Dynamic tidal power

Amhran Nua

I came across this interesting concept while doing some research, Dynamic Tidal Power, not sure if its been covered in this forum before. From the looks of it this could supply 100% of our energy needs, with plenty to spare.

Dynamic tidal power or DTP is a new and untested method of tidal power generation. It would involve creating large dam-like structure extending from the coast straight to the ocean, with a perpendicular barrier at the far end, forming a large 'T' shape.

This long T-dam would interfere with coast-parallel oscillating tidal waves which run along the coasts of continental shelves, containing powerful hydraulic currents

A DTP dam is a long dam of 30 to 60 km which is built perpendicular to the coast, running straight out into the ocean, without enclosing an area. The horizontal acceleration of the tides is blocked by the dam. In many coastal areas the main tidal movement runs parallel to the coast: the entire mass of the ocean water accelerates in one direction, and later in the day back the other way. A DTP dam is long enough to exert an influence on the horizontal tidal movement, which generates a water level differential (head) over both sides of the dam. The head can be converted into power using a long series of conventional low-head turbines installed in the dam.

It seems this supplies anywhere from 6 to 15 GW, and is as yet untested since you can't do scale model testing. The science behind it is good and it's being proposed by a couple of Dutch engineers who know a thing or two about dams though so I'd be willing to countenance some deeper investigation. If you build two of them 200km apart they complement one another, so one produces power while the other doesn't, apparently. Cost wise, if they come in at anywhere under €6 billion each they are easily as good as or better than most other power generation sources, all in I'd guess €10 billion each would be competitive.

The main problem with them is sedimentation, or silting, beaches tend to build up around tidal obstacles rather quickly, but there are a few different methods used to prevent that in various different fields, even if regular dredging may be required. Environmentally I'm not sure what other damage it would cause.

So can it be done, should it be done, and has anyone got a few billion spare change hanging around so we can find out? Coupled with existing wind resources we'd have a 100% renewable energy energy base and exports too, and it should be unencumbered by patents by 2017.

Amhran Nua

Note, to scale in length only not width of barrier. The Porcupine Bank has a depth of 200m on average.

Amhran Nua

I'd estimate roughly 40-50 million cubic meters of reinforced concrete each, assuming say 4-6 meters wide, may be way off on that though.

Alekalen

I am enthralled by this concept so I decided to do some work on it and made this mockup of the eastern coast of the US. My estimates put this at approximately 236-295 GW. The cost would need to come under $1.2 trillion to be more cost effective than nuclear.

Capt'n Midnight

our seas are too deep, somewhere like the Dogger bank in the North Sea might be a better option (or the chinese have some nice sites / Oz to New Guinea also likely )

actually if you look at your map it would be easier to finish building the Giants Causeway, far shorter and you have the whole of the Irish sea.

Sure why not build one across the English channel if it's so easy ??

Capt'n Midnight

Amhran Nua wrote: »

I'd estimate roughly 40-50 million cubic meters of reinforced concrete each, assuming say 4-6 meters wide, may be way off on that though.

Dam 30Km long with 20Km T piece x 2 = 100Km of Dam

4m wide AT THE TOP

200m down say it's 50m wide

to make it simple let's say it's triangular , and the seabed is rock and there isn't primordial ooze on the sea bed

50m * 200m * 0.5m * 100,000m = 500,000,000m3 - so I'd guess at least 10 times as many , in reality it would be far more



Of course a floating barrage with curtains might be a lot cheaper

robtri

whats the enviromental impact of putting 60km long dams on the costline???

tidal movements, plant life, beachs and sand issues?

Capt'n Midnight

robtri wrote: »

whats the enviromental impact of putting 60km long dams on the costline???

tidal movements, plant life, beachs and sand issues?

if it stops global warming then less damage done to other coasts

people forget that where we live was under a kilometer of Ice not that long ago. compared to the tropics and poles , the temperate regions are very unstable

easychair

Alekalen wrote: »

I am enthralled by this concept so I decided to do some work on it and made this mockup of the eastern coast of the US. My estimates put this at approximately 236-295 GW. The cost would need to come under $1.2 trillion to be more cost effective than nuclear.

I'm not sure if you are serious or not. I'm sure if you are right, then some enterprising individual, or corporation, would spot the opportunity and proceed to raise the funds and build.

The usual problem with alternative schemes is that the power they produce is unreliable in that it only works some of the time. Does this work 24/7 or out of a 24 hour period, can you calculate what the ratio to working and not working is likely to be?

djpbarry

easychair wrote: »

I'm sure if you are right, then some enterprising individual, or corporation, would spot the opportunity and proceed to raise the funds and build.

Ah, the free market paradox – if something is worth doing, then someone would have done it already. Logical conclusion: nothing is worth doing, as it’s already been done.

Capt'n Midnight

Tides are predictable,
Tides happen at different times in different places, you just need spacing and a grid. Soem places like the Irish Sea have very strange tidal patterns and so could generate power more or less continually.

robtri

Capt'n Midnight wrote: »

if it stops global warming then less damage done to other coasts

people forget that where we live was under a kilometer of Ice not that long ago. compared to the tropics and poles , the temperate regions are very unstable

how will it stop global warming???? if C02 is the cause of global warming then doing this will mak no difference as we already have pumped too much into the air, and even if we stop now surely the temp will continue to rise and all we will do is get a few extra years ??

dlofnep

robtri wrote: »

how will it stop global warming???? if C02 is the cause of global warming then doing this will mak no difference as we already have pumped too much into the air, and even if we stop now surely the temp will continue to rise and all we will do is get a few extra years ??

Less trees = Less ability to absorb CO2. Find alternative energy sources, and we can reduce CO2 levels if we reduce our CO2 output.

slowburner

djpbarry wrote: »

Ah, the free market paradox – if something is worth doing, then someone would have done it already. Logical conclusion: nothing is worth doing, as it’s already been done.

Surely the (il)logical conclusion would be;
Definitely, nothing is worth doing as it has probably already been shown, that it probably can't be done.

slowburner

robtri wrote: »

how will it stop global warming???? if C02 is the cause of global warming then doing this will mak no difference as we already have pumped too much into the air, and even if we stop now surely the temp will continue to rise and all we will do is get a few extra years ??

See above

Pataman

How about building a road/rail bridge from dublin to holyhead and incorporating it into the bridge.

easychair

Capt'n Midnight wrote: »

Tides are predictable,
Tides happen at different times in different places, you just need spacing and a grid. Soem places like the Irish Sea have very strange tidal patterns and so could generate power more or less continually.

Thats fantastic. How much would it cost to generate power more or less continually? I'm assuming that that your view that the "strange tidal patterns and so could generate power more or less continually" is an opinion, and not based on actual evidence?

Capt'n Midnight

easychair wrote: »

Thats fantastic. How much would it cost to generate power more or less continually? I'm assuming that that your view that the "strange tidal patterns and so could generate power more or less continually" is an opinion, and not based on actual evidence?

A tidal cycle takes 12.4206 hours - so even if you only generate power at at the peaks you are generating power every 6 hours 12.6 minutes

http://www.irishtimes.com/weather/tides.html
you'll notice that the tide time changes between the south and east coast are spread out by this amount of time so you have a complete cycle along the coast more or less between our two largest cities.

have a look at the Severn Barrage (about twice our national output) and other schemes on the UK west coast.

we could put use the Aran islands as such a dam


more stats
http://www.marine.ie/home/services/operational/oceanography/TideGauge.htm


we have some of the highest tides



we could also use these things https://secure.wikimedia.org/wikipedia/en/wiki/SeaGen

robtri

dlofnep wrote: »

Less trees = Less ability to absorb CO2. Find alternative energy sources, and we can reduce CO2 levels if we reduce our CO2 output.

slowburner wrote: »

See above

ok we have too much C02 in the atmosphere at the min, which is causing a slow increase in temp....
so even if humans stop completly producing C02 right now, surely the temp will still continue to rise??

so still curious how this tidal power will reduce global warming..

Capt'n Midnight

robtri wrote: »

so still curious how this tidal power will reduce global warming..

if you have electricity you can make fuel from water, air and CO2


But more importantly if the rate of CO2 emission rises then we may hit one of the tipping points that we can't easily reverse, release of oceanic methane hydrates, amazon hinterland drying out, methane release from permafrost etc.

easychair

Capt'n Midnight wrote: »

A tidal cycle takes 12.4206 hours - so even if you only generate power at at the peaks you are generating power every 6 hours 12.6 minutes

http://www.irishtimes.com/weather/tides.html
you'll notice that the tide time changes between the south and east coast are spread out by this amount of time so you have a complete cycle along the coast more or less between our two largest cities.

have a look at the Severn Barrage (about twice our national output) and other schemes on the UK west coast.

we could put use the Aran islands as such a dam

So we can produce electricity at the peak (however long that lasts) every 6 hours or so.

WHat do we do for all the other times when it's not at its peak?

How much would it cost and how practical will it be to have a scheme which takes in the south and east coasts of Ireland?

The Severn has the pretty unique feature in that it has a very wide estuary which narrows into a river, and most of us can envisage how that works, and how relatively easy it might be to harness, compared to trying to harness the energuy from around 100 miles of coastline from the south to the easy coastline.

The issue with most alternative power sources (even the severn barrage) is that they can't provide continuous and reliable power. I love the idea of "free" energy from the tides, or waves, or wind, but practically their inability to provide continuous power is their achillees heel.

wildefalcon

Capt'n Midnight wrote: »

if you have electricity you can make fuel from water, air and CO2


But more importantly if the rate of CO2 emission rises then we may hit one of the tipping points that we can't easily reverse, release of oceanic methane hydrates, amazon hinterland drying out, methane release from permafrost etc.

Who cares about the global warming theory? What matters is the fossil fuel are running out, fast! And we need a replacement.

Nuclear is only a stopgap, as there is only so much uranium, fusion is too big, thorium research is in its infancy.

We need sustainable electricity generation, no choice, no option, we've got to explore these things.

Sure, it will change the sea coast, and it will disrupt wildlife (especially the Salmon) but we've done that before, and found that we have a good skill at creating habitats, if necessary.

I think the killer will be making it strong enough - the Sea is a incredibly tough environment - and the hydraulic pressures would be immense! We are at the cusp of a huge change in our materials science, with aerogels, graphines and other new materials offering many possible new techniques for construction.

Imagine Ireland at the forefront of this! And, of course, a 6 bn building project would restart the economy! Sean Quinn would be delighted!

And the co2 theorists could plant trees along the barrier. I like Beech trees - and have planted several hundred, though the salt would be an issue.

Capt'n Midnight

easychair wrote: »

So we can produce electricity at the peak (however long that lasts) every 6 hours or so.

WHat do we do for all the other times when it's not at its peak?

How much would it cost and how practical will it be to have a scheme which takes in the south and east coasts of Ireland?

The Severn has the pretty unique feature in that it has a very wide estuary which narrows into a river, and most of us can envisage how that works, and how relatively easy it might be to harness, compared to trying to harness the energuy from around 100 miles of coastline from the south to the easy coastline.

The issue with most alternative power sources (even the severn barrage) is that they can't provide continuous and reliable power. I love the idea of "free" energy from the tides, or waves, or wind, but practically their inability to provide continuous power is their achillees heel.

Did you even read my posts ????

You mention 6 hours but you seem to have missed my point that the East and south coast are out of sync so you could have continuous generation with strategically along the coast.

As for cost I've already pointed out that we have deep seas around the coast and suggested finishing the Giant's Causeway instead.


The Severn is unique , just like the Shannon or indeed many rivers and bays on the west coasts of the British Isles.

As for continuous and reliable power, tides are predictable decades in advance. Continuous power from a tidal system is possible, you just need to use more than one barrage but you get most power when you have the greatest difference in height, it's a compromise but very easy to link in to a Grid.

It should be possible to link the rising tide to pumped storage using hydraulics and valves and giant floats. But that's probably not cost effective.

wildefalcon

There's a storm blowing, and a Volcano has blown it's top in Iceland.

Ferries have been cancelled and air travel is at risk.

Would it make sense to incorporate one of these tidal booms in a bridge to Wales? A high speed rail link? Or a road bridge?

Just throwing ideas about, you understand.

Pataman

The Chinese can manage to build bridges that survive earthquakes and real typhoons not the gentle breeze we get every now and then.

Capt'n Midnight

Irish sea is deep and wide.

The two resonably short crossing points both have problems. Giant's causeway means you have a very long drive down whereas the Larne route goes through deeper water and all the UXB's from WWII


In Japan they built a bridge after a ferry disaster. But the toll is so high most people still use the ferry.

When will the shorter and busier Chunnel break even ?

wildefalcon

I would imagine that it would break even sooner than the Metro North scheme!

Seriously though, if the link to Wales was making electric from tidal power it would break even quite quickly, as, by then, the price of a barrel of oil would be (in real terms) in excess of 200 USD and rising.

djpbarry

wildefalcon wrote: »

Seriously though, if the link to Wales was making electric from tidal power it would break even quite quickly...

How quickly? I think you're seriously underestimating the scale and cost of such a project.

wildefalcon

djpbarry wrote: »

How quickly? I think you're seriously underestimating the scale and cost of such a project.

30 years? Compare this to the time and expense of nuclear (including the decreasing reserves of uranium, and the storage costs of the waste).

Capt'n Midnight

wildefalcon wrote: »

Seriously though, if the link to Wales was making electric from tidal power it would break even quite quickly

Why would the UK share with us when they could build a link from NI to Scotland for for a fraction of the price ?

djpbarry

wildefalcon wrote: »

30 years?

Is that an estimate or a guess? What's your basis for such a timeframe?