Tidal Generation

2011

I was shown a presentation and given a tour of Openhydro's facility in Greenore County Louth recently.
They are working on a number of fascinating projects with their "open centre" bidirectional turbines (they generate power on both flowing and ebbing tides).

This animation provides an overview of how their turbines are installed and how they operate:

To get an idea of the shear scale of these turbines check out these photos:

Interesting stuff. I think that they are really onto something these turbines are clean, use 100% renewable energy and silent. . Obviously subsea is a very hostile environment, but there have many advantages over wind turbines. For example:
● Unlike the wind the tides can be predicted with 100% accuracy
● The tides strong enough to generate power can be guaranteed every day of the year.
● Nobody is going to object to living beside a subsea turbine.
● They are only visible to divers.

SeaGen have a 1.2MW tidal turbine of a very different type installed in Strangford Lough, Co. Down. I also had a tour and attended a presentation on this facility, well worth a visit.

Perhaps this is the future?

antoinolachtnai

There is obviously plenty of ocean out there, but when I researched it before, there seemed to be a relatively small number of sites that these turbines suit. You could only get a small percentage of national demand from them as a result.

2011

antoinolachtnai wrote: »

There is obviously plenty of ocean out there, but when I researched it before, there seemed to be a relatively small number of sites that these turbines suit.

Really? I would have thought that any area with strong tidal currents would be suitable once it is not too deep or too shallow. We have a large coastline and I assume that these turbines can be installed reliively close together.

You could only get a small percentage of national demand from them as a result.

I would like to think that they could be part of the solution.

antoinolachtnai

Worth looking at

http://www.seai.ie/Publications/Renewables_Publications_/Ocean/Tidal_Current_Energy_Resources_in_Ireland_Report.pdf

It turns out that there are 11 viable sites around the coastline.

It takes a lot of engineering to do anything that can survive in the environment.

Bruthal

The main problem with sea type generation is the hostile environment for fully submerged turbines etc.

Other than that not unsubstantial problem, there is a practically unlimited resource there.

adrian92

Just a thought - need a Physisist to answer. Electricity generation requires three elements. Conductor, Magnetic field and relative! Movement

Can sea water (conductor), tide (movement) and Magnetic field (the Earth's)

Generate electricity ?

2011

adrian92 wrote: »

Just a thought - need a Physisist to answer. Electricity generation requires three elements. Conductor, Magnetic field and relative! Movement

Can sea water (conductor), tide (movement) and Magnetic field (the Earth's)

Generate electricity ?

No.

2011

antoinolachtnai wrote: »

Worth looking at

http://www.seai.ie/Publications/Renewables_Publications_/Ocean/Tidal_Current_Energy_Resources_in_Ireland_Report.pdf

It turns out that there are 11 viable sites around the coastline.

Not just that, Openhydro are working on a number of projects for deployment in other counties.

It takes a lot of engineering to do anything that can survive in the environment.

Absolutely, I had a good chat with some of the engineers involved.
These turbines designed to be placed on the sea bed for a number of years without maintenance with an export cable running for several kilometers under water.

Bruthal

adrian92 wrote: »

Just a thought - need a Physisist to answer. Electricity generation requires three elements. Conductor, Magnetic field and relative! Movement

Can sea water (conductor), tide (movement) and Magnetic field (the Earth's)

Generate electricity ?

Even if you forget about the sea water and form a large set of windings, spin it so it's "cutting" the earth's magnetic field, the earth's field is so weak at any given point that it won't work.

Add the sea water to the equation and that's not forming any sort of usable circuit either. Its one large mass.

Sea water has much higher resistance than copper as a matter of interest too.

ted1

Do open hydro rely on subsidies/ grants etc to stay in buisness. They've being around for over a decade have they are turbines that are turning a profit ?

antoinolachtnai

They get a high feed in tariff from HMG I think.

CJhaughey

Hard to see any Tidal Turbine surviving on the West Coast, its just too rugged.

2011

CJhaughey wrote: »

Hard to see any Tidal Turbine surviving on the West Coast, its just too rugged.

The turbines sit on the seabed.

The fact that a coast line is rugged I would think is irrelevant, unless you mean that a rugged seabed may cause the tidal currents to be turbulent?

I see in the link posted above by antoinolachtnai that 11 suitable sites have been identified in Ireland.

Bruthal

Once under the surface, the ruggedness of the coastline will be irrelevant really.

antoinolachtnai

My point re 11 suitable sites is that it really isn't that many sites. It seems to need some sort of inlet, and it needs a certain depth of water.

What makes the site 'suitable' in these calculations, as far as I can tell, is that the current is sufficiently fast. It doesn't necessarily mean it's feasible to actually put the gear in from what I can see.

It is certainly possible, but there are a lot of difficulties.

Lots of things aren't feasible until someone ups production. There was a time only satellites could afford PV, wind is quickly maturing, offshore wind won't be far behind. The Japs need tidal and theirs has to float.
Thermoelectric? Give it another decade or two.

CJhaughey

Bruthal wrote: »

Once under the surface, the ruggedness of the coastline will be irrelevant really.

I am talking about wave heights during periods of bad weather.
Undersea topography is usually pretty similar to the the adjacent shoreline, when you get big rock steps leading down to the sea, you find the same under the water.
When big waves roll in they meet the steps,jack up and create waves like the one in Easky, co Sligo.
I think these may have a future but in more sheltered waters like inlets or where the is some protection from wave action.
Even 40-50m down is not enough protection from wave action on the W. coast.

adrian92

Bruthal wrote: »

Even if you forget about the sea water and form a large set of windings, spin it so it's "cutting" the earth's magnetic field, the earth's field is so weak at any given point that it won't work.

Add the sea water to the equation and that's not forming any sort of usable circuit either. Its one large mass.

Sea water has much higher resistance than copper as a matter of interest too.

Thanks Bruthal for explaining why. Magnetic flux density etc.

2011

Yesterday OpenHydro sucessfully deployed the first of a pair of tidal turbines for EDF in Paimpol in Brittany, France. These grid connected turbines sit on the sea bed about 40m under water a number of kilometres out to sea. This article shows some interesting photos along with a video that shows part of the turbine assembly process as well as part of some of the latter stages of the commissioning process (carried out at sea).

syklops

Nobody is going to object to living beside a subsea turbine.

I'll have to stop you there. There will. There will be some tinfoil hat wearing "protester" who says under water turbines make their TV fuzzy or their tap water cloudy or gives their cat indigestion or something..

ted1

What's the output from it?

2011

ted1 wrote: »

What's the output from it?

Relitively small as it is primarily an R & D type project. The aim is to test the technology and see how robust it is in such a harsh environment.

Stoner

adrian92 wrote: »

Just a thought - need a Physisist to answer. Electricity generation requires three elements. Conductor, Magnetic field and relative! Movement

Can sea water (conductor), tide (movement) and Magnetic field (the Earth's)

Generate electricity ?

Just wondering about the source of this.
I've heard people ask this question 4 or 5 times in the last few months, is there a source in some from popular culture generating this concept? Was it asked in a Movie or the Flash or the Fringe or something

cros13

adrian92 wrote: »

Just a thought - need a Physisist to answer. Electricity generation requires three elements. Conductor, Magnetic field and relative! Movement

Can sea water (conductor), tide (movement) and Magnetic field (the Earth's)

Generate electricity ?

No, but you could generate power from where freshwater flows into salt water by harnessing osmotic pressure because of the difference in salinity. It's just not that easy to do.
There is some research being done... http://www.staff.science.uu.nl/~roij0101/

2011 wrote: »

Relitively small as it is primarily an R & D type project. The aim is to test the technology and see how robust it is in such a harsh environment.

Tidal power will never be a significant contributor to the grid. Wind turbines and solar require less maintenance, and the prices of both have come down to the point of or close to grid parity. The only piece missing at the moment is storage, I'd lay a very heavy bet on grid-scale battery storage dropping by 70-75% in price over the next 20 years.... and even at current prices is viable in many locations. Hawaii and a number of other isolated grids have already started large scale deployments. Batteries are also useful for maximising the efficiency of existing fossil fuel power stations.

Other technologies on the generation side are largely a distraction.

2011

cros13 wrote: »

Tidal power will never be a significant contributor to the grid.

Perhaps but OpenHydro seem to be doing pretty well from it.
http://www.openhydro.com/news/archive.html

Regardless of whether this technology takes off or not these projects are pretty unique. They provide design "challenges" that are hard to imagine. If you get up close to these turbines it is impossible not to be impressed.

Wind turbines and solar require less maintenance, and the prices of both have come down to the point of or close to grid parity.

Yes, but unlike the weather tides are 100% predictable and politicaly there is no opposition.

Other technologies on the generation side are largely a distraction.

I am sure there was a time when people thought that electricity would not catch on either
Time will tell and in the meantime it provides employment for quite a few people including engineers, electricians, and manufacturing personnel.

Bruthal

cros13 wrote: »

Tidal power will never be a significant contributor to the grid.

"Never" is a word likely incorrectly used many times in relatively recent history. Especially since it covers all time to come.

cros13

Bruthal wrote: »

"Never" is a word likely incorrectly used many times in relatively recent history. Especially since it covers all time to come.

I'm fairly confident on my use of never. In the same way I'm confident cars will never be en-masse powered by hydrogen fuel cells.

There are inherent engineering challenges which alternatives don't face. And those challenges add cost and limit the amount of recoverable power.

Another issue for tidal is that there are no apparent barriers that would limit expanding power production using those alternatives 100 fold.

Tidal's predictability isn't enough of an advantage vs the alternatives + grid storage. Grid storage can solve other issues like frequency regulation, black start, voltage support and also improves the efficiency of fossil fuel plants by eliminating the need for reserve capacity.

I'm also not saying that tidal will never be commercially viable.... just that it won't be a significant source of power.

2011

cros13 wrote: »

I'm also not saying that tidal will never be commercially viable.

There you go

Bruthal

cros13 wrote: »

I'm fairly confident on my use of never. In the same way I'm confident cars will never be en-masse powered by hydrogen fuel cells.

You could be right, no.doubt.

But I am just as confident to say a man will never jump unaided into orbit. It's easy to give confident examples of never. They don't necessarily strengthen other examples.

Imagine bringing someone from 1016 to this day. Id say there would be some serious alterations to his idea of "never".

If you think.its commercially viable, then.it would seem an enormous resource to keep commercialising.

cros13

The IEA doesn't believe tidal will be significant between now and 2040 either.

Bruthal

cros13 wrote: »

The IEA doesn't believe tidal will be significant between now and 2040 either.

Like I said, you, they, could be right. But what will the primary method be in 2050. 2060. 2160. What about in 8160, what then?
Perhaps never only means within our lifetime:)

2011

OpenHydro are very secretive, but they have just released this fascinating video of a recent project for EDF on YouTube. Much of this was filmed in the DCNS facility in the military port in Brest, France where they are normally pretty sensitive about the presence of cameras. The assembly process is a fantastic feat of engineering.