yeah, but like i said, its irrelevant... first, the science is sketchy.. all they said was the core of the planet generate energy... but not how it does so... i know they said something about radiation etc... but without getting into the Theory of Nuclear Power, radiation etc doesnt generate power without a generator...
basically, we saw in the first episode a hologram of the location of Earth in relation to the Destiny, and yeah, it was a fair few galaxies away. but like i said, they've moved away from some basic Stargate canon which calls the whole range thing into question...
technically... there has to be more energy in a Star than in any planet, no matter how exotic it's core is... once they get control of the ship, theory would dictate that they park themselves in a star, soak up all the power they can, or even just channel some straight into the gate like they did in that episode where the scientists from Earth came to 'help'
of course... if that happened there would be no story... so really i think we are stuck with these people until the bitter (however shortlived) end