What is Meant by Solar Energy ?

In popular usage the term solar energy is usually used to refer to usable forms of energy, especially electrical energy, derived from sunlight. Sunlight can be used to provide usable energy in three ways. The first and most obvious way is through the heating effect of light. Frequently heating is an undesirable effect of sunlight. Fortunately the heating effect can be used to provide the power to cool or do other useful things. The heating effect of sunlight is also responsible for wind, which can be used as a power source,

The second way that sunlight can be used to provide power is through photosynthesis or other photochemical reactions. Photosynthesis first appeared on Earth about 3.4 billion years ago. Photosynthesis is the process by which the energy from light is used by plants and some other micro-organisms to produce carbohydrates such as sugar. Sugars are used by most life-forms on Earth to supply the energy for growth and most life-functions.

The third way that sunlight energy can be captured is through the photovoltaic effect. The photovoltaic effect converts light energy directly into electricity. The first known photovoltaic cell was developed by A.E. Becquerel in 1839. Photovoltaic cells were basically a laboratory curiosity until about 1960 because the technology to produce them at any reasonable price did not exist until the space race of the late 1950s forced the development of an industry which had a need for such technology. It is worth noting that this program was a project funded by the people through their state, not by private industry. Of course, a large and powerful industrial complex profited by this program, but it was paid for by the people.

Today we are in a situation similar to the space race. Now we are in an energy race. Barring some scientific breakthrough in an unexpected area, development of large scale renewable solar energy collection technology is the most likely solution to the energy technology needed for the future survival of mankind.  I use the term renewable solar energy because most fossil fuel is, in fact, stored solar energy which is not  easily renewable.

For billions of years after photosynthesis appeared on Earth life was dominated by simple organisms that could survive in the harsh conditions that existed on the primeval Earth. Vast amounts of carbon was removed from the atmosphere and stored in the form of bio-mass, coal, oil, and natural gas. At the same time, much Oxygen was freed into the atmosphere, making modern life possible.

When fossil fuels are used to produce power they remove oxygen from the atmosphere and release carbon dioxide and carbon monoxide into the atmosphere. We need oxygen to survive. Carbon dioxide at increased levels becomes toxic to humans. Carbon monoxide is toxic at virtually any level.

Carbon dioxide is also what is called a greenhouse gas. When sunlight heats the Earth the Earth tries to radiate heat back into space by way of infra-red light. Greenhouse gasses trap that infra-red light, which keeps the heat energy on Earth .When photosynthesis began to remove significant amounts of carbon from the atmosphere the average temperature on Earth began to fall because there was less carbon dioxide to trap the heat. When coal and shale-oil are mined large amounts of methane are released into the atmosphere because methane is trapped in the geologic formations holding coal and shale oil. Methane is a far worse greenhouse gas than carbon dioxide . Utilizing solar energy can help combat global warming, as it has in the past.