Fusion isn't a silver bullet even if it works. If it costs more than solar+battery then it's worthless.
If that's too annoying to store you can get it hot and squeeze it over some nickel to get methane.
Electrolyzation becomes cheaper than mining methane for hydrogen (and thus ammonia) production if solar hits the $0.2-0.3/Watt threshold somewhere (which is predicted to happen in 3-7 years).
It's complicated and expensive, but I'm not sure I'd bet on a sabatier reactor (or hydrogen storage if it gets cheap), an electrolyzer and 4x the solar panels being more expensive than a fusion reactor with the average output of 1 unit of solar.
Plus the sabatier thing means we don't have to upgrade all the heating furnaces and expand the grid to have 8x the capacity.
Fusion will be real handy where power density is king though. And if there's some non thermal way of getting work out of it, I can see it being cheaper.
Hydroponics with fusion technology allows us to produce food without relying on the sun at all. I'd say that alone is worth the investment.
As for the future, beamed power will work out to interstellar distances, so energy sources other than our Sun (and other stars) aren't necessarily required.
(From your question you might have been thinking of laser propelled light sails. These are best at speeds high enough that fusion is out of the picture.)
Basically everything except fission, tidal and a portion of geothermal. Admittedly it's not a terribly useful classification.
I'm not sure what benefit density provides, especially since people obsessed with density seem to only focus on the reaction chamber, which is the smallest part of the massive building and heat rejection apparatus that will be needed.
Rejecting waste heat is a real difficulty, and part of the reason that's France's fission fleet is at less than 50% capacity right now.
Thermal electricity production has a chance of becoming obsolete compared to direct conversion of photons into electricity. When solar plus storage costs less than steam turbines plus heat rejection, then it doesn't matter how cheap or dense the fusion part is in terms of economics.
[1] https://apnews.com/article/technology-government-and-politic...
> But a group of residents organized as “Save Our Mesa” argued such a large installation would be an eyesore and could curtail the area’s popular recreational activities — biking, ATVs and skydiving — and deter tourists from visiting sculptor Michael Heizer’s land installation, “Double Negative.”
I also searched the page and the word 'climate' doesn't appear even once. Why do you consider this to be an example of 'climate activists' shutting down a solar farm project, and do you have any other (actual) examples of it happening?
For another actual example of this happening, see the scaling back of the Ivanpah Solar Power Facility
Those are NIMBYS who want their view. Maybe with a mix of oil lobbyists.
Don't get me wrong, I am very frustrated by people who see themselves as environmentalists, for whom climate change (and thus non-carbon energy sources) is not the top priority. I think they have wrong priorities. But that doesn't mean they're hypocrites, they're just (IMO) wrong.
All that said, I agree with your topline observation that we need all the help we can get.
Maybe in a few more years/decade/s we will reach a point where in some places in the world it will be economical viable to have exclusive solar and battery, and that assuming prices will continue to drop and that there won't be any resource or physical limitations. Then we got colder climates where solar + battery is unlikely to ever become viable. Exports of solar generated green hydrogen could solve that assuming that the technology for that becomes cheap enough.
Multiple different directions where specific technologies could be economical dominant in the future.
- under the earth
- under the ocean
- deeper into space
Granted, we don't need a lot of power in these places right now. But if we have the option...then maybe we'll find some good ways to use it.
There will always be places where solar+battery isn't viable. Northern Canada and Alaska come to mind.
Solar is great but not simply alone. (Latitude is less of an issue as (proper) power systems are interconnected markets that sell/buy excess load.)
India is going to end up with perhaps two billion people and will have extraordinary population density/spacing problems. They're going to desperately need huge numbers of nuclear fission power plants or fusion plants to provide for that. They will not have the space for epic scale solar farms. Singapore, South Korea, Taiwan, Bangladesh, Pakistan, Philippines, Vietnam, Israel, Belgium, Netherlands (among others) are in the same space vs population situation. And given the population explosion across parts of the Middle East and Africa, it's a certainty nations in those regions will have the same problem as well.
Your math is totally wrong, space was never an issie for solar. It tales 100x less space for a coutry to cover it's power needs with solar, than it does for a country to grow it's own food and feed it's own people. So every country thats not a city-state, like Vatikan, is fine.
All the challaneges of Solar are around intermittency, cost and ofcourse it's less viable in northern lattitudes. But none of them are around space.
Solar needs more space in such locations but space is abundant and also nobody lives there so you dont need much power anyway.
The sun shines 24 hrs a day during summer, so you can generate lots of hydrogen for use during winter.