Can a concentration of energy in a small region of space produce a black hole?

Yes, but you have to concentrate the energy into a region of space smaller than the event horizon of the black hole you want to create.

Example, for a 0.00001 gram black hole, the region of concentration must be smaller than 10^-33 centimeters which is twenty powers of ten smaller than the nucleus of an atom.

For a one trillion kilogram black hole, the size is about that of a proton. And one trillion kilograms is a LOT of energy according to E = m c^2.

Technically, it is impossible to make black holes artificially.