  It has been recently shown that magnetic reconnection can provide us a novel
mechanism to extract black hole rotational energy from a Kerr black holes. In
this paper, we study the energy extraction from the Kerr-de Sitter black hole
via this magnetic reconnection process. The result shows that, with the
increase of the cosmological constant, a slowly spinning Kerr-de Sitter black
hole can implement the energy extraction better than its Kerr counterpart.
Interestingly, although the numerical results show that the maximum values of
the power and efficiency slightly decrease with the cosmological constant,
Kerr-de Sitter black hole still has significant advantages when the black hole
spin is larger than 1 and the dominant reconnection $X$-point is far away from
the event horizon. This is mainly attributed to the higher upper spin bound and
wider ergosphere in the presence of the cosmological constant. These results
uncover the significant effects of the cosmological constant on the energy
extraction via the magnetic reconnection process.
