Jet-engine inspired FloDesign boosts wind turbine output

BOSTON--Start-up FloDesign Wind, one of a number of companies looking to shake up the wind turbine business, said a prototype of its jet engine-inspired turbine was three times more efficient at converting wind to usable energy than traditional designs.

The Massachusetts-based company is seeking to raise a series B round of $25 million later this year to deploy and test the real-life performance of its 150-kilowatt turbines, said CEO Stanley Kowalski III at the Cleantech Forum conference here on Thursday.

FloDesign Wind last year was spun out of aerospace engineering company FloDesign, which has supplied components used in military helicopters and fighter planes. Using its expertise in aerodynamics, the company is developing a wind turbine that more resembles a jet engine than a typical three-blade turbine.

Its plan is to develop relatively small turbines and market them for use by businesses, communities, or wind farm developers. The company is now testing prototypes, a process that will take at least a year, Kowalski indicated.

"I think it's exciting that there's an oligopoly (among wind turbine suppliers)," he said during a panel on Thursday. "There is a resistance to change and that's how things disrupt and we hope to be one of the disruptors."

Utility-scale wind farms typically use giant wind turbines capable of turning out one or two megawatts of electricity--enough to supply hundreds of homes. By contrast, FloDesign wind--along with a other wind challengers--is developing its turbine for use in locations not well suited for large turbines, such as mountain ridge lines, or to customers that want to make power on site, such as municipalities or businesses, Kowalski said.

FloDesign Wind estimates that it can produce power at about 40 percent cheaper than traditional turbines, although the performance depends on the location. Part of the lower cost is from being able to extract more usable energy from the available wind--the company tested a prototype of its turbine at the Massachusetts Institute of Technology earlier this year and found that it delivered a three times improvement over traditional designs, Kowalski said.

The turbine is built around a fan and a shroud that surrounds it. It's designed so that air passes through the fan blades and around the edges of the shroud. This creates a mix of two air speeds at the back of the unit, with fast air going around the edges of the shroud and slow air passing through the blades. When the two air flows meet, the rapid mixing causes air to be pulled through the turbine, Kowalski explained. The electricity is generated at the tips of blades rather than using a gear box.

The product, which has a 60-foot diameter, is being made so that it can be transported onto a standard truck bed, which should make installation cheaper and easier than large turbines. The company expects that it will be less dangerous to birds and bats because it will be easier to see, Kowalski said. He said it should be quieter than traditional turbines as well.

Taking on incumbents
FloDesign Wind is among a number of start-up wind companies trying to crack into the wind market by introducing different product designs and by targeting different customers than the large suppliers, such as Siemens, Vestas, and GE, which sell to large-scale wind farm developers.

Incumbents have made turbines larger and larger over the years to generate more power from an existing location and bring down the cost of delivered electricity. There have been attempts to make mid-size turbines big enough to supply a school or community using the traditional three-blade wind turbine design. But there have been technical problems and those projects which typically have a higher cost per kilowatt to install, according to a report from the National Renewable Energy published last year.

New companies, however, are entering the mid-size turbine field, including FloDesign Wind, OptiWind, and BroadStar Wind Systems. Developers envision that the machines could be deployed in existing wind farms among larger turbines, at a big-box stores, or for locations where there isn't enough land available.

"For the first time, we can build a turbine that can compete on price with big turbines at small scale--it's like the PC versus the mainframe," said Kowalski.

A more distributed model of wind generation addresses one of the biggest problems today in wind: having the transmission lines to bring megawatts worth of electricity to places where it is consumed. T. Boone Pickens, for example, had to delay its planned wind farm in Texas because a lack of transmission.

With its second round of funding, FloDesign Wind is seeking partnerships to help bring the product to market, Kowalski said. The company raised a series A round of $6 million from Kleiner, Perkins, Caufield & Byers and is hoping to close its second round by the end of the year. It has also received funding from the Department of Energy.

The company has already gotten interest from at least one utility to use its turbine, Kowalski said, although he also said that he expects utilities overall will be slower to adopt new wind technologies.

[Harlan879]

That's pretty cool. I wonder how well it deals with bird ingestion? Is it likely to be damaged? And is it more or less likely to kill migrating birds? (It's an overblown issue, but still an issue...)

[Joe Real]

Should be no problem. The front blades are fixed and are not moving, so aerodynamically designed netting can be placed over those fixed blades without too much trouble. This would be excellent for nocturnal birds that can fly into the turbine.

Another option for daytime birds is to color some of the fixed blades with red prismatic reflectors. We use this trick to discourage birds from feasting on our cherry trees. We dangle red reflecting tapes from the trees, and the birds thinks the tree is on fire and would not fly near it.

[SlurmSlurper]

Early wind turbine designs were plagued by noise issues, I wonder how these small high speed wind turbines compare in that respect.

[mlamonica]

The CEO said yesterday that this should be quieter as the fan blades are covered by a shroud.

[dadcss]

Definitely a step in the right direction.

[Mergatroid Mania]

Very cool. Can't wait to see one in action.

[Pishkado]

Most types of aircraft went from propellors to turbofans between roughly 1950 and 1970, because turbofans are a better way to turn energy into wind. It's about time someone realized that the same is true when you want to go in the other direction.

[zyxxy]

Blades are more efficient than fans, but the blade length required to harness the power of the engines on a large passenger jet would require really long landing gear. Blades are also speed limited compared to turbines, but wind power does not have those speed restriction issues. That is why you see turbofans on so many aircraft, power density (not efficiency) and speed.

Small regional airlines are returning to propeller driven craft because of the better fuel economy in comparison to small turbofans. Here in EWR you see a large number of propeller driven regionals that didn't exist three or four years ago, all driven by fuel efficiency demands.

So I am not convinced that this design is more efficient than the large turbines that are currently being installed. They may just be better for certain application domains.

[zyxxy]

A three blade turbine with a blade length of 150 ft sweeps a disk of roughly:

150 * 150 * pi == 70,686 sq ft

One of these turbines, with a diameter of 60 ft covers a disk of roughly:

30 * 30 * pi == 2,826 sq ft

Assuming it is three times better at extracting power, that is 8,482 equivalent sq ft.

70,686 / 8482 == 8.33, so you need about 8 of these for every 1 of the monsters. Given that you can space them at 3x the diameter, a grid of 3 horizontal by three high would take

60(3) + 180(2) == 540 ft wide and 540 ft tall. This compares with a traditional large turbine that is 400 ft tall (ground to tip) and 300 ft wide (tip to tip).

Also, 150KW * 9 == 1.35 MW, and the large turbines you see sprouting all over Western NY are rated at 1.5 MW. So what gives? Also, I think nine of these in a three by three grid would be far more visibly intrusive than one large three blade turbine.

Obviously, they are looking at a different market. That is my point. I wish them good luck, because we need every energy source we can find, but they are not going to displace the large turbines that are going up on wind farms across the country. Different technology, different domain, different market.

[texaslabrat]

Your numbers seem to add up ok, but you've only taken into consideration 2 dimensions. If you add in the 3rd dimension (row-to-row spacing...typically 10x rotor diameter), I think you'll find that the power density per acre is markedly higher with this new technology if you put up arrays in the gridded fashion that you described. Even if you went 30:1 spacing to account for the additional energy being extracted from the wind stream, the energy density per acre is still much higher than the "big boys".

[carlhage]

Great comments, Z! Your analysis is probably a best case-- it may take more than 8 units to match a large prop turbine. The wind speed is greater at the taller tower height, with power increasing by the cube, so 1.25x wind speed gives double the energy. In the video, they say the prop units only extract 50% of the power, so that means only a 2X increase is possible, not 3 (maybe it depends on the wind speed). Though it may cut in at lower wind speed, the energy available in low wind areas won't generate enough power to pay for the unit.

I don't see how the 3*150 foot blades would be less cost than 8 units that have 12+12 30 foot blades. Add to that the cost of the tower. It would seem to me that material costs for a 60 foot FlowDesign would be no less than half a large turbine. Enercon makes generators without a gearbox, but it seems like units with gearboxes are more popular, so doesn't seem to be a real disadvantage.

[Vegaman_Dan]

A small note in the article caught my eye:

"The electricity is generated at the tips of blades rather than using a gear box"

That's very interesting. Inductive magnets or coils in the shroud generating power by the blades moving past them. That's a lot more efficient than having the blades turning a central shaft through a gearbox and then to a generator. All those bearings and mechanical areas of lost power due to resistance can really add up. This should have a simple beefed up bearing assembly in the middle and... well, that's it for moving parts. Less wear and tear, easier maintenance, etc.

[zyxxy]

I found that interesting as well. Here is another point to ponder. Do they just use rare-earth permanent magnets in the blade tips? Or do they embed coils as well, and use exciter coils in the blade tips to generate a larger field once the disk spins up? That would allow you to limit the physical magnet installed on the tip and then have the load capacity go up with speed. That would also have the advantage of the disk being able to absorb higher wind speeds since the torq could be proportional to the exciter current. Still no moving parts or slip rings. The exciter circuit in each tip could be independent. In fact, designed properly, you may not have permanent magnets in the blades at all, just 'brushless' exciters, though I am not sure how well that would work at really low speeds.

[scottthesculptor]

with permanent magnets you can use a spring weight to decrease the gap as the rpm goes up.
extracting just a bit more power at high rpm without bogging it down in the low.
also allows for a braking system at max rpms
the trick is to balance the forces - weights of the parts, push of the coils, strength of the springs

think mechnical advance on an automotive distributor

sure simplifies the electronics side

[NocturnalCT]

I'm sure electromechanical experts would know how to calculate what is better. It seems that building a small high efficiency generator is easier and cheaper than making a giant one (coils in the shroud and permanent magnets in the blades). The coils would need to be accessible for maintenance which puts some limitations on how thin the shroud can be. In addition it's possible that generators have an optimum speed, something that can be achieved with a gear box and a shaft driven generator, not in this scheme.

I don't know enough about this to judge the design either way but I don't think it's straight forward. Luckily the shrouded design does not preclude a switch to a single generator. The ability to do both is a definite advantage of this design.

[USDecliningDollar]

Very interesting. It is also interesting to see the convoy of semis needed to bring in traditional blades. You really get a sense of how massive the traditional utility scale 3 blade turbines are when passing a semi with one blade! I've been watching 2 utility scale turbines being assembeld at the NREL Wind Research Center outside of Boulder, CO - they are massive, and take quite a bit of engineering to get them assembled.

[Ronin_1]

Without a "backbone" to transmit the power generated these units will be as irrelevant as their less efficient counterparts which sit idle much of the time.

[zyxxy]

The last time I was up through Western NY, I only saw two turbines in the Java/Wethersfield region that was not turning. Wow, there are a lot of turbines down there now. I know that not everyone is happy about that, I am just stating the fact. If you live anywhere near Wyoming County in Western NY, and you haven't seen a significant wind farm, you owe yourself a drive through there. Find your way to Frink's Corner, and drive along Perry Road to Wethersfield Road. Continue at least to Hermitage road at Wethersfield Springs. Please drive carefully and respect the locals.

[NocturnalCT]

I wonder if the low blade count of traditional turbines lowers their efficiency? Compared to a turbine such as the one shown here it seems that most of the air passes 'harmlessly' between the blades rather than hitting them. It doesn't really say that above but isn't that the key to the claimed efficiency increase? That would also mean that the air behind the turbine is less 'useful' so you'd still need considerable spacing. At least I'd expect the fouled air from the exhaust of a turbine to be far less capable of turning another turbine behind it.

One potential problem I see is that the turbine with its shroud seems very top-heavy and would need a strong pole to sit on and a very strong connection to it. A traditional mill can be configured to have relatively little wind resistance in case of storms, that seems hard to do with a shrouded turbine.

I'm liking this idea a lot. I hope they pull it off.

[TronCnet]

Once we let go our "material" image of "not in my back yard" and look more into ourselves and the world we live in .. and whether one believes in global warming or not...we should do whatever small step we can to preserve the nature around us and the natural resources we have. FloDesign Wind Turbine is taking that one small step. I hope them success in their research and development.

[kojacked]

It's great to see this market taking off. New ideas & more players means better solutions and more jobs. Great, constructive comments here too.

[markhh1]

The comparisons to large scale traditional turbines in the u-tube video are done in quite a misleading way. Please try to compare apples with apples.
Comparing 150kW with 1.5MW sized turbines of any designed turbine will show different challenges that need to be addressed. I don't know why these guys are trying to put down the large conventional designed systems? Do they really think there are going to compete in this market and so need to scaremonger with images of exploding turbines etc?
Their design appears very promising for mid sized turbines and it does appear they are better suited in this size range than the conventional ones. I would suggest they focus their attention to this market.

[ralfthedog]

"This creates a mix of two air speeds at the back of the unit, with fast air going around the edges of the shroud and slow air passing through the blades. When the two air flows meet, the rapid mixing causes air to be pulled through the turbine, Kowalski explained...."

I am not sure. Are they trying to say that their wind generators suck?

[HaPPI-52]

Fast-turning blades can not be as quiet as slow. Shroud or not, the sound will get out because the air must get out. Turbulence makes noise and reduces efficiency, and moving blades near stationary blades makes a lot. Real installations will tell all.