And how much ground you need to cover to have equivalent of an average nuclear power plant? And yes, one needs storage, and viable storage technology is not even on the horizon.
It is so sad and so bad for our planet that for instance Germany decided to spend billions of billions on renewable energy plants while spending the same amount on nuclear power plant would made Germany zero emission economy.
That statement definitely needs some numbers to check out, it's a claim that needs backing up. The full nuclear power "pipeline" isn't CO2-neutral either and depends on resources we'll eventually run out of, probably within the next hundred years, maybe sooner [1].
I also don't think that "but what about space requirements" is an argument with enough weight to dismiss the long list of advantages given by the GP. We have so much unused space on roofs. We could get rid of a few parking lots if you're concerned for ground.
We don't even need to get rid of parking lots, we can build roofs with panels over them, which will help shade cars and even minimally lower co2 emissions from running car ac units of people who get back to cars.
Viable storage is already here. It's called green hydrogen or hydrogen-from-seawater, and pilot plants are coming online or being built right now.
The storage is limited only by tank size, and we already know how to store and use large quantities of hydrogen. The hydrogen produced from the process can be pumped elsewhere by pipeline and used as fuel for gas turbines to balance the grid, or combined with carbon dioxide or nitrogen from the atmosphere to produce zero net carbon methane and ammonia for use as denser fuel sources, or feedstock for industrial processes. You can even make zero net carbon synthetic jet fuel this way.
Hydrogen is an extremely inefficient energy storage medium. We don't have massive amounts of energy to just waste away in an inefficient system. If we did, green hydrogen would have been chewing away at current hydrogen production for industrial usage (95% gray hydrogen).
You're of course free to believe that countries will build 3 times the capacity of their energy production to compensate for that inefficiency.
To give an idea of the order of magnitude of inefficiency :
* Currently a grid => hydrogen => grid round trip is 40-45% efficient.
* A grid => battery => grid round trip is 90-95% efficient.
You can recover 2x more energy by NOT using hydrogen. There is no competition. Unless the lost energy from green hydrogen production can be recovered somehow (co-generation)...
Green hydrogen is produced thanks to electricity produced by renewables (wind, solar...) when it is useless (not immediately consumed). It's a "use it or lose it" situation: using it, even at a loss, seems sound.
Many applications (transportation, industry...) can use it as such, without any way from hydrogen to electricity, and more and more probably will.
I have no doubt that batteries will also form part of the grid energy storage solution. But they don't scale as well as hydrogen and have higher maintenance costs and replacement rates.
Given how cheap renewables are becoming, yes, countries will absolutely build overcapacity.
But we won't need 3 times the amount - hydrogen will only be used to balance the grid. Most grid energy will come direct from renewables. Most of Europe would only need about 20 days' worth of hydrogen as insurance against a lack of wind or sun.
Green hydrogen has only become viable to replace hydrogen-from-fossils within the last few years as the cost of renewable energy has plummeted. That drop in renewable energy costs is what has changed recently and what has taken so many people by surprise.
> spending the same amount on nuclear power plant would made Germany zero emission economy.
Power generation is only a small part of Germany's emissions. Germany would still be a large CO2 source with full nuclear power generation, just like France is because of transportation, food, heating, industry, etc.
It is so sad and so bad for our planet that for instance Germany decided to spend billions of billions on renewable energy plants while spending the same amount on nuclear power plant would made Germany zero emission economy.