You Might
want to look here for some related info I provided Raoul on the question of Enceladus generating the E-ring. All things are relative, but the heat source sure is significant on a mere 500 km world. As far as life goes I'd bet it's energy per unit area or volume that matters far more than total available energy in terms of supporting life. Evolution of complexity though should be somewhat a function of total energy due to a greater possible number of random variations.
Regards,
Mark