Nah its all good, most hydro energy comes in the form of water turbines,as the tide flows through the turbine spins and creates electricity,through diodes or mechanical gears, think of like the old water wheels.
However the resistance does slow down the tide and can disrupt fish breeding and ecology/waterflow to a degree particularly if there are dams and weirs involved.
As a side note they reckon if they could capture half the "lost" energy in the pilbarra during the wet from big rains it could run all of Wa easy.

A couple of the big players rio/bhp looked at it pretty seriously for a while but it ended up fizzing out.

If you google the snowy mountain irrigation scheme it will give you an idea, however its more reliant on gravity than tides but similar in principle.

Final answer, Tides are dependent on the moon so they run seperatley to the earth, as the moon goes through phases and orbit its gravity will have different amounts of "pull" over the earths water/surface friction. This results in differing tidal patterns throughout the moons orbit and proximity to earth.
A month is really a moonth which is one cycle of the moon, full to new, this equates to 29.53 days which although not perfectly aligned with our calander gives a close approximation.
If we run off a lunar year however it does not synchronize with the seasonal year,hence the leap year and 365 days to keep us in sync.
Many scientists (and nutcases like myself) believe this relationship with the moon and its affect on our gravity assist with keeping us in what can only be described as a perfect orbit, kinda like two magnets pushing and pulling.

As an additional waffle all women used to get their period on the full moon and the men would go hunting. (cause the men were super smart back then)
Nowadays due to artifical light and the changing of peoples circadian pattern this is not the case. Although if you put 4 women in one house they all bluetooth in to each other and its hell for any male in that house for a period of 3-7 days per month.
Anyway enjoy

Geez sea breeze is a diverse bunch.nice thread.

Thanks Elroy, nice short understandable vid. So the friction of tides over the ocean/sea floor slows the earth down, I guess turbines in the flow has the same effect, and adds to that slow down.
The earth won't be such a nice place once it stops rotating, but humanity probably won't be around then.
When is the sun due to do it's red giant thing?

they reckon the sun has another 4billion years of stability, however there is a large scientific war in regards to this. Im not starting a conspiracy war but have a bit of a google

Elroy Jetson said..
I just did a quick calculation:


The Carnegie tidal power station at Garden island would have to operate non stop for 1000 million years to slow the rotation of the earth by 5 milliseconds.


The dissipation of energy by tidal friction on earth averages about 3.75 terawatts, slowing the rotation of the earth by 2 milliseconds a century

Carnegie wave energy plant at Garden island produces 250kW of energy. Lets assume it dissipates 1000kW of tidal energy. Which is 0.000001 terawatt

3.75 / 0.000001 = 3 750 000


2 milliseconds divided by 3 750 000 = 0.00000053 milliseconds a century

0.0053 milliseconds every million years

Or 5.3 milliseconds every billion years

I dont think your answer is correct! Ya forgot to carry the 1!

Razzonater said..
The more we pump and burn, the less mass we have and the less gravitational strength to keep our sync with the moon. You must take into account that although it may seem a trivial amount of mass, over years and decades it can and will have an effect. Apparently there is a couple nuclear power stations that if

Is that suggesting we have worked out a way to make matter disappear?

Burning fossil fuels won't make the earth lighter.

I really hope you are joking...

One day I will come back and read the other responses, but the tides come from the moon, so slowing the tides must slow the moon. Now basic physics will tell you that if you slow the moon, it will crash into us, so tidal must be bad, mkay.

pweedas said...
Tidal power systems act as a shock absorber on the movement of the earth's tidal flow, that is, they restrict the movement of the tide, but to a minuscule amount considering the huge volumes of water movement worldwide.
As such. all energy extracted by this method must act to slow down the earths rotation.

It's not a renewable resource. It is not replenished by anything which would add momentum to the earths rotation.

It has no real effect at the moment because there is very little energy derived from tidal power.
If it ever became a major contributor to the planets power generation it would have a more significant effect.

Another thing which affects the planets rotational balance is the recent shipping of hundreds of millions of tons of iron ore every year from the southern hemisphere to the northern hemisphere. Most of the products made from this remain in the northern hemisphere.
It's a bit like moving the balance weights on your car wheel and then wondering why the wheels wobble.
Eventually this will have a noticeable effect.

One day we will awake to find the earth has fallen over.

Well, maybe not quite,.. but it must have some effect.

Please dont encourage me,but stic a coin to a basketball,spin it on your finger than move the coin offset from the axis/off centre.....you are correct pweedas.
Dawn patrol I am serious,for shizzle

Where is the mass lost to?

As far as I am aware Earth does lose some mass to space. But not as a result of burning fossil fuels.

Slight bit of tongue in cheek when I said the moon will slow and crash into the earth, forgot to use

There are many papers investigating the loss of mass to energies. I made it clear Im not saying it is significant, was just pointing out it is real.

Should subtext that I studied physics at uni for 5 years, so my humour might have been too subtle.

Kamikuza said..
>>>>

Does the OP actually mean wave power?

No! The energy from wave power obviously comes from the sun, same as hydroelectricity, somebody else mentioned earlier.

Uni? Back in my day we did orbital mechanics in year 12 physics.

I agree with Elroy. The tidal energy comes from the kinetic and gravitational potential energy of the earth moon system. I might add that although the moon is slowing down it's actually gaining energy by going into a higher orbit. The tidal bulge acts on the moon like you wind up a tennis ball tied to the end of an elastic band. So to run those power stations the earth must lose more rotational energy than the moon gains in orbital energy.

There are many permutations and combinations of the earth's rotation speed and moon orbits that could balance the energy budget to run power stations. To find the one and only solution you could call on conservation of angular momentum. Angular momentum in the earth/moon system is conserved no matter what sort of internal energy exchanges are going on. (Unless of course the sun somehow exerts an external torque on the earth moon system, which maybe it does, you'd need to be someone like Milakovic to work that out)

decrepit said...

Kamikuza said..
>>>>

Does the OP actually mean wave power?

No! The energy from wave power obviously comes from the sun, same as hydroelectricity, somebody else mentioned earlier.

Hydro uses gravity, which is not from the sun. UNLESS you mean that solar energy evaporates the water which condenses into clouds that fall as rain which is collected at elevation to store kinetic energy to be turned into power as the water falls through a turbine under gravity?

Cal said..
If you mean wave power, that is of complex origin (what isnt though). I think the most basic explanation of wave generation, particularly the type driving power generation, is that it is wind powered utilising the distances of our oceans to allow sufficient energy accumulation. Now wind is basically thermally derived, so potentially of solar origin too!

A fair component of wind energy is derived from the earths rotation. Which also serves to slow the earth down. Even without the sun, the internal stresses within a gas sitting on a rotating sphere would generate highs and lows.