HARNESSING THE SUN
_The Solar Motor_
It seems daring and wonderful enough, the idea of setting the sun itself
to the heavy work of men, producing the power which will help to turn
the wheels of this age of machinery.
At Los Angeles, Cal., I went out to see the sun at work pumping water.
The solar motor, as it is called, was set up at one end of a great
enclosure where ostriches are raised. I don't know which interested me
more at first, the sight of these tall birds striding with dignity about
their roomy pens or sitting on their big yellow eggs--just as we imagine
them wild in the desert--or the huge, strange creation of man by which
the sun is made to toil. I do not believe I could have guessed the
purpose of this unique invention if I had not known what to expect.
I might have hazarded the opinion that it was some new and monstrous
searchlight: beyond that I think my imagination would have failed me.
It resembled a huge inverted lamp-shade, or possibly a tremendous
iron-ribbed colander, bottomless, set on its edge and supported by a
steel framework. Near by there was a little wooden building which served
as a shop or engine-house. A trough full of running water led away
on one side, and from within came the steady chug-chug, chug-chug of
machinery, apparently a pump. So this was the sun-subduer! A little
closer inspection, with an audience of ostriches, very sober, looking
over the fence behind me and wondering, I suppose, if I had a cracker in
my pocket, I made out some other very interesting particulars in regard
to this strange invention. The colander-like device was in reality, I
discovered, made up of hundreds and hundreds (nearly 1,800 in all) of
small mirrors, the reflecting side turned inward, set in rows on the
strong steel framework which composed the body of the great colander.
By looking up through the hole in the bottom of the colander I was
astonished by the sight of an object of such brightness that it dazzled
my eyes. It looked, indeed, like a miniature sun, or at least like a
huge arc light or a white-hot column of metal. And, indeed, it was white
hot, glowing, burning hot--a slim cylinder of copper set in the exact
centre of the colander. At the top there was a jet of white steam like a
plume, for this was the boiler of this extraordinary engine.
[Illustration: Side View of the Solar Motor.]
"It is all very simple when you come to see it," the manager was saying
to me. "Every boy has tried the experiment of flashing the sunshine into
his chum's window with a mirror. Well, we simply utilise that principle.
By means of these hundreds of mirrors we reflect the light and heat of
the sun on a single point at the centre of what you have described as a
colander. Here we have the cylinder of steel containing the water which
we wish heated for steam. This cylinder is thirteen and one-half feet
long and will hold one hundred gallons of water. If you could see it
cold, instead of glowing with heat, you would find it jet black, for
we cover it with a peculiar heat-absorbing substance made partly of
lampblack, for if we left it shiny it would re-reflect some of the heat
which comes from the mirrors. The cold water runs in at one end through
this flexible metallic hose, and the steam goes out at the other through
a similar hose to the engine in the house."
Though this colander, or "reflector," as it is called, is thirty-three
and one-half feet in diameter at the outer edge and weighs over four
tons, it is yet balanced perfectly on its tall standards. It is, indeed,
mounted very much like a telescope, in meridian, and a common little
clock in the engine-room operates it so that it always faces the sun,
like a sunflower, looking east in the morning and west in the evening,
gathering up the burning rays of the sun and throwing them upon the
boiler at the centre. In the engine-house I found a pump at work,
chug-chugging like any pump run by steam-power, and the water raised by
sun-power flowing merrily away. The manager told me that he could easily
get ten horse-power; that, if the sun was shining brightly, he could
heat cold water in an hour to produce 150 pounds of steam.
[Illustration: Front View of the Los Angeles Solar Motor.]
The wind sometimes blows a gale in Southern California, and I asked the
manager what provision had been made for keeping this huge reflector
from blowing away.
"Provision is made for varying wind-pressures," he said, "so that the
machine is always locked in any position, and may only be moved by
the operating mechanism, unless, indeed, the whole structure should be
carried away. It is designed to withstand a wind-pressure of 100 miles
an hour. It went through the high gales of the November storm without
a particle of damage. One of the peculiar characteristics of its
construction is that it avoids wind-pressure as much as possible."
The operation of the motor is so simple that it requires very little
human labour. When power is desired, the reflector must be swung into
focus--that is, pointed exactly toward the sun--which is done by turning
a crank. This is not beyond the power of a good-sized boy. There is an
indicator which readily shows when a true focus is obtained. This done,
the reflector follows the sun closely all day. In about an hour the
engine can be started by a turn of the throttle-valve. As the engine is
automatic and self-oiling, it runs without further attention. The
supply of water to the boiler is also automatic, and is maintained at
a constant height without any danger of either too much or too little
water. Steam-pressure is controlled by means of a safety-valve, so that
it may never reach a dangerous point. The steam passes from the engine
to the condenser and thence to the boiler, and the process is repeated
indefinitely.
Having now the solar motor, let us see what it is good for, what is
expected of it. Of course when the sun does not shine the motor does not
work, so that its usefulness would be much curtailed in a very cloudy
country like England, for instance; but here in Southern California and
in all the desert region of the United States and Mexico, to say nothing
of the Sahara in Africa, where the sun shines almost continuously, the
solar motor has its greatest sphere of usefulness, and, indeed, its
greatest need; for these lands of long sunshine, the deserts, are
also the lands of parched fruitlessness, of little water, so that
the invention of a motor which will utilise the abundant sunshine for
pumping the much-needed water has a peculiar value here.
[Illustration: The Brilliant Steam Boiler Glistens in the Centre.]
The solar motor is expected to operate at all seasons of the year,
regardless of all climatic conditions, with the single exception of
cloudy skies. Cold makes no difference whatever. The best results from
the first model used in experimental work at Denver were obtained at a
time when the pond from which the water was pumped was covered with a
thick coating of ice. But, of course, the length of the solar day is
longer in the summer, giving more heat and more power. The motor may be
depended upon for work from about one hour and a half after sunrise to
within half an hour of sunset. In the summer time this would mean about
twelve hours' constant pumping.
Think what such an invention means, if practically successful, to the
vast stretches of our arid Western land, valueless without water. Spread
all over this country of Arizona, New Mexico, Southern California, and
other States are thousands of miles of canals to bring in water from
the rivers for irrigating the deserts, and there are untold numbers of
wind-mills, steam and gasoline pumps which accomplish the same purpose
more laboriously. Think what a new source of cheap power will do--making
valuable hundreds of acres of desert land, providing homes for thousands
of busy Americans. Indeed, a practical solar motor might make habitable
even the Sahara Desert. And it can be used in many other ways besides
for pumping water. Threshing machines might be run by this power, and,
converted into electricity and saved up in storage batteries, it might
be used for lighting houses, even for cooking dinners, or in fact for
any purpose requiring power.
These solar motors can be built at no great expense. I was told that
ten-horse-power plants would cost about $200 per horse-power, and
one-hundred-horse-power plants about $100 per horse-power. This would
include the entire plant, with engine and pump complete. When it is
considered that the annual rental of electric power is frequently $50
per horse-power, whether it is used or not, it will be seen that the
solar motor means a great deal, especially in connection with irrigation
enterprises.
[Illustration: The Rear Machinery for Operating the Reflector.]
And the time is coming--long-headed inventors saw it many years
ago--when some device for the direct utilisation of the sun's heat will
be a necessity. The world is now using its coal at a very rapid rate;
its wood, for fuel purposes, has already nearly disappeared, so that,
within a century or two, new ways of furnishing heat and power must be
devised or the human race will perish of cold and hunger. Fortunately
there are other sources of power at hand; the waterfalls, the Niagaras,
which, converted into electricity, may yet heat our sitting-rooms and
cook our dinners. There is also wind-power, now used to a limited extent
by means of wind-mills. But greater than either of these sources is the
unlimited potentiality of the tides of the sea, which men have sought in
vain to harness, and the direct heat of the sun itself. Some time in
the future these will be subdued to the purpose of men, perhaps our main
dependence for heat and power.
When we come to think of it, the harnessing of the sun is not so very
strange. In fact, we have had the sun harnessed since the dawn of man
on the earth, only indirectly. Without the sun there would be nothing
here--no men, no life. Coal is nothing but stored-up, bottled sunshine.
The sunlight of a million years ago produced forests, which, falling,
were buried in the earth and changed into coal. So when we put coal in
the cook-stove we may truthfully say that we are boiling the kettle with
million-year-old sunshine. Similarly there would be no waterfalls for
us to chain and convert into electricity, as we have chained Niagara, if
the sun did not evaporate the waters of the sea, take it up in clouds,
and afterward empty the clouds in rain on the mountain-tops from whence
the water tumbles down again to the sea. So no wind would blow without
the sun to work changes in the air.
In short, therefore, we have been using the sunlight all these years,
hardly knowing it, but not directly. And think of the tremendous amount
of heat which comes to the earth from the sun. Every boy has tried using
a burning-glass, which, focusing a few inches of the sun's rays, will
set fire to paper or cloth.
Professor Langley says that "the heat which the sun, when near the
zenith, radiates upon the deck of a steamship would suffice, could it be
turned into work without loss, to drive her at a fair rate of speed."
The knowledge of this enormous power going to waste daily and hourly has
inspired many inventors to work on the problem of the solar motor. Among
the greatest of these was the famous Swedish engineer, John Ericsson,
who invented the iron-clad Monitor. He constructed a really workable
solar motor, different in construction but similar in principle to the
one in California which I have described. In 1876 Ericsson said:
"Upon one square mile, using only one-half of the surface and devoting
the rest to buildings, roads, etc., we can drive 64,800 steam-engines,
each of 100 horse-power, simply by the heat radiating from the sun.
Archimedes, having completed his calculation of the force of a lever,
said that he could move the earth. I affirm that the concentration of
the heat radiated by the sun would produce a force capable of stopping
the earth in its course."
A firm believer in the truth of his theories, he devoted the last
fifteen years of his life and $100,000 to experimental work on his solar
engine. For various reasons Ericsson's invention was not a practical
success; but now that modern inventors, with their advancing knowledge
of mechanics, have turned their attention to the problem, and now that
the need of the solar motor is greater than ever before, especially
in the world's deserts, we may look to see a practical and successful
machine. Perhaps the California motor may prove the solution of the
problem; perhaps it will need improvements, which use and experience
will indicate; perhaps it may be left for a reader of these words to
discover the great secret and make his fortune.