How is the sun relates to different sources of energy on the earth?

Answer 1

This is a complicated question, so you're going to get a long answer.

One could argue that every source of energy ultimately comes from the stars, but not necessarily our sun. Stars are powered by fusion, in which four hydrogen atoms are fused into two helium atoms. (Yes, other fusion reactions go on in later stages of the star's life, but hydrogen fusion is by far the most common).

Energy sources that come from our sun in particular are fossil fuels, hydroelectricity, biomass, wind, photovoltaics, and solar thermal.

Fossil fuels came from ancient life forms (plants and plankton) that used the energy from photosynthesis to produce biomass. They died, became buried, and were transformed over millions of years by heat and pressure deep inside the earth.

Hydroelectricity comes from rivers fed by rain, and the rain comes from the sun's energy evaporating water from the oceans, lakes, and the land.

Biomass, such as wood, is produced by biochemical processes powered by photosynthesis.

Wind is produced because the sun heats up different parts of the earth at different rates, and these temperature differences create air movement.

Photovoltaics is the most direct way of getting useful energy from the sun. Photons of sufficiency energy are absorbed into a semiconductor (Si is the most common one used today), exciting an electron and allowing it to travel in a circuit where it can do useful work.

Solar thermal uses sunlight to heat something, such as water or molten salt, which can be then be stored to provide energy during times of low or no sunlight. The heat can be used to turn water into steam, which can turn turbines to generate electricity.

There are three other sources that come not from our sun, but ancient stars.

Nuclear energy, the kind used in a nuclear power plant, comes from fission of plutonium or uranium. These elements were created in supernova. Our sun will not produce these heavy elements, as it isn't massive enough to die in such a violent way. But bigger stars in the distant past did sometimes go supernova, spewing out these elements which eventually got incorporated into the primordial soup that became our solar system.

Geothermal energy has two sources: gravity and nuclear. As mentioned above, when some stars die, they go boom and spread little bits of dust across the galaxy. Sometimes these clouds condense into solar systems. The heavy stuff, iron, calcium, silicon, oxygen, etc., formed the rocky planets, and the light stuff, hydrogen and helium, formed our sun and the gas planets. As the gas and dust condensed under gravity, that energy turned to heat, some of which is still stored in the core of the earth. But a lot of the earth's heat also comes from radioactive decay, a byproduct of the supernovas discussed above.

Tidal energy, created by the moon as it orbits the earth, is similar to geothermal, in that it is created by gravity, which benefited from those ancient supernova that created the dust clouds which could then collapse. The moon is slowly getting closer to the earth, and that gradual drop is fueling the tides, much like the falling weights of a grandfather clock power the hands and chimes.

I saved the most controversial answer to the end. Fusion power, like what happens in stars, only needs hydrogen, which is the basic building block of the universe. So you could argue that hydrogen doesn't come from any star--it came from the big bang and thus has "always" been around, and you would be right. But the hydrogen we humans will hopefully eventually use for fusion power (and currently use for hydrogen bombs, alas) came from those same ancient supernova that gave us all the other elements that make up the earth. The exception is, the hydrogen wasn't transformed by those supernova into heavier elements; it was just stored and then dispersed.

Answer 2

OK