Well it's common knowledge, that windmills have problems in generating consistent torque, especially in extreme conditions (no wind, super high wind...). This leads to voltage variations, which (if unregulated) kill appliances and batteries.

It's also common knowledge, that - in order to make electricity useful, you need to deliver it constantly and evenly.

It's also common knowledge, that systems incorporating batteries and capacitors, which smooth out the power ripples from windmills are notorious for high prices and high energy loss.

Here's an idea:

Use the windmill to mechanically pump air into huge air tanks at insanely high preassures. Then use a high efficiency air turbine to generate consistent energy output.

Oh yes. By compressing and then decompressing the air, one could make use of thermal energy which is released (heat during pumping and cold during release) for heating/cooling of buildings arround the windmill. Or perhaps heat exchangers could cool down the intake valve and warm up the exhaust (make them last longer).

Benefits: 1. put the actual generator on the ground (easier servicing, cheaper tower construction), 2. make use of extremely high and extremely low wind conditions as well. 3. eliminate the need for electricity storage, which is poluting and expensive

Things to consider: Windmills and turbines achieve about 50% efficiency. Generators about 90%. Do we loose too much energy in the storage? Do the savings from circutry and batteries justify this?
-- anzlovar, Jul 22 2004

Windmill home energy system. http://www.halfbake...e_20Energy_20System
[Fussass, Oct 04 2004]

Proof of Betz's Law http://www.windpowe...en/stat/betzpro.htm
Why you'll never get more than 59% of the energy out of the wind. [willard_b_trophy, Feb 15 2005]

Klil the village that proves its possible http://scitation.ai...type=cvips&gifs=yes
Village tried living without grid, resolved to air turbines [pashute, Sep 12 2006]

Sounds good to me. You can design the support of the windmill to be a cylinder and contain the high pressure air.
-- Worldgineer, Jul 22 2004


Yes. To your questions, that is.
-- dpsyplc, Jul 22 2004


Read this, thought "nah...".
Read it again... this is a good idea. Especially with [world]'s siting of the storage tank. Maybe have a couple of turbines, so that one or both could be used depending on how much energy was stored in the tanks. If the pressure was high, use both in series to keep the shaft speed down (and thus keep voltage and frequency where they should be). Low pressure -> use one turbine. High demand -> use both in parallel.
-- david_scothern, Jul 23 2004


Do the figures work out? Seems like adding inefficiencies to me.
-- scubadooper, Jul 23 2004


I think the point is that it's better to be 60% efficient all of the time than 90% some of the time and 10% the rest of the time.
-- angel, Jul 23 2004


I see a problem with getting a constant high pressure in the huge air tanks.
-- Ling, Jul 23 2004


Yeah, and releasing the air will provide no constant power. there will be more power output at the start, yada yada. you could modify your design to account for this, but that'll surely add inefficiencies...

And compressing air isn't very easy. You need alot of power to get high pressure. This means adding all sorts of gear ratios, saving the energy in spurts, and then releasing it to compress the air. More inefficienies. I wouldn't put a dime in this, but I might be wrong...
-- daseva, Jul 23 2004


This is something of a Rube Goldberg approach--adding complexity to eliminate what is only a perceived problem. In reality, any reasonably sized windmill would be part of a grid. The windmill would always produce its maximum safe output for the wind conditions, and whatever it contributed would allow a central power station to burn less oil. A load leveling system would operate as a separate unit altogether, taking power from the grid during low load situations, and returning it during peak load. It doesn’t care where the original power came from.
-- ldischler, Jul 23 2004


I had assumed this was for smaller installations - such as for a house.
-- Worldgineer, Jul 23 2004


For a house! He said "huge air tanks at insanely high preassures..." But even home generators can be tied into a grid.
-- ldischler, Jul 23 2004


Compressed air is pretty tricky to contain and move around. The cost would probably outweigh the efficiency gains. Perhaps some kind of thermal reservoir would work better.
-- the_art, Jul 23 2004


//tied into a grid// Assuming there is a grid. Now I'm wondering if this is a good case for replacing electricity in a house with all pneumatic devices. Um... other than lights. And electronic devices - though those could use individual generators that supply low-voltage and skip the wall wart.

Odd, I can't find a "pneumatic house" idea anywhere on the 'bakery. Should I add it?
-- Worldgineer, Jul 23 2004


While you're there, you could add "pnuematic TV, fridge, washing machine, vacuum cleaner". Hold on a moment: Washine machine and vacuum cleaner could work, couldn't they?
<edit>So could the refrigerator, thinking about it.
-- Ling, Jul 23 2004


[Ling], go back to mechanical TV systems and you could probably make one of those run on pneumatics too, with a dynamo to generate power for the lighting.
-- suctionpad, Jul 23 2004


No dynamos allowed in the pnuematic house :(
-- Ling, Jul 23 2004


I'm sure you could re-design most electronic devices to be pneumatic, but it wouldn't be easy. I'm picturing a screen of tiny multicolored wheels controlled in such a way as to create a non-glowing television. We'd need a pneumatic cable that runs from the pneumatic television station to control it. However, we still end up without light.
-- Worldgineer, Jul 23 2004


While I think there will be more loss than gain by complicating the system, I'm going to bun this simply because you actually gave some thought to recovering the energy wasted by the compression heating.
-- Freefall, Jul 23 2004


Nice try [anzlovar] but peak power storage is normal. So is compressed-air energy storage though not used much. In any case the idea in the link has precedence on most of this including heat recovery and the pneumatic house concept. It is good but boned for redundancy.
-- Fussass, Jul 23 2004


//replacing electricity in a house with all pneumatic devices//
At one time, there were some rudimentary pneumatic distribution networks. But you couldn’t go very far with it, due to the pressure losses.
-- ldischler, Jul 24 2004


I like this; pneumatics are a pretty efficient method of energy storage. It's the conversion that's tricky.

I think I could come up with an efficient enough reduction system to avoid heavy gear trains. It's all in the system sizing. You could use this as a backup system to even out the low power days.
-- RayfordSteele, Jul 24 2004


I would give the "pneumatic house" idea a Chindogu Bun for effort. But I am afraid this Windmill is just not interesting enough for one. Not necessarily "Bad science" just a bit "Al Gore" (dull and probably ineffective).
-- PainOCommonSense, Jul 26 2004


Wind turbines are already as close to being as efficient as they can be. There are machines operating at 90%+ of the Betz Limit, linked to above.
-- willard_b_trophy, Feb 15 2005


When I was 17 (1981) I had done research for an invention of mine, at the Ministry of Energy, comparing wind and solar power containment with the technologies available at the time. Wind gave you electricity at a fraction of the price vs PV, and I had read that the best way to store energy and the most efficient mode to convert to was potential energy(pulling weight higher up)! A village called Kllil, had signed a contract with our electric co that they would not use the grid. They spent a mint on PV roofs, and gas fridges, only to invest another tiny amount in wind turbines, then selling the excess energy back to the elctric co! Of course the power leaving the storage is normalized according to standards. Proof that your idea would work as well.
-- pashute, Sep 12 2006


It seems to me the solution proposed here can be considered simply an energy storage system. Surely there are better ways: hydrogen (very baked) or a flywheel-farm, which excites my imagination more than air pressure...

I like the idea of pneumatic apliances. A pneumatic remote control would be a great way to clean dust and tease pets.
-- Ehrm, Sep 12 2006


I came up with [Worldgineer]'s addition, too. Make the tower into an air tank, and some advantages accrue. I looked around, and most big towers have ladders and conduits inside, but in many cases it would work well.

I object to the "insanely high" pressures bit. Large volumes at low pressure have advantages over smaller volumes at high pressures.

I fully support the idea of using compressed air as the power output. Electricity doesn't store well at all, and converting air to electricity is inefficient. Just use the air for everything it can be used for, and deal with everything else in some other way.

This is one of the cases where some people want perfect solutions to 100% of the problems in every conceivable situation. Compressed air out of a windmill is quite clever, and would be very useful in many situations, with a little more engineering.

Even though the title sucks and there are some flaws, (+).
-- baconbrain, Apr 19 2009



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