tidal electricity production

[fraxinus]

Inspired in part by jebatty's Modest Proposal in the Ashcan (yeah, you really do have to act on your beliefs), I'm asking for suggestions about where to go for good information on the latest technology for using the tides to produce electricty. I live on a tidal river and I'm really thinking about the possibility of a local municipal power company involving the four towns that border the river.

Tidal power was harnessed in this part of Maine as early as the 1600's to run sawmills and grist mills. The possibility of using tidal energy to produce electricity on a relatively small local level, seems to me to be closer to green, renewable base load electricity production than any other alternative. The massive tidal project proposed (and actually begun) in the 1930's (Quoddy/Dickey-Lincoln) for northern Maine, New Brunswick/Nova Scotia was to be the TVA of the north. According to legend at least, it was scuttled by intense pressure from Eastern coal and oil interests. The concept of tidal power was brilliant in 1930 and remains so today. Smaller local utilization seems to me a real possibility.

 

[jebatty]

Take a look:

(broken link removed)
http://media.cleantech.com/2269/bay-of-fundy-to-get-three-test-turbines

Tides represent a massive energy source, but they're kind of like a generator that produces only one volt and a million amps. I expect more progress in this area too.

 

[Dune]

Traditional hydropower involves dams, which is what makes it difficult to get by the fishhuggers. Modern tidal (current) gen. shemes involve large turbines, well beneath the surface in areas of massive current flow. As far as I know, the minimum requirement for siting a turbine is about 15 meters of depth and a current velocity of 7 nautical miles per hour. This tells me that the technolgy is in a state of infancy, because one knot of current is aproximately equal in force to twenty knots of wind. As it stands now, finding a place to site a turbine with such stringent requirements is difficult, but there are places with that much force. In order to utilize other areas where there is plenty of potential energy, more effective turbines are being developed. Also, there are many other ways this energy could be extracted.

 

[fraxinus]

Jim and Dunebilly - Thanks for your replies. Re fish huggers: My original post was a bit misleading. Dickey-Lincoln (first proposed in the 30's but not begun then) was a conventional hydro system using the St. Johns River (border between Maine and New Brunswick). The whole thing came to a halt in the 70's. The endangered furbish lousewort was the cause. Not fish huggers but plant huggers.

The Quoddy tidal project utilizing Passamaquoddy and Cobscook Bays was begun - you can see remnants of some of the dams designed to capture water at high tide today. I do agree that dam building is not likely to be a possibility today, but the amount of unutilized tidal power in this part of the world is awesome.

Dunebilly, I wish you would elaborate of other ways of capturing tidal energy and supply the names of some companies working on underwater turbines if you know of any.

 

[Dune]

Beleive me, I am no fishhugger either. Sometimes at night, the souls of all the fish I've killed come back to haunt me. Here on the Cape, an aplication to site a different type of turbine in the canal (6 knots tidal current) was submitted at the same time as the much hyped wind farm. This application has also lanquished through one agency ( town, state, federal) after another( 7 years so far). This is why I often comment that the Gov. will not solve this problem for us. If I remember correctly, the canal project utilizes a simple design, similar to a screw. It is secured at each end, and the current rushing by causes it to spin. Such a turbine, when and if proven, could be anchored in a great many places. Mississipi, Saint Lawrence Seaway, any river or chanel with strong current. My idea for situations where dams would be a problem is giant undershot wheels. For example, the Cape Cod Canal could have both sides, lined for the entire lenth, with 100 foot diamenter ferris-type wheels, with just the buckect or blade intruding into the water. I am quite sure this would work, as undershot wheels as far from a new design, certainly not as efficient as turbines or overshot wheels, but effective nonetheless. One interesting feature of tidal power is it's constancy. 24-7-365, with a breif (aprox. 30 minute) slowdown every 6 hours or so. Neither wind nor solar can make this claim. Also because of the tremendous potential energy, and giant size of the resource, easily all our needs could be met, if hydro, tidal, solar and wind were maximized. As far as providing links, type tidal current turbines into google, you should get many hits. By the way, there is another, unmentioned source of potential hydro-power sites, that being existing unused dams on rivers and streams all throughtout New England, and I would assume other parts of the country as well. You would be amazed at the output of even a small properly designed millpond/dam. Many of these are abandoned, and the issue of blocking fish travel is moot, as these dams are pre-existing.

 

[webbie]

The power in tides is just amazing......and I'm fairly certain the only reason a solution is not further along is lack of trying. The technology is not beyond current processes and understandings...for instance, it's not a problem as hard as getting rid of nuclear waste (cheaply). I have seen everything from small wave generators which create power just by rocking back and forth - to larger tidal generators. If you think about it - areas with 8 foot or larger tides - even a boat dock ends up moving 16 feet up or down twice every 24 hours.....that is a LOT of power. It might be possible to do tidal on both large scale and small scale.

But, for now, I think wind and solar will be the technologies of the next decade.

 

[Dune]

Along those lines, one of the concepts I have been playing with for many years (20-plus) is giant floating concrete barges, anchored on spuds ( huge collums driven into the seabed). If sited in areas of large tide height, they could be geared to spin generator as they rise and fall. The size (bouyancy) and weight ( resistance to lifting) would determine the electrical output, which could be immence if the barges were big. Laugh if you will, but a few acres of such barges in Cape Cod bay, could power much of the Bay State. If more power were needed, build more barges. Too costly? I don't think so, at least compared with nuclear. Current estimates by the D.O.E., project a cost to build one nuke at 18 billion dollars, and they admit it may be much higher, especialy if radioactive waste storage is brought into account (not subsidized by the feds, as ALL of it is now). Give me 18 billion, and I will give you clean, everlasting power. And just think, if they were to be built in the Bay of Fundy, they would generate FOUR times as much power.

 

[rhetoric]

Here's a pretty good news link on a tidal turbine in Great Britain. I have since seen it installed and running (not in person, mind you).

http://www.youtube.com/watch?v=TrhfFLNah24

 

[pete324rocket]

I read about these new designs in a popular science magazine under "new ideas" in the local library some time ago.Then one of our politicians(minister of energy) got on t.v. on a call in show and talked about a whole lot of nothin' so I got mad and called in and started to explain about this new technology. Long and the short of it,there was a lot of dead air coming from his end and he didn't have the first clue of what I was talking about.Later I emailed him the location of the website in England where this was being developed and funny enough....about two to three months later,the local paper is announcing all of this research they were planning to undertake,mostly in Nova Scotia but partners with our province here in New Brunswick. The tides here are really huge, and you can depend on them. I hope it all works out. By the way,I still have copies of the email. And he isn't the minister of energy anymore.

 

[Dune]

This first link is interesting, because the flow rate required of 2.5 knots is not nearly as hard to find as seven knots. In fact there are many places with this strenght of tide in massachussets. http://.energybulletin.net/node/2273 The second link is the type which requires siting only in very high current flow rate areas, but I included it, because it is installed, and will shortly be powering 1000 homes, cleanly and benignly. (broken link removed to http://ceseeps.blogspot.com/2008/os/worlds-largest-tidal-energy-generator.html) I don't know why only one became a link, and when I tried to edit it, it got worse.

 

[Telco]

Best idea I saw is the one that you can't see. It was proposed that we take advantage of the Gulf Stream by planting giant turbines underwater. The picture showed giant units that resembled windmills. It doesn't move all that fast, but it is a constant, unstopping force. These watermills, for want of a better term, were shown to be deep enough that the largest oceangoing ship did not need to worry about hitting a blade. This was a concept though, with artist's renditions.

A more realistic method is in the making, at this NPS story shows.

Dunebilly- if you greet the souls of those fish with tar-tar sauce I doubt they will stick around to haunt you anymore.

 

[mainemac]

Looks like downeasters are onto this already

(broken link removed to http://canadianpress.google.com/article/ALeqM5h4_97bK4_urR9AP6zdke1NHyfU4g)

 

[EatenByLimestone]

If we were to take advantage of the gulf stream averaging 4mph we would take care of a good amount of our energy needs. The turbines could be well below the surface of the water. Think of the energy Florida alone could produce.

Matt

 

[Dune]

Nice link Telco, and you other folks as well. Tuna and striped bass tonight, but I didn't kill 'em this time. Think a little tartar sauce will do it huh?

 

[renewablejohn]

If you have a salt marsh you can use one of these at each main drain to produce electric

http://www.westernrenew.co.uk/index.html

can be used with very low heads.