How Much Solar Energy per Square Foot Hits the Earth?
Solar energy results when you convert sunshine to power but how much solar energy per square foot hits the earth? This is part of the discussion when considering whether solar energy can be used to replace the traditional energy sources we are accustomed to.
Of course, the other part of the question is how much of that solar energy can we capture, convert to power and use?
More Than Enough Solar Energy per Square Foot Hits the Earth
It may surprise you to learn that more than enough solar energy per square foot hits the earth to provide a solution for the entire energy consumption of the earth. This is measured in watt hours by scientists. The earth has 197 million square miles of surface which includes the surface of the oceans.
The solar energy reaching the earth is 12,211 gigawatt/hour. Using the measurement of the earth's surface and the number of hours in a year, scientists conclude the earth receives 82 million quads of Btu energy from the sun each year. A "quad" is one quadrillion British Thermal Units (BTUs) of energy.
The total solar energy that hits the earth each and every year is enough to provide 20,000 times the power used by the entire human race. Those numbers are staggering but they explain why there is so much excitement about solar energy.
The sun is doing its part to send energy to us on Earth. In a perfect world, every home and appliance and vehicle on earth would be powered by the clean energy of the sun.
The Problem is Human
The problem is not in how much solar energy per square foot hits the earth each day or each year. The problem is we have not yet fully developed our capability for harnessing and using that free energy. To be truly useful, technology must be able to capture the sun's energy, store it and convert it to usable electricity at a reasonable cost.
We have always used the sun's energy as far back as humans have existed. Five thousand years ago, there were civilizations that worshipped the sun god, Ra. This god was believed to have been the first kind of Egypt. Shamash was the sun god in Mesopotamia; in Greece, Apollo and Helios were deities related to the sun.
Over the centuries, the sun's energy has been recognized by humans and worshipped for its power. Many religions still practiced today were influenced by the worship of the sun. These include Hinduism, Buddhism, the Druids, Astecs and many Native American Indian tribes. The sun was worshipped because of the heat it provided but primarily because of solar energy.
The term "solar energy" is fairly new but for thousands of years people have understood the power of the sun to grow crops and raise livestock. It is the sun's rays that dry laundry on an outdoor clothesline and the power of the sun whitens and sterilizes the clothing dried out of doors.
The sun has a primary place in the history of our survival as a species. It is sunlight that makes the plants grow and the plants that feed wildlife and livestock to provide food for us all. In one way or another, the sun is responsible for all of the energy on earth.
Fossil fuels are coal, oil and natural gas. These were formed millions of years ago during the Carboniferous Period (part of the Paleozoic Era). Thus the word "carbon", which is used to refer to the basic ingredient in coal.
The earth was full of swamps, ferns and huge trees and the seas were full of algae. Algae is composed of millions of tiny plants and is the slimy green substance that forms on a surface where there is standing water. As the plants and trees died they were covered by swamp water and formed a substance called peat.
Eons later the peat had been buried by clay, sand and sedimentary rock formed by minerals in the swamps. Rocks continued to form and pressed down on the decaying plant matter.
The decay process was fed by the heat from the sun and after millions of years those ancient plant materials became the oil, coal and gas we harvest for power today. Even the radioactive materials we use to day can be trace back to solar power. Nuclear energy is the result of uranium created by an exploding star.
The Answer is Technology
Technology is working overtime to harness the power of solar energy. In part this is due to the clean power produced by the sun. The particulates and pollution produced by coal and oil has become an environmental problem for many cities. Also concerning is the estimate of the reserves of oil left in the earth as this is not an infinite resource.
The relatively new knowledge of how much solar energy per square foot hits the earth has been a catalyst to development of new methods of harnessing the power of the sun. There is no doubt the energy is limitless and the only limit to use of solar energy is finding ways to capture it and convert it to electricity.