
Turning Water into Watts - sohkamyung
https://physicsworld.com/a/turning-water-into-watts/
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steeve
According to the article, one station is rated at ~100kW (that's maximum power
output).

A typical nuclear 3rd generation nuclear reactor outputs ~900MW-1GW.

Assuming an impossible 100% charge (ratio between rated and actual generated
power), that's still 10000x (!) less power than one nuclear reactor. Put
differently, you'd need 10000 of these stations to generate the same amount of
electricity as _one_ nuclear reactor.

Then one needs to consider how long that plant can deliver energy. They don't
give concrete numbers for that technology, but again taking nuclear again as
an example, reactors are designed to run for a a minimum of 40 years (some
reactors are now certified for 80 years in the US). Solar and wind are ~20
years.

All in all, love the tech, but the laws of physics are pretty harsh.

~~~
bmelton
I've recently become enamored with micro-hydro generation, having seen ways in
which it can be totally non-destructive to local wildlife and/or fish going
through the generator, and while I completely agree with everything you've
said regarding nuclear vs micro-anything, for personal power generation on a
farmstead, nuclear is pretty inaccessible.

On the other hand, this guy's[1] manufactured a micro-hydro 2km drop generator
capable of producing 5-12kWh per day for ~$50 in parts (turbine 3D printed).
That's of course limited to drop power (meaning you have a high body of water
and a low body of water and generate power, like a dam, by capturing energy
from passing the falling water between them through a turbine) but for
relatively level bodies of running water (read: creeks, streams, etc) a small,
non-destructive weir dam can capture 100kWh per day from a single diverted
turbine if conditions are good.[2]

Of course, conditions aren't always, and not everywhere has access to _any_
immediate water supply from which to generate power, but it seems to me that
for those places that do, capturing their own power via micro-hydro frees up
other generated power for the folks that don't -- but that might be a naive
view.

[1] -
[https://www.youtube.com/watch?v=1KyL1-0A0Gw&t=2s](https://www.youtube.com/watch?v=1KyL1-0A0Gw&t=2s)

[2] -
[https://www.youtube.com/watch?v=61lZn1sUkzE&list=PLtTypVpmDd...](https://www.youtube.com/watch?v=61lZn1sUkzE&list=PLtTypVpmDd-
vkT9bJQkXw4I1t0e_4jMYA)

~~~
steeve
Yes, this is exactly what a dam is (pumping or releasing, or using rain).

Hydo is very cool, and very green.

Some things to remember, however:

\- need to drown whole valleys (very high impact on local wildlife)

\- energy density is not that good (i don't have the numbers but the volumes
of water moved are huge, hence dams)

\- very rapid piloting and low maintenance, so nice to absorb spikes

~~~
ch4s3
> Hydo is very cool, and very green.

Well, maybe. I think this depends on what you mean by "green". If you mean low
on CO2 emissions, then sure, but we need to consider habitat loss, methane
emissions from decomposition, and the possibility of triggering earthquakes.
Hydro is also quite expensive to build, and often requires seizing land
through processes like Eminent Domain (in the US).

~~~
steeve
You are right, I was meaning green in the sense of gCO2eq/kWh.

------
spenrose
[https://medium.com/otherlab-news/how-do-we-
decarbonize-7fc2f...](https://medium.com/otherlab-news/how-do-we-
decarbonize-7fc2fa84e887)

"There is enough wind in the world to supply the entire world’s energy needs.
Solar supply exceeds even that by many times and is by far the largest
renewable resource. In reality, wind is a second-order effect of solar energy
anyway — the sun differentially heats the oceans, atmosphere, and land, and
these thermal differences create the wind. This wind, in turn, makes waves;
while there is, in fact, a lot of energy in the waves of the deep ocean, there
is very little nearer to shore. Even if we captured all of the waves hitting
every coastline on the planet, that’s not enough to meet humanity’s demand for
energy. The ocean is a fragile ecosystem and capturing large portions of wave
energy would negatively affect the oxygenation of the oceans, among other
effects."

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jbob2000
> The ocean is essentially a natural engine, converting solar energy into
> mechanical energy.

Given the challenges with putting machines in water, it seems futile to pursue
this method of energy generation when going right to the source (solar) is
also an option.

And how efficient is an ocean at converting solar energy into mechanical
energy? Sure, the waves look big, but there's a lot of friction there eating
up the sun's energy.

~~~
steeve
Solar is not only intermittent (day/night) but also varies greatly with
nebulosity. I would think waves still exist at night.

Also, they advertise the maximum power output, not the actual power output
(wind as a ~20% actual power output for instance).

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papreclip
turning tax money subsidies into watts _

