[zaarn]

Fusion is more expensive to construct reactors for, but once we have figured out how to do it, the cost will go down rapidly. The fuel for reactors is abundant and cheap, it would effectively end producing power by digging up minerals of any type.

Renewable energies will probably survive for a while but eventually it'll be all fusion. In my opinion, the production of fusion energy will be so cheap that it would be more cost effective to just dump the energy, hence the spikes in power consumption can be compensated by running more reactors and dumping the excess.

[pfdietz]

Why do you think the cost will go down rapidly? Fusion reactors are going to be very big, much bigger than fission reactors of the same power output, and also much more complex. Where does this expectation of them being cheap come from?

[zaarn]

They are big and expensive now. If they prove themselves then the economics of scale apply and the price goes down. And of course a lot more funding in the sciences to figure out how to make them cheaper because there is more economic interest.

[pfdietz]

The problem is, the exact same argument can be applied to all the things fusion would be competing against. In engineering, unlike children in Lake Woebegone, it's not possible for all competitors to come out on top.

To put it another way, the same argument you're making could be applied to (say) making computers from vacuum tubes, or balloons out of lead, or any of a myriad of approaches to solving problems that are losers regardless of effort expended. Why are we assuming fusion isn't also similarly a loser?

[zaarn]

There is a stark difference; the fuel for fusion reactors is the most common element in the universe. And literally every other energy source derives it's energy from fusion byproducts.

[pfdietz]

But this is no argument either. It's like arguing "vacuum tube computers have the advantage that they have no moving parts. And all other computer technologies use the electrons that are manipulated in vacuum tubes."

All that could be true, and fusion could still be hopelessly uncompetitive. The problem is the complexity, difficulty, and size of fusion reactors. Free fuel doesn't make up for that. All the long term beyond-fossil fuel competitors fusion has to beat are also only loosely constrained by fuel availability.

[zaarn]

Well, I would disagree, the computer comparison doesn't really hold since normal computers don't have a limited and localized supply of electrons (unless they are a laptop). It's more like arguing that a modern 4U Server has more performance than a laptop, really. Which is true.

Fusion reactors might be complex and difficult to figure out, but once it has been figured out the free market will inevitably make it cheaper.

Fuel availability is indeed a problem, IIRC the uranium reserves will hold us out for another 200 years before running out. At current energy demands. So realistically more like 100 years. Coal and oil will inevitably run out too. Sun and Wind don't produce a lot of power compared to Fusion when considering the rare earths required for the components. Fusion is just a lot more efficient and energy rich.

[74ls00]

Nah, the excess will be used for desalination; especially in parts of the world where potable water is less abundant