Nuclear is a high reliability baseload power source to stabilize a grid when wind and solar is cyclic and energy storage is difficult. There is not enough nuclear fuel reserves in the world for nuclear to be a significant fraction of the energy portfolio, though nuclear might be willing to pay 10x-100x of the present prices of fuel which would make reserves much larger, including ocean harvesting of fuel.
I've been meditating about a previous post about carbon capture and storage, and I think this is where our decarbonized "stored energy" future lies. The cheapest large scale form or carbon capture is bio, as in biofuels, but I watched a video on US corn based bio ethanol claiming to be energy negative when considering all the inputs, but Brazilian sugarcane based one is net positive. I've been thinking about this, and I think corn should be used as a food source, and the rest of the plant, the stalks, leaves, cobs, called stover, is what should be used as the carbon source for fuel. Cellulosic ethanol is difficult, and it wastes part of the carbon as carbon dioxide, plus the fermentation stops without using up all the carbon source. A better way would be to take the carbon in the carbohydrate cellulose as only a carbon source, not an energy source, and combine it with solar derived hydrogen. Hydrogen is a terrible storage medium, requiring either tremendous compression, or cryogenic liquefaction with constant boil off to maintain temperature, it's terrible to store it as strategic oil reserves. Liquid anhydrous ammonia is much better than hydrogen, but nothing beats gasoline in storage efficiency. Liquid hydrogen is about 5 MJ/L, ammonia 11, and gasoline is 36, and out of the 3 gasoline is by far the easiest and cheapest to store.
So basically you take the carbohydrate waste cellulose from dried agricultural waste, (C6H12O6)n which is (C6(H2O)6)n, carbon-hydrate, carbon combined with water, and add hydrogen to create CnH2n+2 gasoline alkanes like 7 heptane or 8 octane plus water. Ideally you could just react the cellulose at high temperature with hydrogen to get this, but the temperatures required from what I've seen are around 600+ Celsius, requiring expensive solar concentrators to provide that heat, most likely molten salt based, that are very difficult to work with because salt freezes around 200-300C during shutdowns and maintenance. A more robust solution is to sacrifice the energy content of the cellulose and partial burn it in a gasifier to get CO+H2O (with some CO2 or H2 depending on gasifier conditions), which is much easier to work with leaving oxide ash behind like potash and phosphate that can be reused as fertilizer, the fields needing only fixed nitrogen as extra input. The gasifier supplies its own thermal input and can easily manage 600C at the cost of needing extra hydrogen to convert the CO and CO2 back to a hydrocarbon.
As far as wind goes, which generates electricity directly, electrolysis is like the only reasonable solution, while with solar you can have photovoltaic modules that produce electricity for the same electrolysis, but I think there is a better option, more economical large scale, solar thermal. Solar thermal can be probably 60-80% energy collection efficient(times 40% or so thermal water splitting), compared to 20% PV, only needs cheap mirrors instead of silicon modules that degrade over the decades, a mirror just needs a polish once in a while, but it does have moving parts. Parabolic troughs are much better large scale than dish based systems, but they are presently limited to 400C due to the oil they use. Unfortunately the thermal methods of breaking water, such as the sulfur iodine cycle, or Westinghouse cycle need 800C for breaking the SO3 back to SO2 + O2, and require molten salt, which does not work well for getting parabolic troughs getting started and flowing. There needs to be inorganic chemistry research for under 400C processes so that thermal oil can be used in parabolic troughs, but in the meantime there is a copper-chlorine cycle that requires only temperatures near 500C, and I'm sad to say this would require NaK, which is liquid at room temperature but a horrible substance to work with, but can work up until the boiling point of potassium. To get the 500C temperature in a parabolic trough collector the collector tube needs to be surrounded by an evacuated glass tube (possibly borosilicate) with an aluminum mirror coating on the inside, which is partially etched away with acid to let the light in from the mirrors. Sergey Yurko on YouTube makes a hodgepodge or cheap and not very efficient solar concentrators, but I think one of his idea, of putting the collector on the ground is something to think about, and he keeps the mirrors stationary and moves the collector around, but I think, because of sealing and coupling issues relating to moving NaK joints, it's much better to just have collectors welded in place and stationary, and move the parabolic mirrors around. Having the collector closer to the ground allows near vertical mirrors that deal easier with snow. And it would need to be east-west direction, not north-south, I don't understand why they make them north-south, still thinking about it.
So basically dry corn stover in the fields like you do hay, run it through a gasifier to get CO, get solar thermal hydrogen from the copper chlorine process via NaK based vacuum insulated parabolic troughs, and your everyday refinery guys can tell you how to convert CO and H2 into gasoline reserves via the Fisher Tropsch process. This would be bio-solar fuel, the bio the carbon source, and solar hydrogen the energy source, the carbon being a robust hydrogen carrier. This is where the US transportation energy future lies, the corn belt is at low enough latitude for solar hydrogen to make sense there. Or even electrolyzed wind hydrogen, but it feels solar thermal hydrogen should be the cheapest and most energy dense, and more reliable than wind.
I've been also looking into duckweed and azolla and sargassum. I don't like algae because they are difficult to extract from water and low density, duckweed grows fast but it's very high protein and for good economy it probably requires a lysis to create and protein extract for fake meat, plus the leftover carbon turned into fuel, else you can't justify the high nitrogen input, azolla grows slower but creates its own nitrogen via anabaena symbiont, it's used in inundated rice fields, but cannot be directly consumed because of bioaccumulating neurotoxins (though ducks are grown on rice fields), and sargassum is expensive to haul long distances, but it's the only reasonable renewable phosphate source from the sea, difficult to dry to gasify, but the ash would be valuable phosphate from the sea, where all urban sewage phosphate washes away. Basically bio production on land is phosphate limited, fixed nitrogen can be created in abundance but phosphate, well you have to get actual phosphate atoms.