The relevant applications for hydrogen are ones where efficiency doesn't much matter (long term storage, rare event grid backup). What matters is minimizing capital cost, which probably means using combustion turbines, not fuel cells.
The inefficiency of hydrogen doesn't matter as much for the use cases hydrogen would be good for: long term storage, and rare event backup (like, no wind over Europe for two weeks). There are few charge/discharge cycles for these use cases, so low capital cost is far more important than round trip efficiency.
I agree that hydrogen efficiency doesn't matter here, but the capital expenditure to build a giant electrolyzer with 5% utilization doesn't really make sense. The cost of the electrolyzer is the things that needs to greatly fall if hydrogen is going to be used for long-term storage.
Efficiency is quite irrelevant to this subject when the cost of energy is nearly zero. Hydrogen will win out simply because it is cheaper and more sustainable than batteries.
Hydrogen may be cheaper as energy storage for meeting peak load on a mostly-renewable electrical grid. In the short term (20 years) the loss of thermodynamic efficiency isn't much compared to the ability to re-use existing steam turbines from natural gas plants. Water and carbon fiber is much more widely available than the precursors to batteries and so the working medium is more accessible world-wide.
If there's a place for hydrogen in the electrical grid then there will be cheap hydrogen available for other potential uses and the market will likely find some niches. Long-haul transport is a big one; instead of electrifying all freight rails in a country use locomotives with hydrogen fuel cells.
I'm not particularly knowledgeable, but my impression is that hydrogen might work for specific applications, but we don't have a very efficient of generating it. It still takes substantially more energy than if we just store the energy in batteries.
Elektrolysis isn't very efficient, neither are fuel cells, when you compare it to batteries. On top of that you have the energy usage for transporting and most of all compressing the hydrogen for storage.
If there is an application for hydrogen, i'd say the container ships are it. The fuel cell gives great efficiency and hydrogen storage has higher kwh/kg than batteries.
Hydrogen is useful as a fuel for things that demand high energy density relative to mass. Like air travel.
But its use for energy storage is much more limited. Actually producing , storing, and converting the hydrogen back into electricity is much more expensive than just producing the electricity when it's in demand.
The big advantage afaict is that storing hydrogen for a long time inevitably leads to losses so you can't for instance do seasonal offset with it, and using hydrogen at grid scale for combustion is tricky whereas using metal as a fuel should be very scalable. The true test will be the economics.
I think this was posted on HN a while back, can't find it, but the energy losses from production, to storage, through transport and delivery are much greater for hydrogen compared to electricity delivered on the grid and stored in lithium batteries. I think that, overall, there are very few applications where hydrogen makes sense. Even in places where the much greater energy density of hydrogen vs. lithium batteries matters a lot (e.g. aircraft), hydrogen is still not a great choice, and seems to me it would be better to just put research into making carbon-based fuels from renewable energy sources.
Hydrogen makes a great way to store excess energy produced by wind and/or solar farms too.
Efficiency isn't even particularly important - in many cases farms can produce too much power for grids to absorb so you just convert it to hydrogen and use in those rare times you don't have solar or wind power for longer than batteries can absorb.
I’ve been wondering also why fuel cells aren’t used. Hydrogen is less energy dense than fossil fuels in terms of energy per unit of volume, but much more dense in terms of weight (almost 3) and far far more than batteries, which matters more in aviation.
Someone under shadow ban mentioned the inefficiency of electrolysis. Which is also around 60% at best.
That is an important consideration, but on a national level it may still be useful as redundant capacity. If your hydrogen tanks are fill up over months when production is vastly above demand, and only used in very rare situations then it might still be viable. At that point it's more a question of economics then thermodynamics.
However, the standby generators which use this hydrogen are a more direct comparison in cost and efficiency terms.
It's true that high efficiency catalytic electrolysis requires expensive materials. But at significantly lower efficiencies you can just do the same thing we all did with a battery in grade school. That's not quite free to build out, but it's close. And relying on low-efficiency energy storage to fill the gaps in production is still better than firing up a gas plant to supply the power.
It seems not unlikely to me that a lot of wind and solar plants might see building out a local hydrogen electrolyzer and generator (or just sell the hydrogen) as a useful choice.
But yes: there's no silver bullet, and there are a lot of very reasonable competitors in the energy storage market.
This still misses the primary reason why hydrogen won’t ever be useful, where lithium-ion batteries can do the job. Hydrogen is just too energy inefficient from an end-to-end efficiency perspective.
Lithium-ion achieves a 80%+ efficiency from energy input to usage via an AC motor, or more if DC is usable. Hydrogen fuel cells only achieve 40-60% efficiency, and that’s just one step (converting it back from storage to electric energy, not even the motor itself). No matter how much is being invested, this can’t just be wished away and effects how expensive something is per kWh.
On top of that, there’s a massive Li-ion R&D and production train already under way that will be hard if not impossible to catch up with.
In short, right now it looks like this will only be useful for a few edge cases that battery electric can’t feasibly support.
Fuel cells are low efficiency (<60%) and expensive so they are a poor fit for grid energy storage. One option is to just burn hydrogen in traditional gas turbines which can also have 60% efficiency ed: (62.22%), but are much cheaper to build.
PS: This also simplifies the problem to: Can you make and store hydrogen for a lower cost than natural gas.
Hydrogen fuel cells are not especially efficient, and are quite expensive. Efficient electrolysis is also expensive. Hydrogen storage is quite expensive. And, mitigating explosion risks around hydrogen is complicated. So, there are sound reasons to prefer other non-problematic storage.
If panels get cheap enough, overprovisioning to account for even a large round-trip loss may become a thing. Then, the cost of the storage and conversion equipment dominates. So, it seems like even after you have other reasons to make hydrogen anyway, a better storage medium seems worth using, too.
Nobody is quoting round-trip efficiency for the iron-air battery, so I would guess that is not very close to as good as lithium tech. Their descriptions of battery installations say they include a fraction of lithium cells; probably the lithium cells are used to smooth off the peaks, falling back to iron when the lithium cells get low. We have lots of other reasons to overprovision panels.
It is possible that, as hydrogen gets more integrated into the energy system, starting with steel production and later aviation, its use for primary storage will increase. That probably depends on developing cheap, volume production of aerogels for LH2 tankage. Cost will always be important.
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