Reference: Moore, Thomas A., A General Relativity Workbook, University Science Books (2013) – Chapter 16; Problem P16.1.
The crude calculation presented earlier gives the energy at infinity of a particle created near the event horizon of a black hole as
In GR units
For a solar mass black hole , so
In other units, this is (using )
This is an almost unimaginably small energy. For comparison, the energy of a single photon of visible light (with a wavelength of 500 nm) is around 2.5 eV: