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Tidal energy is not renewable

cs.stanford.edu

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Re: Tidal energy is not renewable

#161

Post by hollerith »

RetroTechie wrote: post #104
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 s…

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

Not so. The calculation of the 1031 years is equation 19 and assumes the decrease in rotational energy all goes to human purposes.

The flaw in the OP is the assumption that human consumption keeps rising at .02 per year for 1031 years: we would probably boil the oceans away because of the waste heat from using that much electrical power.

Re: Tidal energy is not renewable

#162

Post by [deleted] »

mattmaroon wrote: post #157
ben_w wrote: post #155

Earlier quoted context omitted.

> I can’t even imagine what I could do on Earth using that much power. Fly my own 737 to a new city every day? Sure, why not? It's absurd today for the average person, but it's the kind of thing rich people get to do already, and looking at the rich today is a decent (though imperfect because inflation and invention don't work like that) hint for what normal people can afford in a richer future.

Aviation historically, has not gotten cheaper overtime. If anything, it is more expensive. Only rich people had planes 100 years ago and only rich people own them now and the trend line doesn’t indicate it’ll be different in another hundred.

[deleted]

Re: Tidal energy is not renewable

#163

Post by [deleted] »

Zenst wrote: post #54

So they postulate how the moon will in 1000 years become stationary in orbit due to the tidal energy extraction as to why tidal energy is not renewable. Sorry but I'd need a few more than one institution to be backing this. Otherwise, it seems a bit too reaching to be anything other than a great plot for some cheesy disaster movie that they have phases of doing. [EDIT - Reversed AI's rewrite of my humble English, raw…

[deleted]

Re: Tidal energy is not renewable

#164

Post by deepsun »

quotemstr wrote: post #141
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.

Almost every human population is under strong selection pressure towards having more people. This dip in fertility cannot and will not last.

Unless external factors kick in, like depletion of resources and soils. There's no any law of nature that says homo sapiens must be able to survive. Smaller scale examples are:

1. Easter island -- we, humans, deforested the island, that degraded and depleted human population significantly even before the first european ships discovered the island. From what I've heard, "Rapa Nui" movie is unusually historically correct on the events.

2. St. Matthew Island -- 29 introduced reindeer rapidly overpopulated the island and ate all the available food there, so the whole population died.

Same thing can happen on planet Earth.

Re: Tidal energy is not renewable

#165

Post by svnt »

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…

> gets us to about 150 trillion humans in 1,000 years

I realize the big issue is settled here but just to scope this detail: the total land area of earth is coincidentally approximately 150 million km^2

At 150 trillion humans each human would get just about a square meter. Many of those square meters are uninhabitable.

Re: Tidal energy is not renewable

#166

Post by dredmorbius »

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 lesson that constant percentage (that is, exponential) growth cannot continue endlessly is the fundamental message behind the concept of Limits to Growth. That is, there exist intractable limits to growth, and that no matter how convenient it may be to pretend otherwise, humans ignore this fact at their extreme peril.

Long-term ongoing economic growth, expressed as a constant percentage, is baked in to most current orthodox economics and economic policy. Even apparent mavericks such as Thomas Piketty assume that growth will continue interminably (noted in Capital in the Twenty-First Century).

Rather than being a critique of Liu, you've actually written a criticism of those he himself is generally addressing.

Re: Tidal energy is not renewable

#167

Post by joelthelion »

hn_throwaway_99 wrote: post #59
joelthelion wrote: post #49

Issues with exponential growth set aside, does wind power suffer from the same problem? If I understand correctly, wind mostly caused by the coriolis force, which is a consequence of the earth's rotation. Would building too many wind turbines slow down earth's rotation?

> If I understand correctly, wind mostly caused by the coriolis force, which is a consequence of the earth's rotation. You understand incorrectly. Wind is largely a form of solar energy. The sun heats the earth and its atmosphere at different rates depending on the location, and wind is primarily the result of temperature differentials. The Coriolis effect can definitely affect how wind behaves, but it doesn't provid…

Thank you!

Re: Tidal energy is not renewable

#168

Post by ggm »

Is it not the case that the moon-earth system may become locked, irrespective? I mean if we're worried about future decades.. As long as this happens before the sun expands to make the earth uninhabitably hot, it's a risk for .. some intelligence?

Re: Tidal energy is not renewable

#169

Post by rodgerd »

api wrote: post #136
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…

20000X the energy of a current human shows how absurd it would be for growth and energy use to not decouple. I can’t even imagine what I could do on Earth using that much power. Fly my own 737 to a new city every day? I suppose spacefaring humans might use that kind of power but if they are living in space they are no longer part of the biosphere of Earth.

> Fly my own 737 to a new city every day?

That's literally the billionaire lifestyle.

Meanwhile cryptocurrency is seeing decades of power efficiency undone as miners bring old power plants online and want to burn tyres to power their scams.

Re: Tidal energy is not renewable

#170

Post by hgsgm »

littlestymaar wrote: post #99
Nition wrote: post #78

Earlier quoted context omitted.

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…

> one of the first harbingers of the coming World Energy Crisis, It's been well known since at least The limits to growth [1], 51 years ago. [1]: https://en.wikipedia.org/wiki/The_Limits_to_Growth

250 years

https://en.m.wikipedia.org/wiki/Thomas_Robert_Malthus

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