So I know nuclear is supposed to be able to handle current power needs of humanity for quite a while, but if we fill earth with super intensive vertical farms powered by artificial light...
Anyone ran the numbers on how long uranium would last running sun-less agriculture for a few billion people?
When fusion arrives in the next 40 years: "Lithium from sea water would last 60 million years, however, and a more complicated fusion process using only deuterium would have fuel for 150 billion years." [calculated at 1995 global power output]
Why will fusion arrive in the next 40 years? I feel like that's what was stated 40 years ago too. Are there 0 barriers at this point and it's just a matter of obtaining funding and starting to build plants and by then there will be a big enough track record for widespread deployment?
Despite this attitude being memed, multiple efforts to refine fusion reactors to the point they are useful for energy purposes have made fairly constant (albeit slow and incremental) progress over the years. Furthermore, all the science and engineering concepts are sound based on the physics models.
One thing people don't get is we only need a tiny fraction of net positive output due to the insanely large amount of fuel available to us. 2-3% positive output is all we're talking about and it'll be able to economically replace most other energy sources (though it will take time to ramp up of course.)
Basically it's just a matter of time and continued advances in material sciences. Purity of materials and perfection of manufacturing are the primary barriers. Operational consistency a secondary one (and continued improvement in microcontroller tech and data analysis/AI/etc. will help here.)
One example, in focus fusion, the current progress has definitely been incremental but basically every step of the way the progress has been hindered by exactly the same problem: the materials and apparatus have to be nearly perfect to increase plasma duration sufficiently; to avoid contamination of the self-sustaining plasmoid. And indeed, the progress on that end has been continuous. Once it's proven it will be a matter of perfecting the manufacturing process and automations/etc. to ensure that degree of material quality and device engineering and voila we'll have cheap scalable power.
Based on what I've been watching for the last 15 years, I think within 40 years is quite reasonable. In fact, I think it would not be a surprised to see consistent 0.5% net positive or better in the next 5-10 years, whether it is focus fusion or tokamak or whatever.
TL;DR: Fusion is a 100% sound energy generation avenue that is simply waiting for its "welding" moment. By which I refer to the point where gas production became suddenly economically viable due to the invention of welding (which was motivated at least partly by the desire to improve gasoline production.)
That is certainly an exaggeration on the low end. By some estimates we don't have more than about 100 years of nuclear power. It's not really beneficial to give these wildly overoptimistic estimates of recoverable resources.
Right now human civilization is running off something like 18TW of energy.
If you add in 2000 kilocalories per day for 7.8 billion people, you add another 750 GW; if you add in a factor of 10 for biological & technological inefficiencies on actually turning electricity into edible calories, you're up to 7.5TW.
As long as you don't throw another factor of 10 on top of that -- imagine growing all food indoors, and then feeding it to cows, before subsisting entirely on beef -- you're probably looking at an amount of energy comparable to that used by humans currently.
Obviously it doesn't make a lot of sense to just switch over to indoor agriculture when there's free sunlight outside, but if we were to do so, the energy demands are probably on a scale comparable to what we're working with already.
So you're probably only halving or so the runway of available uranium.
What they say in their interview is scaling this to make it economically is possible if they just have the scale. Personally I’m extremely skeptical of their success...
And what is the price for the produce in those areas? Less as well. In these areas, it's highly unlikely this system would be feasible if land costs are relatively low and energy prices are a relatively higher expense compared to incomes in higher earning countries (as a percentage of income).
Anyone ran the numbers on how long uranium would last running sun-less agriculture for a few billion people?