this PhysOrg article on the work of Derek Abbot is a must read.
In order to meet all of today's electricity generation needs Humankind would need 15,000 nuclear power generators, ideally each of them constituting a separate plant (otherwise Fukushima). Today there are only 440 reactors providing a mere 2.5% of all energy needs worldwide (and creating some 90% of energy generation derived problems maybe).
Expanding nuclear power generation capacity to fill Humankind's current use would be impossible because:
- Land: you cannot find 15,000 suitable locations: large enough to accommodate reactor, exclusion zone, reprocessing and storage facilities..., far enough from cities, close enough to water masses, out of earthquake prone areas...
- Lifetime: with 15,000 active nuclear reactors, one would need to be decommissioned and built every single day, each requiring 6-12 years to build and 20 years to decommission (most unrealistic).
- Nuclear waste: no clear way of disposal of nuclear waste exists, danger looms even if buried.
- Accident rate: there have been 11 major accidents (core meltdown) in some 60 years of nuclear power history: one every five years. There's no way to guarantee less accidents. With 15,000 reactors, there would be one such extreme accident every month.
- Proliferation: with 15,000 nuclear reactors, almost every single state would have the ability to build nuclear weapons.
- Uranium availability: with 15,000 nuclear reactors uranium reserves would last five years. A proposed method of extraction from seawater is plainly unworkable, at least for large amounts.
- Exotic metals availability: nuclear reactors require rare metals like hafnium, beryllium, zirconium or niobium, all of which have alternative uses (in microchips for instance) and are relatively scarce. If a nuclear reactor is built every day, these metals would become unavailable very soon.
Some of these limits also apply to (so far hypothetical) fusion reactors.
In contrast a solar thermal energy plant lacks of most of these limitations. It still needs space but not with the high requirements of nuclear plants. The main limit of solar and other renewable energies is intermittency, because of the day/night cycle or climate variability. This could be solved with efficient electricity storage systems. But otherwise they only have advantages.
Ref. Derek Abbott. “Is nuclear power globally scalable?” Proceedings of the IEEE. To be published.