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Tidal energy is not renewable

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Re: Tidal energy is not renewable

#141

Post by quotemstr »

bobthepanda wrote: post #45
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 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.

Re: Tidal energy is not renewable

#142

Post by rwoerz »

Let me nitpick: The headline alone is right: Tidal energy cannot be renewed. But that is true for all renewables like wind and solar, because "renewable" is a misnomer. Real renewal would violate thermodynamic's 2nd law. What the author actually seems to doubt is the ABUNDANCE of tidal energy (but supports that with questionable assumptions (cf. other comments here))

Re: Tidal energy is not renewable

#143

Post by ricardobeat »

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…

Yes, the assumption seems to be that any energy extracted is in addition to the friction with the ocean floor and continental plates, as those will continue to exist.

Re: Tidal energy is not renewable

#144

Post by smcin »

popol12 wrote: post #65
coldcode wrote: post #53

Earlier quoted context omitted.

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.

A Google search for “china children per woman” gives me 1.705 Are you talking about something else ?

The Google hit China TFR 1.705 for 2023 is bogus (and 2023 isn't even over yet, which should have alerted you), it's single-sourced from macrotrends.net which is quoting an old (pre-pandemic) UN forecast; you can see from their graph their (forecasted) numbers for 2020-2 turned out totally wrong. Lots of other sites are quoting the Google and macrotrends as fact. So now the #1 Google hit on that is misinformation. (Always look for attributions and dates).

As to 2022, China did briefly drop to a TFR of 1.09, like GP said [1]; but the moving average over several years is more like 1.3. You have to put the 2022 drop in context that their very strict lockdown went into its third year, and there were two cases of pregnant women losing their babies e.g. because the hospital denied them entry for having negative Covid tests but a few hours too old [2].

[0]: https://www.macrotrends.net/countries/CHN/china/fertility-ra...

[1]: "China's fertility rate drops to record low 1.09 in 2022- state media" https://www.reuters.com/world/china/chinas-fertility-rate-dr...

[2]: https://fortune.com/2022/01/07/china-covid-cases-miscarriage...

Re: Tidal energy is not renewable

#145

Post by ricardobeat »

rwoerz wrote: post #142

Let me nitpick: The headline alone is right: Tidal energy cannot be renewed. But that is true for all renewables like wind and solar, because "renewable" is a misnomer. Real renewal would violate thermodynamic's 2nd law. What the author actually seems to doubt is the ABUNDANCE of tidal energy (but supports that with questionable assumptions (cf. other comments here))

Even then conflating them makes no sense. Solar and wind power are both coming from an external source, the sun, which we might as well consider infinite; whereas tidal energy is not. It can be depleted.

Re: Tidal energy is not renewable

#146

Post by Nemrod67 »

bbor wrote: post #74
adventured wrote: post #68

Earlier quoted context omitted.

> Which is more likely? Everyone lives like a European (from a consumption perspective)? Or a bunch of people don’t or die while some do? There are no systems that can ever be created to actually balance out / eliminate inequality, outside of very small communities operated via extreme authoritarianism. See: modern Sweden. A formerly highly effective welfare state, increasingly brought to its knees by poor immigrants…

You have some sources for “Sweden and France are failed countries”? Something tells me that’s not quite an objective take. “Inequality exists now so it will always” is also not the objective scientific take I think you’re implying it to be

just a feeling of insecurity ;)

Re: Tidal energy is not renewable

#149

Post by wmf »

littlestymaar wrote: post #101
WillPostForFood wrote: post #63

Earlier quoted context omitted.

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.

Here you go https://ourworldindata.org/grapher/consumption-based-energy-...

Re: Tidal energy is not renewable

#150

Post by casparvitch »

codethief wrote: post #140
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. […] How much energy will we consume in 1,000 years I keep posting this link here on HN but, once again, it seems very appropriate: > The upshot is that at a 2.3% growth rate (conveniently chosen to represent a 10× increase every century), we would reach boiling temperature in about 400 years. https://dothemat…

If HN was reading Murphy the front page would look very different every day
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