NO... humanity should explore fusion because we might desperately need it to survive.
To what amount can you scale up solar in a particular region?!
Yeah, I know, we're into low-power everything nowadays... but let's say that you end up with a desperate need for smth like 1 TW of power for something like a sea-water desalination plant, massive irrigation needs because climate change fucked you up, or building a huge set of flood barriers (think what Nederlands has now, but you need them 100x larger, 5x cheaper and done FAST) because sea levels rose and people will die if you don't get the massive cheap energy needs for these projects ASAP. Or maybe a huge TW power laser for some space-dev project if you don't want to think of disasters. Or maybe to decontaminate large amounts of water/soil/air after the first large-ish nuclear/bio/chemical war that will take place on Earth.
If you're betting on solar and wind and you end up suddenly needing high levels of cheap (it can be "long-term like 100 years on cheap" if you're a country with a good credit score) power, you're.... fucked! Yeah, fusion won't be scalable to massive energy needs "out of the lab", but in 100 years from now when your grandchildren will need it to save their lives from the consequences of our planetary fuck-ups, it will be!
(And yeah, short term you can scale fission better probably. So investment into "dirt-cheap fission power that anyone can have" is also crucial. But longer term it hits other scalability bounds.).
In a perfect world where we don't totally fuck-up the planet, solar and hydro and geotermal and wind and waves would be enough.
In the real world, where we will fuck-up the planet, things like fusion are desperately needed to un-fuck regions of it and re-terraform them (and also to get into space exploration fast and big, not "snail-paced solar-powered").
It's not engineering problems. It's assumptions about how humans will behave!
Maybe the region where solar needs can be scaled is not in your country. Maybe you're at war with that country. Or maybe the company producing that power would only sell you the power at some outrageous price that you don't want to pay. Maybe you want to be the one selling not buying that power, you want to be the one making profit. Maybe your neighbor just considers you're an inferior race so he will not even sell you the power for the flood dams or the desalination plant. Or maybe you're the bad guy, but now because people won't sell you what you need at realistic prices you contemplate of... maybe nuking some sense into them, because if 1mil of your people might die of hunger, why not have 2mil of theirs die burned and irradiated?
Any solutions that assumes people working well together in some "perfect world order" are very dangerous. Humanity ain't "a giant organism". We're a bunch of warring tribes with carefully disguised racist, xenophobic and even purely sadistical tendencies just waiting for an excuse to come out!
We need more technologies that just work and can be used SUSTAINABLY in any random place and at any scale regardless of how bad we fucked up or we're planning to fuck up.
Energy diversity and energy security are important.
On the one hand, global trade can strengthen relationships between nations and make war less likely. On the other hand, look at how Russia uses the threat of turning off gas supplies to pressure european countries.
A solar farm has higher energy density than you might think. New York City could get ~100 gigawatts of solar power without importing anything. Further, if anyplace used close to as much energy as provided by sunlight it would get really hot.
There's other reasons you might want fusion power: any place you need a large source of power, but siphoning off ambient energy (i.e. wind, solar) isn't feasible or sufficient, fusion is the way to go or else you have to use fission or fossil fuels.
This applies to things like ships and submarines, and to spacecraft.
So yeah, solar/etc. sounds great in an ideal scenario in a perfect world, but what if you're not on this world? Solar power isn't sufficient to do serious mining operations in the asteroid belt or to redirect a large asteroid threatening to impact the Earth. It also won't power your aircraft carrier or cruise ship. A clean source of nuclear power would be ideal for all these things, if we can figure out how to make such a thing work.
Fission fits the bill perfectly in the scenarios you posit and we have almost fifty years of hard-won production experience with it. Fusion isn't really 'cleaner' than fission for most practical purposes, so why pin your hopes on something we can't even do in a practical manner at the moment? Fission also scales down much better (or at least we know how to scale it down effectively) so the power plant is much more likely to fit into the spaces available in these examples.
How is fission possibly as clean as fusion? Fission leaves behind radioactive waste material; fusion leaves behind helium. This doesn't make any sense at all.
Yes, we can't do fusion in any practical manner at the moment, but we can't do fission scaled-down either: if you disagree, please show me an example which is economically successful. US Navy ships don't count (not "economically successful"). Someone actually tried building a fission-powered commercial cargo ship ages ago; it didn't last very long. It cost so much to operate that it was retired in a few years and sent to a museum in Charleston SC. With absurdly expensive fuel, nasty waste which needs to be disposed of somehow, and extremely dangerous operation requiring highly-trained personnel, fission plants only make commercial sense when they're scaled up to gigawatt scale power plants. Fusion plants may not be practical yet, but they'll never be practical if no effort is spent on R&D to make them that way.
Neutron bombardment of your fusion containment vessel creates radioactive material. I am not sure where you get this idea that fusion is 'clean', but everything that involves pushing around fundamental particles creates radioactive waste. There are theoretical designs for fusion reactors that limit the radioactive side-effects somewhat but nothing in this area is clean.
Scaled down fission reactors like the Toshiba 4S can be sized to power an apartment building or city block. There are numerous micro reactor designs available and a variety of companies working to try to create a market for them.
When it comes to terrestrial reactors then fusion reactors will be enormous (need to generate a lot of power to compensate for the huge risk and the massive costs that it will take to build them) and if you are talking about putting reactors in space then it is foolish to consider anything but fission for at least our lifetime.
Do you need 1TW tomorrow? If so, you are fucked, sorry.
Fusion takes longer to scale than any kind of power supply we use. At least H2 + H3 fusion, that is the easiest kind does. You'd be much better building a huge solar array on demand.
If things are that fucked, any given government will have no qualms building fission plants everywhere. If you aren't super-duper paranoid about safety and radiation, fission is already pretty damn cheap.
To what amount can you scale up solar in a particular region?!
Yeah, I know, we're into low-power everything nowadays... but let's say that you end up with a desperate need for smth like 1 TW of power for something like a sea-water desalination plant, massive irrigation needs because climate change fucked you up, or building a huge set of flood barriers (think what Nederlands has now, but you need them 100x larger, 5x cheaper and done FAST) because sea levels rose and people will die if you don't get the massive cheap energy needs for these projects ASAP. Or maybe a huge TW power laser for some space-dev project if you don't want to think of disasters. Or maybe to decontaminate large amounts of water/soil/air after the first large-ish nuclear/bio/chemical war that will take place on Earth.
If you're betting on solar and wind and you end up suddenly needing high levels of cheap (it can be "long-term like 100 years on cheap" if you're a country with a good credit score) power, you're.... fucked! Yeah, fusion won't be scalable to massive energy needs "out of the lab", but in 100 years from now when your grandchildren will need it to save their lives from the consequences of our planetary fuck-ups, it will be!
(And yeah, short term you can scale fission better probably. So investment into "dirt-cheap fission power that anyone can have" is also crucial. But longer term it hits other scalability bounds.).
In a perfect world where we don't totally fuck-up the planet, solar and hydro and geotermal and wind and waves would be enough.
In the real world, where we will fuck-up the planet, things like fusion are desperately needed to un-fuck regions of it and re-terraform them (and also to get into space exploration fast and big, not "snail-paced solar-powered").