There's some evidence for volcanism (which was a surprise to me), but it's probably far less geologically active than the Earth.
Any way, the point is not to have energy as an absolute value, but to have energy that you can use. Useful energy input. You can't extract energy from heat. For example, you'd be unable to set a colony inside the sun due to the lack of extractable energy. If you had energy, you could use it to cool down the colony enough so you can safely stay inside the sun. But you simply can't find the energy to use to cool your colony down, which is why you can't have a colony inside the sun.
Venus is a less extreme example of that.
(Well, you could run a fission reactor on Venus or a fusion reactor on the Sun, so it's not completely out of the question, but beside that, nothing.)