A bathtub per person per 30 years doesn't sound very efficient.. That's a lot of bathtubs per day for all of humanity.

so have you heard of these things called....uhhhh... OCEANS?

..Warning, bad calculations ahead..
The population of humons on planet earth is 6 milliard. Lets assume half the energy usage will be replaced by fusion. A human lives to about 60 years, which is 2 bathtubs. In total the current population of earth would then need 6 * 10^9 bathtubs for their entire lives. About 1,460 teratonnes of water exists on earth, which is about 5 times that amount in bath tubs. Which means we have about 7,500 * 10^12 bathtubs.

(7,500 * 10^12) / 60 * (6 * 10^9) = 75,000,000 years until we run out of water. Seems reasonable..

Nice sift, thanks for posting.

Physics rules.

The Fusion they are describing here is done with deuterium-tritium. (1)

Deuterium is a stable Hydrogen form that can be found in "abundance" in ocean water. (2)
".... approximately one atom in 6500 of hydrogen (~154 PPM). Deuterium thus accounts for approximately 0.015% (on a weight basis, 0.030%) of all naturally occurring hydrogen in the oceans on Earth" (2)

Tritium is an unstable hydrogen Isotope, also found naturally though not as often. It is found in abundance on the moon. (3)

In other words, of that bathtub, only 0,015% of the hydrogen is actually used. 2 hydrogens are still a lot lighter then 1 oxygen (H2O ;-), so in total only a fraction of 0,015% of all the water is used. After that, we will have to use other materials. Since all of the materials you find on earth are made in the sun through Fusion, well, you can see how endless our fuel supply is. If technology can find ways to harvest the energy without blowing us all up.

One thing though: Fusion also creates radioactive materials. It is less of a problem then with Fission, but they are still there. Dont know why they mention it does not.

(1) http://en.wikipedia.org/wiki/Nuclear_fusion
(2) http://en.wikipedia.org/wiki/Deuterium
(3) http://en.wikipedia.org/wiki/Tritium

It would of course be more accurate to say a bathtub of HEAVY water. Strictly speaking they are right that the fusion reaction itself does not create radioactive isotopes but the high energy neutrons released do activate the metal in the structure. The isotopes created are short lived though and the reactor could be buried on site for only 50-100 and would then be safe. tritium is not found on the moon, only helium 3.

Love the last line... there is NO downside, no risk to living next to a fusion reactor.... but ... we do like to build them behind 6 foot concrete walls and giant sliding steel doors and super magnetic containment facilities and personally, we're going to be in another location altogether controlling the damn thing with puffs of air only...

He's perfectly correct. There is no downside to living near one. All the neutron radiation emitted by the reactor is blocked by its concrete containment structure, magnetic fields can not escape the building and the reaction is incapable of going out of control.

Is it really more efficient to first produce tritium (through fission from lithium) and then use it and deuterium for fusion? I mean wouldn't it be easier to just use D-D fusion for example and compensate for the worse efficiency by skipping the tritium production phase? I'm sure this is exactly the best place on the internet to ask such questions!

*dead

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