3 ms·

That's correct, while clean it'd be a mistake to classify it as "renewable". https://cs.stanford.edu/people/zjl/pdf/tide.pdf https://cs.stanford.edu/people/zjl

That's correct, while clean it'd be a mistake to classify it as "renewable". https://cs.stanford.edu/people/zjl/pdf/tide.pdf https://cs.stanford.edu/people/zjl/pdf/tide.pdf is a pretty accessible entry.

MostlyStable 1y ago
I am extremely skeptical of that 1000 year estimate. It is almost entirely depending on the assumption of the continuous energy increase of 2% per year every year, for the next 1000 years, and that tidal energy remains 1% of that total the entire time. I think that those assumptions are wrong in multiple ways and that reasonable estimates of the amount of tidal energy that could be extracted would lead to time scales where the risk no longer becomes relevant.
- nick238 1y ago
  Yeah, the "2% growth forever" feels like a sneaky addition which is extremely controversial in economic theory: if endless growth is required. 1.02 ** 1000 ~= 400,000,000. So if the world population continued to grow at 2% in those same 1000 years, there'd be 2.8 quintillion people. Evenly distributed over the planet (water included), each person would get a square 1.35 centimeters on a side.
theptip 1y ago
On the timescales involved here, there is no such thing as renewable energy.
Symmetry 1y ago
I think if we're positing a world where our energy use increases 2% annually for a thousand years and that tidal power will remain a fixed fraction of that we're not dealing with a reasonable projection. In any event, at the end of those thousand years humanity won't be very far from Dyson Sphere territory and the tidal locking of Earth wouldn't be much of a problem for the civilization implied, but I don't think it's possible to extract tidal energy that fast.
- stouset 1y ago
  If the world’s energy use increases by 2% annually for a thousand years and we’re generating it with anything other than wind/solar/tidal/geothermal, we will raise the equilibrium temperature of the Earth by tens of degrees just from thermodynamics.
  - Symmetry 1y ago
    Nah, to keep extracting the Earth's rotational energy that fast through tidal means we'll have had to import all the available liquid water from the rest of the solar system, rendering the climate change effects of the other energy use moot. ;)
  - CorrectHorseBat 1y ago
    If the world's energy usage increases by 2% for a thousand years we use 3.4 * 10^4 times more power than the solar radiation reaching the earth (1.02^1000 * 15/170000). Enough power to boil off the oceans in about a day (if I can believe Reddit and my math isn't off)
    - stouset 1y ago
      Yeah, I've done the calculations for 3% at 2%. I didn't feel like doing them again, so just went with a conservative bet.
IshKebab 1y ago
It isn't a mistake to classify it as "renewable" because "renewable" doesn't literally mean until the end of time. Is solar not renewable because the sun will eventually explode? Ridiculous. And as others have said, 1000 years is a hilariously wrong estimate.

MostlyStable 1y ago

I am extremely skeptical of that 1000 year estimate. It is almost entirely depending on the assumption of the continuous energy increase of 2% per year every year, for the next 1000 years, and that tidal energy remains 1% of that total the entire time. I think that those assumptions are wrong in multiple ways and that reasonable estimates of the amount of tidal energy that could be extracted would lead to time scales where the risk no longer becomes relevant.

nick238 1y ago
Yeah, the "2% growth forever" feels like a sneaky addition which is extremely controversial in economic theory: if endless growth is required. 1.02 ** 1000 ~= 400,000,000. So if the world population continued to grow at 2% in those same 1000 years, there'd be 2.8 quintillion people. Evenly distributed over the planet (water included), each person would get a square 1.35 centimeters on a side.

theptip 1y ago

On the timescales involved here, there is no such thing as renewable energy.

Symmetry 1y ago

I think if we're positing a world where our energy use increases 2% annually for a thousand years and that tidal power will remain a fixed fraction of that we're not dealing with a reasonable projection. In any event, at the end of those thousand years humanity won't be very far from Dyson Sphere territory and the tidal locking of Earth wouldn't be much of a problem for the civilization implied, but I don't think it's possible to extract tidal energy that fast.

stouset 1y ago
If the world’s energy use increases by 2% annually for a thousand years and we’re generating it with anything other than wind/solar/tidal/geothermal, we will raise the equilibrium temperature of the Earth by tens of degrees just from thermodynamics.
- Symmetry 1y ago
  Nah, to keep extracting the Earth's rotational energy that fast through tidal means we'll have had to import all the available liquid water from the rest of the solar system, rendering the climate change effects of the other energy use moot. ;)
- CorrectHorseBat 1y ago
  If the world's energy usage increases by 2% for a thousand years we use 3.4 * 10^4 times more power than the solar radiation reaching the earth (1.02^1000 * 15/170000). Enough power to boil off the oceans in about a day (if I can believe Reddit and my math isn't off)
  - stouset 1y ago
    Yeah, I've done the calculations for 3% at 2%. I didn't feel like doing them again, so just went with a conservative bet.

IshKebab 1y ago

It isn't a mistake to classify it as "renewable" because "renewable" doesn't literally mean until the end of time. Is solar not renewable because the sun will eventually explode? Ridiculous. And as others have said, 1000 years is a hilariously wrong estimate.