Isobe, Syuzo
National Astronomical Observatory of Japan

Currently, we can measure the distribution of light intensity over the terrestrial
surface using data from the DMSP (Defense Meteorological Satellite Program)
and evaluate light energy loss (ref. Isobe and Hamamura). Recently we have,
with their kind co-operation, obtained energy production data from the nine
Japanese electrical energy generation companies.

From these data we have obtained a linear relation between light energy loss
observed over the different territories of each of these companies versus the
electrical energy generated. These data show that light energy loss to space is
equivalent to about 0.1 % - 0.2 % of the energy generated. More detailed
investigation shows that the graphs for each company do not pass through
the origin; the postive light-energy-loss loss intercept varies between different
companies. These results suggest that there are additional light-energy sources
such as that ejected from the headlights of cars.

It is now clearly shown that the total annual light energy loss of Japan is
about 100 to 200 million US dollars per year and it is expected to be well
over 1 billion US dollars per year world-wide.