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High efficiency wind turbine based on jet engine technology

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December 11, 2008

FloDesign wind turbine

FloDesign wind turbine

December 12, 2008 Massachusetts-based FloDesign has developed a wind turbine that could generate electricity at half the cost of conventional wind turbines. The company's design, which draws on technology developed for jet engines, circumvents a fundamental limit to conventional wind turbines. Typically, as wind approaches a turbine, almost half of the air is forced around the blades rather than through them, and the energy in that deflected wind is lost. At best, traditional wind turbines capture only 59.3 percent of the energy in wind, a value called the Betz limit.

Jet engine wind turbine

FloDesign is a spin-off from the aerospace company FloDesign based in Wilbraham, MA which recently raised $6 million in its first round of venture financing. Their turbine design surrounds its wind-turbine blades with a shroud that directs air through the blades and speeds it up, which increases power production. The shroud concept is based on the same principles as a high bypass jet engine design that is used by all commercial jet aircraft engines to reduce noise and significantly improve efficiency. The new design generates as much power as a conventional wind turbine with blades twice as big in diameter. The smaller blade size and other factors allow the new turbines to be packed closer together in the field compared to conventional turbines, increasing the amount of power that can be generated per acre of land.

From the front, these wind turbine looks something like the air intake of a jet engine. As air approaches, it first encounters a set of fixed blades, called the stator which are common in jet and steam turbines designs used in power generation, which redirect the air onto a set of movable blades, called the rotor. The air turns the rotor and emerges on the other side, moving more slowly now than the air flowing outside the turbine. The shroud is shaped so that it guides this relatively fast-moving outside air into the area just behind the rotors. The fast-moving air speeds up the slow-moving air, creating an area of low pressure behind the turbine blades that sucks more air through them.

Double or triple a turbine's power output

It's plausible that such a design could double or triple a turbine's power output, says Paul Sclavounos, a professor of mechanical engineering at MIT. Part of the increase comes simply from guiding the air to the turbine with the shroud. But Sclavounos notes that it also helps to use the wind surrounding the turbine to speed up the airflow, because the power produced by a wind turbine increases with the cube of the wind speed. The key question is whether the new turbines can be built and maintained at a low-enough cost. A shrouded turbines can be half to a third the size of a conventional 30+ story tall 3 blade turbine for the same power output and with tall towers and blades up to 90 meters long transportation alone can make up to 20% of turbine construction costs so a shrouded turbine may lead to significant reduction in construction costs and as a result cheaper power generation.

It is still early days for the FloDesign turbines as they have only built a small prototype for wind-tunnel tests. Its next step is to build a 12-foot diameter, 10-kilowatt system for field tests. The prototype is expected to be finished by the end of next year or early in 2010, with commercial wind turbines to follow. Eventually the company plans to make turbines as large as one megawatt, but is not yet taking orders.

Paul Evans

FloDesign via Future Blogger.

11 Comments

As one who designs and builds wind generators, I'd doubt this would make as much power as a standard 3 blade design at far less money. The cowling is not a good one. While it would work well for increasing thrust, increasing power in a windgen is another story.

It's large size, weight requires more money, tower strength for it's output.

The number of blades makes it less eff as each interferes with the next one, making it less eff, more costly. Most eff is 3 blades which is why most use them.

jerryd
4th November, 2009 @ 06:59 am PST

If this is a less efficient design, then why do turbine engines not have three blades? People have been studying them for decades. Both this and a turbine are sub-sonic, so the comparison is valid.

EnviroDude
28th February, 2010 @ 01:18 pm PST

to EnviroDude, external and internal flows, dude

Facebook User
9th May, 2010 @ 12:04 pm PDT

This thing would kill way more birds than a conventional three bladed propeller turbine, and the bird carcasses would clog the mechanism. There's a kind of bladeless turbine invented by Nikola Tesla over a hundred years ago that would be less likely to be clogged by bird carcasses.

HenryFarkas
14th October, 2010 @ 09:17 am PDT

HenryFarkas - are you talking about a boundary layer Tesla turbine? How would you propose building laminated sheets only millimeters apart yet large enough to extract power from the wind, and still be financially feasible?

Blixdevil
30th November, 2010 @ 07:31 am PST

Interesting.

Gizmag, can you provide an update to the story ("...The prototype is expected to be finished by the end of next year or early in 2010")?

Fred Meyers
30th January, 2011 @ 04:51 pm PST

SpiralAirfoil vs FloDesign,

I would like to congradulate FloDesign on a good attempt at extracting energy from the wind, from what I understand, they do come somewhat close to our SpiralAirfoil Design in efficeincy, however their bird is far more complicated and costly then our unique approach. Our test data shows the Spiralairfoil design is over 4.2 : 1 times more efficient then the traditional tri-blades. SpiralAirfoil.com

Thank you

Dan'l

Dan B Parker
5th February, 2011 @ 08:08 am PST

the design is already being used and proven on small scale systems one of the greatest benefits is the ability to produce power at loser wind speeds. Wind tamer was established in 2002 so check them out http://www.windtamerturbines.com/our-company/ I am in no way affiliated with the company I just find it interesting that this was developed 6 years prior to this article.

Facebook User
24th March, 2011 @ 06:28 am PDT

Turbofan engines on aircraft are not nearly as efficient on aircraft as turboprop engines ( turbines with propellers), and I expect the same will be true for wind turbines. The smaller blades on the proposed enclosed turbines would probably have to turn at a much higher RPM than the 3-blade turbines. Also it would be diffucult, if not impossible ,to have variable pitch blades to compensate for change in wind speed.There would be many problems associated with enclosed turbines before they would be economically superior to the 3-blade types.

Larry Clement
23rd April, 2012 @ 12:36 pm PDT

I wish people would stop blaming turbines for bird deaths. Glass covered buildings kill tens of millions of birds a year, just by standing there and looking like sky. Better to work on shrouding buildings so birds miss them, than trying to worry about minimal comparable wind turbine deaths.

Chizzy
27th May, 2013 @ 10:55 am PDT

I am following a trail of crazy claims wind turbines. The article itself says "At best, traditional wind turbines capture only 59.3 percent of the energy in wind, a value called the Betz limit." yet only few lines later a claim of doubling or tripling the output is outed.

What would the comparison be anyway? I guess the claim is that the same sweep area would produce more energy. As Betz limit states there is a LIMIT to this. But its also obvious that a ginormous structure - given that it needs to work in storm and ice etc. - will be far more obstructing, heavier, complicated etc. So even without the fact that conventional turbines are actually efficient its obvious that the comparison wouldn't be apples to apples.

One doesn't have to be a genius to understand that claims are against laws of physics and utterly non feasible. Some critical thinking by the staff would be nice.

Kent Risine
1st August, 2013 @ 08:57 am PDT
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