  We discuss how cosmic strings can be used to mine energy from black holes. A
string attached to the black hole gives rise to an additional channel for the
energy release. It is demonstrated that when a string crosses the event
horizon, its transverse degrees of freedom are thermally excited and thermal
string perturbations propagate along the string to infinity. The internal
metric induced on the 2D worldsheet of the static string crossing the horizon
describes a 2D black hole. For this reason thermal radiation of string
excitations propagating along the string can be interpreted as Hawking
radiation of the 2D black hole. It is shown that the rate of energy emission
through the string channel is of the same order of magnitude as the bulk
radiation of the black hole. Thus, for N strings attached to the black hole the
efficiency of string channels is increased by factor N. We discuss restrictions
on N which exist because of the finite thickness of strings, the gravitational
backreaction and quantum fluctuations. Our conclusion is that the energy
emission rate by strings can be increased as compared to the standard emission
in the bulk by the factor 10^3 for GUT strings and up to the factor 10^{31} for
electroweak strings.
