Evening star. [volume] (Washington, D.C.) 1854-1972, 1931-04-19
Energy From Sun
By Electricity Seen

Continued From First Page)
ance in a circuit already in existence
and supplied with voltage from any
suitable source. The first report of
any method Of obtaining photo-electric
energy directly from light was that by
DR.. Paul H. Geiger and the author at
the Toronto meeting of the American
Association for the Advancement of
Science held in December, 1921. 1t
was shown that many natural crystals,
especially argentite, produced q current
when illuminated. The crystal, clamp
ed at both ends, was connected di-
rectly to a current-indicattng instru-
ment, Illuminated, and q current shown
to exist.
The crude method was later improved
upon by DR.. Geiger and DR.. L. o. Gron-
dahl, who invented the so-called copper
oxide cell. A copper-oxide cell Of an
improved form has been used by DR..
Lange to drive a small motor In the
SiemanS laboratories. The new cell,
which DR.. Lange has announced, is a
silver-selenide cell. This material is
coated with a layer Of selenium of mole
cular Dimensions. Light passing through
this current sets up currents between
the silver-Selenide and the selenium
will produce so to $50 times as much
current as the copper-oxide cell. This
should bring the method within eco
nornic limits.
But, assuming that the cost of build
ing the necessary cell surface Is not
excessive, there are still two more prob
lens TO be confronted. One of these
is space. It Is estimated that to gen.
crate 100000 kilowatts Of energy q
square mile of surface would be need
ed. This offers q tremendous obstacle
at any place where the power would
be likely to be needed. The other OBJ
stacle is that Of power storage to take
care of the load during darkness or to
pick up the load during the passing of
a cloud. This problem would not only
be one difficult to solve, but the neces-
sary equipment would occupy a great
deal of space and be costly both to
provide and to maintain as we'll. Our
present methods of storing electrical
energy are very unsatisfactory. Per-
haps this will provide the next point of
attack.
The fact remains. however, that we
have made remarkable progress in the
solution Of q problem which will not
face us for many years, or even GEN.
turtles, to come. When oil has failed
US we still have coal resources SUM-
cient to supply us with energy for CEN
turtles. We already know how to pro-
duce gasoline for our motors from coal
Our water power, already in use, will
still be available. Wind mills are still
subject to further development
Georges Claude has shown us how to
get power from the tropical ocean by
utilizing the difference in temperature
between the surface and q depth. H.
Barjot had devised a method for OBJ
tanning power in the Arctic by har-
Messing the temperature difference be-
tween the surface and the water under
the ice.
Our improved agricultural methods
will release acres and acres Of land for
the growth of quick-growing plants
from which we can obtain alcohol for
motor fuel or which we can burn d.
rectly underneath our furnaces. And
now we are well on our way toward
solving the problem of obtaining power
directly from sunlight. Posterity will
have little to complain of If, instead of
oil wells. We leave them something in
fnitely better.