Could trees provide another model for wind power generation?

Duffis

Obviously windmills extract some power from the wind using blades that rotate etc, but I wonder if it would be possible to get energy from the wind by mimicing the rocking/swaying motion of trees on a windy day?

I believe that larger windmills with a larger area of blade space exposed to the wind will spin with less wind speed. A tree or something like it provides a lot of space for a less powerful wind to push against...so...would it be possible to construct something like a sail on a hinge to extract more power at lower wind speeds?

I apologise if this all sounds like nonsense. I’m not a scientist, hence the question and I’m guessing that windmills work in a way that is more efficient than my oddball suggestion/idea.

What do you think anyway?

Is this nonsensical or impractical?

Any thoughts/comments appreciated.

BB.

Re: Could trees provide another model for wind power generation?

No--There is nothing in the motion of trees that would give a theoretical base for deriving alternative mechanical methods of generating power from wind--That I can see.

The motion of trees waving back and forth is probably the "rolling motion" of turbulent airflow near the ground. You also have leaves/branches that move with the wind and change airflow characteristics (leaves "flutter", etc.) which tends to dissipate energy rather than to any real work.

There have been a lot of attempts to create "better" wind turbines--But many of the "novel" designs never really went anywhere useful.

Wind turbines are fairly efficient (when operating at wind speeds for which they are designed). There have been experiments at using ducted fans (for example)--but those have been found to not generate the amount of power first estimated and also where heavy/expensive devices that just were not worth it.

-Bill

mtdoc

Re: Could trees provide another model for wind power generation?

Duffis wrote: »

I believe that larger windmills with a larger area of blade space exposed to the wind will spin with less wind speed. A tree or something like it provides a lot of space for a less powerful wind to push against...so...would it be possible to construct something like a sail on a hinge to extract more power at lower wind speeds?

I realize that this is not exactly the same as what you are describing, but the early windmills I believe did essentially do just that: use large sails to harness the energy from low wind speeds: LINK

solarix

Re: Could trees provide another model for wind power generation?

Its all about dollars per watt. What if you used an actual tree and mounted lets say four hydraulic cylinders around its trunk plumbed through check valves to a hydraulic motor driving a gearbox and then a generator. The movement would be short strokes but have a lot of force so the net power might be good enough when geared up to generator speeds to be valuable. Think of a forest of trees generating juice! If you've ever camped overnight in forest during a windstorm, this idea is compelling. The equipment might not cost that much. For sure, you don't have to build the "tower". Main objection I see is that the minimum windspeed threshold is probably pretty high.

Cariboocoot

Re: Could trees provide another model for wind power generation?

Actually it's all about efficiency of converting one type of energy to another. As it is HAWT's are not very efficient, VAWT's even less so. The mechanical resistance involved in either is one of the big problems; much of the energy in the wind goes in to overcoming this resistance and keeping the mass in motion. The more resistance points (pivots as expressed in either of the ideas mentioned) and more mass that must be kept moving the greater the losses would be.

Have some fun: design a whirligig that flaps back and forth wiggling magnets between coils like the old magneto ignition systems on early engines. See how efficient that is.

icarus

Re: Could trees provide another model for wind power generation?

There was a piece I read somewhere just recently about this very idea. Can't remember where, but if I do, I post a link. Pretty interesting , iirc one of the potential benefits was that these "swaying" generators were much more forgiving of gusting, and turbulence than a conventional wind turbine.

Tony

PS. I would add, it is not really a matter of how efficient a sytem is in % of potential energy harvested, but rather what is the lifetime net cost per KWH. For example a wind turbine harvests say 20% of the available wind on averge, and has a net cost of say $.50/kwh, compared to a different system that collects only 10% of the energy, but the net lifetime cost is .$25/kwh the net cost per kwh is the same.

Not unlike the quest for more efficnt PV. If you double the EF, but also double the price per kwh, you haven't gained anything, except in specialty applications.

Offgridandlovingit

Re: Could trees provide another model for wind power generation?

When you started talking about the way trees rock and sway, this is what I thought about. Dont know if wind produces enough energy to power something like this, but it might could work...http://www.alternative-energy-news.info/technology/hydro/wave-power/

bill von novak

Re: Could trees provide another model for wind power generation?

solarix wrote: »

Its all about dollars per watt. What if you used an actual tree and mounted lets say four hydraulic cylinders around its trunk plumbed through check valves to a hydraulic motor driving a gearbox and then a generator.

I was thinking more of just a bunch of piezo vanes all wired together. The wind "shakes" them and they generate power.