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Tidal energy is not renewable

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Re: Tidal energy is not renewable

#281

Post by RetroTechie »

7speter wrote: post #106
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…

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…

Either some new physics is found enabling faster-than-light travel, which would break a good chunk of our current understanding of physics. So... doubtful (imho).

Or the only thing achievable is travel at some fraction of the speed of light. Say, a few %. At which point the nearest stars are a few-centuries away (one way trip), making interstellar travel feasible at least in theory.

But say, 99% or 99.99% of lightspeed? That's what's done with a few particles in huge projects like the LHC. So ehm.. no. Not unless (see above).

Re: Tidal energy is not renewable

#282

Post by bliteben »

XorNot wrote: post #190
dredmorbius wrote: post #185

Earlier quoted context omitted.

The problem with this, or any other hypothetical "decoupled growth" argument is that, well, it's purely hypothetical. There's no evidence whatsoever that economic growth can be decoupled from resource, and most especially energy, usage. There are instances of increased efficiencies , which thanks to the Jevons Paradox increase overall resource utilisation (economically, efficiency is equivalent to a reduced price, an…

Conversely the people who argue against growth never have any answers they want to elaborate on. They have "well we can't have endless growth" and that's where the conversation stops. They never want to examine the consequences of that thought (no growth means we're into a zero-sum game) or whether they think we're even plausibly close to the limit (instead they want to have a proxy argument about environmental damag…

At some point unlimited growth would mean the heat death of earth. Remember all used energy no matter how green the source emits heat.

Even stars have limits to their energy. If you don't believe in limits then you aren't accepting physical reality.

Re: Tidal energy is not renewable

#283

Post by paulryanrogers »

Dma54rhs wrote: post #261
paulryanrogers wrote: post #199

Earlier quoted context omitted.

Exceptions like 10 EUR flights aren't sustainable. They're just auctioning off empty seats to cut costs. The comparison was conceptual thing to similar thing. Only the rich own and operate private planes, that hasn't changed. The fact that other, more sophisticated planes exist doesn't undermine the point. There are also diminishing returns. And past leaps in lifestyles aren't guaranteed to continue the same trends,…

European cheap airlines have shown these prices are indeed sustainable for the last 20 years now?

Is every seat on every flight 10 EUR?

Re: Tidal energy is not renewable

#284

Post by Detrytus »

Dma54rhs wrote: post #261
paulryanrogers wrote: post #199

Earlier quoted context omitted.

Exceptions like 10 EUR flights aren't sustainable. They're just auctioning off empty seats to cut costs. The comparison was conceptual thing to similar thing. Only the rich own and operate private planes, that hasn't changed. The fact that other, more sophisticated planes exist doesn't undermine the point. There are also diminishing returns. And past leaps in lifestyles aren't guaranteed to continue the same trends,…

European cheap airlines have shown these prices are indeed sustainable for the last 20 years now?

The way it works is that ticket price of 10 EUR only really covers the cost of printing the ticket :) Everything else costs extra, which means that if you, for example, want to take some luggage with you, you would need to pay around 100-150 EUR

Re: Tidal energy is not renewable

#285

Post by f33d5173 »

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…

Suppose we put solar panels in space. Then we would be entirely unconstrained by the amount of energy received by the earth. Heat dissipation would also no longer affect earth. Given our current trajectory with regards to spaceflight, it seems plausible we will be doing large projects of that scale in space in say 300 years, enough time to meet such exponential growth targets.

Re: Tidal energy is not renewable

#286

Post by idlewords »

exitheone wrote: post #37
idlewords wrote: post #4

Every energy source becomes renewable on the right time scale.

That's not actually true. The conditions for the formation of coal and oil may likely never happen again because the bacteria to break decompose trees did not exist then but exist now, making oil formation impossible because trees decompose now. Unless they all die out, we won't get any new oil ever.

This nerdbait story is all over the internet but is not true.

See https://www.pnas.org/doi/abs/10.1073/pnas.1517943113, "Delayed fungal evolution did not cause the Paleozoic peak in coal production"

Stop burning petroleum and wait long enough and it will re-form just fine.

Re: Tidal energy is not renewable

#287

Post by XorNot »

codethief wrote: post #268
XorNot wrote: post #189

Earlier quoted context omitted.

100% of the heat we get from the sun is currently lost as waste heat, by one means or another. So you're not boiling the oceans by any reasonable projection of energy usage increase of solar energy. (yes yes some of it is reflected back into space as non-IR light, but you can also lose IR-emissions back into space without heating the Earth as well).

Most of that incoming heat is reflected / radiated off actually. It doesn't "stay" on Earth. https://en.m.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law

That is literally what I said.

Re: Tidal energy is not renewable

#288

Post by Shorel »

Jweb_Guru wrote: post #243
zamadatix wrote: post #159

Earlier quoted context omitted.

Any useful interpretation of renewable energy has to do with purely human timeframes as thermodynamics doesn't allow for any energy source to be endlessly renewable. "If I use this source today will more of it naturally be there tomorrow" type consideration, otherwise you end up with a definition which either includes things like fossil fuels as renewable because you can wait millions of years or excludes things like…

Well, there is a more important sense in which solar is renewable but not tidal energy. The sun does not burn out appreciably more quickly if we use a larger percentage of the available solar energy, it's there whether we use it or not. This is not the case for tidal energy.

The sun doesn't burn more quickly if we use it, but also not slower.

The sun will start becoming a red giant and kill us all in about one billion years, long before this tidal lock will eventually happen.

Re: Tidal energy is not renewable

#289

Post by somat »

Regarding the "How Are Tides Formed?" section with a nice neat diagram and some math"

But that is not really correct. it would be but there are large land masses interfering with the process. Ocean tides are better conceptualized as water sloshing in a bathtub.

https://www.youtube.com/watch?v=PSJRymZ5bJs

Re: Tidal energy is not renewable

#290

Post by Dma54rhs »

paulryanrogers wrote: post #283
Dma54rhs wrote: post #261

Earlier quoted context omitted.

European cheap airlines have shown these prices are indeed sustainable for the last 20 years now?

Is every seat on every flight 10 EUR?

No, but you can check yourself. Flying in Europe is cheaper than train or bus. Not sure if there are Ryanair style cheap airlines in the US or other parts of the world.
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