Energy Extraction from the Einstein-Born-Infeld Black Hole
  The energy extraction from a Einstein-Born-Infeld (EBI) black hole is addressed determining the extension of the ergosphere as well as the extractable energy using the irreducible mass concept. These results are compared with the Reissner-Nordstrom (RN) ones; RN is the linear electromagnetic counterpart of the BI black hole. It turns out that for a fixed charge Q, more energy can be extracted from the RN black hole than from the EBI one. The extreme case is investigated as well, presenting remarkable features, for instance that more energy can be extracted from extreme EBI black holes than from extreme RN, however, extreme EBI black holes lack of a linear electromagnetic black hole limit. 
Nora Breton
gr-qc