this post was submitted on 02 Oct 2024
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If only there were some way to take energy made from sunshine and store it in some form for later. Like in a battery. Or as heat. Or in a flywheel. Or just use the energy for something we'd really like to do as cheaply as possible. Like sequester CO2. Or desalinate water. Or run industries that would otherwise use natural gas.
This is what gets me. Relative efficiency of stuff is pretty much nullified when the energy used is free. Total power use still matters because it will determine the total size of the array of solar panels to generate the power needed.
But this is near and dear to my heart. I like hydrogen as energy storage. If you burn it, you get water. Natural gas is just CH4, so the output of burning it is 1CO2 + 2H2O. But a lot of natural gas stuff can also use hydrogen with little modification, so we don't have to upend entire industries to adapt. Machines can be updated to use the new fuel type with little expense and we're not throwing out entire production lines to replace them with ones based on electricity.
Why hydrogen? Simple, hydrolysis. Using power generated for free from the sun, you can split water into its base components. Hydrogen and oxygen. With some fancy knowledge, you can capture pretty much all of the hydrogen and none of the oxygen, and store it for use.
It's inefficient compared to some other technologies, in that it takes a lot of power compared to how much hydrogen/oxygen you get, but bluntly, if it's coming from solar, who cares? Not like we're paying for the power anyways.
I keep thinking about this in the form of industry. Say a factory uses natural gas in boilers to make something hot. Whatever the material, whatever the reason, that's what they're doing. With little modification, the system can be adapted to hydrogen, and the company can build a hydrogen hydrolysis reactor on site using either city water, rain water, lake or river water.... Even an underground well. The reactor runs all day and generates hydrogen, stored in a large, high pressure tank, also on site, then pipelines run it to the machines, boilers, whatever, to run the production lines. It's free to run, and only requires a single capital investment.
Hydrogen, also, can be stored indefinitely and not "lose charge" unlike other, battery-based storage systems (or heat, or flywheels). So hydrogen is ideal for long term energy storage. Fuel cells are still the most efficient way to convert hydrogen to electricity, and yeah, you lose a lot of potential energy in the electrolysis/fuel cell conversions, but the energy input is free in the first place, so who cares?
I'm not saying we should go all in on hydrogen. I'm just saying that it's worth continuing to develop the technology for it. Batteries, capacitors, storage via heat or flywheels, they all have their place in the energy future. At least until fusion makes them all obsolete (once we find a way to make that self fueling or use materials that are not extremely limited. IMO, we're making good progress but we're decades, if not centuries away from something practical, given our currently known planetary resources).
And yes, battery EVs are a good thing. Hydrogen electric vehicles... Let's just say "too soon", and leave it at that. Batteries for daily charge/discharge for home use, absolutely. Larger scale heat/flywheel storage, absolutely. But longer term than days to months, hydrogen may be the better option. It's certainly a good option for industry that currently relies almost exclusively on natural gas.
I agree that H2 can have certain applications as a bridge technology in some industries, but there is a very important parameter missing in your premise.
Even if solar power seems "free" at first glance it really isn't. It needs infrastructure, e.g. Photovoltaic Panels and lots of it. So just having H2 instead of a battery for an application means, it needs thrice the PV capacity or even more and with it the grid capacity. Now add to that, we aren't just talking about replacing electricity from fossil fuel plants by PV, but about primary energy as a whole, which makes the endeavor even more massive. Also H2 will not magically become much more energetically efficient in its production, transport, storage and usage, because there are physical limits. (Maybe with bacteria for production) The tech could and should get better concerning longevity of the electrodes for example. Also as the smallest molecule out there, storage will never be completely without losses. And long term storage requires even more energy and/or material.
All this is to say, that efficiency is still paramount to future energy supply, since also the material is limited or just simply because of costs of infrastructure and its implications on the biosphere. Therefore such inefficient energy carriers as H2 or what people call "e-fuels" should be used only where the enormous power and/or energy density is critical. H2 cars should therefore never be a thing. H2 or e-fuel planes, construction machines or tractors on the other hand could be more appropriate uses.
There's certainly costs involved with solar. Even the act of cleaning the panels is going to increase maintenance costs. More panels to clean, more cost. More space needed for the panels, more cost. It might not be much per panel, but it's still a cost. The wear of the panels is more cost, they only last so long before they degrade, and replacements are not free, so if the panels degrade without doing a lot of "work" (aka the outcome of having them) vs the cost of installing and maintaining them, was it worth it? These are all economic questions that also need to be considered.
Yes, it's not free, but it's the closest thing to "free" power we have. Literally pennies for gigawatt hours of output. If that power isn't consumed, then it wasn't useful to produce. Whether that generated power goes into batteries, homes, or hydrogen production, that's going to be something we have to solve for.
I see a hydrogen reactor + fuel cell "generator" as a secondary storage system to batteries. When production is unusually high, push the power into hydrogen. It's not nearly as efficient, but it can be stored for much longer without losing any. It can be stored far more densely than what can be accomplished by batteries. If the batteries are full and your PV plant is still pouring out unused watts, rather then let that energy go to waste, pushing it into hydrogen storage is a better option. If you don't need it for 6 months, a year, two years? No big deal. When production is low and your batteries are almost out, just fire up the fuel cell and recharge from the excess energy you couldn't put in the batteries. It's inefficient, yes, but bluntly, it's better than letting any of the excess production go to waste.
There's other competing technologies for the same purpose. I see hydrogen as the second stage of storage. It's not as good as the first stage, but it's better than turning to fossil fuels to generate power.
I don't know if that's the right answer to the problem. I don't know if it's even a good idea. All I know is that it is possible. IMO, it's not a bad idea.
I've said it before and I'll say it again: if I'm saying anything at all here, it's that we need to keep researching everything. I don't want anyone to drop research on another technology to dedicate to hydrogen, just as I wouldn't want anyone to drop hydrogen to research something else. We need to keep looking into this stuff.
There's no single solution to our energy needs, as of right now. I don't see one emerging in our lifetimes. The only goal I want to see pursued, if not obtained, is net zero for climate change. Stop the destruction of the environment, especially, but not limited to, our energy needs. Whatever gets us there, whether hydrogen, nuclear, fusion, solid state, flywheel, heat storage, thermoelectric, geothermal, hydroelectric, or whatever... I'm game. I feel like hydrogen still has a lot of discoveries that can be made, and I really don't want to see it abandoned because of a lack of popularity in the consumer space. It's there, it's green, it's got potential, let's keep trying to get it to a place where it can be beneficial, just like with everything else in that market segment.
It is not only economic cost though. As I've mentioned, materials are also limited (on the same level as: There isn't enough copper to wire all motors needed to replace all cars today with EVs). And it needs alot of surface area compared to the concentrated power plants of the past, which means an even bigger impact on the biosphere (especially if not done on rooftops in cities but in mountain ranges or fields, etc.). Don't get me wrong; solar energy, if done right, is the only source that doesn't interfere with natural cycles and does not increase entropy of the planet (which makes it actually sustainable). Using it inefficiently though, means inefficient use of other resources which are limited. (Not only economic. But on that note: Public infrastructure is always built with costs in mind, because we shouldn't waste tax money, so we can do a better and more comprehensive job with what we have.)
So if there is a more efficient way to store energy for long periods, then it should take precedence over a very inefficient one. This will get complex since it is very much dependent on the local conditions such as sunshine, water sources and precipitation, landscape, temperatures, grid infrastructure and much more. As an engineer, I would throw in though, that if you need this secondary storage, that is not much cheaper, doesn't have some very essential advantage, or doesn't mitigate some specific risk, but is much more inefficient over your primary storage, then the system's design is... sub-optimal to put it mildly.
For the argument of exploring everything: We simply can't. More precisely we could, but it would need much more time, money and resources to arrive at the goal. And since climate catastrophe is already upon us, we don't have that time and need to prioritize. Therefore a technology that has a physical, not human-made, efficiency limit loses priority as a main solution. That doesn't mean, that H2 should not be looked into (for specific purposes, where it is essential or the reuse of existing infrastructure is the better option), but that we have to prioritize different avenues, with which we can take faster strides towards true carbon neutrality.
P.S. it doesn't help, that today's H2 is almost exclusively derived from natural gas.
H2 from natural gas is more efficient, but obviously creates pollution. Because of the relative efficiency and the prevalence of natural gas in society, most companies have gone to natural gas conversion to hydrogen, as it's easier to implement, not because it's greener.
To touch on it, when I'm discussing economics, I'm talking about the discipline of economics, not specifically the economy. The money economy is only concerned with the dollars and cents of everything, economics as a discipline, considers all factors, both in and out, and the adverse effects of everything, both financial and sometimes not financial (since nonfinancial effects can affect the future financial viability of a system).
I'll be clear, storage isn't the debate on hydrogen being inefficient. Hydrogen storage is more efficient than most other storage systems. The materials are minimal, a pressure tank with the appropriate seals and safeguards, and the tank can output 100% of the hydrogen that goes into it. There's no concern with cycle life, as the system can cycle infinitely as long as the structure of the container isn't compromised. The waste produced when a storage vessel is no longer suitable, is essentially metals that can be fully recycled or otherwise reconstituted into other items without any degradation in the quality of those items, with few exceptions.
The discussion is entirely around how hydrogen is created, and how it is converted back to whatever energy format that is desirable, such as electricity. Coming from electricity, electrolysis is about 70-82% efficient, with 1kg of hydrogen, which has a specific energy density of 143 MJ/kg needing about 50-55 kWh of electricity to create. The most inefficient part of the system is conversation back from hydrogen to electricity, where internal combustion style generators are common (basically a slightly modified natural gas generator), but less efficient than fuel cells. Fuel cells generally have 40-60% efficiency.
Batteries on the other hand have much higher efficiency, but never 100%. Since they're generally not self regulating, systems for battery management are required. Charge controllers and voltage conversion (or inverters) reduce efficiency further, but generally battery systems are considered to be better than 90% efficient. The downside with battery systems is the relatively short life of the battery and the large amount of waste produced, in comparison with something like hydrogen.
Hydrogen can achieve much higher energy density and the container weighs next to nothing when empty, while batteries weigh approximately the same whether charged or not.
My main argument for hydrogen surrounds the fact that we're pretty close. 80% efficiency in hydrolysis and 60% on fuel cells, with storage being significantly cheaper on materials and significantly better with cycles, with much less to recycle when the system is replaced or otherwise decommissioned. You can pack a lot more energy in the same volume of space using hydrogen compared to batteries because it can be significantly pressurized to several atmospheres.
There are benefits here that batteries simply cannot match. If we can get the fuel cells and electrolysis to a level that's comparable to batteries with efficiency, then hydrogen would really become the better option.
With over 8.2 billion people on the planet, we certainly can research all of these options at the same time. Only a very small fraction is even doing the work right now. That number can increase a lot, but we choose to pursue what is financially profitable rather than purely looking towards scientific discovery. Capitalism at work.
If companies can't sell it, they don't care. So it doesn't get done. We should do it anyways because there's potential here.
There's two problems with your last post which have to do with physics.
I'm not disputing that capitalism has it's thumb on the scale; as you've written, the synergy to use H2 derived from natural gas is one effect, but it doesn't stop them from advertising it as green. The physical limits though, one cannot argue with. Their effects would mean a lot more infrastructure that is necessary, with it more materials, which are limited too. Even if possible, we have limited construction capacity, which means that it would take us longer to reach the goal, when time is of the essence. Which leads me to the same conclusion, that where the advantages like power density isn't absolutely necessary or other solutions are not available, use a better solution.
When speaking to the overall system, there are always inefficiencies with all forms due to the conservation of energy laws.
Similar arguments can be made regarding batteries, as resistance in the wires that connect the cells in a pack together waste power as heat. While overall this may be minimal, the physics provide hard limits here. Unless a superconducting material is made commercially viable without needing to be super cooled, these limits will always be nontrivial.
My entire point is, battery tech has reached a high level of development and there is significantly more we're trying to achieve with the technology (whether solid state or otherwise), meanwhile, I would argue that hydrogen hasn't even reached the same level of development as battery technology, yet everyone seems to think it's a dead end.
It's hard to argue with the energy density per kg of hydrogen as a material. It's possibly one of the highest specific potentials of existing technology. What we should be doing is trying to create power from that with as few losses as possible. Fuel cell technology was, in my mind, the first real push in that direction, when it didn't immediately pay off, we gave up. Meanwhile, alkaline and cadmium based batteries were much worse, but we used them, and continued using them for decades before lithium based batteries became more commercially viable.
I see battery research as looking for the last, most efficient type of battery, while hydrogen isn't even half way through the possible research we could do on it. Forgetting hydrogen, while it's in the infancy of the research, for batteries that are very nearly as efficient as physics allows for, to me, is doing ourselves a disservice as a society.
I have no idea what further research into hydrogen will yield. Maybe you're right and it's going to go nowhere, maybe not. We don't know unless we keep trying, same with batteries, same with kinetic storage (flywheel/gravity systems), same with thermal storage..... There's just a lot of material science we can experiment with that wasn't really something that was possible before now.
I still think it's worthwhile, clearly you disagree. I appreciate the discussion either way.
Have a good day.