  We investigate whether, and to what extent, the physical phenomenon of
long-lifetime resonant electromagnetic states with localized slowly-evanescent
field patterns can be used to transfer energy efficiently over non-negligible
distances, even in the presence of extraneous environmental objects. Via
detailed theoretical and numerical analyses of typical real-world
model-situations and realistic material parameters, we establish that such a
non-radiative scheme could indeed be practical for medium-range wireless energy
transfer.
