EMC2 Corp. (the polywell fusion guys) are working to discover if boron can be used as a fuel for nuclear fusion. As the boron cycle is aneutronic (no neutrons), electricity can be extracted directly and very efficiently (as opposed to generating steam and using steam turbines to generate power), hence I’m not going to consider efficiency issues which would be very complex in any case. But enough chit-chat, let’s have a closer look at the energy production math for such a boron cycle reactor and the resources we have to fuel it . . .
Given:
The annual world-wide boron production is ~1,000,000 tons. And,
1000000 (1 × 106) metric tons = 1 × 1012 grams. And,
1 mole of Boron = 10.81 grams. So:
1 × 1012 g ÷ 10.81 g/m
= 9.251 × 1010 moles
boron11 isotope is only 80.1% of all total boron isotopes, so we’ll slice out 20%, leaving us with: 7.4 × 1010 moles of boron11.
The energy yield from the expenditure of one atom of boron11 is:
p + boron11 → 3He4 + 8.7 MeV
1 MeV = 1.61 × 10-13 joules. So:
8.7MeV × 1.61 × 10-13 J/MeV
= 1.394 × 10–12 J
1.394 × 10–12 J is released for every successful fusion reaction of one Boron11 atom and one proton. And
There are 6.022 × 1023 atoms of boron11/mole (Avagodro’s number). So:
1.394 × 10–12 J/atom × 6.022 × 1023 atms/m
= 8.394 × 1011 J/m
Multiplying the (Joules/mole) × (total moles) yields total joules. So:
8.394 × 1011 J/m × 73998705022.64 m
= 6.211 × 1022 J
1KWH (kilowatt hours) = 3.6 × 106 Joules. So:
6.211 × 1022 J ÷ 3.6 × 106 J/KWH
= 1.725 × 1016 KWH
Hence we are currently only mining enough boron11 to produce 17,250,000,000,000,000 KWH every year.
In 2008, total worldwide energy consumption was 474 exajoules (474 × 1018 joules)
Putting it in perspective, the boron mined in one year could produce enough energy to last approximately 131 years (at 2008 levels of consumption).
Is that sustainable? I dunno. define sustainable? I think it looks pretty sustainable to me. With that amount of energy at our fingertips, we can mine asteroids and other planets and moons, and is thus mostly unlimited as far as humanity is likely concerned
I did pretty much the same calculations a few years ago, and came to the same conclusion.