Rosie, What is so interesting and refreshing about your videos on hydrogen (and many oither topics) is that you approach it from an unbaised, pure engineering standpoint. Normally the standpoint on hydrogen videos is very much from the point of view of battery electric cars and nothing else!
When I was a teenager back in the 1970's we made an electrolyzser in my friends basement (which was definitely a den of various iniquities, such as foosball, underage drinking, etc). We use it to fill up balloons with the off-gas. We lit the balloons on fire to produce wonderfully impressive conflagrations. Only recently did I find out that because of the chemistry that we used we probably produced chlorine, along with the hydrogen and oxygen. So kids, if you try this at home, you probably should use lye rather than table salt to increase the conductivity of your water.
We of course did electrolysis in high school chemistry, with the warnings that if you used too much NaCl in the electrolyte, chlorine gas would be made.... so what did I do at home on the weekend? It really is quite yellow too, and I of course had to smell the pure chlorine gas (only did that bit once!).....
Ha ha, I never did it so I was super impressed! It's crazy to see how simple it can be, and complicated it needs to get if you want it to be cheap, reliable and efficient.
I live in the Western USA and we put solar cells on the roof of one of our shops that produces much more than all our needs combined. It is set up to feed back into the grid but we discovered that this feature is only active when there are local peak usage. With a couple neighbors installing them we are wanting to do something with all the unused power. We did try setting up some hydrogen production with a company in Oregon that was producing some nifty 2way hydrolyzer/power units but before we could get them that company was bought by some unknown giant corporation (through shell subsidiaries) and we never heard from them again. We dropped plans for any more solar and cancelled wind turbines because we couldn't use or store the power.
What a shame! Pressurize the water going IN and the gas will be at 1/2 the pressure coming OUT. At 60 degrees F you'd need 92psig to compress into a used propane tank. Using gas-tight quick disconnect couplings and in-line cut-off valves (all fittings non-steel and all components earth-grounded) you SHOULD be safe. Whatever you do - DON'T try to pressurize the GAS using a compressor. Pressurizing the intake water is MUCH safer!
Thank you Rosie, your video is very informative. I watched your video several times to see how my small mobile system that I’ve built (and still improving) compares to the one from Green Hydrogen Systems. My system has been built on a shoestring budget but the important components seem to be present. One difference is that I don’t vent the O2, I dry the O2 and compress that too. My biggest challenge at the moment is the degradation of my membrane (or diaphragm as Kasper calls it), my KOH dissolves my membrane much too fast when I run my system at full power; 200 Amps at 27 VDC. Most of the gas that I produce is grey H2 and O2. I recently install a solar system with battery bank to produce green hydrogen instead. It would be great if you could make a video on the different types of membranes, design, manufacturing, availability and cost thereof. Thank you in advance John.
Wow, have you really hand built an electrolyser? I have never heard of that before, I am really impressed! If you're on Facebook or Instagram please share photos and tag the Engineering with Rosie page 🙌🙌
A couple things: 1) his efficiency is in terms of the HHV of the hydrogen produced, which includes the heat of condensation of the product water once you burn the H2. That value is 39.4 kWh/kg. You don't get that back- 6 kWh is lost therefore, so you really should use the LHV of H2 which is 33 kWh/kg. So they use 39.4/.76 = about 52 kWh per kg of H2- but really, when you feed it to a fuelcell, even an impossibly perfect one will only give you 33 kWh back again (most give you only 16.5!) So the efficiency really is 33/52 or about 63%. Once you store it (90% best case) and then use it in a fuelcell (50%), you have a "round trip" efficiency of only .63*.9*.5 = 28%, versus over 90% for a lithium ion battery. That's a lot of loss, so he's dead right- you would only convert electricity into hydrogen to use it AS hydrogen, not to make electricity again from it!
2) He forgot to talk about current density. If he put twice as may electrodes in his beaker, the voltage would drop too- efficiency would go up. But for every doubling, you only get a small increase in efficiency (drop in voltage). And every unit of area means more electrode metal, and more separators etc. etc. So you are in a balancing act between increasing efficiency (which makes the electrolyzer more expensive, not cheaper!) or decreasing capital cost (which makes the electrolyzer less efficient...)
Thanks for the detailed comments! We did actually discuss your second point briefly, but I had to cut so much of what we talked about... my first cut was 30 minutes long and no one wants to watch that 😊 So thanks for adding the point here.
Still, hydrogen car (electricity->hydrogen->electricity) has better efficiency than a petrol or diesel. You should compare with internal combustion engine, and see that just having low efficiency does not mean it's not feasible solution. It solves many problems with transport and long term storage (i.e. transport in time domain 😆) of electricity.
@@EngineeringwithRosie I'd also appreciate being able to watch longer unedited interviews. If you're afraid that they would scare away new viewers, you could always put them up unlisted and only link to them from the video description of the edited video.
Hi Rosie, this was a great video. The questions were great without being too simple and very informative. Feeling more confident for a hydrogen job interview next week!
This is a fantastic video that clearly presents the challenges. The energy cost here is going to be hard to overcome. Your guest validated a conclusion I arrived at a couple of years ago: that green hydrogen only makes sense if you have a massive surplus of renewable generation, you've maxed out all your storage, and that excess is otherwise just going to waste. We can build a grid that does this (particularly with a healthy nuclear baseline), but it's going to take us awhile to get there.
Great video, Rosie. This was actually the first, practical experiment my mother tought me to do as I was in my 4th or 5th grade. We used a 4.5V battery, a deep glass bowl, two wires connected to a carbon rod each (from old dry cell batteries) and we used washing soda as electrolyte and water glass from the cupboard as collectors. It was SO easy and it made me take up physics and chemistry because of this perfectly working experiment. So thank you for the reminder! But I wonder why you have made several videos from my little Denmark. Aren't you from Australia?
Wow, that is really cool you did that experiment with your mum! I never did this one at home or at school, so I was really impressed when Kasper showed me. I lived in Denmark until a couple of months ago. I was in Kolding for nearly 5 years. That's why there are so many videos in that region 😀
@@EngineeringwithRosie Sorry to hear you have left us. If you should ever come back I'd like to invite you to visit our rocket shop at Copenhagen Suborbitals. Could be fun.
Hooray! I've been looking forward to this! I'm always impressed to hear smart people talking about their field, which includes yourself! It's funny to think that I first heard about this technology from scam UA-cam videos pretending to run cars on water, and now it's potentially going to be powering a huge proportion of the world! It seems pretty likely that various energy storage systems are going to become more widespread and I was wondering if you had a take on combining renewables and energy storage technologies (such as using wind turbine towers to store hydrogen or compressed gas) or whether it's best to let generation be generation and storage be storage? I can think of pros and cons to creating combined systems but there only currently seems to be academic interest in the topic. Thanks for the brilliant video and looking forward to the next one!
Hi, I'm glad you raised these topics, because that is similar to what I am already thinking😊 I plan to move on to other types of energy storage soon after a few more videos on hydrogen (hopefully including a wind power to hydrogen project) and also finally finishing up my wave energy series. I want to make some videos on what kinds of storage are needed for what purposes, how generation, storage and flexible demand all work together (now and in the future with more renewables) and then look at some specific technologies including a thermal energy storage company I visited already plus others. So that is obviously a lot, it will probably take most of 2021 to get through all that, and then I didn't even mention what I want to cover on e-mobility! What do you think? Does that sound like a good program for 2021?
@@EngineeringwithRosie It's good to hear we're on the same page and I'm enjoying coming along for the ride! That is a busy schedule and all sound like interesting topics! As long as you are interested I'm sure they'll be great videos. I'm all for focusing on power generation/storage and how future grids may operate. E-mobility is quite a saturated topic (although I'm sure you'll bring something fresh to it) I would be keen to see more napkin calculations/mythbusting like your waste video as that was a real eye opener! Maybe rough calculations on the future energy mix of different countries comparing land, energy sources, main uses? I really appreciate all the effort you put into this channel and hopefully you continue to grow over the coming year!
The local kommune (Lolland ind Denmark) tried a system in a village, where the hydrogen was fed to the houses, where it could be used as cookinggas or converted to electricity at the house. Lolland produces windenergy more than 5 times what we use.
I would love a deeper explanation as to how they got their numbers for efficiency and if they actually have the wiggle room available that they say they do.
The efficiency of an electrolyser is normally calculated as the energy content of the hydrogen produced (142MJ/kg), divided by the energy spent in producing it. The wriggle room they talk about in the video is because you can increase or decrease the power input (the voltage and current) within certain limits, much like you can throttle up and down a car engine. As a general rule, the lower the power input, the higher the efficiency. You can check this Wikipedia page to read more about this: en.wikipedia.org/wiki/Electrolysis_of_water#Efficiency
PEM membrane improvements to increase current flow, anode and cathode can be optimised, with platinum, rhodium, palladium, Tio2, cobalt dioxides, photo catalysts can assist process, as can certain electrolyte catalysts, work is being done with half cell catalysts with some iron/pt. Compounds where partial electrolysis can proceed stepwise more efficiently than direct.
It is perhaps worth mentioning that the attraction of high pressure electrolysis is that hydrogen comes out at high pressure. Water going in can be raised in pressure without heat loss because water is incompressible. A big plant might expand the oxygen through a turbine to regain energy. In a conventional power plant you also pump water up to pressure, turn it into a gas and then expand it through a turbine.
H2 out should be at no greater pressure than atmosphere when the feedstock (water) is AT atmospheric pressure. Want to increase the pressure of both gases exiting a reactor? Maintain high pressure IN of the water and have 2 polarized output ports/porous electrodes to collect the (now) pressurized gases. Got that from a NASA Tech Briefs design when they were exploring manufacturing their own fuel/oxidizer at the cape from sea water. But, again, chlorine was a problem.
Rosie, many years ago, I built an Edison hydrogen generator for my truck which I used to increase my gasoline mileage. I went from 16 MPG up to 25. Both the hydrogen and oxygen were added to the incoming carburetor air. This resulted in a very large decrease in my miles per dollar, or reducing my gallons per hour of gas. The problem I ran into however was that the new auto computer systems would enrich the gasoline to meet its computer specifications, negating the huge advantage. (Also increasing heat output on my catalytic converter.) And if I modify my computer to avoid this my car would not pass inspection, because inspection looks at computer settings only, and ignores the actual tailpipe emissions, which was actually significantly improved! I can see the only reason for this being Big Oils concern for their profits! I know, I just asked you to walk into a mine field. But I am a scientist. Truth is all that matters to me. This would significantly reduce greenhouse gasses until we can get totally on a green energy solution. But some people will lose a lot of money. Very powerful people.
Shouldn't have input the O2 consistently - only when a boost in horsepower is needed - hence the overheating and 'computer' enriching the mixture (O2 sensors in the exhaust line) - raising the O2 output causes the O2 sensors to heat hotter - telling the computer the engine is running too 'lean'. (My friendly Meineke dealer's diagnosis - ;-)
This is great Rosie. Brava! I am a postgraduate energy engineering student and, I have got to know that we need hydrogen in CCUS. I would like you to do a video on how to integrate industries that emit CO2 with CCUS and green production. I think we could form a closed-loop system from the integration.
Fascinating, thanks Rosie! To know if H2 is the energy of the future, we must consider all parts of the math of the return on investment (ROI). Meaning is it really better than any other energy sources? 1) where does the electrolysis energy (kWh) comes from? "Coal and all other fossil fuels, plus waste burned for electricity, amounted to 20% of the electricity production. The other 80% of the electricity produced came from renewables: wind power (57%; see wind power in Denmark), biomass and other combustible renewables (20%) and solar power (3%)" source Wikipedia, 2019 Energy in Denmark. It is a larger renewable portion than a lot of countries - kudos to Denmark! However "burned...other combustible" do not qualify for Green Hydrogen. Still a good show. To be clear, they use electrical grid power to produce their H2. 2) Are there hidden costs to that process and delivery to end-users? We must compress H2 at around 10,000 psi to fill a "gas tank" of H2 in a car in order to obtain around 275 miles (434 KM) range. That's inevitable also to power a house. A whiff of it stored at 1 atmosphere won't do much. Natural gas or electricity must be consumed also, to power the H2 compressors, which ads to your price and carbon footprint. Then, in a car, for instance, the most efficient H2 car on the market (operating only in South California) has rather poor performance (over 9 seconds 0-100kmh). Re-conditioning the gasoline/petrol worldwide distribution grid into an H2 grid may very well cost $trillions, and inevitably, bottom consumers like yourself and I, will pay for it in high H2 prices at the pump, or through a spike in our income tax. Yes, these costs are not mentioned but they positively will have to be paid. 3) a practical application of thermodynamics, the second law; Every time you transform, transport, transduce... energy from one form or one location to another, you lose some energy. It's part of entropy. The more vias there are between your initial source of energy and the delivered item in the hands of consumers, then the less effective it is, as you lose some energy every steps of the way. The final analysis is that a Tesla Model S costs US$17.55 for a full 651 km range (only around $6-$8 if you home-charge). Toyota's H2 champion car cost US$65 for 442 km. Hidden costs? As mentioned, we will pay for the huge change in distribution and storage of H2. Tesla has already a fairly good distribution network of charging stations, and although they felt the need to increase their re-charge fees, however it is still much lower than H2 or gasoline. Why? Less vias is cheaper. The sun will be around for another 5 billion years, and nobody has to pay for getting a nice sun tan. Other car manufacturers are moving ahead with building their own charging-grids. It's only a matter of time before they all agree to integrate into one global charging system. Power strips fixed to each road and highways would be great, while the Chinese are working out a photovoltaic coating that adheres to roads to yield more electricity. Now, if the brave Danes will consider all the above parameters and still come out the winner, I'm all in for it and I will gladly post their flag on my wall. The wrong thing to do is to do nothing. Cheers! *I don't work for Tesla. Nobody pays me to say this.
thanks a lot ! i like this optimistic stuff ! among all the bad news of war and pollution and nuclear threat maybe this is a silver lining in the clouds.let the winds of change blow ! Serge from France.
Rosie always has a good video with the basics covered, and brings all along who are curious. My 2sense When you see "green anything" it requires free electricity from renewable electricity. That will never happen. Because the electricity will be needed to decarbonize our houses and our industries, 1st. 2nd, it will be used 1.2:1, not 3:1 input to output, comparing electrical used for electrical needs, vs H2 production. We have these thingies called batteries, for storage, they win, up to 4 hours of storage a day, because of RTE. Using overproduction of wind and/or solar means the utilization of the electrolyzer is poor. Or you wait a 1/2 to a full century, when we have 200% RE. Or you put in batteries. Ohh wait a minute... That's the solution we are comparing to! Ha! Storage, up to 10%, allows extinction of 28% to 38% FF burning, when overproduction is 130%, and FF Burn % is 60%. Once we figure out how to monetize storage properly with the savings of the shared efficiencies across running FF plants, this will be possible. 1st pay for storage capitol costs 2ns, split profits with T&D, and power plants that became more efficient, some % for offline reliability payments. This new efficiency mode means your run 3 or 4 FF plant at peak efficiency, instead of 5 or 6 FF plants at partial load, just so if one goes off line the others can cover with a quick ramp time to higher output power, compared to a cold start of a FF plant. if enough storage is added, even cold starts can be covered, removing the last two partial throttled FF plants in region. The Gaia hypothesis, Storage, the FF burn extinction provider. Ron Davison 1-7-2023
Offer valid till no more practical over-production is left to be harvested. AKA "While (over) supplies last". then the 2.8x drops to 1.8x with storage being more bulk, than balancing. The crossover back to 1.2:1 also is the 3rd tail of profitable storage add, the last. At roughly the same % as we will achieve with over-production extinction and capture, is my opac crystal ball prediction. That's about an extra 10% storage, beyond the 1st 10%. This may be mind bending amount to think about, at least in terms of batteries, only. But to put this in perspective, the USA is ~20% hydro, 1 way hydro, that still is a form of storage, but we do not think of it this way. Because we do not control the filling, per say, I suspect. Winners sorted best 1st. 1) Lithium (Home/Industry/Utility) 2% to 3%, must have high utilization 2x a day, add 1% on energy/day 2) Lead Acid (home) & Flow (Utility) take us 3% to 10%, (delta 7%, flow can go higher, still. RTE limited, low utilization, Lithium % augmentation in extreme demand/supply unbalances vs using after Lithium is not available. In reality, there will be overlap, based on price arbitrage and RTE hit for each chemistry type. 3) Pumped hydro can be added to existing hydro in at 10% to 20% storage needs. If assuming doubling of upconverting hydro capacity at one way dams to 4%, co-locating and co-using added turbines for one way or pumped hydro operation with valving. 4) One way Hydro, used more effectivly, producing more power per acre-feet of water. 5) 1) & 2) can be operated more efficiently together with a lower C rate per unit storage, even though one is a lower RTE, up to a point, also beyond this point by some multiplier, say 2x as an example, so that, the higher efficiency storage is not exhausted early, allowing the poorer RTE storage to not be hammered with power losses, AKA heat and destruction, AKA bricking cycle non-life...1)&2) allow 3) to be conserved, that allows 4) to be conserved and be true. Together they arer all called storage. Add 6) thermal storage,TESS to be complete.
I think the most relevant thing he said is to use electricity as electricity and covert it only if you have too much or have a specific need. I still have a hard time with H2 as a widespread fuel. As a storage medium I think there are better alternatives. Compressed air takes less energy to create and coverts back to electricity easily. You can also extract useful gasses for ancillary sales and if you believe in CO2 sequestration then you can get that too. Certainly better than blue H2.
Agreed, Rosie mentioned this article on her podcast, which ranks uses of (clean) Hydrogen from most likely (industrial processes which already use Hydrogen) to least likely (personal Hydrogen cars). As clean H2 gets better, it can "move up the ladder", but the ladder order will be the order in which it moves
Making hydrogen through electrolysis is very similar to producing chlorine and caustic, except salt water is used. The application is the same too. Electrical energy is used to split molecules which then want to recombine to release that stored energy. Using hydrogen to deliver energy is using it like a battery. So hydrogen has to work better than a battery to really be useful, and battery technology is advancing quickly. Batteries are easy to store while hydrogen requires a thick and heavy metal tank. But hydrogen fuel tanks can probably be refilled a lot faster than batteries get recharged. I see hydrogen vehicles being limited to big heavy things like city buses, semi trucks, or ships. This video discussed using hydrogen to buffer excess electricity that may be produced in the future. I don't see that as superior to just lifting water and letting it drop back down. To really be efficient at making hydrogen you have to learn a lesson from making chlorine/caustic. It takes an unbelievable amount of electricity for just one plant to make it in quantity - about what an entire smaller sized city uses. Any small improvements in the process result in significant energy savings. One big efficiency improvement was building an electric generation plant next to the chlorine/caustic plant. That allowed the leftover electric generation steam to be sent to the chlorine plant reducing the need to boil its own steam. When the electric plant is not adjacent, the energy in its leftover steam is lost. Likewise, if when you generate hydrogen you just throw away the energy invested in the oxygen, then that significantly raises the cost. Something profitable will have to been done with the leftover oxygen to get value from the energy that has been shoved into it. The issue of whether the hydrogen was made from "green" or non-green electricity is diversionary at this stage.
Great comment, you've raised lots of interesting points. I agree on the limitations of hydrogen, you can check out this other video I made on hydrogen and I am going to make more on the topic this year so I hope you will check back later to see them! ua-cam.com/video/ge4ux1Y1ric/v-deo.html
Hi Rosie, Very nice video! There are two points in the video that don't match up regarding efficiency in my mind. First is at 9:00 where they are using 430kW to make 4kg per hour, so that's 420kWh of electrical energy to produce 4kg of hydrogen or 105kWh/kg which contains 33.33kWh of energy per kg. 33.33/105 = 31.7% efficient. But in the literature, at 12:04 it says 76.5% and that they can produce 1kg of hydrogen with only 51.44kWh, not 105. Is he doing something useful with the heat generated? or was he just guessing wrong at 9:00? Also if you take the numbers in the brochure, 51.44kWh per kg of hydrogen and there's 33.33 kWh of energy in each kg of hydrogen, then the efficiency would be 33.33/51.44 = 64.8% or am I missing something. Thanks.
@@rexossai1441 Sorry, I was just asking questions about material in the video. Besides the amount of energy contained in hydrogen, the rest is just basic math and keeping the units the same. Just recently I read something about 4 major electrolizers starting production and in each case, they either give the output in kg/hr or kW in. None of them give both numbers so that you could divide the energy in vs energy out to simply arrive at the efficiency to verify their claims. Clearly it's been something the H2 industry has been shying away from. If Rosie saw the comment, I could understand not responding since pointing out flaws in the math doesn't do well for getting invited back and continuing to make UA-cam content.
For example at 9:00 there's the equation 430kW = 4kg per hr. So 430kW for an hour is 430kWh = 4kg. 4 kg contains 4 kg x 33.3 kWh/kg = 133.2 kWh of energy. So 430 in to get 133 out. Doesn't sound like 70 something percent efficient to me. But at the same time, he says "aaah, about 4" That doesn't sound like some precise measurement either. But he'd need to output 430* 0.76 = 327 kWh worth or 327/33.3 = 9.8kg and I doubt someone that's working with it all day long would be off by more than double. I too am an engineer and follow the basic grade school process of checking your math other ways to insure your answer makes sense.
@@scottkolaya2110 in my report i have 3.47kwh to 0.063kg hydrogen, at a high heating value...and be sure his not referring to FC here..note......but still the economics with no government tarriffs leaves nothing
@@rexossai1441 I've also seen numbers like that quoted. So 3.47/0.063kg is 55kWh/kg. Which 55kWh in to make 33.3kWh of energy is 33.3/55 = 61%. 61% sounds more reasonable. But I'm also suspicious that it doesn't include all the energy costs in that number. Is that for 700 bar pressurized hydrogen or atmospheric pressure H2? I know it's not for liquified H2. That tacks on another 12kWh/kg to bring it down below −253°C (−423°F). I've heard that in much larger scale, it's down to 8kWh/kg. But, for example in a large electrolyzer plant, there's much more equipment to make it run, not just the electrolyzer itself. I would love to see the plant's electric meter for the month and it's output in kg for the month to get a real efficiency number. I suspect it's closer to 55% once you include pumps, HVAC, lightning, etc. Just like I'd like to see a gasoline refinement plant's electric bill to see how much electric is used per gallon of product.
How about a future short video of a co-generation style electrolyzer system ? As touched briefly on in this video .. the energy needed to split 2(H2O) -> 2(H2) + 2(O2) comes partially from electricity and partially from heat .. I think the electricity side of that frequently gets a disproportional amount of attention .. higher amounts of heat reduce the amount of electrical input needed .. That continues all the way out until eventually the splitting of water can be zero-electrical input and 100% heat energy input .. given the enormous amounts of 'waste heat' out there , absorbing that 'waste heat' as a partner with another process would seem to be a synergy style system , and co-generate instead of solo-generate. Maybe not only further improve the efficiency of the energy you have to pay for compared to the amount of hydrogen you get out , but also by taking away that 'waste heat' to do so from that other processes you might further improve the efficiency of that other processes as well. Without a partner processes , it could still be done with a co-generation solar style system .. Photovoltaic collectors are actually better at (do more of it) converting solar light energy input into heat energy ~80% than directly into electrical energy ~20% .. and that heat lowers the electrical conversion efficiency for the PV module (soo it's waste heat for the PV). Or at the extreme end of the solar heat water splitting to hydrogen end of the spectrum would be to modify a large solar heat collector system like the molten salt facilities , to use all that enormous amounts of concentrated solar heat energy to drive a water splitting system.
@@agritech802 The scientific term for using only electricity is electrolysis .. decomposition of a chemical compound by electrical energy .. the term for using only heat is thermolysis .. decomposition of a chemical compound by heat energy .. there are even some microbial fuel cells that have shown that microbes can also use the chemical energy of the materials they biologically decompose in order to contribute some of the decomposition energy needed for secondary reaction like hydrogen production .. in the real world they do not have to be mutually exclusive , you just need a net overall amount of energy put in to break it apart .. using 'waste' .. be it waste heat , or biological waste , from some other processes (that needed to be done anyway) , is my personal preferred energy source for such thermolysis. There are lots of pubic sources about thermolysis , here are a few examples (in no particular order) : www.energy.gov/eere/fuelcells/hydrogen-production-thermochemical-water-splitting www.osti.gov/biblio/7335245-thermolysis-water-production-hydrogen-energy-vector-compared-electrolysis-which-has-higher-efficiency Discussion of the biological method to contribute energy and reduce the needed input from other energy sources is one of the topics discussed in the introductory book .. Microbial Fuel Cells by Brude Logan smile.amazon.com/dp/0470239484?psc=1&ref=ppx_yo2ov_dt_b_product_details
I'd really like to see a small scale device to produce hydrogen and then convert it to ammonia. If it was sized to match up with wind turbines, and the capex was small enough, it would provide a means to make use of distributed wind power. Ammonia is easier to transport than hydrogen, and it seems like it would be practical to transport it from remote areas to urban centers.
Ok...... This was the video really,I like it. Really...I am interested to produce and store hydrogen gas by Electrolysis process is one of the best method to produce hydrogen gas. Ma'am will you please explain production of hydrogen with different types of methods in another video?
Bloom Energy just released a high efficiency steam Solid Oxide Electrolyser that gets pretty high efficiency. If steam is supplied via nuclear or geothermal, it takes only 39kWh to make a kg of H2, which will produce ~33kWh of power, so you are only losing like 6 kWh in the conversion. It would be fantastic if you did a video with Bloom!
thanks for the video. automobile enthusiasts I've been using electrolysis to increase the burn efficiency of gasoline for a couple of decades if not longer. Some of these enthusiast have even installed systems on their car to power internal combustion engines completely on hydrogen. Are they looking into smaller units for automobiles?
Loved this video! Thanks, Rosie! Leads me to believe this is an ancient technology that was lost until recently. Does anyone else think this is what the pyramids and mega structures around the world could have been used for? Love the way you break down the processes and your questions from an engineer's perspective. Would love to see you explore whether megalithic buildings would have housed this and other chemical processes. Best, -CJ
Three related questions Rosie, how efficient are hydrogen fuel cells now & are they improving? If they are how long before these efficiencies come into being?
The hydrogen economy seemed to show such promise - is its lack of progress down to the fact that developing other green energy sources was cheaper and likely to come online earlier? Also, is there any chance of you looking into how the use of sunlight to produce hydrogen is going? Also the various types of fuel cell and hydrogen storage systems?
You noticed how the 'stack' is put together so it lasts a long time. But it depends on how clean the water is so minerals don't build up. Clean water gives many years.
Im extremely curious on what this membrane or diaphragm is made from? He waves it around so casually which makes me guess it’s not nafion or such. I’m asking for a uni project and since getting my hands on nafion is off the table due to cost any working substitute is very welcome.
Hi Rosie, thanks for another great video, can you do one on ammonia if you get a chance? I think ammonia production would be another great way of utilizing excess renewable energy and it can be used as a fertiliser or as a substitute for fossil fuels. It would have many many advantages of it can be made cost effectively. It has particular significance at the moment with the war in Ukraine and the cost and availability of gas and fertiliser
Talk about diminishing returns, like the man said 'if you have electricity use it. As a question, can he show that this will be better than the corn to ethanol conversion; BTU to BTU. I know cellulose processing has recently improved efficiencies. I get ROI, windmills cost money to build and dispose of properly. If that's what you are using to power, heat loss, material costs as you both pointed out. Subsidies always weigh in in my book too.
can you use Conventional source of electricity to start producing Hydrogen then same hydrogen produced may be used to operated electrolyser to produce more Hydrogen and oxygen preferably in any Hospital where energy and oxygen both required for regular use? please clarify
Hi Rosie, Can you please make a simple explanation on (onshore/offshore wind turbine to Hydrogen storage usage for customers end or the heating in households) ?? I would very much love to learn that Thank you
Researchers at Penn State recently combined water purification technology into a new proofofconcept design for a seawater electrolyzer, which employs an electric current to separate the oxygen and hydrogen present in water molecules. The new technique meant for “seawater splitting” could render it easier to convert solar and wind energy into a portable and storable fuel, according to Bruce Logan, Kappe Professor of Environmental Engineering, and Evan Pugh, University Professor. Hydrogen is a great fuel, but you have to make it. The only sustainable way to do that is to use renewable energy and produce it from water. You also need to use water that people do not want to use for other things, and that would be seawater. So, the holy grail of producing hydrogen would be to combine the seawater and the wind and solar energy found in coastal and offshore environments.
Ok so what it looks like is that what we have here is a 'dry cell HHO' generator - this makes what is known as 'browns gas' this is a mixture of both Hydrogen and Oxygen, what is not shown is how they separate the two gasses. You will notice a blur @7:40 and I suspect that is the separation process but I don't know how they are doing this. I bet this looks familiar ua-cam.com/video/LXMJ5bi6Fog/v-deo.html
What about creating ammonia as a vehicle for transporting hydrogen, then converting the ammonia to hydrogen closer to its source of use? Is ammonia not easier to make and transport than hydrogen itself?
What kind of voltage is fed into a typical system? Some sort of inverter is needed to produce 1.48 VDC I should think. Do they start with 3 phase 440 VAC?
I like your videos and recently subscribed to your channel. Can you do a video on Green Hydrogen/ Fuel cells as an alternate fuel for Aviation please? I don't really understand why it is not commercially viable yet especially considering the Gravimetric Density of H2 is much higher than the best batteries available in today's market.
If the cost of green hydrogen can be lowered to where it can compete with biofuels then hydrogen fuel will be used for aviation. It's all about money and the "green premium".
@@acmefixer1 so why not use Grey or Blue H2 till Green achieve the cost parity? Just like Electric cars it is greener to use Fossil fuel Electricity driven Electric cars than Internal Combustion Cars?
Hello, interesting topic. But we are in the presence of an installation that the private individual could never have installed at his home. Perhaps a presentation would be needed that would show that electrolysis and the fuel cell are possible on a smaller scale like that of a simple individual dwelling. This other level of detail will make it possible to better understand the possibilities offered for the individual, and also the cost of such an installation to store the green hydrogen produced from photovoltaic panels, and then to produce electricity during less sunny periods. However, solutions do exist for homes, we should perhaps try to promote them to start freeing oneself from fossil energy at the level of individuals. The AEM is perhaps for the moment the one that offers a lower cost thanks to less noble matérials in its construction. The prices are starting to drop. A bit like the price of LifePo4 batteries, which drop quite well, and allow battery storage to complement hydrogen storage. For good efficiency, consider producing hydrogen from renewable energy (sun, wind, hydraulic). In any case, avoid fossil fuels to obtain the energy necessary for the separation of Hydrogen, Oxygen. It is not necessary either to seek profitability with regard to the installations in the particular houses. The prices are high. We must seek to be able to do without fossil fuels. while thinking that profitability will never be there. Profitability will undoubtedly be present for the very large companies which will build power stations of this type and finally return to an economic model almost equivalent to the current model of fossil fuels. Large companies are currently seizing the market by using models of the power to gas type, ... Thus, they prevent as much as possible a possibility of autonomy for individual houses which could however easily have a hydrogen system installed in each of them. If this develops too much for single-family homes, they could cause a significant loss for these large companies who could no longer sell the hydrogen they produce at prices that will be almost identical to that of current fossil fuels. These large companies will in any case seek to maintain their profits at a level almost identical to what they do with current fossil fuels. Even if the new technology costs less, if not much less. And yet this has been the case for the past 10 years. The price of batteries goes down, the price of fuel cells and hydrolysers goes down. However, currently 100% electric cars are still very expensive, while they are technically and mechanically easier to manufacture, and have fewer precision mechanical parts than combustion or hybrid cars, and they have less usury ... if the goal is to leave the fossil, we must try to pull up the smaller companies that could offer us decentralized production for us individuals ... because as we often say, small streams make the big rivers ...
Hi Rosie, a German company HPS,based in Berlin produces a compact green hydrogen, off grid power solution including storage for home owners using their Picea system. It is still quite expensive but gaining new users continuously. With your engineering knowledge you might uncover more producers of similar small scale systems Will these become more widespread and above all affordable to more home owners?
I didn't know about Picea, thanks for pointing it out to me. I have seen some other home hydrogen storage (e.g. Lava), but I haven't looked into it in depth yet, I need to add that to my list!
if you use a resonant frequency of the water with the voltage, I'm thinking you would solve the energy requirements to split the water with less power...
If you want to deal with electrical energy availability variation, you might want to turn some industrial facilities on/off? This is suitable for turning off on for that? I suppose you either have to pair it with hydrogen storage, or pair it with another industrial process that use hydrogen you can turn on/off in sync? Do any exist? Like suppose you can ask whether you can turn it on/off based on electrical supply/demand for more processes than this. I'm thinking of hydrogen reduction of iron oxides, but it may well be a poor candidate.. Though it's a "just" hot chamber with good hydrogen iron/oxides mixing and a way to get rid of the water produced..
Recently US DOE sponsored research announced employing a catalyst for H2 efficient release from liquid organic hydrogen carrier (LOHC) at ambient temperature and pressure (cryogenic-pressure unnecessary); LOHC meets the critical need to store and transport H2 energy. Retooling the existing petroleum pipeline network (including maritime, rail and truck tankers) for a liquid H2 carrier makes H2 distribution pacify oil companies but makes available sector-wide, technology-wide and ubiquitous for zero-carbon hydrogen innovations for fuel cell electric, HFCV and other H2 innovations.
Thanks for the informative video and I wanted to let you know that Tony Seba predicted that the LCOE in an article in the San Francisco examiner in 2013 would fall to about where it is now. Rethink X is where you can find him on UA-cam
A question: When we leave the plant - I expect carrying, managing the hydrogen is pretty difficult. I heard from stainlees steel tanks that embrittle seriously. Hydrogen is so small - it leaks through most materials and harms them. Can you try to find statements about?
There is one thing that perplexes me about all that. If the current efficiency stated is indeed 76%, i.e. you get 76% of the electricity input back when you combine the hydrogen with oxygen again then what is the world waiting for? This is THE solution to get into green energy. The greatest problem of green energy is not the production of green energy but the storage to provide energy when the green energy sources are down for several hours (no wind for wind farms, the sun does not shine for solar farms etc.). What does it matter what is costs as long as we can save the planet with it? Even if it was 3 times as expensive as coal power stations, so what? The idea is really very simple: Use green electricity at times of access to run the electrolysers and use the reverse reaction to run a power station to top up supply during times of high demand. Even if it was somewhat less efficient, it is still THE solution.
No, you got the definition of efficiency wrong! It was 76% HHV. This means, from 100 kWh energy input, you get hydrogen with 76 kWh higher heating value (HHV), which would be 64 kWh "normal" lower heating value (LHV). If you feed an efficient fuel cell with it, you could get up to 38 kWh electricity back. Plus heat. On average rather less. Without counting in energy demand of compression, liquefaction,...
If you'd use up this hydrogen (from the 100 kWh energy input) for heating, you could get up to 64 kWh heat (theoretically) with a normal heating system (water vapor leaves the house) and up to 76 kWh heat (theoretically) with a condensing boiler.
Thank you Rosie, you have given me the first approach no Electrolyzers in a very easy to understand way. Please keep on doing such a good work
Glad it was helpful!
Rosie,
What is so interesting and refreshing about your videos on hydrogen (and many oither topics) is that you approach it from an unbaised, pure engineering standpoint. Normally the standpoint on hydrogen videos is very much from the point of view of battery electric cars and nothing else!
When I was a teenager back in the 1970's we made an electrolyzser in my friends basement (which was definitely a den of various iniquities, such as foosball, underage drinking, etc). We use it to fill up balloons with the off-gas. We lit the balloons on fire to produce wonderfully impressive conflagrations. Only recently did I find out that because of the chemistry that we used we probably produced chlorine, along with the hydrogen and oxygen. So kids, if you try this at home, you probably should use lye rather than table salt to increase the conductivity of your water.
We of course did electrolysis in high school chemistry, with the warnings that if you used too much NaCl in the electrolyte, chlorine gas would be made.... so what did I do at home on the weekend? It really is quite yellow too, and I of course had to smell the pure chlorine gas (only did that bit once!).....
@@geoninja8971 .
I would think that baking powder would be safer than either of those chemicals?
@@geoninja8971 The chloride releasing chlorine gas - same as when U-boats salt water got into the battery electrics.
Great video! I remember doing the experiment in high school, 22 years ago!
Ha ha, I never did it so I was super impressed! It's crazy to see how simple it can be, and complicated it needs to get if you want it to be cheap, reliable and efficient.
I live in the Western USA and we put solar cells on the roof of one of our shops that produces much more than all our needs combined. It is set up to feed back into the grid but we discovered that this feature is only active when there are local peak usage. With a couple neighbors installing them we are wanting to do something with all the unused power. We did try setting up some hydrogen production with a company in Oregon that was producing some nifty 2way hydrolyzer/power units but before we could get them that company was bought by some unknown giant corporation (through shell subsidiaries) and we never heard from them again. We dropped plans for any more solar and cancelled wind turbines because we couldn't use or store the power.
What a shame! Pressurize the water going IN and the gas will be at 1/2 the pressure coming OUT. At 60 degrees F you'd need 92psig to compress into a used propane tank. Using gas-tight quick disconnect couplings and in-line cut-off valves (all fittings non-steel and all components earth-grounded) you SHOULD be safe.
Whatever you do - DON'T try to pressurize the GAS using a compressor. Pressurizing the intake water is MUCH safer!
Thank you Rosie, your video is very informative. I watched your video several times to see how my small mobile system that I’ve built (and still improving) compares to the one from Green Hydrogen Systems. My system has been built on a shoestring budget but the important components seem to be present. One difference is that I don’t vent the O2, I dry the O2 and compress that too. My biggest challenge at the moment is the degradation of my membrane (or diaphragm as Kasper calls it), my KOH dissolves my membrane much too fast when I run my system at full power; 200 Amps at 27 VDC. Most of the gas that I produce is grey H2 and O2. I recently install a solar system with battery bank to produce green hydrogen instead. It would be great if you could make a video on the different types of membranes, design, manufacturing, availability and cost thereof. Thank you in advance John.
Wow, have you really hand built an electrolyser? I have never heard of that before, I am really impressed! If you're on Facebook or Instagram please share photos and tag the Engineering with Rosie page 🙌🙌
@@EngineeringwithRosie Thanks, I've uploaded some photos and videos of my electrolyzer build on Facebook and tagged your FB page.
Hello Rosie This is my first Engineering with Rosie video 👍🏻👍🏻👍🏻. I’ll be checking out your other video and looking forward to your new ones too.
This was the title of my research at the university in 2018
Greetings to you from the South of Iraq
A couple things: 1) his efficiency is in terms of the HHV of the hydrogen produced, which includes the heat of condensation of the product water once you burn the H2. That value is 39.4 kWh/kg. You don't get that back- 6 kWh is lost therefore, so you really should use the LHV of H2 which is 33 kWh/kg. So they use 39.4/.76 = about 52 kWh per kg of H2- but really, when you feed it to a fuelcell, even an impossibly perfect one will only give you 33 kWh back again (most give you only 16.5!) So the efficiency really is 33/52 or about 63%. Once you store it (90% best case) and then use it in a fuelcell (50%), you have a "round trip" efficiency of only .63*.9*.5 = 28%, versus over 90% for a lithium ion battery. That's a lot of loss, so he's dead right- you would only convert electricity into hydrogen to use it AS hydrogen, not to make electricity again from it!
2) He forgot to talk about current density. If he put twice as may electrodes in his beaker, the voltage would drop too- efficiency would go up. But for every doubling, you only get a small increase in efficiency (drop in voltage). And every unit of area means more electrode metal, and more separators etc. etc. So you are in a balancing act between increasing efficiency (which makes the electrolyzer more expensive, not cheaper!) or decreasing capital cost (which makes the electrolyzer less efficient...)
Thanks for the detailed comments! We did actually discuss your second point briefly, but I had to cut so much of what we talked about... my first cut was 30 minutes long and no one wants to watch that 😊 So thanks for adding the point here.
@@EngineeringwithRosie You've got a vote for a longer video here!
Still, hydrogen car (electricity->hydrogen->electricity) has better efficiency than a petrol or diesel. You should compare with internal combustion engine, and see that just having low efficiency does not mean it's not feasible solution. It solves many problems with transport and long term storage (i.e. transport in time domain 😆) of electricity.
@@EngineeringwithRosie I'd also appreciate being able to watch longer unedited interviews. If you're afraid that they would scare away new viewers, you could always put them up unlisted and only link to them from the video description of the edited video.
Good video and shows how hydrogen is the battery that we desperately need when too much renewable energy is available
NO, it proves the last thing you should do with excess electricity is make H2 and the best thing to do is charge a battery.
It was awsome, it answered a lot of questions I had about the technology. Thank you.
Hi Rosie, this was a great video. The questions were great without being too simple and very informative. Feeling more confident for a hydrogen job interview next week!
That's really nice feedback, thanks! And how cool that you have a hydrogen job interview, good luck!
This is a fantastic video that clearly presents the challenges. The energy cost here is going to be hard to overcome.
Your guest validated a conclusion I arrived at a couple of years ago: that green hydrogen only makes sense if you have a massive surplus of renewable generation, you've maxed out all your storage, and that excess is otherwise just going to waste. We can build a grid that does this (particularly with a healthy nuclear baseline), but it's going to take us awhile to get there.
Thanks for given my future plan green hydrogen production knowledge, I need your support in future, thanks
Thanks this is very informative video. Pl share more. I soon update of membrane and details of electrolyser.
Great video! So glad to see something with intelligence on UA-cam instead of kids doing pranks or stupid stunts.
Great video, Rosie. This was actually the first, practical experiment my mother tought me to do as I was in my 4th or 5th grade. We used a 4.5V battery, a deep glass bowl, two wires connected to a carbon rod each (from old dry cell batteries) and we used washing soda as electrolyte and water glass from the cupboard as collectors. It was SO easy and it made me take up physics and chemistry because of this perfectly working experiment. So thank you for the reminder!
But I wonder why you have made several videos from my little Denmark. Aren't you from Australia?
Wow, that is really cool you did that experiment with your mum! I never did this one at home or at school, so I was really impressed when Kasper showed me.
I lived in Denmark until a couple of months ago. I was in Kolding for nearly 5 years. That's why there are so many videos in that region 😀
@@EngineeringwithRosie Sorry to hear you have left us. If you should ever come back I'd like to invite you to visit our rocket shop at Copenhagen Suborbitals. Could be fun.
+1 on electrolyzer pricing video!
Thanks for letting me know 😊
Hooray! I've been looking forward to this! I'm always impressed to hear smart people talking about their field, which includes yourself! It's funny to think that I first heard about this technology from scam UA-cam videos pretending to run cars on water, and now it's potentially going to be powering a huge proportion of the world! It seems pretty likely that various energy storage systems are going to become more widespread and I was wondering if you had a take on combining renewables and energy storage technologies (such as using wind turbine towers to store hydrogen or compressed gas) or whether it's best to let generation be generation and storage be storage? I can think of pros and cons to creating combined systems but there only currently seems to be academic interest in the topic. Thanks for the brilliant video and looking forward to the next one!
Hi, I'm glad you raised these topics, because that is similar to what I am already thinking😊 I plan to move on to other types of energy storage soon after a few more videos on hydrogen (hopefully including a wind power to hydrogen project) and also finally finishing up my wave energy series. I want to make some videos on what kinds of storage are needed for what purposes, how generation, storage and flexible demand all work together (now and in the future with more renewables) and then look at some specific technologies including a thermal energy storage company I visited already plus others. So that is obviously a lot, it will probably take most of 2021 to get through all that, and then I didn't even mention what I want to cover on e-mobility! What do you think? Does that sound like a good program for 2021?
@@EngineeringwithRosie It's good to hear we're on the same page and I'm enjoying coming along for the ride! That is a busy schedule and all sound like interesting topics! As long as you are interested I'm sure they'll be great videos. I'm all for focusing on power generation/storage and how future grids may operate. E-mobility is quite a saturated topic (although I'm sure you'll bring something fresh to it) I would be keen to see more napkin calculations/mythbusting like your waste video as that was a real eye opener! Maybe rough calculations on the future energy mix of different countries comparing land, energy sources, main uses? I really appreciate all the effort you put into this channel and hopefully you continue to grow over the coming year!
The local kommune (Lolland ind Denmark) tried a system in a village, where the hydrogen was fed to the houses, where it could be used as cookinggas or converted to electricity at the house. Lolland produces windenergy more than 5 times what we use.
Loved 1926❤❤❤ Cutting edge tech has never been so old 😂😂😂
I would like a report like this but about PEM electrolyzers, Thanks Rosie
Very informative video! I watch chemistry and renewable energy topics. I became a subscriber.
Another outstanding video Rosie, thanks. As you are already down the Hydrogen rabbit hole, "Plasma Kinetics" might be interesting to research.
Such an Excellent Video!
I would love a deeper explanation as to how they got their numbers for efficiency and if they actually have the wiggle room available that they say they do.
The efficiency of an electrolyser is normally calculated as the energy content of the hydrogen produced (142MJ/kg), divided by the energy spent in producing it. The wriggle room they talk about in the video is because you can increase or decrease the power input (the voltage and current) within certain limits, much like you can throttle up and down a car engine. As a general rule, the lower the power input, the higher the efficiency.
You can check this Wikipedia page to read more about this: en.wikipedia.org/wiki/Electrolysis_of_water#Efficiency
The AC input must be rectified to get DC, and the rectifiers use some power, so that subtracts a few percent.
PEM membrane improvements to increase current flow, anode and cathode can be optimised, with platinum, rhodium, palladium, Tio2, cobalt dioxides, photo catalysts can assist process, as can certain electrolyte catalysts, work is being done with half cell catalysts with some iron/pt. Compounds where partial electrolysis can proceed stepwise more efficiently than direct.
Yes I'm wondering a bit because most numbers I heard were some 30% loss that cannot overcome.
Hi Rosie very nice video. Very inspiring youtube channel also. Congrats on the excellent work.
Thank you rosie and kasper!👍
It is perhaps worth mentioning that the attraction of high pressure electrolysis is that hydrogen comes out at high pressure. Water going in can be raised in pressure without heat loss because water is incompressible. A big plant might expand the oxygen through a turbine to regain energy.
In a conventional power plant you also pump water up to pressure, turn it into a gas and then expand it through a turbine.
How High pressure H2 is generated? Do we send water at that high press or we use compressor??
H2 out should be at no greater pressure than atmosphere when the feedstock (water) is AT atmospheric pressure.
Want to increase the pressure of both gases exiting a reactor? Maintain high pressure IN of the water and have 2 polarized output ports/porous electrodes to collect the (now) pressurized gases.
Got that from a NASA Tech Briefs design when they were exploring manufacturing their own fuel/oxidizer at the cape from sea water. But, again, chlorine was a problem.
Great video. Hydrogen tech is really promising
Rosie, many years ago, I built an Edison hydrogen generator for my truck which I used to increase my gasoline mileage. I went from 16 MPG up to 25. Both the hydrogen and oxygen were added to the incoming carburetor air. This resulted in a very large decrease in my miles per dollar, or reducing my gallons per hour of gas. The problem I ran into however was that the new auto computer systems would enrich the gasoline to meet its computer specifications, negating the huge advantage. (Also increasing heat output on my catalytic converter.) And if I modify my computer to avoid this my car would not pass inspection, because inspection looks at computer settings only, and ignores the actual tailpipe emissions, which was actually significantly improved! I can see the only reason for this being Big Oils concern for their profits! I know, I just asked you to walk into a mine field. But I am a scientist. Truth is all that matters to me. This would significantly reduce greenhouse gasses until we can get totally on a green energy solution. But some people will lose a lot of money. Very powerful people.
Shouldn't have input the O2 consistently - only when a boost in horsepower is needed - hence the overheating and 'computer' enriching the mixture (O2 sensors in the exhaust line) - raising the O2 output causes the O2 sensors to heat hotter - telling the computer the engine is running too 'lean'. (My friendly Meineke dealer's diagnosis - ;-)
Great video Rosie. Could you please make video about airborne wind energy. Thank you 😊 💓
Thank you for this wonderful videos you have 😊it help me with my case study of electrochemical production of hydrogen ❤
This is great Rosie. Brava! I am a postgraduate energy engineering student and, I have got to know that we need hydrogen in CCUS. I would like you to do a video on how to integrate industries that emit CO2 with CCUS and green production. I think we could form a closed-loop system from the integration.
Fascinating, thanks Rosie! To know if H2 is the energy of the future, we must consider all parts of the math of the return on investment (ROI). Meaning is it really better than any other energy sources? 1) where does the electrolysis energy (kWh) comes from? "Coal and all other fossil fuels, plus waste burned for electricity, amounted to 20% of the electricity production. The other 80% of the electricity produced came from renewables: wind power (57%; see wind power in Denmark), biomass and other combustible renewables (20%) and solar power (3%)" source Wikipedia, 2019 Energy in Denmark. It is a larger renewable portion than a lot of countries - kudos to Denmark! However "burned...other combustible" do not qualify for Green Hydrogen. Still a good show. To be clear, they use electrical grid power to produce their H2. 2) Are there hidden costs to that process and delivery to end-users? We must compress H2 at around 10,000 psi to fill a "gas tank" of H2 in a car in order to obtain around 275 miles (434 KM) range. That's inevitable also to power a house. A whiff of it stored at 1 atmosphere won't do much. Natural gas or electricity must be consumed also, to power the H2 compressors, which ads to your price and carbon footprint. Then, in a car, for instance, the most efficient H2 car on the market (operating only in South California) has rather poor performance (over 9 seconds 0-100kmh). Re-conditioning the gasoline/petrol worldwide distribution grid into an H2 grid may very well cost $trillions, and inevitably, bottom consumers like yourself and I, will pay for it in high H2 prices at the pump, or through a spike in our income tax. Yes, these costs are not mentioned but they positively will have to be paid. 3) a practical application of thermodynamics, the second law; Every time you transform, transport, transduce... energy from one form or one location to another, you lose some energy. It's part of entropy. The more vias there are between your initial source of energy and the delivered item in the hands of consumers, then the less effective it is, as you lose some energy every steps of the way. The final analysis is that a Tesla Model S costs US$17.55 for a full 651 km range (only around $6-$8 if you home-charge). Toyota's H2 champion car cost US$65 for 442 km. Hidden costs? As mentioned, we will pay for the huge change in distribution and storage of H2. Tesla has already a fairly good distribution network of charging stations, and although they felt the need to increase their re-charge fees, however it is still much lower than H2 or gasoline. Why? Less vias is cheaper. The sun will be around for another 5 billion years, and nobody has to pay for getting a nice sun tan. Other car manufacturers are moving ahead with building their own charging-grids. It's only a matter of time before they all agree to integrate into one global charging system. Power strips fixed to each road and highways would be great, while the Chinese are working out a photovoltaic coating that adheres to roads to yield more electricity. Now, if the brave Danes will consider all the above parameters and still come out the winner, I'm all in for it and I will gladly post their flag on my wall. The wrong thing to do is to do nothing. Cheers! *I don't work for Tesla. Nobody pays me to say this.
Waiting for breakthrough for 1.48V. want to know what is the efficiency now. Been two years for this video.
thanks a lot ! i like this optimistic stuff ! among all the bad news of war and pollution and nuclear threat maybe this is a silver lining in the clouds.let the winds of change blow ! Serge from France.
Rosie always has a good video with the basics covered, and brings all along who are curious.
My 2sense
When you see "green anything" it requires free electricity from renewable electricity.
That will never happen.
Because the electricity will be needed to decarbonize our houses and our industries, 1st.
2nd, it will be used 1.2:1, not 3:1 input to output, comparing electrical used for electrical needs, vs H2 production.
We have these thingies called batteries, for storage, they win, up to 4 hours of storage a day, because of RTE.
Using overproduction of wind and/or solar means the utilization of the electrolyzer is poor.
Or you wait a 1/2 to a full century, when we have 200% RE.
Or you put in batteries.
Ohh wait a minute...
That's the solution we are comparing to!
Ha!
Storage, up to 10%, allows extinction of 28% to 38% FF burning, when overproduction is 130%, and FF Burn % is 60%.
Once we figure out how to monetize storage properly with the savings of the shared efficiencies across running FF plants, this will be possible.
1st pay for storage capitol costs
2ns, split profits with T&D, and power plants that became more efficient, some % for offline reliability payments.
This new efficiency mode means your run 3 or 4 FF plant at peak efficiency, instead of 5 or 6 FF plants at partial load, just so if one goes off line the others can cover with a quick ramp time to higher output power, compared to a cold start of a FF plant. if enough storage is added, even cold starts can be covered, removing the last two partial throttled FF plants in region.
The Gaia hypothesis, Storage, the FF burn extinction provider. Ron Davison 1-7-2023
Offer valid till no more practical over-production is left to be harvested.
AKA "While (over) supplies last". then the 2.8x drops to 1.8x with storage being more bulk, than balancing.
The crossover back to 1.2:1 also is the 3rd tail of profitable storage add, the last.
At roughly the same % as we will achieve with over-production extinction and capture, is my opac crystal ball prediction.
That's about an extra 10% storage, beyond the 1st 10%.
This may be mind bending amount to think about, at least in terms of batteries, only.
But to put this in perspective, the USA is ~20% hydro, 1 way hydro, that still is a form of storage, but we do not think of it this way.
Because we do not control the filling, per say, I suspect.
Winners sorted best 1st.
1) Lithium (Home/Industry/Utility)
2% to 3%, must have high utilization 2x a day, add 1% on energy/day
2) Lead Acid (home) & Flow (Utility) take us 3% to 10%, (delta 7%, flow can go higher, still. RTE limited, low utilization, Lithium % augmentation in extreme demand/supply unbalances vs using after Lithium is not available. In reality, there will be overlap, based on price arbitrage and RTE hit for each chemistry type.
3) Pumped hydro can be added to existing hydro in at 10% to 20% storage needs. If assuming doubling of upconverting hydro capacity at one way dams to 4%, co-locating and co-using added turbines for one way or pumped hydro operation with valving.
4) One way Hydro, used more effectivly, producing more power per acre-feet of water.
5) 1) & 2) can be operated more efficiently together with a lower C rate per unit storage, even though one is a lower RTE, up to a point, also beyond this point by some multiplier, say 2x as an example, so that, the higher efficiency storage is not exhausted early, allowing the poorer RTE storage to not be hammered with power losses, AKA heat and destruction, AKA bricking cycle non-life...1)&2) allow 3) to be conserved, that allows 4) to be conserved and be true.
Together they arer all called storage.
Add 6) thermal storage,TESS to be complete.
I think the most relevant thing he said is to use electricity as electricity and covert it only if you have too much or have a specific need. I still have a hard time with H2 as a widespread fuel. As a storage medium I think there are better alternatives. Compressed air takes less energy to create and coverts back to electricity easily. You can also extract useful gasses for ancillary sales and if you believe in CO2 sequestration then you can get that too. Certainly better than blue H2.
Agreed, Rosie mentioned this article on her podcast, which ranks uses of (clean) Hydrogen from most likely (industrial processes which already use Hydrogen) to least likely (personal Hydrogen cars). As clean H2 gets better, it can "move up the ladder", but the ladder order will be the order in which it moves
Hi Rosie, great content. Do you have an Idea where I can find this membrane
beautiful explanation thank you
Making hydrogen through electrolysis is very similar to producing chlorine and caustic, except salt water is used. The application is the same too. Electrical energy is used to split molecules which then want to recombine to release that stored energy. Using hydrogen to deliver energy is using it like a battery. So hydrogen has to work better than a battery to really be useful, and battery technology is advancing quickly. Batteries are easy to store while hydrogen requires a thick and heavy metal tank. But hydrogen fuel tanks can probably be refilled a lot faster than batteries get recharged. I see hydrogen vehicles being limited to big heavy things like city buses, semi trucks, or ships. This video discussed using hydrogen to buffer excess electricity that may be produced in the future. I don't see that as superior to just lifting water and letting it drop back down.
To really be efficient at making hydrogen you have to learn a lesson from making chlorine/caustic. It takes an unbelievable amount of electricity for just one plant to make it in quantity - about what an entire smaller sized city uses. Any small improvements in the process result in significant energy savings. One big efficiency improvement was building an electric generation plant next to the chlorine/caustic plant. That allowed the leftover electric generation steam to be sent to the chlorine plant reducing the need to boil its own steam. When the electric plant is not adjacent, the energy in its leftover steam is lost. Likewise, if when you generate hydrogen you just throw away the energy invested in the oxygen, then that significantly raises the cost. Something profitable will have to been done with the leftover oxygen to get value from the energy that has been shoved into it.
The issue of whether the hydrogen was made from "green" or non-green electricity is diversionary at this stage.
Great comment, you've raised lots of interesting points.
I agree on the limitations of hydrogen, you can check out this other video I made on hydrogen and I am going to make more on the topic this year so I hope you will check back later to see them!
ua-cam.com/video/ge4ux1Y1ric/v-deo.html
Admirable presentation
Very interesting. Thumbs up. Keep making videos!
Hi Rosie, Very nice video! There are two points in the video that don't match up regarding efficiency in my mind. First is at 9:00 where they are using 430kW to make 4kg per hour, so that's 420kWh of electrical energy to produce 4kg of hydrogen or 105kWh/kg which contains 33.33kWh of energy per kg. 33.33/105 = 31.7% efficient. But in the literature, at 12:04 it says 76.5% and that they can produce 1kg of hydrogen with only 51.44kWh, not 105. Is he doing something useful with the heat generated? or was he just guessing wrong at 9:00? Also if you take the numbers in the brochure, 51.44kWh per kg of hydrogen and there's 33.33 kWh of energy in each kg of hydrogen, then the efficiency would be 33.33/51.44 = 64.8% or am I missing something. Thanks.
exactly what i am working on now, please do you have reference materials, maybe i can further support my research..thanks man
@@rexossai1441 Sorry, I was just asking questions about material in the video. Besides the amount of energy contained in hydrogen, the rest is just basic math and keeping the units the same. Just recently I read something about 4 major electrolizers starting production and in each case, they either give the output in kg/hr or kW in. None of them give both numbers so that you could divide the energy in vs energy out to simply arrive at the efficiency to verify their claims. Clearly it's been something the H2 industry has been shying away from. If Rosie saw the comment, I could understand not responding since pointing out flaws in the math doesn't do well for getting invited back and continuing to make UA-cam content.
For example at 9:00 there's the equation 430kW = 4kg per hr. So 430kW for an hour is 430kWh = 4kg. 4 kg contains 4 kg x 33.3 kWh/kg = 133.2 kWh of energy. So 430 in to get 133 out. Doesn't sound like 70 something percent efficient to me. But at the same time, he says "aaah, about 4" That doesn't sound like some precise measurement either. But he'd need to output 430* 0.76 = 327 kWh worth or 327/33.3 = 9.8kg and I doubt someone that's working with it all day long would be off by more than double. I too am an engineer and follow the basic grade school process of checking your math other ways to insure your answer makes sense.
@@scottkolaya2110 in my report i have 3.47kwh to 0.063kg hydrogen, at a high heating value...and be sure his not referring to FC here..note......but still the economics with no government tarriffs leaves nothing
@@rexossai1441 I've also seen numbers like that quoted. So 3.47/0.063kg is 55kWh/kg. Which 55kWh in to make 33.3kWh of energy is 33.3/55 = 61%. 61% sounds more reasonable. But I'm also suspicious that it doesn't include all the energy costs in that number. Is that for 700 bar pressurized hydrogen or atmospheric pressure H2? I know it's not for liquified H2. That tacks on another 12kWh/kg to bring it down below −253°C (−423°F). I've heard that in much larger scale, it's down to 8kWh/kg. But, for example in a large electrolyzer plant, there's much more equipment to make it run, not just the electrolyzer itself. I would love to see the plant's electric meter for the month and it's output in kg for the month to get a real efficiency number. I suspect it's closer to 55% once you include pumps, HVAC, lightning, etc. Just like I'd like to see a gasoline refinement plant's electric bill to see how much electric is used per gallon of product.
Super project, I'm just preparing a video with hydrogen produced by solar energy, green energy, green hydrogen. Good luck
A smaller project but I did some tests and it works
Cool, sounds interesting I will check it out 😊
Great video!
How about a future short video of a co-generation style electrolyzer system ?
As touched briefly on in this video .. the energy needed to split 2(H2O) -> 2(H2) + 2(O2) comes partially from electricity and partially from heat .. I think the electricity side of that frequently gets a disproportional amount of attention .. higher amounts of heat reduce the amount of electrical input needed .. That continues all the way out until eventually the splitting of water can be zero-electrical input and 100% heat energy input .. given the enormous amounts of 'waste heat' out there , absorbing that 'waste heat' as a partner with another process would seem to be a synergy style system , and co-generate instead of solo-generate.
Maybe not only further improve the efficiency of the energy you have to pay for compared to the amount of hydrogen you get out , but also by taking away that 'waste heat' to do so from that other processes you might further improve the efficiency of that other processes as well.
Without a partner processes , it could still be done with a co-generation solar style system .. Photovoltaic collectors are actually better at (do more of it) converting solar light energy input into heat energy ~80% than directly into electrical energy ~20% .. and that heat lowers the electrical conversion efficiency for the PV module (soo it's waste heat for the PV).
Or at the extreme end of the solar heat water splitting to hydrogen end of the spectrum would be to modify a large solar heat collector system like the molten salt facilities , to use all that enormous amounts of concentrated solar heat energy to drive a water splitting system.
The non electrical heat method sounds ideal Ian, can you point me to any literature to show how it's done? Thanks
@@agritech802 The scientific term for using only electricity is electrolysis .. decomposition of a chemical compound by electrical energy .. the term for using only heat is thermolysis .. decomposition of a chemical compound by heat energy .. there are even some microbial fuel cells that have shown that microbes can also use the chemical energy of the materials they biologically decompose in order to contribute some of the decomposition energy needed for secondary reaction like hydrogen production .. in the real world they do not have to be mutually exclusive , you just need a net overall amount of energy put in to break it apart .. using 'waste' .. be it waste heat , or biological waste , from some other processes (that needed to be done anyway) , is my personal preferred energy source for such thermolysis.
There are lots of pubic sources about thermolysis , here are a few examples (in no particular order) :
www.energy.gov/eere/fuelcells/hydrogen-production-thermochemical-water-splitting
www.osti.gov/biblio/7335245-thermolysis-water-production-hydrogen-energy-vector-compared-electrolysis-which-has-higher-efficiency
Discussion of the biological method to contribute energy and reduce the needed input from other energy sources is one of the topics discussed in the introductory book .. Microbial Fuel Cells by Brude Logan
smile.amazon.com/dp/0470239484?psc=1&ref=ppx_yo2ov_dt_b_product_details
@@ianpgeorge that's great, thanks for that, I'll check them out
Very informative video Rosie! Subscribing.
Excellent video. Many thanks.
Thank you for sharing knowledge
Really good informative video. Thanks!
I'd really like to see a small scale device to produce hydrogen and then convert it to ammonia. If it was sized to match up with wind turbines, and the capex was small enough, it would provide a means to make use of distributed wind power. Ammonia is easier to transport than hydrogen, and it seems like it would be practical to transport it from remote areas to urban centers.
Ok...... This was the video really,I like it. Really...I am interested to produce and store hydrogen gas by Electrolysis process is one of the best method to produce hydrogen gas. Ma'am will you please explain production of hydrogen with different types of methods in another video?
Wonderful source, need more info for commercial
Bloom Energy just released a high efficiency steam Solid Oxide Electrolyser that gets pretty high efficiency. If steam is supplied via nuclear or geothermal, it takes only 39kWh to make a kg of H2, which will produce ~33kWh of power, so you are only losing like 6 kWh in the conversion. It would be fantastic if you did a video with Bloom!
What impact does adding more light and what frequency of light increases hydrogen production. Does adding more light work with urea hydrolysis.
thanks for the video.
automobile enthusiasts I've been using electrolysis to increase the burn efficiency of gasoline for a couple of decades if not longer.
Some of these enthusiast have even installed systems on their car to power internal combustion engines completely on hydrogen.
Are they looking into smaller units for automobiles?
Loved this video! Thanks, Rosie! Leads me to believe this is an ancient technology that was lost until recently. Does anyone else think this is what the pyramids and mega structures around the world could have been used for?
Love the way you break down the processes and your questions from an engineer's perspective. Would love to see you explore whether megalithic buildings would have housed this and other chemical processes.
Best,
-CJ
Three related questions Rosie, how efficient are hydrogen fuel cells now & are they improving? If they are how long before these efficiencies come into being?
Hi Rosie, great video here! Can you also cover the "wind vortex"? Thanks
The hydrogen economy seemed to show such promise - is its lack of progress down to the fact that developing other green energy sources was cheaper and likely to come online earlier? Also, is there any chance of you looking into how the use of sunlight to produce hydrogen is going? Also the various types of fuel cell and hydrogen storage systems?
Good point Mike, ammonia might have better potential as both a fuel and fertiliser source if an efficient system of production can be found.
Great Rosie, How to calculate the capacity of an electrolyser for a particular industry. Factors to be calculated.
Do you store the H2 as a liquid or gas and at what pressure ?
Very cool. How often do the Cathode, Anode and Diaphragm need replacing?
You noticed how the 'stack' is put together so it lasts a long time. But it depends on how clean the water is so minerals don't build up. Clean water gives many years.
Im extremely curious on what this membrane or diaphragm is made from? He waves it around so casually which makes me guess it’s not nafion or such. I’m asking for a uni project and since getting my hands on nafion is off the table due to cost any working substitute is very welcome.
8:59 It has to be 4kg per hour for 200KW, not 430 (if efficiency is really 70%)
As 50 KWh x 0.7 = 35KWh - the amount of energy in 1 kg H2
Thank you for that Rosie, very clear.
If a significant part of their inefficiency is AC DC conversion, any reason they can't pair them with DC producing renewables to sidestep the issue?
Hi Rosie, thanks for another great video, can you do one on ammonia if you get a chance? I think ammonia production would be another great way of utilizing excess renewable energy and it can be used as a fertiliser or as a substitute for fossil fuels. It would have many many advantages of it can be made cost effectively. It has particular significance at the moment with the war in Ukraine and the cost and availability of gas and fertiliser
You cannot afford to make ammonia by using hydrogen from electrolysis, its way too expensive and would make fertilizers too costly to use.;
The heat electrolysis 🔥 produces could it be used for something??
Talk about diminishing returns, like the man said 'if you have electricity use it. As a question, can he show that this will be better than the corn to ethanol conversion; BTU to BTU. I know cellulose processing has recently improved efficiencies. I get ROI, windmills cost money to build and dispose of properly. If that's what you are using to power, heat loss, material costs as you both pointed out. Subsidies always weigh in in my book too.
can you use Conventional source of electricity to start producing Hydrogen then same hydrogen produced may be used to operated electrolyser to produce more Hydrogen and oxygen preferably in any Hospital where energy and oxygen both required for regular use? please clarify
Hi Rosie,
Can you please make a simple explanation on (onshore/offshore wind turbine to Hydrogen storage usage for customers end or the heating in households) ??
I would very much love to learn that
Thank you
Researchers at Penn State recently combined water purification technology into a new proofofconcept
design for a seawater electrolyzer, which employs an electric current to separate the
oxygen and hydrogen present in water molecules.
The new technique meant for “seawater splitting” could render it easier to convert solar
and wind energy into a portable and storable fuel, according to Bruce Logan, Kappe
Professor of Environmental Engineering, and Evan Pugh, University Professor.
Hydrogen is a great fuel, but you have to make it. The only sustainable
way to do that is to use renewable energy and produce it from water. You
also need to use water that people do not want to use for other things,
and that would be seawater. So, the holy grail of producing hydrogen
would be to combine the seawater and the wind and solar energy found in
coastal and offshore environments.
Interesting, thanks for commenting 😀
Ok so what it looks like is that what we have here is a 'dry cell HHO' generator - this makes what is known as 'browns gas' this is a mixture of both Hydrogen and Oxygen, what is not shown is how they separate the two gasses. You will notice a blur @7:40 and I suspect that is the separation process but I don't know how they are doing this. I bet this looks familiar ua-cam.com/video/LXMJ5bi6Fog/v-deo.html
Great Video 👍 Useful 👍 love you ❤️
What about creating ammonia as a vehicle for transporting hydrogen, then converting the ammonia to hydrogen closer to its source of use? Is ammonia not easier to make and transport than hydrogen itself?
What kind of voltage is fed into a typical system? Some sort of inverter is needed to produce 1.48 VDC I should think. Do they start with 3 phase 440 VAC?
I like your videos and recently subscribed to your channel.
Can you do a video on Green Hydrogen/ Fuel cells as an alternate fuel for Aviation please?
I don't really understand why it is not commercially viable yet especially considering the Gravimetric Density of H2 is much higher than the best batteries available in today's market.
If the cost of green hydrogen can be lowered to where it can compete with biofuels then hydrogen fuel will be used for aviation. It's all about money and the "green premium".
@@acmefixer1 so why not use Grey or Blue H2 till Green achieve the cost parity? Just like Electric cars it is greener to use Fossil fuel Electricity driven Electric cars than Internal Combustion Cars?
i want to know the calculation behind the efficiency by thermodynamics... how to calculate mathematically?
Thank you.
Hello, interesting topic. But we are in the presence of an installation that the private individual could never have installed at his home. Perhaps a presentation would be needed that would show that electrolysis and the fuel cell are possible on a smaller scale like that of a simple individual dwelling. This other level of detail will make it possible to better understand the possibilities offered for the individual, and also the cost of such an installation to store the green hydrogen produced from photovoltaic panels, and then to produce electricity during less sunny periods. However, solutions do exist for homes, we should perhaps try to promote them to start freeing oneself from fossil energy at the level of individuals. The AEM is perhaps for the moment the one that offers a lower cost thanks to less noble matérials in its construction. The prices are starting to drop. A bit like the price of LifePo4 batteries, which drop quite well, and allow battery storage to complement hydrogen storage. For good efficiency, consider producing hydrogen from renewable energy (sun, wind, hydraulic). In any case, avoid fossil fuels to obtain the energy necessary for the separation of Hydrogen, Oxygen. It is not necessary either to seek profitability with regard to the installations in the particular houses. The prices are high. We must seek to be able to do without fossil fuels. while thinking that profitability will never be there. Profitability will undoubtedly be present for the very large companies which will build power stations of this type and finally return to an economic model almost equivalent to the current model of fossil fuels. Large companies are currently seizing the market by using models of the power to gas type, ... Thus, they prevent as much as possible a possibility of autonomy for individual houses which could however easily have a hydrogen system installed in each of them.
If this develops too much for single-family homes, they could cause a significant loss for these large companies who could no longer sell the hydrogen they produce at prices that will be almost identical to that of current fossil fuels. These large companies will in any case seek to maintain their profits at a level almost identical to what they do with current fossil fuels. Even if the new technology costs less, if not much less. And yet this has been the case for the past 10 years. The price of batteries goes down, the price of fuel cells and hydrolysers goes down.
However, currently 100% electric cars are still very expensive, while they are technically and mechanically easier to manufacture, and have fewer precision mechanical parts than combustion or hybrid cars, and they have less usury ... if the goal is to leave the fossil, we must try to pull up the smaller companies that could offer us decentralized production for us individuals ... because as we often say, small streams make the big rivers ...
Is it safe to use in your aqutic fish tank? Would it be beneficial for fish and aquatic plants?
Would it be possible to use the excess heat using a heat exchanger?
"How much does it cost?"
"Something something, capex."
-Translation: it costs a lot more than is worth doing on any scale at the moment.
But that will get ground down into ...balh blah "economies of scale" blah" government start up involvement" ...
Hi Rosie, a German company HPS,based in Berlin produces a compact green hydrogen, off grid power solution including storage for home owners using their Picea system. It is still quite expensive but gaining new users continuously. With your engineering knowledge you might uncover more producers of similar small scale systems Will these become more widespread and above all affordable to more home owners?
I didn't know about Picea, thanks for pointing it out to me. I have seen some other home hydrogen storage (e.g. Lava), but I haven't looked into it in depth yet, I need to add that to my list!
Rosie,
Thanks for the video
Important topic!
I think so too 😀
if you use a resonant frequency of the water with the voltage, I'm thinking you would solve the energy requirements to split the water with less power...
If you want to deal with electrical energy availability variation, you might want to turn some industrial facilities on/off? This is suitable for turning off on for that?
I suppose you either have to pair it with hydrogen storage, or pair it with another industrial process that use hydrogen you can turn on/off in sync? Do any exist? Like suppose you can ask whether you can turn it on/off based on electrical supply/demand for more processes than this.
I'm thinking of hydrogen reduction of iron oxides, but it may well be a poor candidate.. Though it's a "just" hot chamber with good hydrogen iron/oxides mixing and a way to get rid of the water produced..
May be you can help us to explore various Hydrogen Electrolyzers available, their advantages and disadvantages in your future videos
oooo. it's pretty interesting to watch a topic when it's actually your major. Hahahah
Very good.
Recently US DOE sponsored research announced employing a catalyst for H2 efficient release from liquid organic hydrogen carrier (LOHC) at ambient temperature and pressure (cryogenic-pressure unnecessary); LOHC meets the critical need to store and transport H2 energy. Retooling the existing petroleum pipeline network (including maritime, rail and truck tankers) for a liquid H2 carrier makes H2 distribution pacify oil companies but makes available sector-wide, technology-wide and ubiquitous for zero-carbon hydrogen innovations for fuel cell electric, HFCV and other H2 innovations.
Thanks for the informative video and I wanted to let you know that Tony Seba predicted that the LCOE in an article in the San Francisco examiner in 2013 would fall to about where it is now. Rethink X is where you can find him on UA-cam
Very educational!
Great video Rosie, subscribed
A question: When we leave the plant - I expect carrying, managing the hydrogen is pretty difficult. I heard from stainlees steel tanks that embrittle seriously. Hydrogen is so small - it leaks through most materials and harms them.
Can you try to find statements about?
You can also use composite tanks. I'd assume they're less susceptible to embrittlement (though leakage is still going to happen).
There is one thing that perplexes me about all that.
If the current efficiency stated is indeed 76%, i.e. you get 76% of the electricity input back when you combine the hydrogen with oxygen again then what is the world waiting for? This is THE solution to get into green energy. The greatest problem of green energy is not the production of green energy but the storage to provide energy when the green energy sources are down for several hours (no wind for wind farms, the sun does not shine for solar farms etc.). What does it matter what is costs as long as we can save the planet with it? Even if it was 3 times as expensive as coal power stations, so what?
The idea is really very simple: Use green electricity at times of access to run the electrolysers and use the reverse reaction to run a power station to top up supply during times of high demand.
Even if it was somewhat less efficient, it is still THE solution.
No, you got the definition of efficiency wrong!
It was 76% HHV. This means, from 100 kWh energy input, you get hydrogen with 76 kWh higher heating value (HHV), which would be 64 kWh "normal" lower heating value (LHV).
If you feed an efficient fuel cell with it, you could get up to 38 kWh electricity back. Plus heat. On average rather less.
Without counting in energy demand of compression, liquefaction,...
By the way: 64 kWh LHV hydrogen is 1.92 kg of hydrogen.
The other way round: For 1 kg of hydrogen, they need 52 kWh energy input.
If you'd use up this hydrogen (from the 100 kWh energy input) for heating, you could get up to 64 kWh heat (theoretically) with a normal heating system (water vapor leaves the house) and up to 76 kWh heat (theoretically) with a condensing boiler.