  In this paper, we have studied the accretion of phantom energy on a
(2+1)-dimensional stationary Banados-Teitelboim-Zanelli (BTZ) black hole. It
has already been shown by Babichev et al that for the accretion of phantom
energy onto a Schwarzschild black hole, the mass of black hole would decrease
and the rate of change of mass would be dependent on the mass of the black
hole. However, in the case of (2+1)-dimensional BTZ black hole, the mass
evolution due to phantom accretion is independent of the mass of the black hole
and is dependent only on the pressure and density of the phantom energy. We
also study the generalized second law of thermodynamics at the event horizon
and construct a condition that puts an lower bound on the pressure of the
phantom energy.
