Energy from the Sun
Written by Fraser Cain
Ultraviolet view of the Sun. Image credit: SOHO
Almost all the energy on Earth comes from the Sun. If it weren't for the Sun, the Earth would be a cold, lifeless world. Plants grow because of energy from the Sun, the wind blows, and even fossil fuel are just energy stored from the Sun over millions of years. But how much energy is actually coming from the Sun, and how much of it makes it all the way to the Earth?
As you probably know, in the core of the Sun, the temperatures and pressures are so high that hydrogen atoms are being fused into helium atoms at a rate of 600 million tons per second. In fact, the Sun consumes an equivalent amount of mass to the entire Earth every 70,000 years.
Because of this fusion reaction, the Sun puts out 386 billion billion megawatts of energy. Most of this energy just heads off into space. That's why we can see stars which are light-years away. But enough of that energy reaches the Earth to warm us up.
89000 terawatts actually pass through the atmosphere and reach the Earth's surface. Just for comparison, the total energy use of all human beings is 15 terawatts. So there is 5900 times more energy hitting the Earth from the Sun than humans are currently using. We just need to harness it.
The most effective way to use energy from the Sun is with photovoltaic cells. These convert photons streaming from the Sun into electricity. But energy from the Sun also creates the wind to power wind generators. It grows the crops which are used for biofuel. And as we said at the top of this article, the energy from fossil fuels like oil and coal is just the concentrated solar energy gathered by plants over millions of years.
We've written many articles about the Sun on Universe Today. For example, here's one about how the Sun was shining early on in the history of the Solar System. Don't worry, the Sun isn't responsible for climate change.
Here's an article from the Department of Energy about energy from the Sun, and another cool page for kids.
We have recorded an episode of Astronomy Cast just about the Sun called The Sun, Spots and All.
Filed under: Astronomy
