydrogen, and inert gas (Such as N2).
The pump is described as being constructed from stainless steel, but has options on seals, optimised for hydrogen if the pump is specified by the customer to be used for hydrogen.
The specifications are given in a completely different way than the Terek pump, we see far less detail on performance.
To be sure this pump is capable as a higher quality replacement of the Terek pump, we have to do some comparisons between the very differently presented specifications for each pump, to confirm that the newly specified pump will do what we worked out should have been possible with the Terek pump.
On searching the internet for more information on how to relate throughput flowrates to displacement specifications, we find a Haskel pump catalogue, which appears to have all the specifications for both flowrate and displacement for a more or less identical pump model.
The photographs in the Haskel catalogue appear very similar to those of the Hydr-star pump. In fact we can identify a part number in the Haskell catalogue (higlighted in yellow), which has the same displacement and pressure ratings for all three gases specified. This has to be more than a coincidence.
Haskel part number AG-152 has the same displacement and pressure specification as Hydr-star AGB06–2S-150. Notably, both part numbers begin with AG despite being different manufacturers.
Further we find the technical drawing for the two pumps is almost identical (Compare drawing below with the drawing in the Hydr-Star specifications image above):
The biggest difference appears to be 13mm more in overall length of the Hydr-Star pump. All other dimensions look identical, though there seems (Strategically?) a lack of ability to directly compare, the only dimension taken from the same aspect is the overall length. All the others are impossible to relate directly. This could be because they are exactly the same (Revealing the Hydr-Pump to be a more or less exact copy of the Haskel design).
Who knows what kinds of commercial dealings or non-dealings might be going on, or have gone on between Haskel and Hydr-Star historically, for Hydr-star to be offering what looks like an almost identical pump independently. We can probably guess Haskel will have had pumps manufactured in China, just like nearly all manufacturers have done.
We can’t concern ourselves with the moral questions of copying! Personally I have no problem with it. Patenting and Copyrighting is something I’ve grown more and more skeptical of, since I dabbled in it, having a historical registered patent for an electrical energy handling device myself, but that is just a personal opinion. It gives me pleasure now to know that the device I created was adopted for supply by a major international components manufacturer — even though I’ve never seen a cent or penny of revenue from the sales of it.
Interestingly the device I patented is an electrical analogy of what this pump is. The whole purpose of the pump is to translate low air pressure, high flowrate in the primary (air) circuit, to high pressure, low flowrate in the secondary (H2) circuit.
The pump is the gas equivalent of an electrical transformer.
So I am completely “At home” with it.
What should matter most to us right now is that this pump is on the table, on sale via Alibaba. It is possible we could invest the time and effort to go through the process of trying to acquire the authentic Haskel version of the pump, at most likely much greater expense, but Haskel is not showing it available “Off the shelf”, whereas Alibaba is.
Anyhow, knowing these pumps are more or less physically identical, we can use the Haskel specifications which are far more comprehensive than the specs for the Hydr-Star pump.
We find a handy summary with flow rate at 12000 psi for the Haskel equivalent pump on page 15 of the catalogue. I’ve highlighted the line detailing our pump of interest in yellow:
To compare the flowrate specified above with the flowrates we had for the Terek pump, we need to convert above to metric:
3.02 SCFM = 3.02*28.316 NL/min = 85.5 NL/min
This looks like more than twice the Terek pump’s stated 40NL/min capacity.
So it should easily do the job.
Further, Hydr-star offers racked pumping systems which are described as containing “Haskell similar” pumps. This gives us some peace of mind that if we do later find we need to have the pump racked in an assembly, Hydr-Star is capable of doing that too:
Air Compressor
A suitable compressed air pump, which looks like it will easily do the job of supplying the compressed air needed to drive the hydrogen compressor is this one, again from Alibaba:
We need the smallest version of this, 0.8MPa 1.5KW, model number RMC1.5–8B, detailed in the product parameters section on the above web page.
It has a specified flowrate of 180L per minute, and has an integrated 40L tank.
It requires 380V supply which is compatible with an output from our 10KW fuel cell generator detailed in part 2.
Again the duty cycle of this air compressor, driving the hydrogen pump, will be most useful in computing its effect on system throughput efficiency, as used in our application.
Hydrogen Storage Tank
Looking at the various options available, it looks like one or more “type IV” hydrogen storage tanks is the best option for our purposes of a large domestic or small community installation.
These are designed primarily for use in vehicle applications, but because they appear to have had most development effort, warranting and conforming to “type approval” standards, and are in most ubiquitous supply, they most likely also already enjoy economy of scale. The environmental and safety standards applying to them easily cover also the requirements of a residential or fixed building application. So they look like the most obvious choice.
There are racks designed to accommodate multiples of type IV tanks/ bottles, and the way pressure works, it is relatively is easy to scale / expand storage capacity by just adding more bottles with connnecting pipework, if we find a need to do that later, after the economic switch to Kardashev 1.0+ happens.
The tank selected from Alibaba, two of which are shown bussed together with hydrogen piping, is below:
Although the tank on that web page is described as 35Mpa (350 bar), probably because those are in most immediate stock, the same company, Wuxi Daze, offers a 70 Mpa (700 bar) version of it, which probably sells a lot more than the 35 Mpa version advertised.
The specifications for the range of bottles offered by Wuxi Daze is below:
The only 700 bar model there is DAZE410–65–70T
It has a capacity of 65 litres, take it or leave it.
At first this sounds like not much, given Enapter, our electrolyser manufacturer talking in their example about a vehicle hydrogen fuel tank of 500L.
However, using a suitable online calculator we can quickly check how much energy the tank full represents
The Stargate Hydrogen gas density calculator looks reliable, because it cross-checks with the answers from the DMN model I created to do these calculations per the NIST “Revised Standardized Equation for Hydrogen Gas Densities for Fuel Consumption Applications”
Here I advise caution, because unless we have to hand a reliable means of making these calculations, it is more or less impossible to tell when we are getting the truth from an online calculator, and I can say from experience most of them claiming to give hydrogen mass for a given volume and pressure, give seriously wrong answers.
The correct answer for a 65L bottle holding hydrogen at 700 bar, at 25C, is 2.55 kg.
Any calculator that gives a seriously different answer from this is a serious liar, and there should be laws against lying about this, imho. It is actually existentially important we know the truth, in general, but on hydrogen it is uber important, due to it also being something safety critical to work with.
The first online calc I tried gave an answer of 0.04 Kg.
If I accepted that answer I would have stopped the design right there, because that amount of hydrogen is next to nothing. It implies we could not conceivably bottle enough hydrogen to back up the energy requirements of a single household, never mind powering a vehicle for many miles.
So beware of those online liars, they are probably on the payroll of the fossil fuel mob, as always.
I won’t even supply links to them here, as that only helps them.
Gripe over, just pls beware of them.
2.55Kg is 2.55*33KWhrs of energy.
Recall 33KW is the output every 24 hrs from the Electrolyser, and this is the budget we have assigned to our example household.
So a single bottle is 2.5 days worth of energy storage for the household.
I would be inclined to add at least one more bottle to our rack, to ensure we really do have enough stored for any eventuality.
Then I’d add another two, to give us the capability to occasionally offer some hydrogen to others who might need it, or even to sell to passing hydrogen powered transport ^^.
If we had the financial budget to do this, as I am 100% certain we will have very soon, due to the required change of economy to Kardashev 1.0+, which nature will force, sooner or later, this would be a no-brainer, to max out the amount hydrogen we could store, because the more we could store, the more we could sell, and actually the more good we would be doing for the planet, because every kg stored is 33 kWhrs less energy that can go to heating the planet, at least until we sell the hydrogen, and then it is consumed.
As is, lets stick with two 65L bottles for now. We can always add more later.
Regulator
Now we need a regulator to put on the bottles complement, to regulate the flow from the tank comprising bottles, to the feed of our fuel cell based generator, detailed in part 2. This is the last part we need to include in the end-to-end system DMN model, to ensure we include all the losses in the system efficiency calculation.
The regulator selected, again from Alibaba is the one below
Hydrogen Tank Regulator
https://www.alibaba.com/product-detail/70-Mpa-Hydrogen-Pressure-Regulator_1600782295863.html
I am not sure why the above link does not activate to a followable link, whilst all the others in this article did. Hey-ho you will need to copy and paste to open it in a browser view.
Anyhow, this completes part 3, now we have all the parts needed, and the specifications from those, to plug into the DMN design model, except for the panels and battery backed power conditioner for those.
That will be covered in part 4, with part 5 concluding the series with the presentation of the updated DMN model, in all the detail needed for anyone to replicate.
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Further Information General References
Update History:
12/11/2023 — Air Compressor Product Parameters Added, reference to Hefei Sinopower manucturer changed to Wuxi Daze manufacturer.
