Nobody needs 1 full day of storage.
If we actually deploy 50 GWh of hydrogen storage, and demonstrate that it can cheaply and reliability be built at scale then your point would be valid. But until then, hydrogen represents a theoretical solution not an actual solution.
It's existing technology, but it's a novel application of that technology. We haven't used hydrogen electrolysis as a form of grid storage before. And we certainly haven't used it for grid storage at the Terawatt hour scale. And that the scale we'll need to make wind and solar viable. 1 TWh isn't even 30 minutes of global electricity consumption.
We both know the answer: there aren't any.
Back in the 1950s people thought nuclear power would be cheaper than fossil fuels. They thought it'd be effectively free. The energy density of uranium is so much better, so clearly generating electricity with it would be much cheaper. But actually deploying a technology at scale reveals more and more challenges.
Your proposal for hydrogen storage is in the same phase that nuclear power was in during the 1950s. A solution that exists on paper, but one that hasn't actually encountered and overcome the challenges of implementing it at scale. Same with thermal batteries, synthetic methane, and so on. These are proposals that haven't passed the test of actual implementation at scale.
Hydrogen is being stored in a few places. That the storage isn't larger isn't because of any technical obstacles, it's because there's no reason to store it now. In particular, when we can burn natural gas without CO2 charges, using the hydrogen for energy storage is pointless.
This doesn't mean hydrogen CAN'T be stored, it just means the market conditions for widespread adoption of an off-the-self technology aren't there yet.
And it certainly doesn't answer the question of whether or not this represents a viable grid-storage solution, since we haven't built it at remotely close to the scale required.
It's not "if it isn't already being done, it can't be done"
It's "if it isn't already being done, it is extremely reckless to assume that it can be done cheaply at a massive scale".
Screw it, let's just use fusion. Nobody has actually built a fusion plant? Well, who cares if it hasn't already been done, that's a "foolish argument" in your own words. /s
Hydrogen could also be stored in depleted gas fields and in deep saline aquifers. The storage capacity available is more than adequate.
We haven't done this to provide 100 MWh of storage. How on earth can we be confident it'll be easy to provide 1 TWh of storage, or 10 TWh?
People mostly talk about lithium ion storage because that's what's actually available, besides geographically limited options like hydroelectricity. Until there's a company that's building dozens of gigawatt hours of hydrogen storage it's a moot point. It's a technology that exists the laboratory, not one that's commercially available.
We could easily have Petawatt-hour scale hydrogen energy storage.
Back in the 1950s people thought that nuclear power would be effectively free. But actually building it at scale exposed challenges of implementation that weren't foreseen. The cost of a system on paper and the cost after overcoming the challenges of actually building it are two very different things. For hydrogen storage, you only have the former.
Nuclear's problem are fundamentally political in nature. If we really cared about green energy, nuclear power could easily be built out at scale.
The industries that manipulate tens of millions of tons of hydrogen each year would be astounded to hear this statement of yours. What are those facilities made of, unobtainium?
Unfortunately, those alloys that experience embrittlement includes the ones used in steam turbines: https://www.sciencedirect.com/science/article/abs/pii/S09215...
They aren't "off the shelf" technology yet.
https://www.airliquide.com/sites/airliquide.com/files/2017/0...
This presentation says that the Spindletop hydrogen capacity is equivalent to ~120 GWh.
https://ukccsrc.ac.uk/wp-content/uploads/2020/05/John-Willia...
Nobody is arguing the solar and wind power isn’t cheap, but the cost of power on those cloudy windless weeks is going to be real high to make having all that standby generation around. It’s the cost to achieve the same reliability and 99% carbon free that is expensive.
Money is imaginary and global warming isn’t so let’s just print some bonds or move some numbers around in some database and build it all! - an electrical power engineer
Large projects are just expensive now. Nuclear would be competitive with either of these hydro projects.
As we recently saw with Texas’ catastrophic fossil fuel production failures the big problem is not the source but poor management and not being able to get help from the neighbors.
"The solar heavy network wouldn’t need energy storage with an HVDC network."
So no, we wouldn't need that. HVDC would be far cheaper.
All of the Americas experience night time simultaneously for at least 8 hours a day. Even if we ran HVDC lines to the Sahara, there's still a period of time where most sunlight is shining on the pacific ocean.
Also, if you can run HVDC to the Sahara you could run it to hydro plants, so I don't think that's a good hypothetical.
But mostly, talking about pure solar just makes no sense.