Tide-Powered Turbines Face Familiar Renewable Energy Issues

Horus

..."Green renewable technologies like tidal hydro-electric power and wind power need to be a part of Canada’s energy future, but incidents like this – even in the testing phase – prove that they are far from reliable..."

http://www.enviralment.ca/2011/01/10/tide-powered-turbines-face-familiar-renewable-energy-issues/

RCinFLA

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

I also saw a report on a system that works on wave swells.

It had a large concrete 'funnel' into the turbine which automatically reverses turbine blade pitch for incoming and outgoing swells.

waynefromnscanada

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

Perhaps the underwater turbine was not so much "unreliable" as not properly designed. Turns out the currents in the Bay of Fundy were several times stronger / faster / more powerful than was understood when the turbine was designed and dropped in the water. The powerful currents basically tore the thing apart, ripped off every one of it's blades, leaving only a huge gaping hole where they once were. So back to the drawing board for a unit that will stand up to these powerful currents. The good news however, is that they now know there is far more energy there to be harvested than had ever been imagined before this happened. Why didn't they know this before that turbine was designed and lowered into the depths? That's something I'd like to know. Appears some things were, shall we say, - - assumed.
Definitely NOT good engineering practices.
I also find it interesting that the writers of the report linked to in the first post, states: "a water-borne version of the wind-powered turbines you see cropping up with alarming regularity." What's that supposed to mean? Sounds like it was written by someone in the anti-renewable energy camp.
Regardless, I wish them better luck next time.

russ

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

If they didn't know how strong the currents were in the Bay of Fundy before they designed and built the thing the people are world class - idiots - certainly not engineers.

I doubt the new style tidal power devices will ever make the grade. The ocean is not at all forgiving.

Russ

ggunn

Captain Hindsight

russ wrote: »

If they didn't know how strong the currents were in the Bay of Fundy before they designed and built the thing the people are world class - idiots - certainly not engineers.

I doubt the new style tidal power devices will ever make the grade. The ocean is not at all forgiving.

Russ

Sniping at engineering failures is easy with the benefit of hindsight. You don't even have to be an engineer to do it. The truth is that engineering projects are typically full of assumptions when they are on the cutting edge, and failed projects provide invaluable lessons going forward.

Of course, that's not to say that stupid mistakes are never made. A lack of explicit units in some numbers handed off from one engineer to another (one meant "pounds" and the other read it as "kilos") led to the augering in of an unmanned Mars probe a few years ago. A large photo on the wall in one of the engineering buildings at the University of Texas (where I earned my engineering degree) of the twisted wreckage at the bottom of the Tacoma Narrows gorge has the caption: "Misplaced decimal point? NO PARTIAL CREDIT!" ;^)

But anyway, I object to the assertion that the designers of the Bay of Fundy turbine project were "idiots" by someone who knows far less about the project than the guys with their boots on the ground. Armchair quarterbacking is easy.

BB.

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

That is what pilot projects are for--to learn...

Personally, I think the bigger issue is the reduction in silt flow and beach erosion and possible biosphere changes (marine life feeding/breading grounds, etc.)...

I am not sure that those problems will ever be solvable by engineering--it can be reduced, but never eliminated.

Pulling "energy" out of the ocean shore system or interfering with natural currents will always have an effect on the environment.

The solutions (more dredging, pumping sand back onto beaches, etc.) may somewhat mitigate the problems--but there will be added expenses and what may be a positive for one land owner (more wet lands from retained silt) will cause others problems (slit blocking shipping channels, beach erosion/storm damage up to miles away) and lawsuits associated with those problems.

Let alone the issues with impact to marine life and the lawsuits from environmental organizations.

I can see a growth industry here--but it probably will not be "green power" companies and utilities.

-Bill

ggunn

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

BB. wrote: »

Pulling "energy" out of the ocean shore system or interfering with natural currents will always have an effect on the environment.

Well, yes, but how much of an effect it will have depends on how much is extracted compared to how much is there. Wind generators, for example, pull energy from moving air, and by the laws of thermodynamics you don't get something for nothing, so the energy in the wind is lessened by at least the amount of energy that is fed to the grid. I don't see the wind turbines up in the Panhandle affecting the weather here in Austin that much, though. ;^)

BB.

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

On the California coast and also many barrier islands (probably around the world) there are lots of "local issues" with erosion due to jetties, dams, and such interfering with natural flow of sand down the beaches from river deltas... Somebody builds another jetty to catch sand for their beach/limit cliff erosion, then the next guy down the beach has worse erosion. Just another vicious cycle.

And even then, there is just natural erosion and people try to prevent their property from falling into the sea--which then makes the properties on either side of theirs even erode faster...

At some point people are going to have to either toss the whole generating power from moving water idea (there is a good sized movement to pull out "all" dams here in the western US)--Or accept local environmental impacts for the "greater good".

Wind turbines certainly impact local environments. Would wind cause worse smog because the prevent atmospheric mixing (and creating more inversions) or is killing birds enough of an issue (let alone the noise, flickering from blades, even interference with radio transmission) be acceptable losses or not...

I don't know the answer to those questions on a political level.

-Bill

icarus

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

A cool conceptual idea I heard about once was a wave generator, that instead of trying to turn directional energy (waves) into rotational energy, the idea was you build a fixed armature on a vertical shaft, and the field moves up and down on that shaft generating power on the up and on the down strokes. It gets away from the complex problems of rotational forces in the water. Simply buoy farms wired together could take huge amounts of energy out of waves and swells, with much more simple mechanical engineering,, at least in theory.

ggunn

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

icarus wrote: »

A cool conceptual idea I heard about once was a wave generator, that instead of trying to turn directional energy (waves) into rotational energy, the idea was you build a fixed armature on a vertical shaft, and the field moves up and down on that shaft generating power on the up and on the down strokes. It gets away from the complex problems of rotational forces in the water. Simply buoy farms wired together could take huge amounts of energy out of waves and swells, with much more simple mechanical engineering,, at least in theory.

I saw that, too. I think that there is a pilot plant somewhere off the coast of Britain.

icarus

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

http://en.wikipedia.org/wiki/Wave_power

More info...

ggunn

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

BB. wrote: »

At some point people are going to have to either toss the whole generating power from moving water idea (there is a good sized movement to pull out "all" dams here in the western US)--Or accept local environmental impacts for the "greater good".

Not to worry, that's not going to happen. There are plenty of other reasons dams have been built other than to produce power, like for municipal water supply, irrigation, and flood control. Austin could not exist in anything like its present form without Mansfield Dam keeping the Colorado River from flooding the downtown area every few years. Call it the greater good if you will because that's what it is, but dams are not going away.

icarus

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

Nothing comes "for free". Even PV comes at some environmental costs. The question becomes what is a rational trade off? Personally, with little evidence in my head to support it, I think that low impact hydro, wind, tide, PV etc is a far better trade off. Not even including the climate debate, the mere fact that other energy sources are going to become increasingly "rare" and therefore costly.

Tony

waynefromnscanada

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

I often hear of the possible, or real killing of a number birds used as one of the argument against wind power. But if we think about it, what of the millions killed by the pollution we produce through the burning of fossil fuels to produce electricity? Here in Nova Scotia, I'm ashamed to say, a large percentage of our grid power comes from the burning of coal, the good old fashioned way

russ

Re: Captain Hindsight

ggunn wrote: »

Sniping at engineering failures is easy with the benefit of hindsight.
But anyway, I object to the assertion that the designers of the Bay of Fundy turbine project were "idiots" by someone who knows far less about the project than the guys with their boots on the ground. Armchair quarterbacking is easy.

I designed, constructed and operated iron ore processing plants during my working days - I do know design and what should go into it - like it or not I would say the results have proven this to be one sorry lot of engineers.

You don't have to know much about a project to say that they did not do their homework before designing.

Russ

russ

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

The 'snake' (Pelamis) started off Portugal and was a disaster. Later rescued and tried off England. Last I read (recently) they were projecting optimistic results but time will tell.

Anyone who ever served in the Navy (afloat) is well aware of the power of the ocean and the violent nature of it.

I read sometime back about a company trying something offshore in the Oregon area. That is some very rough water!

Some groups want to put small turbines in rivers using only natural currents. Having seen the size of even 30 mW turbines in hydro projects in Oregon (largish) that have considerable head to work with I have trouble imagining the river current based units producing enough to be worthwhile.

Spring floods would probably clear most out anyway I suppose.

Russ

bmet

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

Natural flow means that there wouldn't be any management to prevent the 'drain' from backing up once these turbines were introduced into the water. It all flows downhill, and even the slightest obstruction would cause a river to 'go around' to the path of least resistance. Who knows what a long term obstruction would influence systems upstream?

mike95490

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

ggunn wrote: »

Well, yes, but how much of an effect it will have depends on how much is extracted compared to how much is there. Wind generators, for example, pull energy from moving air, and by the laws of thermodynamics you don't get something for nothing, so the energy in the wind is lessened by at least the amount of energy that is fed to the grid. I don't see the wind turbines up in the Panhandle affecting the weather here in Austin that much, though. ;^)

But look at all the rain in Australia !! (in their summertime)

bmet

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

ggunn wrote: »

Well, yes, but how much of an effect it will have depends on how much is extracted compared to how much is there. Wind generators, for example, pull energy from moving air, and by the laws of thermodynamics you don't get something for nothing, so the energy in the wind is lessened by at least the amount of energy that is fed to the grid. I don't see the wind turbines up in the Panhandle affecting the weather here in Austin that much, though. ;^)

How far does the wake of big ships extend behind them? How about an entire Carrier group? Austin may be too distant for the prevailing winds, but I wonder if the national weather service records turbulence, or wind-shear around these massive wind farms. Abilene has one, and if you could record the movement of a thousand randomly-placed 'windsocks' let's say, east of Clyde, Tx., I'd bet they have more than their share of microbursts, dust devils, etc. I wouldn't want to put an airport there.

waynefromnscanada

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

bmet wrote: »

How far does the wake of big ships extend behind them? How about an entire Carrier group? Austin may be too distant for the prevailing winds, but I wonder if the national weather service records turbulence, or wind-shear around these massive wind farms. Abilene has one, and if you could record the movement of a thousand randomly-placed 'windsocks' let's say, east of Clyde, Tx., I'd bet they have more than their share of microbursts, dust devils, etc. I wouldn't want to put an airport there.

And what of one area that's forested, slowing the wind, while another is without trees?

mike95490

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

When I was a kid, my dad told me that tide power stuff had been tried, and then abandoned, as it was discovered to be changing the earths rotation (we're sucking power out of the earth/moon/sun gravity sink. So, look for 24.2 hours days in a dozen years or so ????

xiphias

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

Turbines, turbulence and environmental effects is an interesting area of research. Very much up in the air, as it were....

Recent editorial in Nature here:
http://www.nature.com/nature/journal/v468/n7327/full/4681001a.html

waynefromnscanada

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

mike90045 wrote: »

When I was a kid, my dad told me that tide power stuff had been tried, and then abandoned, as it was discovered to be changing the earths rotation (we're sucking power out of the earth/moon/sun gravity sink. So, look for 24.2 hours days in a dozen years or so ????

Never heard of that one (being tried and abandoned) but look at it this way - - - if we as a society don't mind destroying the world as we know it with the pollution resulting from our present methods of energy production, then we aren't going to mind slowing down the earth either. It's all about I, I, I, ME, ME, ME, RIGHT NOW, and the consequences really don't register in such thinking. Plus, the retail giants of the world would love it. More hours in the day to spend your money. But I digress. lol

icarus

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

mike90045 wrote: »

When I was a kid, my dad told me that tide power stuff had been tried, and then abandoned, as it was discovered to be changing the earths rotation (we're sucking power out of the earth/moon/sun gravity sink. So, look for 24.2 hours days in a dozen years or so ????

Oh come on, you don't take that seriously do you? Consider this, even if you were "taking energy out of the earth/moon/sun gravity sink, and even if we would be very unlikely to take enough energy to be remotely measurable.

But from the pure physics point of view, you are not taking energy out of the cycle, yo are only moving it! Picture this the energy in the flowing water turning a turbine is the same energy that eventually ends up on the shore! It's just like capturing wind energy. The same wind energy captured (and used) in a wind turbine is the same energy that would be captured by the surrounding land area. Or PV solar, the energy striking the panels and being converted into electricity , is the same energy whether it is being used as electricity or absorbed as heat. There is no loss or gain of net energy.

(I am not a physicist nor do I play one on TV, so perhaps someone can explain it better!)

mike95490

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

icarus wrote: »

Picture this the energy in the flowing water turning a turbine is the same energy that eventually ends up on the shore! It's just like capturing wind energy.

Well, it's NOT wind energy, which is obtained via the solar heat engine cycle, but it's rotational energy being converted to heat, from the orbital system. eveytime we slingshoot a spacecraft around a planet for "gravataional boost" we can measure exactly the amount "stolen" we used for boost . A few KWH for a space craft won't deorbit Jupiter anytime soon, but on earth, tidal drag friction is eventually going to stop rotation, and lock earth & moon together, generators may speed that up by a few minutes.

icarus

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

Mike,

You raise a point that I had thought about while I was writing the previous response. Every time we send something out of earth's gravity the equation does indeed change, even minutely.

But the issue with tides is different. No energy is lost by capturing it in tide generators unless my understanding of physics is flawed,, which it admittedly may well be.

T

PS I do stand corrected, of one assumes that Wiki is smarter than I!

The movement of the tides causes a continual loss of mechanical energy in the Earth–Moon system due to pumping of water through the natural restrictions around coastlines, and consequent viscous dissipation at the seabed and in turbulence. This loss of energy has caused the rotation of the Earth to slow in the 4.5 billion years since formation. During the last 620 million years the period of rotation has increased from 21.9 hours to the 24 hours[4] we see now; in this period the Earth has lost 17% of its rotational energy. While tidal power may take additional energy from the system, increasing the rate of slowdown, the effect would be noticeable over millions of years only, thus being negligible.

I guess I would have to quote Alfred E. Newman at this point,,"What,, me worry?"

Still better than burning coal IMHO.

ggunn

Re: Captain Hindsight

russ wrote: »

You don't have to know much about a project to say that they did not do their homework before designing.

To say it, of course not.

russ

Re: Captain Hindsight

ggunn wrote: »

To say it, of course not.

You must be an accountant or gardener or some such equally technical type of person.

These fellows engineered a disaster and you try to defend them?

ggunn

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

mike90045 wrote: »

Well, it's NOT wind energy, which is obtained via the solar heat engine cycle, but it's rotational energy being converted to heat, from the orbital system. eveytime we slingshoot a spacecraft around a planet for "gravataional boost" we can measure exactly the amount "stolen" we used for boost . A few KWH for a space craft won't deorbit Jupiter anytime soon, but on earth, tidal drag friction is eventually going to stop rotation, and lock earth & moon together, generators may speed that up by a few minutes.

OMG! I need to buy land where the terminator will end up! Everywhere else on the planet will become uninhabitable when rotation stops! It's a good thing we had this discussion, it puts me a few billion years ahead of the curve.

ggunn

Re: Captain Hindsight

russ wrote: »

You must be an accountant or gardener or some such equally technical type of person.

These fellows engineered a disaster and you try to defend them?

Not at all. I am an engineer and a chemist. And I'm not defending them, actually; in reality I have no idea which variables they hadn't taken into account rose up to bite them, or if whatever it was was something they should or could have known about ahead of time. My point is that I don't think you do, either. We can all look at what happened and speculate as to what it was that doomed the project, but it's hindsight.

BB.

Re: Tide-Powered Turbines Face Familiar Renewable Energy Issues

Engineering is always a trade off between cost and reliability... If this was intended to be a cost efficient prototype for production--they may have underestimated the forces or even been damaged by a log/other stuff (from local river, pier, floating in from ocean, or even damaged by local boaters/ships dragging anchor, etc.).

Given that the energy in a moving fluid (including air) is based on the cube of the velocity, even a relatively small error in maximum velocity can make a huge difference in the design strength and possible braking design, etc.

Could also be improper material selection (saltwater under pressure combined with flexing of blades, water colder than expected, etc.)... Even manufacturing issues could have also had an impact.

Add that local currents may have changed due to moving sand bars or even the turbine affecting local sediment flows changing the flow rates over time...

It would be interesting to find out what they think the causes of the failures were.

-Bill