For seasonal variation, simply overbuilding is also a possibility. No storage would be needed at all in Minnesota, for example, until renewables get to 70% of consumed electrical energy.
And where's hydrogen going to come from? You need to overprovision renewables so that they not only provide power for now, but also store enough power (via batteries or hydrogen or whatever) to get around daily, seasonal and inter-seasonal variability.
And by the way, hydrogen from renewables is massively inefficient.
Overprovisioning renewables for immediate consumption works in tandem with hydrogen, since it means there will be times excess power is available to make the hydrogen.
The round trip efficiency of power->hydrogen->power through turbines will be maybe 33%. But this is FINE, if the capital cost of storing hydrogen in underground caverns is low enough and renewables are otherwise cheap enough (low LCoE).
Hydrogen gas would be useful for things like shipping. Such gas would likely be produced close to the port through thermochemical means, powered by a nuclear plant. This would minimize the amount of pipeline that needs to be built to transfer the gas to ships.
Not really. It has lower energy/mole. There is the possibility that if CO2 is present that microorganisms could react the two to make methane. But aside from that, where is this much greater complexity coming from? The equipment required for storing either is similar.
Hydrogen is already dealt with on a very large scale. If expanded to STP, the amount of hydrogen produced every year globally would occupy 700 cubic kilometers. This is not Power Point technology of the kind you find in pro-nuclear arguments.
Did you read my post? Because I explain how it's permeability and corrosion make it challenging to build long lasting containers to store hydrogen.
It's not the same technology to store methane. Methane can be liquified and kept as a liquid at room temperature. Hydrogen cannot, it must either be kept as a gas (drastically reducing it's energy density per liter) or cryogenically cooled. The scale at which it is produced, stored, and transported is not even remotely close to natural gas.
Show me where you get this figure that 700 cubic kilometers of hydrogen is produced yearly? And even if it is, using it for energy storage is much more challenging than using it for things like chemical production because the latter doesn't involve storing hydrogen for long periods of time.
The amount of hydrogen produced yearly doesn't hold a torch to Methane. 3.9 trillion cubic meters of natural gas are consumed yearly [1]. This works out to 2.7 trillion KG or 297 billion tons. By comparison, 70 million tons of hydrogen are produced annually [2]. We produce over 4000 times as much natural gas as hydrogen annually. I have no idea where you getting this idea that the hydrogen economy and natural gas economies are remotely close to the same scale.
> This is not Power Point technology of the kind you find in pro-nuclear arguments.
You're right, pro-nuclear arguments don't need to hand-wave away severe technological limitations. Because it actually works, and there are real-world examples of it working.
1. https://www.statista.com/statistics/282717/global-natural-ga...
2. https://en.m.wikipedia.org/wiki/Hydrogen_production#:~:text=....
And did you read my post? There is already a great deal of equipment for manipulating hydrogen on an industrial scale. What, did you think they rip that stuff out every month? The issue you are raising is already well solved.
> It's not the same technology to store methane. Methane can be liquified and kept as a liquid at room temperature
The great majority of methane storage is underground as compressed gas, not cryogenic. Underground storage is cheap; the capacity in the US is a good fraction of the annual consumption of natural gas here. It is this long-proven technology I am referring to, which should have been clear from what I wrote earlier.
> Show me where you get this figure that 700 cubic kilometers of hydrogen is produced yearly?
World annual production of hydrogen is 70 million metric tons, or 7.0e10 kg.
https://www.iea.org/reports/the-future-of-hydrogen
The density of hydrogen gas at STP is less than 0.1 kg/m^3. Divide to get 7.0e11 m^3.
> We produce over 4000 times as much natural gas as hydrogen annually.
Globally, 6% of natural gas production is used to make hydrogen. I wasn't talking about hydrogen production by electrolysis; I was talking about total hydrogen production, to show that hydrogen is a material that global industry already has vast experience with.
If by "a great deal" you mean "a fraction of one percent of what is required". No, the issue I'm raising is not well solved. Currently hydrogen is used shortly after it's produced, typically for chemical manufacturing or oil refining. It's not being stored for long periods of time, nor is it being transported in anything close to the amount of natural gas.
> The great majority of methane storage is underground as compressed gas, not cryogenic. Underground storage is cheap; the capacity in the US is a good fraction of the annual consumption of natural gas here. It is this long-proven technology I am referring to, which should have been clear from what I wrote earlier.
That's assuming these underground storage will work with a substance that has greater permeability. And storage is only half the problem, it's also a matter of the infrastructure used to transport gas to the end user. Simply pumping hydrogen through the same pipelines as natural gas isn't as easy as it sounds. Hydrogen has greater permeability and turns metals into hydrides at pressure. Hydrogen pipelines need to be much more corrosion resistant.
To put this in comparison, the US has 2 million miles of natural gas pipelines [1]. It only has 900 miles of hydrogen gas pipelines [2]. Most hydrogen is produced near areas of demand, and is not transported for long distances or stored for long periods of time. There's research into carbon-fiber pipelines that could better resist corrosion, but this is not a mature level of technology. It's more feasible to pipe methane, and then use steam reforming on-site.
> The density of hydrogen gas at STP is less than 0.1 kg/m^3. Divide to get 7.0e11 m^3.
Volume doesn't matter, I converted the volume of methane produced to mass.
> Globally, 6% of natural gas production is used to make hydrogen. I wasn't talking about hydrogen production by electrolysis; I was talking about total hydrogen production, to show that hydrogen is a material that global industry already has vast experience with.
Excellent point, total hydrogen production is 70 million tons with most of it produced through steam reforming (which produces carbon dioxide). Electrolysis only accounts for 4% of hydrogen production: https://en.wikipedia.org/wiki/Hydrogen_production#Methods_of....
The fact that 6% of natural gas production is used to make hydrogen doesn't mean that our hydrogen production equals 6% of our natural gas production. Most of the natural gas used in steam reforming is used to produce heat. And methane is 75% carbon by mass.
To recap, we have 3 orders of magnitude less hydrogen production and hydrogen transport infrastructure. Even less if you only count hydrogen produced through electrolysis. This is in no way "a great deal of equipment for manipulating hydrogen at scale".
1. https://www.ncsl.org/research/energy/state-gas-pipelines.asp...
2. https://en.wikipedia.org/wiki/Hydrogen_pipeline_transport