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Underwater Kites: Minesto's 'Deep Green' Wave Energy Project Scores Prototype

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Kalbas
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« on: March 24, 2011, 11:11:38 pm »

Underwater Kites: Minesto's 'Deep Green' Wave Energy Project Scores Prototype Funding (PICTURE)


Posted: 03/24/11 09:48 AM

From EarthTechling's Caleb Denison:

In the world of clean energy, kites have have become a big deal. Recent advances in technology have lifted ideas like high-altitude wind turbine kites, parakite farms and ship-towing kites off the ground and made them a viable, wind-powered option as clean energy sources. Kites can harness more than just the wind, though.

It was just last year that we covered a story about kites flying under the sea to harness tidal energy. Now, Minesto, the company behind that under-sea kite project called "Deep Green," has announced they've received over $560,000 from The Carbon Trust to dive forward with deploying a prototype of their technology. If their trial is successful, it could lead to a large-scale implementation of underwater kites around the UK coastline that the company says would generate enough juice (530 GWh) to power all of the homes in a city the size of Newcastle (population 189,863) by 2020.


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Kalbas
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« Reply #1 on: March 24, 2011, 11:12:04 pm »

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Kalbas
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« Reply #2 on: March 24, 2011, 11:12:50 pm »

Image via Minesto

These under-sea kites harness the power of oceanic forces in much the same way that land-based kites capture wind energy. As this article from SmartPlanet illustrates, a rudder-controlled kite "flies" through the deep ocean in a figure eight pattern, capturing and magnifying wave energy as water passes through, then channels it through a turbine which sends the power to a generator located below on the sea floor. Because the motion of the kite against the current can intensify the power of the ocean current by a magnitude of 10, this device can work effectively, even in less-than-vigorous waters. That enhances its potential globally and makes it a serious contender in the race for sustainable, renewable energy.

The renewed support Minesto received from The Carbon Trust is an indication of the support that awaits the right energy project. As part of the funding announcement, Benj Sykes, Director of Innovations at the Carbon Trust, said: "Minesto's Deep Green is a very exciting technology as it could provide a step change reduction in the cost of tidal energy and open up swathes of the UK's coast to generating electricity. Tidal energy has the potential to produce up to 18 terawatt hours of electricity, equivalent to over 5% of the UK's electricity consumption."
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Kalbas
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« Reply #3 on: March 24, 2011, 11:18:37 pm »

http://cleantechnica.com/2009/10/23/underwater-kite-harnesses-ocean-energy/
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Kalbas
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« Reply #4 on: March 24, 2011, 11:22:19 pm »

http://cleantechnica.com/2009/09/04/mining-hydrothermal-vents-for-renewable-electricity-drinking-water-valuable-minerals/
Only after I snoozed my way through high school science class did science become more compelling than science fiction.

Back then, there was just no compelling reason to pay attention. Just a browzy fly buzzing in a smelly boring lab full of long agreed-upon dull principles that were really neither here nor there. In those days there were no colliding continents or hydrothermal vents or extremophile lifeforms. We looked to sci-fi for that.

Who knew that our planet would soon be busting at the seams with 7 billion of us. That our fossil fuel use would threaten our survival with climate changes — on a level unseen on the planet since Cyanobacteria made it safe it for oxygen-breathers 4 billion years ago.


Or that we would not only discover vast strange heat sources under the ocean but that we’d actually consider mining these hydrothermal vents for renewable energy: That was the sort of story you’d only find in science fiction back then.

But yet, here we are. This is not science fiction: The energy potential is staggering. In the Gigawatt range per vent.

The Marshall Hydrothermal Recovery System would use the heat from hydrothermal vents 7,000 feet under the sea to make electricity. Its temperature is incredibly high, 750 degrees Fahrenheit; hot enough to melt lead, but it does not boil because of the intense pressures at the depths where the vents are located.

Superheated fluid would be propelled up through a through a (well insulated!) pipe to an oil platform located on the surface above the vent. The superheated fluid is carried by means of flow velocity, convection, conduction, and flash steam pressure as it rises and the ambient pressure is decreased.

Once delivered to the platform, the heat energy contained in the fluid can be extracted to generate electricity. Since the amount of energy available from any thermal system is dependent on the difference in temperature between two points, the system also includes a Thermal Enhancement Pipe.

This is simply an open pipe, like a large drinking straw, which extends down below the layer of relatively warm water on the surface to the permanently frigid waters below. By withdrawing water from that pipe and using it as the cold side of any heat reaction, much more energy can be extracted from the process than could be delivered without it.

But what about those extremophile lifeforms down there at the vent? This has got to be ecologically disruptive!
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Kalbas
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« Reply #5 on: March 24, 2011, 11:25:03 pm »

Marshall Hydrothermal is pretty frank about the horrible ecological consequences: The company says that there is no way to sugar-coat the fact that these organisms will die so that we humans can live our much more exciting lives though electricity.



The company “plans” to relocate the local flora and fauna to another vent nearby. But can people work 7,000 feet down to carefully pull these limpet-like creatures off the sides of volcanic vents? I’m not quite sure how that would happen.

Or, perhaps a closed loop system would be safer? Marshall offers this alternative method:

Closed Loop Version
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Kalbas
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« Reply #6 on: March 24, 2011, 11:26:10 pm »


This looks a little less invasive:  a closed loop system.

Rather than bringing up the hydrothermal fluid itself with bits and pieces of sea creatures as well, a simple heat exchange is effected within a closed loop: all the fluid is contained in the pipe and heated at the vent and circulated up for use to drive the turbines on the surface.

The cooled fluid is then sent back to be reheated by the vent again and again, but the hydrothermal fluid itself is never actually brought to the surface. More than just a huge renewable energy supply is at stake here.

We could also be making desalinated water from the ocean vents:
http://cleantechnica.com/2009/09/04/mining-hydrothermal-vents-for-renewable-electricity-drinking-water-valuable-minerals/2/
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Kalbas
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« Reply #7 on: March 24, 2011, 11:30:12 pm »

At least 264 million gallons of fresh water daily.

20 million gallons of hot fluid would flash to steam at the surface and that could be distilled back into fresh water. Further purification would be needed, but the natural heat from the process itself provides the most important part of the energy needed for the process. Fresh water is the new oil.

If even only 50% of the total volume could be recovered, that would still provide about 264 million gallons of fresh water daily.

Catch 22

Unfortunately, desalination apparently requires the (more ecologically disruptive) open loop system, to work. (See first diagram) But, if that could be solved, there is another argument for mining the actual fluid (open loop); not just the heat (closed loop) system.

The materials in these geologically ancient vent fluids include iron, gold, silver, copper, zinc, cadmium, manganese, and sulfur. Halides, sulphates, chromates, molybdates and tungstates are also abundant.

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Kalbas
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« Reply #8 on: March 24, 2011, 11:31:15 pm »

When the fluid is trapped, the slurry left over after the heat is extracted can be loaded aboard ships for processing elsewhere, or processed on-site.

Cap and Trade would also help fund this completely new form of renewable energy extraction. Who better to carry it out than the oil industry. They already have the expertize with ocean drilling extraction.

Turns out there is also significant amounts of methane gas mixed into the fluid. Maybe there is a way to cap that for remediation-cum-fossil energy at the same time, as well as selling the renewable electricity, fresh water and minerals produced by the vents.

For the oil industry, with all these inducements, surely switching to mining renewable energy would be more cost effective than having to keep on paying media outlets and school districts and think-tanksfull of talking heads to keep enough people ignorant enough about climate change to slow the legislation needed to stop it; decade after decade.

Let’s hope.

Images from Flikr users aakova and thomitheos
http://cleantechnica.com/2009/09/04/mining-hydrothermal-vents-for-renewable-electricity-drinking-water-valuable-minerals/3/
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