Slashdot Mirror
Scotland Builds Power Farms of the Future Under the Sea
HughPickens.com writes "The Pentland Firth is a raw, stormy sound between the Scottish mainland and the Orkney Islands, known for some of the world's fastest flowing marine waters. Daily tides here reach 11 miles per hour, and can go as high as 18 – a breakneck current that's the reason people are describing Scotland as the Saudi Arabia of tidal power. Now Megan Garber reports in The Atlantic that a new tidal power plant, to be installed off the Scottish coast aims to make the Scotland a world leader for turning sea flow into electricity. Underwater windmills, the BBC notes, have the benefit of invisibility—a common objection to wind turbines being how unsightly they are to human eyes. Undersea turbines also benefit from the fact that tides are predictable in ways that winds are not: You know how much power you're generating, basically, on any given day. The tidal currents are also completely carbon-free and since sea water is 832 times denser than air, a 5 knot ocean current has more kinetic energy than a 350 km/h wind.
MeyGen will face a challenge in that work: The turbines are incredibly difficult to install. The Pentland Firth is a harsh environment to begin with; complicating matters is the fact that the turbines can be installed only at the deepest of ocean depths so as not to disrupt the paths of ships on the surface. They also need to be installed in bays or headlands, where tidal flows are at their most intense. It is an unbelievably harsh environment in which to build anything, let alone manage a vast fleet of tidal machines beneath the waves. If each Hammerfest machine delivers its advertised 1MW of power, then you need 1,000 of them to hope to match the output of a typical gas or coal-fired power station. "The real aim," says Keith Anderson, "is to establish the predictability which you get with tidal power, and to feed that into the energy mix which includes the less predictable sources like wind or wave. The whole point of this device is to test that it can produce power, and we believe it can, and to show it's robust and can be maintained."
MeyGen will face a challenge in that work: The turbines are incredibly difficult to install. The Pentland Firth is a harsh environment to begin with; complicating matters is the fact that the turbines can be installed only at the deepest of ocean depths so as not to disrupt the paths of ships on the surface. They also need to be installed in bays or headlands, where tidal flows are at their most intense. It is an unbelievably harsh environment in which to build anything, let alone manage a vast fleet of tidal machines beneath the waves. If each Hammerfest machine delivers its advertised 1MW of power, then you need 1,000 of them to hope to match the output of a typical gas or coal-fired power station. "The real aim," says Keith Anderson, "is to establish the predictability which you get with tidal power, and to feed that into the energy mix which includes the less predictable sources like wind or wave. The whole point of this device is to test that it can produce power, and we believe it can, and to show it's robust and can be maintained."
These turbines will kill all the fishies!
“He’s not deformed, he’s just drunk!”
Any underwater installation will face the same challenges as Tidal power, that is what to do about the biologicals. The ocean is teaming with life and it will literally grow on anything. What do you do when the entire underwater "windmill" is covered in barnacles? Every underwater generation scheme is toasted by the life problem. None of them are tolerant of all the sea life that will grow on and around the facility.
My grandpa always said that Scotsmen and water just don't mix. But then again, maybe he just meant TRUE Scotsmen.
SJW's don't eliminate discrimination. They just expropriate it for themselves.
What is going to be the Energy Return On Energy Invested?
How expensive to install and maintain, as sea water is much harsher than having a wind turbine in atmosphere?
What is the expected lifetime of each generation unit?
Uh, Linux geek since 1999.
A typical (500 megawatt) coal plant burns 1.4 million tons of coal each year. As of 2012, there are 572 operational coal plants in the U.S. with an average capacity of 547 megawatts.
http://www.ucsusa.org/clean_energy/coalvswind/c01.html#.VFe77y0wJIo
I don't know where the poster got their numbers from, but an average coal plant is around 500 megawatts not 1000. This would imply that you only need 500 of the hammerfest machines to equal a powerplant. They should probably be more careful in the future to use accurate data.
The tidal currents are also completely carbon-free
This myth needs to end. There is no such thing as a "Carbon free" energy source. Some are worse than others obviously. But very large, very heavy materials will need to be used to construct those turbines. Mines will get dug, parts will get shipped, maintenance will need to occur.
This doesn't have Tidal on it but you can bet it will fall somewhere between wind and solar.
http://www.scientificamerican....
Solar is the real eye opener and should serve as a lesson on blindly trusting hype and "What seems obvious." Solar panels are terrible for the environment, yet most people don't have a clue. Keep in mind, this chart does not include waste generated by actually collecting the power. That's why oil doesn't look so horrible. Nor does it take into account the environmental impact of hydroelectric damns. If you factor all that in, Nuclear is the least damaging to the environment but people are afraid of it so...
And that's why ocean going super-tankers where never possible.(sarc'). Doesn't stop the Thames Barrier and Dams/hydro power across the world does it.
How about: Clean them off.
Waterfox - a Firefox fork with legacy extension support, security updates and better privacy by default.
You point to that figure and say that solar panels are terrible for the environment. Yes, apparently solar panels need more silver (and other metals) than other generation techniques, however, that doesn't mean that an ABSOLUTELY LARGE amount of silver is going to have to be provided.
Most power generation techniques don't need silver barely at all, so "relative to the current mix",yes, solar is going to need lots. That DOES NOT necessarily mean that supplying that amount of silver is going to cause widespread environmental degradation in the same way that coal DOES.
Also, solar power, once in place, doesn't require megatonnes of fuel like coal, oil, and gas do. (In that order, I guess.)
That figure doesn't DIRECTLY give insight into what energy mix is best for the environment, you can't have any hope of that unless you also compare fuel inputs per kwh generated as well, and other factors.
On the other hand, a stationary object in a strong current is an ideal place to sit there and catch food, so it's likely that sea life has evolved to take hold in such place.
The Bay of Fundy has the most powerful tides in the world. "The estimated potential of the Fundy region alone is upwards of 60,000 megawatts of energy, of which up to 2,500 megawatts may be safely extracted."
Nova Scotia had a trail running in Nov. 2009 with OpenHydro and they ended up having to remove their turbine when, "20 days later, all 12 turbine rotor blades were destroyed by tidal flows that were two and a half times stronger than for what the turbine was designed."
http://www.cbc.ca/news/canada/...
re: "since sea water is 832 times denser than air, a 5 knot ocean current has more kinetic energy than a 350 km/h wind"
Kinetic energy is an integration of the linear mv dv so equals 1/2mv^2 (whereas momentum is the simple product mv.)
So let's set the mass of a volume of wind at 1 and the mass of the same volume of sea water at 832 units.
The kinetic energy of the wind @ 350km/h = 1/2 * 1 * 350^2 = 61,250 units
The kinetic energy of the water @ 5 knots = 1/2 * 832 * (5 * 1.852)^2 = 35,671 units (1 knot = 1.852 km/hr)
-- Insert witty one-liner here. --
Small turbines are easier and cheaper to install. Not a bad choice when there are already enough challenges. After some experience with small turbines, they can work on bigger ones. They didn't start with 6MW+ wind turbines either.
The ocean is teaming with life and it will literally grow on anything. What do you do when the entire underwater "windmill" is covered in barnacles? Every underwater generation scheme is toasted by the life problem.
Cover every bit of metal with an insulating coating, then print, deposit, or laminate gold or platinum electrodes on the surfaces. Connect 'odd' electrodes in one branch of a circuit, 'even' electrodes in another, than apply an alternating voltage between them. The seawater completes the circuit. Unless a life form lands on the metal - then IT completes the circuit. I suspect most life forms will not like a continuous alternating current passing through them, and will 'move to greener pastures". Overall generating efficiency will be reduced, but probably not as much as it would be by barnacles, etc.
I'm not a marine biologist and I don't know if this would work - just tossing the idea out there.
'The Economy' is a giant Ponzi scheme whose most pitiable suckers are the youngest among us and the yet-unborn.
Hard to build? Just build it somewhere else, tie some cement blocks to it, and heave it overboard! See, this is why I should be running everything.
This posting is provided 'AS IS' without warranty of any kind, implied or otherwise.
Stray electrical current... Metal parts... Salt water... What could go wrong?
http://en.wikipedia.org/wiki/G...
Oh, yeah...
You can pick a shallower water area for its higher tidal flow speed, but that increases stresses and chance for damage.
But there are deep water currents that are consistent at 5-6 knots which avoid almost all marine life in some places down 5-6000 feet deep. A few are in close to shorelines.
Not even sea life can ignore the laws of physics, though. ;-) It's been my understanding that barnacles need some time to attach properly, and in some places, I simply don't see it very likely that they'd have a chance.
Ezekiel 23:20
And of course the depth of the area the turbine is being put in is a major factor, unlike wind turbines which keep getting bigger and higher. I'm just impatient, I get sick of hearing about sub 100MW renewable energy projects, ramp it up already!
Waterfox - a Firefox fork with legacy extension support, security updates and better privacy by default.
So how do you clean them? Do you send divers down several hundred feet to hand scrape a moving blade? Do you haul them to the surface? Do you haul them to dry dock like they do ships every 10 years?
Ships constantly scrape while at sea and are typically brought into dry dock every 10 years for a thorough cleaning with high pressure / high temperature cleaning. This isn't a ship, it's a stationary bit of metal underwater in some of the coldest water on the planet. It's not going to be spinning fast enough to puree living mater like a ships propeller and they get fouled and have to be cleaned by hand all the time.
Everything in water ends up covered in living matter. This isn't a problem for stationary non-moving/non-mechanical objects. It is a serious problem for anything mechanical that for example needs to spin freely. Every tidal or current generating scheme requires moving parts under water and that's a problem for anything that isn't operating at puree speed.
With such large amounts of energy why oh why are they pissing about with such tiny turbines? Modern wind turbines are 6MW+, some hydro power turbines are over 700MW each. Are they trying to destroy the financial viability of the project with unimaginative small scale thinking?
Scroll up to the post just above yours, referencing the Bay of Fundy and its failed turbine approach. Big turbines go boom when water move too fast, it turns out. Smaller turbines are made of materials with similar strength, but have much less force exerted on them under extreme tides. And, unlike a hydro power turbine, they can't force the full flow of the water to pass exclusively through the turbine here; a turbine that attempted the same level of energy harvesting would instead build up a head of backpressure, and the water would flow around it. That is, until the tide ripped the thing off the floor of the bay.
For your security, this post has been encrypted with ROT-13, twice.
Since the idea of both tidal and wave energy has been promoted since OPEC price disruptions of the 1970s (see Severn Barrage) but has never been successfully implemented (due to economic costs, largely managing brine and mollusks), either A) they have figured out a simple solution, or 2) they came up with a more novel solution, more interesting than the article suggests, or C) this is /.
Gently reply
Uh, about that, the Rance tidal plant in France has operated for 40 years with nothing but sacrificial anode protection and it looks pretty good to me (see page 22).
There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
It seems that a large scale project is viable, with a conservative large insurance company investing in a tidal power scheme:
UK Renewables May Be Turning The Tide
Large scheme, scalable to GW's of power, cheaper than off-shore wind, able to provide electricity on-demand, something that solar and wind aren't so good at.
Waterfox - a Firefox fork with legacy extension support, security updates and better privacy by default.
Neat.
540,000,000 kWh/year is an interesting way to express power though. Especially when it means that a power plant with 240 MW installed capacity is producing 62 MW average power.
This makes sense if 240 MW is the peak power generation, and 62 MW is average, given the cyclic nature of power generation, but still...