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Tidal energy is not renewable

cs.stanford.edu

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Re: Tidal energy is not renewable

#101

Post by littlestymaar »

WillPostForFood wrote: post #63
wcoenen wrote: post #27

I'm not sure the author realized this, but they're actually making a statement about how crazy exponential growth is. Not about the sustainability of tidal power. This becomes obvious once you look closer at what that 2% growth rate (as assumed in the post) implies. Our global energy consumption in 2008 was estimated to be 474 exajoules. The total energy received by the earth from the sun during a year is about 5 mil…

Any sort of straight line extrapolation is useless. Look at the US energy consumed per capita, flat or declining for the last 50 years. Other parts of the world will follow as they develop. Likely the same for population growth. http://insideenergy.org/wp-content/uploads//2017/01/historic... from: https://insideenergy.org/2017/01/12/energy-explained/

> Look at the US energy consumed per capita, flat or declining for the last 50 years.

This doesn't account for all the “imported energy” that comes when you outsource your industrial production abroad. Granted even then the energy consumption doesn't increase exponentially anymore, but it's not flat either.

Re: Tidal energy is not renewable

#104

Post by RetroTechie »

blake1 wrote: post #32

The single most important assumption in this paper is that energy consumption will increase by 2% per year. This kind of exponential growth leads to outlandish estimates for the amount of tidal energy that society will demand. Energy consumption has decoupled from population growth rates and economic growth. How much energy will we consume in 1,000 years? Most projections of the population have it stabilizing at arou…

> The single most important assumption in this paper is that energy consumption will increase by 2% per year.

There's a 2nd big assumption:

That tidal energy extracted is additional Earth's rotational energy loss above what Earth does by itself.

According to the paper, tidal energy is dissipated through friction between ocean water & the seafloor. This dissipated energy subtracts from Earth's rotational energy. And some rotational energy is transferred to the moon (which makes the moon move further out). Ok so far.

Author's 2nd assumption is that as tidal energy is tapped, this is extra energy that subtracts from Earth's rotation.

But is it? It might also be that tidal energy extracted by humans, comes out of some fixed 'budget', and the remainder is dissipated naturally. More tidal energy extracted by humans -> less tidal energy dissipated through ocean vs. seafloor friction.

Kind of like solar influx: it's a huge but (apart from fluctuations) fixed amount. We can tap some % of that potential, but what's available doesn't increase. And what humans don't tap, gets absorbed / radiated out by other natural processes.

I won't even hazard a guess. But it would be interesting to figure out which of those applies.

Re: Tidal energy is not renewable

#105

Post by sjducb »

wcoenen wrote: post #27

I'm not sure the author realized this, but they're actually making a statement about how crazy exponential growth is. Not about the sustainability of tidal power. This becomes obvious once you look closer at what that 2% growth rate (as assumed in the post) implies. Our global energy consumption in 2008 was estimated to be 474 exajoules. The total energy received by the earth from the sun during a year is about 5 mil…

I think we’ll have colonized space by then, maybe even starting to build a Dyson sphere.

Re: Tidal energy is not renewable

#106

Post by 7speter »

Nition wrote: post #78
wcoenen wrote: post #27

I'm not sure the author realized this, but they're actually making a statement about how crazy exponential growth is. Not about the sustainability of tidal power. This becomes obvious once you look closer at what that 2% growth rate (as assumed in the post) implies. Our global energy consumption in 2008 was estimated to be 474 exajoules. The total energy received by the earth from the sun during a year is about 5 mil…

Humanity needing that amount of energy seems obviously absurd, but then I suppose a CPU with 100 billion transistors seemed clearly impossible in 1960. Maybe a few hundred years from now, Internet archaeologists will find your comment as one of the first harbingers of the coming World Energy Crisis, much as we see the 1912 Rodney & Otamatea Times "Coal Consumption Affecting Climate" snippet today.[0] Then they'll fin…

Right now, the minds that conceive of any practical way of a spacecraft reaching the speed of light says we need the energy of multiple suns to be able to even reach that speed, so who knows where humans are in 500 years…

Re: Tidal energy is not renewable

#107

Post by JumpinJack_Cash »

TheSpiceIsLife wrote: post #81
toomuchtodo wrote: post #34

Earlier quoted context omitted.

Conflict over scarce resources is inevitable. When the violence starts, you should be prepared to win (from a nation state perspective). https://news.ycombinator.com/item?id=37122796 | https://www.mdpi.com/2673-4060/4/3/32 https://news.ycombinator.com/item?id=37313586 | https://medium.com/@samyoureyes/the-busy-workers-handbook-to... https://overshoot.footprintnetwork.org/newsroom/country-over... https://en.wikipedia.…

The future is hard to predict. I'm willing to bet our descendants will be approximately as irrational and lucky as humans have always been. There's a good chance that at least one of those ten billion are going to have some radically good ideas, and an even better chance than a few more will have some really good ideas.

Increasing the number of brains won't help if their mental pattern correlation also increases.

People are acting more and more in unison, that means no variability and no room for radically good ideas

Re: Tidal energy is not renewable

#109

Post by jl6 »

coldcode wrote: post #53
bobthepanda wrote: post #45

Earlier quoted context omitted.

The UN has revised peak projections down several times; the peak is now expected at 10 billion.

More countries are now sub-2.0 replacement, China is down to 1.09 so the peak is unlikely to get much more than that.

The trends are mostly encouraging but there are still 102 countries with a fertility rate above replacement rate, so we’re not out of the woods yet:

https://en.wikipedia.org/wiki/List_of_countries_by_total_fer...

Re: Tidal energy is not renewable

#110

Post by SoftTalker »

kepler1 wrote: post #98

I think out of embarrassment, the student also decided not to showcase his proof that in 1000 years, the mass of human beings will outweigh the Earth. Eh, who am I to criticize? They say that your early grad school years are a time to publish large amounts of papers that you don't think are likely to stick. This is a little bit out there even by this standard though.

Or that because they will be unevenly distributed, the planet might tip over.
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