Winglets on Wind Turbines

My guess is that the design complexity, manufacturing, handling and installation all would see increased costs that probably would not be realized by the improvement in efficiency.

Good question though.

. . . but we did want a block of flats, nice though the abattoir is. (Architect sketch )

I know hydraulics are expensive,but compared to huge generators,are they more expensive?There are large ships that use hydraulics to drive the props.Inverter technology is a mature technology also,and the East-West USA connection where the grids meet, the A/C is converted to DC and then back to A/C by the inverters in sync with each side.Both technologies are mature so why not use them?It would not be critical for the hydraulic pumps to turn the same speed if there was a large nitrogen reservoir to even out the pressure to the hydraulic pump,which would drive the generator at any speed,and it would be converted to the proper frequency.The size of the reservoir would determine the "ride-through" time of the system.

Of course there will be required maintenance for the pumps and generators and inverters but they would be on the ground and easier to maintain.

A more expensive but effective means would be to connect all of the wind farm via high temperature superconductors to smooth out the outputs of the entire grid.

A gravity reservoir could also be used to store excessive power in times of low demand.

https://www.science.org/content/article/gravity-based-batteries-try-beat-their-chemical-cousins-winches-weights-and-mine-shafts

I am sure engineers and accountants have already considered these options,and it might not be cost effective or possible for reasons I do not currently have enough knowledge of.

I would like to see the results of a study on this if one has been performed.

Unlike plane wings, the tips of wind turbine blades will be going much faster than the main foil, so this may be a factor. Noise levels rise with higher tip speeds and can be a limiting factor in siting turbines. All above my pay grade to solve however.

Here are the most efficient energy storage devices of 2023:

1. Lithium-Ion Batteries. ...
2. Thermal Energy Storage. ...
3. Pumped Hydro Storage. ...
4. Liquid Air Energy Storage. ...
5. Compressed Air Energy Storage. ...
6. Flow Batteries. ...
7. Green Hydrogen. ...
8. Flywheel Energy Storage.

More items... • Dec 29, 2023

https://solar.huawei.com/za/blog/za/2023/most-efficient-energy-storage

..."As we get more energy from renewables, our need for energy storage grows, said Chu, who is a professor in Stanford's Department of Physics and in the Department of Molecular and Cellular Physiology in its School of Medicine. Once we get to 50 percent renewable energy, we need far more storage than we have.

The total electricity consumption in the United States in 2018 – 2019 was about 4,000 terawatt-hours (TWh) of energy with a generating capacity of about 1,200 GW. The United States currently has only 31 GW of stored energy power—only 2.5 percent of our current generating capacity.

At 80 percent penetration of renewables such as wind and solar energy, it is estimated we would need four days of storage energy (100 hours) at our full generation capacity to minimize energy curtailment (the throttling back of renewable generation), Chu explained.

Most regional U.S. grids could survive on large-scale electricity storage systems for a few minutes today."...

https://energy.stanford.edu/news/mix-mechanical-and-thermal-energy-storage-seen-best-bet-enable-more-wind-and-solar-power

Most efficient energy storage devices? Based on what? Energy per unit volume? Unit weight? Energy in vs energy out?

There was recently an article here about storing energy in concrete.

This is pretty cool concept for portable hydrogen use...

https://www.techradar.com/vehicle-tech/hybrid-electric-vehicles/toyotas-portable-hydrogen-cartridges-look-like-giant-aa-batteries-and-could-spell-the-end-of-lengthy-ev-charging

Your question raises a conjecture. I regularly travel I-45 on a Houston - Dallas - Houston business trips and often encounter blade sets, 3 trucks with 1 blade each, that are headed northbound to the US interior from the Port of Houston. Did so this week and encountered a set of new +/- 100 footers.

Here lies the conjecture; each blade had at about 3/4's of their length an obvious engineered-designed kink congruent within the slight sweep of the blade. Not as pronounced as a broken-tailed kitty, but definitely a kink. I have seen 100's of blades in transport and annually drive through the mega-farms of West Texas, but this was the first time for this blade design and it made me wonder why. Winglets are never seen and as others have said there are probably serious load dynamic issues. Perhaps these kinks are a double next order highly sophisticated derivation of the same.

Comments please!

I live in the Permian Basin area of West Texas. They've been using the 'kinked' blades here for about 3 years that I know of. They swapped blades on hundreds of turbines in the Sterling City area. They had a blade junk yard there for a while.

Can you post a picture?

The scrap blades were cut into shorter pieces and hauled off a year or two ago.

Do you want a picture of the new blades?

I remember seeing them out there in Sweetwater when I was driving from Dallas to Midland to visit my daughter and her family. Saw Sterling too when we were driving from Midland to Austin when my daughter was house hunting in Austin where she currently lives.

Thanks for the confirmation. I said they were new to me, but obviously their not. About the wing junk piles I have seen those too, I am thinking near Big Spring, but I could be wrong there too. The question still is why the kinks which defy the term aerodynamic?

The question still is why the kinks which defy the term aerodynamic?

Maybe this is the answer. The blade is designed so that under higher wind loads, the blade twists, reducing the pitch (angle of attack).

"

Bend-Twist-Coupled Blades

Wind turbine blades naturally bend when pushed by strong winds, but high gusts that bow blades excessively and wind turbulence that flexes blades back and forth reduce their life span.

Bend-twist-coupled blades twist as they bend. As wind forces the blade to flex, twisting changes the blade’s angle of attack (the angle at which the blade meets the wind), and thus reduces the load on the blade, decreases stress, and allows for longer blade length without added weight or expense."

https://www.energy.gov/eere/wind/articles/bends-twists-and-flat-edges-change-game-wind-energy

What I am seeing is not twists, yes I have seen those sorts of blades too, but these are a hard angle bend in the the order of 5 -10 degrees that you can see the seem line. Twist's make obvious sense, the kinked blade approach needs explanation. Perhaps as the blade warps the approach is to make a quick reorientation of the blade outer length and tips. The fact my fellow Texan sees them in the West Texas mega fields may suggest they are particularly useful in a constant strong wind regime. (Old Texas saying "There are three temperatures in West Texas hot, cold and windy; if you don't think windy isn't temperature you haven't to West Texas"

Like this?

https://www.spinningwing.com/wind-turbines/prebend

No. The blades are kinked like they were brought to my friend's rig and big industrial steel shop, fed 1/4 the length into his 40 ton press-brake and given a single "pop"

Might be these blade extensions you're seeing....

https://www.siemens-energy.com/global/en/home/products-services/product-offerings/high-voltage-direct-current-transmission-solutions.html?

A dual de-icing system for wind turbine blades combining high-power 2 ultrasonic guided waves and low-frequency forced vibrations...

https://research.tees.ac.uk/ws/portalfiles/portal/6555694/621903.pdf

https://www.researchgate.net/figure/Wind-turbine-blade-with-articulated-tip_fig2_311333122

After reviewing some of your links,in particular the Tesla rooftop generators,I noticed the funnel effect of the entrance to the generator turbine.How much pressure could be produced by the frontal area of a vehicle traveling at 60 mph?It would seem to me that it would increase efficiency a small amount by slightly pressuring the intake air and reducing air restriction into the motor.This might be significant on large transport vehicles(semi's) that travel millions of miles over their design lifetime.

Any opinions on this?

I would think that the turbocharger that extracts waste energy from the exhaust flow would essentially override any small increase in pressure by tapping into the high-pressure area on the front of the vehicle. Not sure what happens aerodynamically when you start to extract air from the flow around a vehicle.

Wind turbine blade tips travel MUCH more slowly than a jet's wingtips. No real advantage to justify the cost..

The winglets, along with other design factors, could enable the wing tips to travel faster by reducing drag....

Here are the 2021 facts: wind turbine blade maximum tip speed is between 80 and 90 meters per second. That's 179 to 200 mph. There's no benefit to going above those speeds, in fact it increases drag significantly, so turbine efficiency drops as tip speed increases above those numbers.Feb 24, 2021

Wind turbines can experience losses due to blade number, whirlpools, ends, and airfoil profile. These losses prevent kinetic energy from being converted into mechanical energy...

The configuration and dimensions of the rotor blades can affect the turbine's speed. Blades with a larger surface area and more aerodynamic design can spin faster....

The speed of a wind turbine can be measured in revolutions per minute (RPM) or absolute velocity. Large-scale turbines typically rotate at 20 RPM...

Wind turbines can be classified as to whether they use drag or lift forces, whether the turbine axis is horizontal or vertical and the rotor speed at the same wind velocity. In drag turbines, there is a flat surface which rotates due to the wind pressure applied, whereas wind comes towards the blade at an angle in turbines utilizing lift forces. The lift force, which normally takes place to the direction of wind velocity, produces the rotation in this type of turbine. There is high pressure before the surface whereas low pressure after it ....

..."This turbine boasts a blade wheel diameter of more than 310 meters (1,107 feet) and a hub height of 185 meters (607 feet)."...

26 MW offshore wind turbine...

"This offshore wind turbine is designed for areas with wind speeds of 8 meters per second and above. "

https://electrek.co/2024/10/14/china-debuts-a-record-smashing-26-mw-offshore-wind-turbine/

If this giant would reach a speed of 20 rpm the wing tip speed would be faster than a 747's top speed ...

Those are surprisingly fast wingtip speeds which makes me understand a bit better why birds and bats are getting killed by these turbines.

Several times while out working in the oil patch, I would wonder over to some of these wind turbines to look at them. I've heard of people complaining about the unbearable noise from them, but all I heard was a gentle 'woosh' noise each time a blade passed by. I looked for dead birds, too, and never saw any.

Perhaps they knock the birds into the next county, or, perhaps our local birds are smart enough to stay away.

It's less of a problem out on the plains where there are far fewer birds of prey. Where they site the wind mills on mountain ridges and mountain passes, the bird kill problem is much greater.

As for the noise, that 'woosh' you hear does result in sub-sonic pulses that affect some people but not necessarily everyone. I suspect the acoustic effects are very much a function of the particular design. Some designs may do a better job of managing the noise issues.

https://www.eldiario24.com/en/switched-on-the-largest-wind-turbine/2206/

Old wind turbines could be 'tiny houses' of the future...(or many other things I'm thinking)

Vattenfall asks designers to create living concept from decommissioned Vestas nacelle....

https://www.rechargenews.com/wind/old-wind-turbines-could-be-tiny-houses-of-the-future/2-1-1727449

And what we usually discover in these sorts of endeavors is the cost of modifying and outfitting the widget into "something useful" exceeds the cost of building the whole thing from scratch. .

But it does make someone feel better.