Where Does Solar Energy Come From

Where does solar energy come from?

We’ve posted several times on the different ways of gathering solar energy — PV, solar thermal, commercial plants using concentrated solar power… This time we’re going straight to the source. We’re going to look at how the sun makes power for us to use.

Our sun is just one more star. Look up at the night sky, and you’ll see that our universe is full of them. It’s only distance that makes the stars look so tiny — most of them would be just as big and bright as our sun if we got up close, and some would be bigger still.

Stars form when great clouds of hydrogen gas — the basic material of the universe — coalesce under the force of gravity. As the hydrogen atoms are driven closer and closer together, they heat up to immense temperatures. Eventually the densely-packed and superheated atoms join together to form new elements, first helium and then carbon, nitrogen, oxygen….

Fusion power

In fact, stars are the cosmic forges for making the heavier elements needed to do interesting chemistry — like the reactions that run your body. Well, that a whole other story. What interests us here is that the fusion reactions which produce helium and other substances from simple hydrogen also release immense amounts of energy. Depending on the star, this may take the form of heat, light, X-rays ultraviolet and/or nuclear radiation.

Fortunately for us, our sun makes a lot of heat and light, and not too much dangerous electromagnetics. And it will go on behaving that way. One day it will use up all of its hydrogen fuel and die, but that won’t be for millions of years.

Since the sun will keep on lavishing all those multi-megawatts on us every day, we believe in making the most of it. We’d like to see solar panels on every roof and in every driveway, enough panels that no-one on earth ever has to burn a tree or drill oil out of a seabed again. Think that sounds over-ambitious? Take a look at this.

Dyson sphere

The scientist Freeman Dyson points out that the sun radiates in all directions. The Earth, a relatively tiny object in a distant orbit, receives only a tiny fraction of the total. Dyson proposes using all the material within the solar system to build a sphere enclosing the sun, thus trapping all of its immense energy output for our own purposes. Let’s break down Jupiter and Saturn and the asteroids and use them to build gigantic solar arrays! He suggests looking for Dyson spheres in the universe as evidence of advanced life.

Now, we probably won’t be building a Dyson sphere anytime soon. But maybe Freeman’s ideas will put those solar panel plans of yours into perspective…