A note on the Penrose process in rotating regular black holes

We investigate the Penrose process of energy extraction in the context of rotating regular black holes. For the Neves-Saa class of regular black hole solutions, which includes the Bardeen, Hayward and Fan-Wang spacetimes as special cases, the extraction efficiency is bounded above by the known value for Kerr spacetime. However, in the case of a new rotating regular black hole which does not have a Schwarzschild singular limit for zero rotation, the extraction efficiency can indeed become very large, as shown in our analysis here.