The heat on Europa would not come from the sun but from the gravitational friction (tidal flexing) caused by Jupiter. This would likely cause quite a bit of volcanic activity under the surface and possibly create deep underwater vents. There is an analogue on earth in the deep ocean and the so-called hydrothermal vents. There are ecosystems down there that exist without energy from the sun.
We've pushed out the boundaries where earthly life is found a few 10s of degrees hotter and colder. I'd take that statement more seriously if it was a few 100s.
The range of temperatures over which water is a liquid (assuming reasonable pressures) is well within the range of temperatures that sustain life on this planet.
Man, I would love to see a probe that can find out if there is life on Europa in my lifetime. That would be so amazing.