Further answers to your questions:
"lithium grid scale batteries, what are some examples of the alternatives"Just Google "Grid level battery storage" and you will find a wealth of info. First stop for me is always Wikipedia:
https://en.wikipedia.org/wiki/Grid_energy_storageThere are 2 ASX listed companies that I know of, with completely different technologies: Redflow (RFX) & Altech (ATC).
"As for nuclear, what about extensive build times of 15+ years? And project costs such as the ones quoted here"On the subject of relative costs, such info is usually quoted by people pushing an agenda, so be very careful who you chose to believe. France is easily the most heavily dependent country on nuclear power, producing about 70% of it's electricity from nuclear. It also has about the cheapest electricity in Europe (with the probable exception of Norway). The French actually export electricity to neighboring countries, most notably Germany.
Costs of manufacture/construction are very sensitive to economies of scale. Just look at how wind and solar power have gone from being the most expensive, to among the cheapest over the last few decades. The quoted cost of nuclear is for next gen light water reactors. These will unquestionably be hugely expensive to build and run, not least because of the safety compliance involved every step of the way, and also because the first ones to be built must recoup the development costs. But the main reason is the reactor containment, which must contain an explosion in the event of a reactor failure. This is not an issue with molten salt reactors.
Molten salt reactors may ultimately be cheaper to build than coal or gas fired power stations once the technology is bedded down, and they are rolled out at scale. They will unquestionably be the cheapest of all to run. The main development hurdle has so far been in finding a material that can take the hostile environment of the reactor, which includes highly corrosive, high temperature molten salts, combined with neutron bombardment. The solution is likely to be a very exotic (read expensive) metal alloy. However, the reactor will be very compact compared to a gas or coal-fired boiler, and will not need to be nearly as thick-walled as a light water reactor since the operating pressure is much lower. So the added cost should be quite moderate.
Another factor, usually neglected by all sides, is the disposal of waste, which contributes very significantly to the real cost, and the overall environmental footprint. Think of the disposal problem of old solar panels and wind turbine blades that we are already facing, and then scale that up 1000 times and extend forward 1000 years. There is a very good reason why proper recycling of solar panels has not yet being undertaken. It is because it will cost too much, and in any case will only be partial. And the longer it is not attempted, the longer they can deny the problem. As far as I know, no one has any idea of how to recycle composite plastics. At the moment, old wind turbine blades are just cut into more manageable sections, carted away, and either stacked or buried.
Molten salt reactors produce remarkably little waste which furthermore decays to safe radiation levels in just a few hundred years. Factoring in the smaller volume, and the shorter half lives of waste isotopes, the radioactive waste disposal problem from a molten salt reactor is perhaps a hundred-millionth that of a conventional light water reactor.
A curious fact: Coal-fired power stations actually emit more radioactivity into the environment than conventional nuclear power plants.
"why do we need to spend hundreds of billions on nuclear and wait decades for its arrival?"Because it is the only thing that will work. The west has been very slow to get with the program, but China and India are both working hard on thorium, and alternatives to light water reactors - chiefly the molten salt reactor. They both envisage that this will give them a considerable economic advantage in the future. For all the talk of environmental responsibility in the west, the eventual adoption of thorium nuclear power will probably be more an economic decision.
All IMO.