Underwater Ocean Currents Used to Power Bermuda

Saevio writes to tell us The Royal Gazette is reporting that Bermuda is planning to sink a power generator off the coast to take advantage of ocean currents. The company providing the service, Belco predicts that they will be able to provide approximately 10 percent of the island's energy needs. From the article: "The 150ft long deep sea generator with a four-blade turbine inside would cut Belco's dependency on oil and also benefit the environment by cutting future fuel emissions, he added, stating that the company needed to increase its generating capacity before 2010. Mr. Madeiros, who hailed the technology 'mind-boggling', said: 'This is cutting edge technology, not used anywhere else. One can't help but get excited by this technology.'"

Comments

Original press release

[luder]

Belco's original press release.

Won't this slow down the current?

[aapold]

I mean, the energy that otherwise would keep pushing warm gulf stream water towards Europe, that's going to be harnassed by Bermuda...

Does this not risk at slightly lowering the temperature of Europe?

I mean you never know the full consequences... I know, we have global warming to offset that, but still... (and these diverted warmer waters will linger in the southern atlantic, so mean global temperature is still the same...)

Re:Won't this slow down the current?

[scheming daemons]

Imagine a cookie crumb on your living room floor. That's the relationship that Bermuda has to the Atlantic ocean.

Now, imagine a speck of dust 1/100th the size of the cookie crumb in your living room. That's the relationship of this turbine generator to the Atlantic ocean.

This turbine generator off the coast of Bermuda will have the same effect on the Atlantic ocean currents that the above-mentioned speck of dust will have on the wind currents in your living room.

So small as to not even be measurable.

Re:Won't this slow down the current?

[maggard]

A crumb on your living room floor is a great way to put Bermuda in context of the Atlantic.

However it doesn't work so great in context of the Gulf Stream.

The Gulf Stream is not some huge tide-like current hundreds of kilometers wide, instead it's typically only a kilometer or two wide. Indeed if you fly over it (I have a number of times) it appears as a clearly defined 'river', of a much different color then it's surrounding waters, with large swirls & eddies sometimes breaking off of it, cutting through the otherwise featureless ocean.

So while Bermuda may be a crumb the Gulf Stream is a spider strand.

That said I don't think putting a few turbines, or even 'a lot' will have significant effect on it. The total energy in it is incredible and it's an ongoing process, there's not some hose at one end that can be cut off stopping it all, but rather a push & pull process that keeps the whole thing going. Even if Bermuda were able to pull out 1% of the energy in it that would be less then the effect of a slightly windier or cloudier day in the Gulf on it, completely lost in the noise level.

By the way, if you're ever on the East Coast of the US & have some friends who fly ask them to take a gander next time they're over the seashore for any eddies off of the Gulf Stream that are close to the shore. They're much lighter colored then the usual cold dark blue Atlantic waters, easy to spot. If there are any by a beach then take the opportunity to go swimming in it - it's amazing. Cold cold cold Atlantic waters then suddenly bathwater warm, often with tropical fish trapped inside the thermocline. I've enjoyed a few off of Provincetown, Mass. (tip of Cape Cod) and they're times I treasure , and friends who were along retell of the experience over & over.

Next headline about the project

[maxwell demon]

Power generator mysteriously vanised in the Bermuda sea!

cutting edge technology...

[aapold]

I prefer to say "current" technology.

I suppose this begs the question if they are going to be alternating currents or just using a direct one.

Does anyone know...

[daranz]

What will be the impact of this on the performance of the triangle? I wouldn't want to see halves of ships dissapparing all of a sudden, because there isn't enough power...

Re:Impact on the Currents?

[TheSkepticalOptimist]

It would be very quick to assume that interrupting current flow would be a definite consideration, but your talking about billions of tonnes of water moving at a very strong flow. There is just TOO much energy involved to worry about whether a turbine will stop ocean currents. Turbines are also passive, allowing water to pass through them. The amount of energy they remove is negligible compared to what is needed to make the water move past it.

Hoping the company lives up to promises

[ursabear]

From TFA:Asked about the potential impact on Bermuda's unique reefs, she said the efficient generator would have a "very low" environmental impact and said the noise produced by the generator would be "very, very quiet" and would not impact sea creatures. She said the unit would be sunk past the first layer of marine life, and fish below that level would be able to safely swim through it. An electric cable would link the substation to the generator under the sand.

I guess this means that the generator blades spin slowly enough that the fish just swim around the blades? My first thoughts before RTFA were concerns for the reef's health. I would hope that they would design it such that it would not cause a sort of in-the-ocean-current observer effect.

I'd like to see the opining of those with some physics or ocean dynamics experience.

It sounds like a great idea... I wish we had lots more three finkers out there trying to make power in new ways.

Re:how fast

[Rei]

Probably a fraction of one RPM. Not to mention that most fish have pressure-sensitive organs, and they flee from unexpected motion.

My worries would be about the effects of sapping gulf stream energy (that is what this is using, right?) would have on the stream. This is probably a tiny fraction of it's total energy, but if this sort of thing becomes widespread, it can only serve to slow the vital gulf stream (climate regulation, mineral distribution, etc).

Re:NO, IT WON'T.

[paeanblack]

For crying out loud, why is it every time there's a story about wind power, or ocean thermal power, or any other non-polluting technology, we always get somebody with NO concept of SCALE popping up with this same asinine question?

Because people are dumb. One turbine in the ocean is, literally, a fart in a hurricane.

On the other hand, don't blindly assume humans won't overbuild something. Do you think the first internal combustion engine spurred thoughts of smog-filled valleys hundreds of miles long? No, because it would take tens of millions of combustion engines running non-stop to do such a thing.

Re:how fast

[Hercynium]

It's an interesting conjecture, but probably more or less akin to the idea that windmills may change weather patterns.

Except for solar energy, the energy in this planet is somewhat of a closed system. The trade-off: Possibly affecting an ocean current may well be much better than the effects of smog, mining.

I won't pretend to know nearly enough about such things, but just considering the volume of water moving in the ocean, I believe it would take an incredible number of turbines like this to measurably affect any ocean current.

As far as the fish are concerned, you are correct, a current-driven turbine poses little danger to them, unless it somehow messes with the temperature or causes some sort of pollution. (something I actually know about for a change)

Re:NO, IT WON'T.

[LWATCDR]

"On the other hand, don't blindly assume humans won't overbuild something. Do you think the first internal combustion engine spurred thoughts of smog-filled valleys hundreds of miles long? No, because it would take tens of millions of combustion engines running non-stop to do such a thing."

Yep that is the key. It really is all a matter of scale. How much will be too much. Right now I wouldn't worry. What we need to do is see if it is practical. If so then we need to figure how much we can extract without causing damage.

As one person said, "The solution to pollution is dilution". A little bit here energy taken from here and moved to their will not really matter much.

It is exactly like the wind power issue. One windmill isn't going to hurt anything. What happens when you start extracting mega watts out of the wind pattern? What about changes to the micro climate just down wind from the wind farm?
I worry more when people dismiss things like that without looking at them at all because it would be too small to matter. Sort of like the idea that foam that you can crumble in your hand could shatter a carbon-carbon leading edge tile. I mean the foam when it hits that hard material will just shatter doing no harm right?

Re:NO, IT WON'T.

[fireboy1919]

One turbine in the ocean is, literally, a fart in a hurricane.

I think not! An ocean turbine is literally an mechanical device, while the ocean is literally a body of water.

Turbines are not now - nor have they ever been - farts. And while a hurricane is also mostly water, an ocean is not one.

Literally is not another word for figuratively; it's the opposite.

Literally.

Re:NO, IT WON'T.

[radtea]

What happens when you start extracting mega watts out of the wind pattern? What about changes to the micro climate just down wind from the wind farm?

The latter is irrelevant to all but the people who live there, in the same way the shadow effects of any industrial plant are irrelevant to any but the people who live there. It is not an environmental issue as normally understood--it is a land use or zoning issue. This is not to say it isn't important--it is--but we have centuries of law dealing with things like this, so there are really no signficant unknows with regard to wind farms except for the possibility that they do not have any significant negative downstream effects. That's a pretty good kind of uncertainty to have: "Nothing bad might happen! We just don't know!"

With regard to the question of what happens when we start extracting megawatts from the wind, this is a question that can be answered on the back of an envelope, which I will now proceed to do. Air has a density (rho) of about 1 kg/m**3. Consider wind at 10 kn, which is about 5 m/s. The power per square meter is 0.5*rho*v**3, or about 60 W, of which about half is available to windmills. Wind power has an energy density of about 30 W/m**2, maybe as high at 100 W/m**2 in windy areas. The Canadian province of Ontario has a winter load of about 20 GW and a summer load of about 25 GW. So we're talking about at least 200 million square meters of swept area to accomodate all of it, and maybe over three times this much. This is equivalent to a line of windmills with 100 meter span, 2000 km long removing half the kinetic energy from all the air that passes through them. This is not a small environmental influence. It is hard to imagine that this would not quite fundamentally change energy transport and therefore weather patterns over hundreds of kilometers.

I didn't expect that result when I started writing the paragraph above, but since I'm a scientific rather than a religious environmentalist, I can't simply ignore it. Wind power is still worth pursuing, but it is very clear that it is never going to be more than one element in a mix of alternatives, and is very unlikely to ever generate more than 10% of our power if its environmental impact is to be kept moderate.