  We analyze the energy extraction by the Penrose process in higher dimensions.
Our result shows the efficiency of the process from higher dimensional black
holes and black rings can be rather high compared with than that in four
dimensional Kerr black hole. In particular, if one rotation parameter vanishes,
the maximum efficiency becomes infinitely large because the angular momentum is
not bounded from above. We also apply a catastrophe theory to analyze the
stability of black rings. It indicates a branch of black rings with higher
rotational energy is unstable, which should be a different type of instability
from the Gregory-Laflamme's one.
