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Tidal energy is not renewable

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Re: Tidal energy is not renewable

#131

Post by littlestymaar »

JamisonM wrote: post #127
littlestymaar wrote: post #101

Earlier quoted context omitted.

> 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.

Do you have some data to back up this assertion? For me what I see in the numbers is that Chinese domestic quality of living improvements correlate better with increases in energy consumption than does US imports (or Chinese exports). What is also interesting is that China's "energy intensity" - energy used per unit of GDP is pretty flat, if wealthier nations were exporting energy demand via imports I would expect th…

You can find data related to this phenomenon when searching for “imported emissions”. But then it's only going to be related to the CO2 emissions, not energy, and the measure appears to vary a lot depending on the methodology (from a quick search, France is estimated to import between 117 and 750Mt of CO2 a year, quite a large error margin…).

> if wealthier nations were exporting energy demand via imports I would expect that number to be climbing

Why? These exports from China generates GDP in China so it just grow the energy consumption as well as the Chinese GDP, making the ratio flat.

Re: Tidal energy is not renewable

#132

Post by mcqueenjordan »

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.

I think it's a joke about how all finite sequences will repeat during infinite time. But it doesn't really add anything to the discussion.

Re: Tidal energy is not renewable

#133

Post by Aerroon »

empath75 wrote: post #124
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…

While this is true, a lot of economists build their models assuming unlimited exponential growth. It does seem that we're going to hit a brick wall in growth in a few hundred years if that doesn't stop. There seems to be some idea that we can continue exponential growth if we can just figure out renewable energy and we can't. There is _no such thing_ as renewable energy in a regime with unlimited exponential economic…

Economic growth doesn't necessarily require energy expenditure growth. Figuring out how to do something more efficiently (for half the energy) is also economic growth.

Re: Tidal energy is not renewable

#134

Post by mikeyouse »

Onavo wrote: post #85
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/

It flattened in the midst of manufacturing outsourcing and globalization. Bring back the heavy industries and it would look much more different.

Nope. Common belief but not true: https://ourworldindata.org/consumption-based-co2

More specifically: https://ourworldindata.org/grapher/prod-cons-co2-per-capita

Re: Tidal energy is not renewable

#135

Post by golem14 »

empath75 wrote: post #124
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…

While this is true, a lot of economists build their models assuming unlimited exponential growth. It does seem that we're going to hit a brick wall in growth in a few hundred years if that doesn't stop. There seems to be some idea that we can continue exponential growth if we can just figure out renewable energy and we can't. There is _no such thing_ as renewable energy in a regime with unlimited exponential economic…

I found the Hans Rosling series of talks quite good and a bit reassuring. If we survive the next 100 years, we'll probably do OK for a while longer.

Re: Tidal energy is not renewable

#136

Post by api »

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.

Re: Tidal energy is not renewable

#137

Post by uoaei »

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…

Sci-fi idea: binary star system is really the remnants of an advanced civilization, originally orbiting a single (much larger) star on their own planet, that collapsed in on itself from the consequences of its energy generation technology.

Re: Tidal energy is not renewable

#138

Post by Aerroon »

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…

To extrapolate further on the silliness of 2% growth. Let's convert the entire Earth into pure energy:

Earth's mass is 10^24 kg.

E_earth = mc^2 = 9 * 10^40 J

E_current * 1.02^x = E_earth

474 * 10^18 * 1.02^x = 9 * 10^40

x = 2357.91 years

At a modest 2% growth we would be using up the entire Earth's mass in energy per year in only 2358 years.

Re: Tidal energy is not renewable

#139

Post by gus_massa »

rich_sasha wrote: post #66
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…

> Our global energy consumption in 2008 was estimated to be 474 exajoules. If my maths is right, that's about 40,000 kcal per person per day, or about 15 times the energy consumption of an average adult. I'm trying to figure out if that's a lot or not. On the one hand, not: this ratio is not strictly bounded in any way, and the human energy consumption is an arbitrary denominator. Still, a very rough interpretation i…

It's an interesting comparison.

I got some numbers form a random result in google: http://www.ejolt.org/2012/12/human-energy-use-endosomatic-ex...

Endosomatic energy (i.e. food): 3.5GJ/year/person

Exosomatically energy (i.e. firewood, electricity, solar, fossil fuel, whatever):

hunter-gatherers: 20 GJ/year/person (i.e. x6)

agriculturalists using animals: 60 GJ/year/person (i.e. x17)

industrial society: 200–300 GJ/year/person (i.e. x57-x86)

Re: Tidal energy is not renewable

#140

Post by codethief »

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://dothemath.ucsd.edu/2012/04/economist-meets-physicist...

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