[dr_lew]

You are neglecting the scaling. This 4E6 tons/c² per second is generated over a huge volume corresponding to the reactive core of the sun. Take one pinhead of that and what do you get?

... That's a question.

[FredZarguna]

The answer is: it doesn’t matter because the energy needed is entirely a function of the temperature required to get two protons close enough for the strong nuclear force to overcome the coulomb barrier, and that is the same whether it is happening in a reactor the size of the sun’s core or a nanotubule.

[Nateman]

Your body actually generates more heat per cubic inch than the sun.