Progress on tidal is good! And yes, it should help to reduce storage requirements, and cost should come down over time / with scale.

To address the point in the post, battery storage - at least lithium - is not the only option for the last 5-10%. Iron-air batteries are looking very promising, for instance.

Large scale heat storage with district heating systems or industrial heat is another option.

As is green hydrogen, though it is obviously problematic too: electrolysers don't like running below 50% load, leaks are relatively high now (4%), but can maybe come down to 0.4%, and it's likely that turning it back into electricity will mean burning it (hence NOx pollution, also a greenhouse gas).

Or you can just build way over capacity on renewables. But all of these options have material costs.

We could convert green hydrogen to green methane via the Sabatier Process, which uses an extra 10% of its energy.

But yes, overcapacity is looking better and better as costs of solar + storage plummet. Except in high latitudes.

Moderate overcapacity sure - maybe 200%. But if we rely solely on overcapacity we'll end up needing more rare earths. So some mixture - as I said, iron-air is very promising, very high energy storage density and low mining costs (in every sense).

Interconnectors, dynamic demand, energy efficiency (including not building more data centers) and all that stuff, of course.

There is some need for true synthetic fuels (based on green hydrogen and captured carbon), but only for niche markets such as air ambulances etc.

And we could use hydrogen for electricity more directly, e.g. using large scale fuel cells. But given leaks, current capacity issues, and the fact that electrolysis doesn't easily fit with flexible generation (most of the leaks are during start/stop), it's not clear that hydrogen is a viable means of long term electricity storage.

An Ozzie analyst has estimated using actual data for sunshine, wind and temperature, that we could get by with just 16% overcapacity and some use of legacy gas.

https://volewica.blogspot.com/2024/08/a-98-renewables-grid-is-affordable-and.html