Quote Originally Posted by Bob View Post
I keep pretty up to date on fusion technology, or so I thought. As far as I knew, the only fusion tech we have requires more input energy than it produces.

Further, fusion requires fuel... what are you expecting to fuse, iron? Hydrogen is the only element that we can hope to efficiently use at this point, but 'free' hydrogen is hard to obtain, and limited, just like any other fuel. Cracking hydrogen from water takes as more energy than it makes, by definition.

Do you believe that with fusion we're getting something for nothing? Surely you know that fusion requires free, fusiable elements and is another fuel based energy source, much like fossil and nuclear fission power.

And you're right about space based infrastructure being expensive to create, but remember that in space a collector could be incredibly thin and light, and thus the payload for a rocket would not be that high. The hardest part of the entire process is lifting materials to orbit.



Do you have more info on the ITER project? Specifically, what are they fusing?

Again, it's likely hydrogen. If we had an unlimited source of hydrogen, we could simply burn it for energy, but that's the problem- we don't. Collecting hydrogen is very difficult because it rises to the edge of the atmosphere, and cracking it from water or other hydrogen compounds is more expensive in terms of energy than fusion can make up for.
I'm going to open up Wikipedia as I write this.

ITER will fuse deuterium and tritium, two isotopes of hydrogen with 2 and 3 neutrons respectively as this reaction yields the best energy output for the circumstances. Both deuterium and tritium are naturally occurring in hydrogen, deuterium one every 6500 or so parts, and tritium significantly less than this, yes in fact, 1 part tritium in water to 10^16 parts hydrogen. Cracking water seems to ring a bell as to gain the fuel sources but I can't remember.

Hmm. Current tritium is sourced from certain nuclear reactors on the level of a few kilograms a year. I am looking to find out how deuterium is harvested from water but I cannot find it.