  Higher-dimensional scenarios allow for the formation of mini-black holes from
TeV-scale particle collisions. The purpose of this paper is to review and
compare different methods for the estimate of the total gravitational energy
emitted in this process. To date, black hole formation has mainly been studied
using an apparent horizon search technique. This approach yields only an upper
bound on the gravitational energy emitted during black hole formation.
Alternative calculations based on instantaneous collisions of point particles
and black hole perturbation theory suggest that the emitted gravitational
energy may be smaller. New and more refined methods may be necessary to
accurately describe black hole formation in high-energy particle collisions.
