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Comment by saalweachter | Hacker News Reader

Because I can never pass up a chance to mention it, the fiery core of the Earth that's moving those plates around is an approximately 45 terawatt engine; human civilization is currently around 19 terawatts.

Obviously we're not going to devote our entire economy to producing a mineral, and we're talking about millions of years versus decades, but it's still crazy to me that humans and the Earth itself operate on the same energy-scale.

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Is the 49TW the total amount of energy the earth radiates from the core?

I'm struggling to reason about this. The core is a hot mass of matter, that's slowly cooling down. There is no energy "produced" here, no? So where does the 49TW go?

Edit: my questions got answered by someone posting a wikipedia link elsewhere: https://en.wikipedia.org/wiki/Geothermal_energy#Resources

Seems energy is being produced by means of radioactive decay.

> the fiery core of the Earth that's moving those plates around is an approximately 45 terawatt engine; human civilization is currently around 19 terawatts

Oh wow that is mind blowing! I would have thought we were at a smaller proportion, to be honest.

If you want to feel small again, on the other end of things, 173,000 terawatts of sunlight hits the Earth. Earth's biosphere uses something like 1% of that (depending on your definition of "used", but whatever), so we have Earth's biosphere at something like 1700 terawatts, dwarfing both us and Earth's fiery core.

The energy of sunlight that hits the ocean is absorbed, and flows into the deep ocean. A smaller percentage of the energy that hits land is absorbed, but this rapidly radiated away at night.

Ok, one last one: global warming is basically that energy imbalance: the Earth is currently absorbing, on average, more energy from the sun than it radiates back, for a variety of reasons (change in atmospheric composition, change in surface reflectivity).

That energy imbalance amounts to 500 TW.

I’m skeptical we create a level of power near 50% of the entire heat of the inner planet.

Surprisingly, it is true:

https://en.wikipedia.org/wiki/Geothermal_energy#Resources

The Earth's internal thermal energy flows to the surface by conduction at a rate of 44.2 terawatts (TW) [21], and is replenished by radioactive decay of minerals at a rate of 30 TW. [22]

[21] https://agupubs.onlinelibrary.wiley.com/doi/10.1029/93RG0124...

[22] https://web.archive.org/web/20120217184740/http://geoheat.oi...

The parent said "power near 50% of the entire heat of the inner planet.". What you are describing sounds like the leaked power from the inner planet. These sound very different to me. One statement is about power the other about energy sitting there

I mean as far as production is concerned radioactive decay is the only energy source. The rest is latent heat and friction+tidal forces. The earth has been cooling and slowing rotation every since the theia impact.

Given that heat is a store of _energy_ rather than power, I don't think there's another reasonable interpretation of the _power_ of the core other than the amount that leaks.

The sibling comment to this one helps clear this up: In short, they're not talking about the entire heat of the inner planet. They're talking about the rate at which heat that is transferred to the surface of the planet, not the thermal energy of the interior of the planet.

~180,000TWh of annual human energy production vs ~ 3,000,000,000,000,000TWh of thermal energy inside Earth.

Power is not the same as energy obviously, but otherwise it is the rate at which the thermal energy is spent.

> the entire heat of the inner planet

... is an energy figure, not a power figure, unless you mean either the rate at which heat is added through thermal decay, or the rate at which heat is lost through conduction to the surface, both of which are at the same mid-ten-terrawatts order of magnitude as human power usage.

Over the many nuclear reactors, hydro stations, geothermal stations (which I guess is kind of cheating since it measures energy twice), tidal power stations, solar panels, wind turbines, gas and coal fired generators, and all the other odd-ball power generation devices used around the world, I could believe it. The heat can only get to a place where we actually measure it via lots of thermal mass that would slow things down.

The energy emitted from the core of the earth, and human generated power combined is most likely dwarfed by the equivalent watts from sunlight alone.

Assuming the low "realistic" estimate [0], the total amount of watts hitting the earth at any one time is 694.2 TW [1]... instantaneously. So that would add up much quicker.

Edit: I'm an idiot, the sun doesn't face the whole earth at once. It would still be a lot at half that though!

[0] https://en.wikipedia.org/wiki/Sunlight#Solar_constant [1] https://www.wolframalpha.com/input?i=%281.361+*+5.100644719%...

Integrated over the course of a day, total disk solar irradiance for a rotating planet is 1/4 the solar constant. And in our specific planetary case, about 27% is reflected without reaching ground. So the effective whole-day whole-Earth "solar constant" at ground level is about (1362 W/m^2) * 0.25 * (1 - 0.27) ~= 250 W/m^2.

https://en.wikipedia.org/wiki/Earth%27s_energy_budget#/media...

Obviously, only a very tiny proportion of that power is spent towards making the clays that we needed. We could spend a fraction of what we have and still outdo Earth by orders of magnitude.

Yeah, but we're also talking about out-doing it by about six orders of magnitude, to produce millions of years of production by the Earth in mere years by man.

So I'm not sure which one I'd bet on.

That's fascinating. Thank you for sharing. That really puts the scale of human activity into context.

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