[craig_s_bell]

Too much of a good thing could be considered harmful:

Destroying the Earth by Using Tidal Energy

Jerry Z. Liu

https://cs.stanford.edu/people/zjl/pdf/tide0.pdf

[empath-nirvana]

This is just a special case of this general phenomenon:

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

We can't have unlimited economic growth for ever without boiling the oceans, or without figuring out a way to have economic growth without increasing energy usage. It's not about global warming, it's about just waste heat and entropy, even assuming maximally efficient engines and 100% renewable energy.

And really, all of that blog post is a special case of the observation that life is a way to more rapidly increase entropy on earth by finding and exploiting energy sources. Eventually earth will reach a life-induced thermal equilibrium which will be incompatible with the continued existence of life on earth.

[4death4]

Reversible computation doesn’t need to result in waste heat so that’s one path towards unlimited economic growth.

[p1mrx]

This paper is either naive or a joke, as it assumes energy consumption will increase by 2% per year for 1000+ years.

[a_cardboard_box]

The sun imparts a certain amount of energy into the earth through tidal forces. We can either capture that energy for our use, or let it heat the Earth (https://en.wikipedia.org/wiki/Tidal_heating). The slowdown of the Earth's rotation is the same either way. The paper demonstrates that if you could capture an absurd amount of energy from tides, the earth's rotation would have to slow. But this is vacuously true: you simply can't capture that much energy from tides.

[xaellison]

This article needs to die. People see stanford and think it's legit. This is an early grad school student's work and it probably shouldn't be visible outside the dept.

[liquidise]

tldr: If global energy usage grows at 2% every year, and we generate 1% of the total demand annually with tidal energy, the Earth's rotation will cease in ~1000 years.

While i won't dispute that tidal energy is not truly sustainable, at least not in the way solar appears to be, i think we can agree that in the short team (a few centuries) cargo ships saving fuel would be a net positive with no measurable impact on the rotation of the planet.

Edit: after some more napkin math, i have a hard time taking this paper seriously at all. It appears to suggest that the available tidal energy would remain constant throughout this process? Also, 1.02^1000 equates to a roughly 400 million factor increase in the current energy demands of the planet. That's not something i'd expect such an advanced civilization to be trying to generate out of some waves.

[HPsquared]

I think the general lesson is that 2% annual growth - of anything - is not sustainable for long.

[mjan22640]

A day needs more than 24h anyway.

[cycomanic]

I think I've seen arguments from the same person before.

The key assumption here is a 2% annual increase in world energy demand. No shit sherlock, after 1000 years numbers are huge. Funny thing is he only criticises renewables this way, but if we make the same calculation for any any energy source we pretty much come to the same conclusion. Maybe the person has an agenda?