Solar Constant

The various sources of energy can be roughly divided into renewable and non-renewable energy. The non-renewable forms of energy are the coal, petroleum, natural gas and other such fossil fuels. These have manifested after having been dried and buried under suitable temperature and pressure conditions.

The renewable forms of energy include wind energy, solar photovoltaic energy, solar thermal energy, tidal energy, geothermal energy, hydro energy etc. Wind energy uses the kinetic energy of winds and uses it to rotate a shaft that in-turn generates electricity. Photovoltaic cells directly convert solar radiation to electron movement through the depletion region of the cell. Solar thermal power plants use the thermal energy from solar radiation and use it to evaporate steam that then run turbines. Geothermal energy is used along the same lines as thermal power plants and tidal energy is used to run turbines, the same way it is done in hydro energy.

The common denominator is that these methods of large scale energy generation give the common output, electricity. This is the primary route of utilization of energy both for domestic and industrial purposes. However there is another factor that commonly goes unnoticed, the common destination does not receive energy unless the common source provides it. The common source being the sun.

The Earth is heated from the sun by unequal amounts (because of the Earth’s “tilt”) which creates a pressure difference between different areas of our planet. Due to this unequal heating, large masses of air move from one location to another and we experience them as winds. The incident rays of the sun on the PV panels provide just the right amount of energy for the excitation of electrons so as to cross the band gap to generate electricity. Solar thermal power plants reflect and concentrate the Suns rays to heat an area. Tides are another phenomenon that occur due to the gravitational effects of the moon and the sun (though primarily because of the moon in this case).

Even the fossil fuels need to be dried and be provided with suitable physical conditions to form from the slow processes that we know of. These conditions are maintained with the assistance of reactions that go on in the core of the Earth.

Though, when we compare the core temperatures of the Earth and the Sun, the Earth has been touted to have a core temperature of 6000^oC whereas the sun has an estimated temperature of about 15000000°C (don’t strain your eyes, there are 6 zeros). This clearly tells us about the amount of energy possessed by both these sources. This core temperature of the Earth provides energy to facilitate the formation of fossil fuels.  When comparing these core temperature with the surface temperature values of the sun (about 5000^oC) it becomes evident why environmentalists create such a racket about using renewable energy sources. The surface of the sun continually emits radiations throughout the solar system, a fraction of which is enough to sustain life on a planet.

The intensity of the radiation of the Sun on the Earth, at a mean distance of one Atmospheric Unit from the Sun is called the Solar Constant. The value is 1.361 kW/m² at a minimum and it strays to about 1.362 kW/m² at a maximum when calculations are carried out. This value is not a physical constant and is said to have varied by about .2% over the past 400 years. One can argue hence that it is almost a constant. With the Sun said to possess enough energy to provide energy from to the solar system for at least another 5 billion years, there is no arguing that of all the most faithful friends that we have, the sun remains the most loyal “constant”.

It is a universal fact that the entropy of the world is ever increasing so says the second law of thermodynamics. The Earth as a system, continuously gives off useful energy, because of this law of entropy generation. But it in turn keeps on receiving energy in the form of solar radiation, which largely remains ignored my mankind. With the Earths internal generation means working as fast as it can to make fossil fuels, we must quickly look for means to utilize the immense and moreover constant energy that is being given to us, from the sun. We must aim to utilise this constant solar constant.

Thanks for reading!

PS:  I had written this back in March 2016 for a competition but didn't submit it because the organizers disappeared. I just read it again and have not edited it much because I like to think it represents my thought process at that time (also because I'm lazy).