So in order to extract 5g of C14 you would have to process 5 x 10^12 g (or 5 million) tonnes of raw Carbon. That's an awful lot of balls, Bucky or otherwise..

And since all isotopes of an element are chemically identical, there is no cheap, chemical method of extracting the C14 from coal or CO2 or any other source of carbon. Think of it this way: U235 is about 5% of raw Uranium (U238),
This is why we needed Oak Ridge to fuel one nuclear bomb (just a few pounds of U235 to use on Japan, and this is why Iran is having to invest so much on centrifuges to enrich their Uranium to weapons grade.

This sounds as physically impossible as those lunatic schemes for "sequestering excess carbon dioxide out of the atmosphere". Some things can't be done, even if they do not violate the laws of physics.

This research is using C14 to provide tiny, lightweight power sources for applications that require very low levels of long-lasting energy, but must be safe and durable enough to withstand the rigors of space travel. For example, in microsats. Maybe the C14 power source can run the night light, but certainly not the com laser.