THE PRIMAL SUN

The sun is a nuclear furnace that radiates fantastic amounts of energy, a very small portion of which is intercepted by planet earth.  That portion, the “Solar Constant”, averages 410 BTUs per square foot per hour at the outer edge of our atmosphere.

About one fourth of that energy is scattered by our atmosphere as the solar rays work through the dust and gases that surround us.  On a clear day, by the time the balance of the sun's radiant energy reaches the ground, it can deliver only about 310 BTUs of heat energy per square foot of surface each hour.  In electrical units, that is about 92 watts per hour per square foot.

That solar energy is a mixture of wavelengths that we classify as Radio, X-ray, Infra-red, Ultra-violet, Visible, and so on.   This wide band is the Electromagnetic Spectrum, all of whose waves travel at about 196,000 miles per second.  The ultraviolet, the visible, and the infrared portions of this electromagnetic spectrum provide the light, the heat, and the electrical input that can be captured as Solar Energy.

Of course, compared to the output of the fossil fuels, solar energy in its direct form is low and slow, too thinned out to melt steel or drive transportation equipment.  However, that energy will still be there, still be free, 20 or 30 years from  now, by which time the demand for fossil fuels will exceed the supply by so much that the homeowner will not be able to afford them. We must start now to invest in the alternatives that we can use, and support those that must be built by organizations with deep pockets.

In addition to the energy that comes to us directly from the sun, there are other energy forms that augment it, including the earth’s gravity, the earth’s rotation, and the gravitational pull of the moon. They will be covered in these pages as well.

Although we cannot see very far ahead, we assume herein that tomorrow’s world will continue to provide for the widespread distribution of electrical power, most of which will come from expensive, high-output generating plants.  How air transport will be served, we know not.  

Converting the sun's energy directly into electricity (photovoltaics) is a high-tech process.   Solar-electric is still too expensive to be used in place of fossil-fired generating plants, or to meet the needs of an individual building, although many isolated locations do use it in lieu of long-distance wiring. 

Even harder to fit into a solar scenario is the storage system that is needed to back up the photo-cells, in order to carry the load when the sun is not shining.  However, the cost of the fossils is rising, and the engineers are reducing the cost of manufacture and installation.   The crossover point may be closer than we think.

Solar Thermal, on the other hand is low-tech, easliy collected and stored. In fact, the oceans and the earth store it for us. We just have to find ways to raise or lower the source temperature by less than 50 degreesF to be comfortable.