Understanding the Sun and Solar Energy

by: EJ on 06/28/2017

With solar employing more people in US electricity generation than oil, coal and gas combined, we thought that for today’s blog post we would take a page form Dan Chiras’ book Power from the Sun-2nd Edition: A Practical Guide to Small-Scale Solar Production and found out how do we generate power from the sun and can it really meet all our energy needs?

Images_Powerfromthesun_caption at top of blog

The Sun lies in the center of our solar system, approximately 93 million miles from Earth. Composed primarily of hydrogen and small amounts of helium, the Sun is a massive nuclear reactor. However, it’s not the same type of reactor found in the nuclear power plants that some utility companies use to generate electricity. Those are fission reactors designed to split atoms of uranium-235 in a controlled fashion. The heat generated in this process boils water to generate steam. Steam spins a turbine that drives a generator that produces electricity.

The Sun is a giant fusion reactor. Nuclear fusion occurs in the Sun’s core, where intense pressure and heat force hydrogen atoms to fuse. This results in the formation of slightly larger helium atoms and immense amounts of energy. This energy migrates to the surface of the Sun, taking up to a million years to make it there. When this energy reaches the surface of the Sun, it radiates into space, primarily as light and heat.

Solar radiation streaming into space strikes the Earth, warming and lighting our planet and fueling virtually all life. What’s remarkable, though, is that the Earth receives only a tiny fraction of the Sun’s output — less than one billionth of the energy that radiates from its surface. Although our allotment is small, “the solar energy received each year by the Earth is roughly...10,000 times the total energy consumed by humanity,” according to French energy expert, Jean-Marc Jancovici.

To replace all the oil, coal, gas, and uranium currently used to power human society with solar energy, we’d only need to capture 0.01% of the energy of the sunlight striking the Earth each day. Forty minutes worth of sunlight is equivalent to all the energy consumed by human society in a year!

According to the US Department of Energy’s National Renewable Energy Laboratory (NREL), to generate the electricity the United States consumes, we’d only need to install PVs on 7% of the land surface area currently occupied by cities and homes. We could achieve this goal by installing PVs on rooftops of homes, factories, and office buildings; over parking lots; and on the south sides of buildings where solar arrays could serve as awnings. We wouldn’t have to appropriate a single acre of new land to make PV our primary energy source!

Want to read more? You can receive a 35% discount on Power from the Sun-2nd Edition or any other New Society title until June 30th

Enter Summer17 at the checkout



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