My name is Ryan and I have pondered this question for a long time but I have a limited knowledge on space physics. What type of energy does a black hole produce (electrical, thermal ect.)?
The only way we can detect black holes is through the effect that their gravitating mass has on objects outside the event horizon. These objects can gain energy from the black hole, as they fall into the potential well they heat up and radiate (often in the X-ray region of the spectrum). So black holes have gravitational energy from their mass. A black hole could also have charge, but this is rare in the universe which is largely neutral. Many black holes probably rotate, and these also have rotational energy.
Karen was a graduate student at Cornell from 2000-2005. She went on to work as a researcher in galaxy redshift surveys at Harvard University, and is now on the Faculty at the University of Portsmouth back in her home country of the UK. Her research lately has focused on using the morphology of galaxies to give clues to their formation and evolution. She is the Project Scientist for the Galaxy Zoo project.