New research shows renewables are more profitable than nuclear power

Nuclear is not renewable. It uses uranium as fuel. It is low carbon and emission free, but not renewable.

There are two solutions to intermittency. First one is a large grid with a lot of differen renewable power sources. It is always sunny somewhere, so when you can move the electrcitiy around, you have much less of a problem. Even better ifyou have wind power as well. With a continent sized grid, you basicly avoid the problem of cloudy days.

Next part is storage. Due to the large grid size you have the ability to use hydro power plants with reservoir as long term storage for particullarily cloudy days or winter and battery and pumped hydro for nights. Biomass is also an option if need be. Maybe we later hydrogen as long term storage as well, for really bad weeks and using it mainly for say chemical plants. Again the better large and interconnected the grid the less storage is needed. In some regions namely large sunny deserts having a nights worth of storage and some emergency backup biomass power plants would be enough. Basicly it runs down to less then a day worth of storage

There are also actually renewable baseloads like hydro power for flow power plants and geothermal, which are also good options. Also variable demand is a thing, which allows for even more renewables.

Seriously intermittency is much less of a problem, then it is made out to be. You just have to add a bit of interconnection and storage to it, but even that is not that expensive and seriousyl usefull.

This is the lie that is told, but nuclear has trouble getting grid penetration over 70% even with massive overprovision and storage via foreign interconnect.

Stable output which is totally interrupted for weeks at a time isn't useful for meeting a combination of stable, variable, and dispatchable loads. Nor does it contribute meaningfully alongside variable output.

You and many people overestimate the effect of clouds on solar power generation. Even on cloudy days solar panels still produce mostly the same amount of power. On the absolutely darkest cloud days, solar panels still put out about 50% the same amount of energy they generate on perfectly clear sunny days. And that's only for the absolutely darkest cloud days, whereas if it's just a typical overcast kind of day the output will be a lot higher. So even if society went to being completely solar powered, you'd only need 50% more solar power generation to be completely meeting your needs even on the cloudiest days.

There's so much years old anti storage propaganda in your text, it's painful.

Hydrogen storage is not a mature technology yet

What makes a tech mature to you? We have all the components of a hydrogen storage path up and running everywhere around the world. They're not profitable, at least not without government incentives, but solarpunk is anti-capitalist, so profitability shouldn't be among our primary concerns.

something like 35% round-trip efficiency

That's a worst case figure for purely electrical round trip efficiency. We could use waste heat of the fuel cell process (to a lesser extent also the electrolysis process) in order to bump that number up considerably.

not to mention the issues with hydrogen gas leaking due to its small molecular size

That has not been an issue for quite some time thanks to advances in materials science. Also, we could use methanation, of course sacrificing some more efficiency, but then we could even use old natural gas infrastructure without an issue.

Shouldn't even start discussing lithium ion, but the danger of thermal runaway should alone be enough of a reason to plan it very carefully.

Lithium-ion batteries are environmentally bad for sure, but talking about thermal runaway? Really? You need very high temperatures for that to happen. Most stationary storage applications will never see such high powers that they come even close to thermal runaway by themselves. If in a high power application, you'll have better battery management systems supervising the temperature and reducing the allowed power. It's really a non-issue if you have engineers who know what they're doing working on it.

Coming bad to environmentally bad: see sodium-ion batteries.

For everywhere else we can count on power lines

That's a good point. Having the large scale would afford more room for safety monitoring and control equipment, access for maintenance and operations, and better economies of scale on equipment cost.

Not to mention one plant stays in place on land with unlimited access to support equipment and personal while the other flys though the depths of the ocean, exposed to all its dangers and unpredictability with only the people and equipment that fit onboard.