Does all of our energy come from the Sun?

I remember my high school physics teacher saying,

Is that true?

No. Gravity produces heat in the earths core that we take advantage of.

Most of the heat in the Earth’s core is due to natural radioactivity, not the initial gravitational energy. But it’s still not from the Sun.

There’s also tidal energy, which does ultimately come from the Solar System’s initial gravitational energy. It’s not used to a very great degree yet by humans, but it can be, and there are a few proof-of-concept projects for it.

Still, the vast majority does come from the Sun.

Can you elaborate what you mean by this? Gravity was involved in initially generating earth’s heat, but it’s not a very active process.

There’s two ways earth is heated internally.

One is remnant heat from its formation. And sure, that’s related to gravity, but it does implicitly rely on the formation of the sun to kick off the process in the first place. And that process is ongoing in that the earth is slowly expanding and cooling from that initial formation. The remnant heat is still slowly bleeding off. It will be billions more years before it’s gone. So that came from the sun in a real sense.

The other way the earth’s interior is heated way (and probably the majority) is via radioactive decay. And it is a source that does not come from the sun - it comes from other suns. The heavier elements present at the formation of the solar system are due to supernovas.

So, the vast majority of our energy ultimately comes from the sun. It can be argued a small fraction from the formation of the earth (which was also driven by the sun but less directly). And another small fraction from other suns.

I wouldn’t call the heat of the Earth’s coalescence “driven by the Sun”, not even indirectly. Before the Solar System was a star and planets, it was a diffuse cloud of gas and dust, and that cloud already had gravitational potential energy. That’s the energy that’s relevant here, and it didn’t come from the Sun, since the Sun didn’t even exist at that time.

Iceland gets over half of its energy from geothermal sources. There are other geothermal plants around the world, including in N. CA, for example.

There are also tidal power stations like this one in France that as been in operation since 1966.

There are not many around the world, but there are some big projects planned.

Since the turbines are driven by the tide, you could say they are Moon powered.

The Earth-moon also produces a little tidal heating but not very large.

Of the ~47 terawatts of internal heat released by the Earth, about half is thought to be from radioactive heating and significant portion is from the mantel and not the core. Tidal heating through friction is small with ~3.7 terawatts in total with ~2.5 TW from the main lunar tidal component (M2). The rest of the tidal heating is other lunar and solar components that are probably too complicated for this forum. Other factors like heat released due to primordial heat, crystallization and other factors make up the remainder but this is also on the edge of our knowledge and is increasingly speculative.

Older texts will tend to claim numbers like 90% of the heat is from radiogenic sources, but those are based on very dated assumptions.

For the primordial energy, a portion of it is from differentiation sources like the negative potential energy from infall, accretional energy and accreational heat is from the conversion of the kinetic energy of impacting bodies to thermal energy. Obviously some of this energy also resulted in the rotation which goes back tot he tidal component.

As noted above the primordial energy is not attributable to the sun, but it provides 175,000 terawatts of energy which is much larger than the ~47 terawatts internal heat or the ~3.7 terawatts from tidal heating.

Note: Exact numbers on the origins of Earth’s internal heat is not firmly established, so the numbers above related to primordial heat, radiogenic decay, tidal heating, and other sources have been summarized.

I am also interested in the link between hydroelectricity and the sun.
I get a ‘traditional’ hydroelectric arrangement may be an interception of the water cycle - sun heats ocean/lake, causes evaporation, clouds drop this as rain at a higher elevation and then it flows downhill and is used by a turbine to generate electricity.

But how about glacial melt derived hydro electricity? Are all glaciers due to the sun?
How about pumped hydro? like this cool place -

Rail stored energy?

Depends, how are you turning the glaciers into water?

It doesn’t matter. It’s the gravitational potential energy of the glaciers that is turned into electricity. And that originally came from the Sun - the heat from the Sun vaporized water and lifted it into the sky, which fell as snow and became glaciers.

Those are not energy sources. They are energy storage devices. They store electrical energy that was generated by some other means.

The energy from nuclear plants doesn’t come from our sun, but it came from suns that existed before our sun due to the fusion of heavy elements that happened 5+ billion years ago.

Hydroelectric, including indirect from glaciers, depends on water evaporating and raining down onto higher ground, thereby transforming some of the (solar) energy driving evaporation being transformed into gravitational energy (higher ground), then into kinetic energy as the water rushes down the tubes of the hydroelectric plant to drive the turbines. Whether the water is stored in a storage lake or in a glacier before being used to drive the turbines, it needs to undergo the evaporation/precipitation route to get to high ground.