BS: Wind turbine efficiency

Subject: RE: BS: Wind turbine efficiency
From: Schantieman
Date: 08 Dec 06 - 11:15 AM

Wow, John

Subject: RE: BS: Wind turbine efficiency
From: The Fooles Troupe
Date: 08 Dec 06 - 05:59 AM

Theoretical Power is much easier to achieve than Practical Power, as both Real World Engineers and Politicians eventually discover.

Subject: RE: BS: Wind turbine efficiency
From: JohnInKansas
Date: 07 Dec 06 - 10:15 PM

The direct conversion of low-density electrical energy, from photocells, wind, or other "locally clean" sources to hydrogen for storage until the hydrogen is needed for fuel sounds pretty simple, but there are some drawbacks.

Gaseous hydrogen is incredibly difficult to store and extremely dangerous to handle.

There are several methods of storing hydrogen that various people tout as effective. A popular one has been to combine the hydrogen as a "metal hydride" in storage. Since there's no existing way to pump the metal hydrides through a pipe, this still requires handling gaseous hydrogen at least for fuelling and within the engine for combustion. This might be acceptable for a vehicle, but does nothing for the storage/transport problem.

A disadvantage of metal hydride storage especially in a vehicle is that the entire storage volume must be operated at high temperatures to release the hydrogen for burning. As a "personal opinion" either large high pressure inert gases or very high energy flywheels likely would be safer for any large-scale public use, especially for uses such as in vehicles.

The former Beech Aircraft company started a project to design a "hydrogen powered automobile" using metal hydride storage sometime ca. 1960, and the project was still running (after they became Raytheon Aircraft), without notable success, at least ca. 1998 if information overheard then was correct. A problem is that hydrogen is "very low octane" and tends to explode rather than burning smoothly, so small parts of the engine kept getting propelled into strange places, or mangled and bent inside the engine. (At least ca. 1970 - '74 when I had occasional "direct observation" contact with the project.)

The more "modern" idea for hydrogen burning engines seems to be "generating" the hydrogen directly from petroleum fuels. Lots of people are working on this concept, but few "hardware examples" have appeared outside laboratories. While this may result in lower emissions from the hydrogen burning device, there is at present no efficient way to directly produce more complex hydrogen-bearing molecules (hydrocarbons) from low density electricity, so it doesn't help the "store it as hydrogen" idea.

The "flying engine parts" that Beech/Raytheon encountered illustrates a difficulty of handling/transporting hydrogen as a gas. When compressed enough to provide useful expansion during burning, it has a tendency to detonate (engine knock). When compressed enough to be efficiently pushed through a pipe, it has a tendency to detonate, especially with very low amounts of oxygen intermixed, under any condition that can cause ignition.

Some years ago, ca 1950s(?), a few natural gas "pipeline explosions" occured that were quite spectacular. One or two destroyed more than 100 miles of pipe each.

Increasing the pressure of a gas increases the speed of sound in the gas. A detonation travels at approximately the speed of sound in the gas. A fracture under stress of the pipeline material cannot travel faster than the speed of sound in the material from which the pipe is made.

If the pipe is strong enough to contain the pressure at which burning of the gas transitions to detonation (produces a shock wave), any "ignition" will raise to pressure inside the pipe to the detonation point in the vicinity of the combustion/detonation front.

If the speed of sound in the gas (the speed at which the "explosion" travels) exceeds the speed of sound in the (usually metal) pipe, the shock wave stays ahead of the crack that would release the pressure enough to lower the burning condition below the "detonation transition pressure" so the explosion and the crack both travel to the end of the pipe, exiting potentially (it was suggested) where it blows your kitchen stove through your roof. Being a rather light gas, the speed of sound in moderately compressed hydrogen is "pretty fast."

Natural gas pipelines now have "interrupters" at frequent intervals, with valves that shut down all of the valves on the pipeline if pressure at any point on the line drops, and in some cases vent a few sections on both sides of where the drop was detected. Rupture points are built in that will allow the pipe to break and (hopefully) release the gas pressure locally before it rises high enough to allow the natural gas to produce a sonic shock. Working on natural gas pipelines is still considered a "hazardous occupation" even thought it's very much safer than any easily conceived hydrogen pipe.

There is no pressure at which gaseous hydrogen can be pumped efficiently through a long pipe that will not result in detonation if any ignition accident occurs, if even minute amounts of oxygen are available; and perfect exclusion of oxygen is extremely difficult.

John

Subject: RE: BS: Wind turbine efficiency
From: JohnInKansas
Date: 07 Dec 06 - 09:03 PM

Under thorough analysis, at least at present, photovoltaic (pv) electrical generation isn't really a "low impact" method.

The fossil fuel consumption to produce current pv panels - the fuels burned/consumed directly in the manufacturing process and burned to generate electrical power used during manufacture - now exceed the fuels that would need to be burned in reasonably efficient combustion generators to produce all the electrical energy that the panel will produce in 20 years of using the panel. (Twenty years use is the current "state of the art" lifetime of a typical pv panel under good conditions, according to manufacturers. They tend to be optimistic.)

The pollution at the point of use of the pv device is low, but to get that "clean application" now requires that "somewhere else" quite a lot of pollutants were produced, and a lot of conventional fuels were consumed. The net result is that widespread use of pv devices may actually cause more "global pollution" and fossil fuel consumption than conventional on-site generation with conventional methods for the same amount of energy.

People are working very hard at improving the efficiency of the solar/electric conversion of pv devices, and at reducing manufacturing cost (mfg. cost is proportional to, if not closely equivalent to, "fuel consumed to make"); but for the present, pv devices really are useful only where the cost of transporting the fuel to remote places would be excessive, or where no suitable fuels are available at any cost.

John

Subject: RE: BS: Wind turbine efficiency
From: GUEST,petr
Date: 07 Dec 06 - 08:29 PM

back in the 20s one scientist suggested building 1000s of windturbines
with electrolyzers to convert water in to hydrogen and oxygen.
so the idea isnt new. Electrolysis is probably not the best use of the energy as it is only 35%? effiecient.
WHich is why I think there may be other options to store the energy (eg. flywheel, compressed air, pumping water uphill, batteries etc.

One interesting project is the superconducting pipes which would allow use superconducting wires which would be encased in pipes containing super cooled hydrogen gas. This would allow for long distance transmission with low power loss to resistance as well as provide a storage medium for hydrogen. This kind of helps solve the hydrogen economy infrastructure problem. (Ie. the chicken or the egg of a network of hydrogen gas stations or hydrogen fuel cell ir ICE cars that run on hydrogen)

So theoretically any excess energy generated by wind turbine, solar,
tidal etc. can be converted to hydrogen with electrolysis and pumped into such a grid for later use.
They are already planning to build a test pipe.

OBviously there will be concerns about the dangers of failure of such a system - but there is a quote from an 1880 Congressional report on the invention of gasoline that puts things into perspective- it states that it would be very dangerous substance, would require all sorts of safety regulations for containment, and the subsequent move from a horse based economy would destroy Americas agriculture.

Subject: RE: BS: Wind turbine efficiency
From: Cluin
Date: 07 Dec 06 - 06:11 PM

Many of us are familiar with the lasting effects of a good blow.

Subject: RE: BS: Wind turbine efficiency
From: GUEST,MarkS
Date: 07 Dec 06 - 05:44 PM

This may be real blue sky, but perhaps the low power generated by small solar or wind stations could be used to crack water into hydrogen and oxygen, to be stored and then recombined (burned!) as needed for use as a fuel for transportation or heating.
Even small amounts, but generated over very long times could produce a usable amount of fuel with minor environmental impact.

Subject: RE: BS: Wind turbine efficiency
From: JohnInKansas
Date: 07 Dec 06 - 04:26 PM

Compressed looks a good solution, and you could probably replace the electric generators by compressors directly at the turbine shaft, though the pressure required to store a lot of energy sounds a bit frightening.

Unfortunately there are some "Laws of Thermodynamics" that say that compressed gas is a rather inefficient way of storing and recovering energy. Efficiency (thermodynamic) is usually better using larger volume at lower pressure, but the volumes required for "city scale" storage, at reasonable effectiveness, are immense. The volumes that can be accommodated for a vehicle, or even a single-house, dictate rather high pressures to obtain useful energy density. "Compression losses" followed by "expansion losses" make this a poor scheme in most situations.

Compressed nitrogen bottles are used for "emergency actuators" in many places, particularly in large aircraft. You can pack lots of energy into a small and relatively lightweight package; but the energy consumed to pack it is about 3 times what's contained, and the energy that is recovered (usable) when you fire the release is about one-quarter of what was "in the bottle." (From one specific, but pretty typical, design I'm somewhat familiar with.) Less "explosive" compression and recovery would do a bit better, perhaps.

A few moderate sized facilities have used "air bladder" type storage, where the energy is stored by moderate compression of air (sometimes another gas) contained in a sealed container, but the compression is done by pumping an "incompressible" fluid, often water, in and out. The thermodynamic losses are somewhat smaller for pumping liquids than for gases - usually. On a small scale, this method is used for many home well systems, with the pump putting "stored pressure" into a small reservoir, and the air pressure providing the "pumping work" to deliver the water to the tap as needed, avoiding the necessity of having the pump turn on everytime you draw a cup'a.

Larger ones may occupy an acre or so of ground, with dead-weight(often concrete) "roofs" to contain the pressure, and are used in a few places in lieu of a "water tower" to provide municipal water supply pressure, or for pumping the crud in sewage treatment processes.

John

Subject: RE: BS: Wind turbine efficiency
From: JohnInKansas
Date: 07 Dec 06 - 03:55 PM

^#%@$!

Make that page 24.

John

Subject: RE: BS: Wind turbine efficiency
From: JohnInKansas
Date: 07 Dec 06 - 03:52 PM

Steve -

From the NIST Special Publication 330, 2001 Edition, The International System of Units (SI)

Page 14

10²⁴ = yotta, symbol Y
10²¹ = zetta, symbol Z
10¹⁸ = exa, symbol E
10¹⁵ = peta, symbol P
10¹² = tera, symbol T
10⁹ = giga, symbol G
10⁶ = mega, symbol M
10³ = kilo, symbol k
10² = hecto, symbol h
10¹ = deka, symbol da
10^-1 = deci, symbol d
10^-2 = centi, symbol c
10^-3 = milli, symbol m
10^-6 = micro, symbol
10^-9 = nano, symbol n
10^-12 = pico, symbol p
10^-15 = femto, symbol f
10^-18 = atto, symbol a
10^-21 = zepto, symbol z
10^-24 = yocto, symbol y

For US users, at least (if I didn't make any transcription errors).

John

Subject: RE: BS: Wind turbine efficiency
From: Schantieman
Date: 07 Dec 06 - 01:58 PM

Petr - what's an "Exojoule"?

I've heard of kilo- (10^3)), Mega- (10^6), Giga- (10^9) and Tera- (10^12). Is Exo- 10^15 ?   If so why do they use such a confusing prefix? - exo- normally means 'outside'

Steve

Subject: RE: BS: Wind turbine efficiency
From: The Fooles Troupe
Date: 07 Dec 06 - 05:01 AM

"pumping water uphill"

This is used in Brisbane - we have two dams ar different levels - at off-peaks the water is pumped back up, and power generated during peaks. Well, it was done when we had plenty of water in the dams before the drought...

Subject: RE: BS: Wind turbine efficiency
From: JohnInKansas
Date: 06 Dec 06 - 11:49 PM

While the flywheels at the Bitter Magnet Lab are 10 tons each, around 10 feet in diameter, take hours or days to spin up to speeds of a few hundred rpm and dim the lights in Cambridge while running up, they store a very large amount of energy, which is fed into the magnet coils to bring the flywheels to a halt in a few milliseconds. They "simulate" briefly directing approximately the full generating capacity of the Cambridge MA grid to one user.

There was a spurt of publicity several years ago though about flywheels for vehicle "load leveling" where they used fiberglass/composite flywheels encased in vacuum enclosures, generally with "dynamic bearings" of a couple of kinds, with peak speeds of up to 100,000 rpm or so. These flywheels were on the order of 10 to 30 pounds, and under about 100 pounds for the whole "storage assembly." A few prototype buses were built and were used in test/demonstration street use. Laboratory efficiency numbers looked good; but I don't recall ever hearing of a "final report" on the street testing; and haven't heard of any continuing advocacy for these schemes among transportation engineering companies or groups.

Someone mentioned flywheel bearing problems earlier. In either kind of flywheel storage system, there are adquate bearing designs, if intelligently used. (But good bearing designers are really scarce.)

There is a very real problem with containment in a failure for the casual experimenter, but with the lighter weight very high speed flywheels used in the vehicle tests the cases required to hold the vacuum were almost automatically provable (at least by analysis) as being adequate to contain the energy dump in case of failure. (Flywheels of this kind would be very inefficient due to "windage" without the vacuum.) The flywheel itself of course self-destructs in almost any failure, but for small amounts of energy storage fail-safe design isn't too much of a problem.

The amount of energy to be stored dictates whether the small high-speed flywheel or the massive low speed one is more efficient, and unfortunately the difference between energy storage requirements for a small bus (or single home) and storage requirements even for a local municipal power grid are like the difference between a flea-fart and a hurricane.

John

Subject: RE: BS: Wind turbine efficiency
From: GUEST,petr
Date: 06 Dec 06 - 08:49 PM

Paul, I would be so dismissive of Benfords ideas,
here is the link Gregory Benford

Regarding your point on flywheels - it is true they are dangerous
but one idea being developed is to make flywheels from compressed composite material that would disintegrate into dust. (Already in 1890
when the InterUrban railway was being built in Vancouver, the design incorporated energy storage in a flywheel)

ALso your point on pumping water uphill, is another good energy storage solution, (one example in the US being Raccoon Mountain )

it is interesting to see how efficient small wind turbine might be. In Ontario the Bruce peninsula which gets a lot of wind from the lakes there is a large wind turbine which generates enough power for 500 homes (about a 1/4 of the inhabitants of the peninsula).

ONly a few months ago, I noticed Canadian tire selling small wind turbines as well as solar roof top systems. Since our house gets alot of
the southern sun - its too hot to even sit on the deck in the summer.
I had been considering trying out a system. Now ideally if the govt gets its act together and comes up with a carbon trading system, homeowners with such systems should get some credits..

Subject: RE: BS: Wind turbine efficiency
From: dick greenhaus
Date: 06 Dec 06 - 12:07 PM

the key word in "appropriate technology" is "appropriate" (though "technology counts, too). Wind energy is most suitable for (surprise!) windy areas; solar, either passive or active, works best in sunny areas.
What's needed in the US are things like solar-powered air conditioners and irrigation pumps.

Subject: RE: BS: Wind turbine efficiency
From: The Fooles Troupe
Date: 06 Dec 06 - 07:27 AM

He should put it in a Mudcat BS thread...

Subject: RE: BS: Wind turbine efficiency
From: Grab
Date: 06 Dec 06 - 07:16 AM

Hunkin says that the fan is actually from a blower (presumably leaf blower or similar). So I doubt it would have the problems with flexibility and stuff that you mention, John. Granted, it's still not the most efficient turbine in the world! :-) But as he said, even improving blade efficiency wasn't going to cut it. As you say, the critical part is whether you get enough wind over it, day in, day out, for it to cut the mustard.

Graham.

Subject: RE: BS: Wind turbine efficiency
From: JohnInKansas
Date: 05 Dec 06 - 10:04 PM

So Go Fly a Kite?

John

Subject: RE: BS: Wind turbine efficiency
From: JohnInKansas
Date: 05 Dec 06 - 07:10 AM

Grab's original post linked two different pages. I did look at the first one immediately to get an idea of where he was going, but only glanced at the second. I just got around to taking a closer look at the second (Tim Hunkin) link.

In Hunkin's first picture it looks like he's attempted to use an automotive "radiator fan." I can't tell from later pictures whether he got something much better for later trials, but the auto fan is one of the worst possible "randomly selected" propellers one might choose for a wind turbine project. It's designed to push a lot of air at low speed (low rpm), but doesn't derive much torque from air flowing through it. The thin flexible blades, in fact, are intentionally designed to "bend out of the way" when ram air due to vehicle motion is sufficient for engine cooling, and to "flatten" and pump nothing at high engine rpm (where it's assumed the vehicle's moving and the fan isn't needed).

If one must use a fan of this kind, he's got it mounted backward to what is needed to get best (which won't be much) result from this kind of fan.

A fixed, stiff-bladed fan from an older automobile (pre-1950s emission regulations and the push for efficiency?) would be a slightly better choice. A blade salvaged from a "shop fan" would also be a possibility, and you might find one up to about 30" diameter if you look around a bit. But for an effective "propeller" generator, I'd suggest visiting the nearest model airplane shop and asking for "the biggest ya' got." That probably won't be quite as big as you'd want for a practical generator, but would give you a starting point for trying out things.

An "airplane propeller" actually is "built backwards" for use as a generator driver, but the efficiency with a true airfoil will be very much higher even "running in reverse." For an airplane prop, the "angle of attack" is off the plane of rotation of the prop, so that rotation produces lift in the airplane forward direction. For a turbine-generator prop, the angle of attack needs to be off the perpendicular to that (from the plane of the blade and direction of flow) to produce lift in the direction of rotation of the prop. Approximately, the prop blade needs to be rotated 90 degrees on the hub, and the propeller ¹allowed to rotate in the opposite direction - not an exact description but close enough.

¹ If you want to keep the same direction of rotation, you have to reverse the twist of the blades.

For a starting point for developing your propeller turbine, a full airfoil blade section probably isn't necessary. You'll need it when you start to work up the efficiency, but a proper "lifting line" in a flat (metal?) blade would give reasonable performance for a start.

The classic reference is Abbott and Doenhoff, Theory of Wing Sections, from NACA wind tunnel research ca. 1949, republished 1958 by Dover and probably still easily available since it's a "classic." My copy was $4.50 but that was in 1970, so it's probably a bit more now.

I won't attempt to estimate how many draughts you'll need to buy for your neighborhood aerodynamicist for assistance with the calculations, but they're not really all that difficult once you get the definitions straight. (Although getting the "twist" right, so the angle of attack varies with distance from the hub can be tricky.) Just be sure to design so that tip speed doesn't exceet about 0.7M at your max design wind speed, for the airfoils in the book.

If you prefer to work with the "vertical" turbine, considerable information on the design was published when one of the ocean research vessels tried using one as a sail. The generic search term "Darius sail" or "Darius turbine" should get some info, although the sail application may be a bit old to find much of the technical stuff via Google.

I will suggest that although technology has advanced somewhat, and the requirements are better known, it's not likely that you'll get much better results with a "home built" than was available when an uncle tried a commercial wind generator ca. 1950.

Results were:

In Kansas wind with avg wind velocity 27 mph (approximately),

on a 40' windmill tower on top of a hill,

with 2-bladed prop direct coupled via a step-up gearbox (unknown ratio, probably 4:1 but maybe 7:1?),

running 24 hours per day, 7 days per week,

he was able to keep a bank of 6 or 8 auto batteries sufficiently charged to listen to the radio for about 2 hours at a stretch - usually on at least 3 days per week.

You can do much better with commercially available hardware now; but location and weather are critical to whether you'll get useful results, relative to what you hope for.

John

Subject: RE: BS: Wind turbine efficiency
From: The Fooles Troupe
Date: 05 Dec 06 - 06:56 AM

Incidentally, if you have a lot of water flow and a small head (?!) you can use a Ram Pump to lift a percentage of it up higher than teh stream.

Subject: RE: BS: Wind turbine efficiency
From: Paul Burke
Date: 05 Dec 06 - 06:39 AM

But this study suggests that the old- fashioned waterwheel, properly constructed, may be as good as anything for a site like your mates. He can have it both ways- effiecient AND romantic!

Subject: RE: BS: Wind turbine efficiency
From: Paul Burke
Date: 05 Dec 06 - 06:27 AM

The Pelton wheel is for high- head applications, so he's using it very inefficiently. A Kaplan turbine is usually used for small heads, it's basically a propellor. He might be able to make one out of an old boat propellor and fabricate a chamber for it.

Subject: RE: BS: Wind turbine efficiency
From: Gervase
Date: 05 Dec 06 - 05:49 AM

A neighbour of mine has been trying for the past two years to do just that - he lives in an old mill which has a leet, with a working water head of around three feet (albeit a slow flow), powering an enclosed Pelton wheel coupled to the working parts of an old two-stroke generator.
He's chuffed to bits because he can light a 60 watt bulb in his shed/office. Somehow I don't think it's going to remove his dependency on the grid!

Subject: RE: BS: Wind turbine efficiency
From: Paul Burke
Date: 05 Dec 06 - 04:59 AM

Well, Jim. The water has to come from somewhere. If there's a big head of water, it needs to be taken from a good way above the site of the generator. The smaller the flow, the bigger the head needed for a useful output. So either the user of the power needs to own all the land from the water take off point to the generator, or he needs to have kind neighbours who will let him cross their land with his pipe. They also need to be forebearing about the loss of water in their bit of the stream, which might also damage local woldlife (stet, I like that word).

It was in fact such a scheme that we looked at for our village, and the stream is just too small for worthwhile power, even if we could get everyone to agree. And this stream ran at least 4 mills in the 18th century, which just goes to show how our demand for power has changed. The mills can't have been more than a few hundred watts each (though perhaps mining and opencast working has disrupted the water flows so the stream is smaller).

Subject: RE: BS: Wind turbine efficiency
From: Paul Burke
Date: 05 Dec 06 - 03:41 AM

Sounds like a rather dumb solution. We've messed up the atmosphere, let's try to cure it by messing up the sea as well.

As for global dimming, that's already been implicated in the desertification of sub- Saharan Africa. The big problems with such schemes are that once you put it in, it's a devil of a job to get the stuff out again when you need to; and that you can't tell what it's going to do in enough detail to be sure whether it will make the problem better or worse.

Flywheels are big and very heavy, and need a lot of maintenence around the bearings. And if they crack up, it's like a bomb going off. Compressed looks a good solution, and you could probably replace the electric generators by compressors directly at the turbine shaft, though the pressure required to store a lot of energy sounds a bit frightening. Hydrogen is of course dangerous to storeas a gas, but I expect some clever scientists can work out a chemical way to store it if they haven't already.

There is another solution, currently used by nuclear power stations. These can't be turned on and off quickly to meet demand, and are kept on more-or-less constant (thermal) output. At times of low demand, the energy produced is usually just dumped. But in some cases, in the UK notably Wylfa power station in Anglesey, they have been combined with pumped- storage hydro- electric schemes. Water is pumped uphill at times of low demand, and can then be released to meet short- term peaks like when everybody puts the kettle on at the end of the Queen's Speech. This kind of scheme could be used to store energy from intermittent wind power.

They have of course all the disadvanages of hydroelectric schemes.

Subject: RE: BS: Wind turbine efficiency
From: GUEST,Jim and the whippets
Date: 05 Dec 06 - 03:40 AM

You dinner party greens can't read either.

The style of hydro I'm talking about works on small steep streams with no need for damming - single property installations, based (as I said) on converted AC electric motors (typically 5hp size).

Just to square the record I'm actually a fiancial industry worker living in East London and the whippets are imaginary.

Sorry, Yorkies everywhere.

Jim

Subject: RE: BS: Wind turbine efficiency
From: GUEST,petr
Date: 04 Dec 06 - 08:41 PM

re; solar - germany and austria have installed over several hundred thousand solar roof systems, more than anywhere else in the world.
And they arent in particularly sunny latitude.

also an Interesting bit of info (from Mark Jaccards book - Unusual Suspects - Sustainable Fossil Fuels)
not counting the 30% of the solar energy that is reflected back into space the amount of solar energy that hits the earth is 390,000 Exojoules.
The total worldwide energy usage is 400 Exojoules (ie. 1/10,000th)
Of course it doesnt mean all that energy is usable, as most of it goes the latent heat, evaporation of water etc. (only less than 1% goes to support life on earth) but its an interesting fact.

- regarding ghg reduction (a U. Cal physicist did a study that the US could actually meet its Kyoto co2 reduction requirements by dumping farmwaste into the oceans at a fairly small cost of $3billion US
- (which would not totally get rid of the co2) rather it would take 1000s of years to breakdown) but it would sequester the co2 long enough to do something about the problem.

- this same physicist also proposed using fine diatomaceous dust (released from planes) to block particular wavelengths of solar radiation - in such a way to reduce the heating (we already know that global dimming - due to pollution and jet trails from planes -has a cooling effect).

- regarding excess energy storage from say windpower, rather than batteries, why not a flywheel (which is 90% efficient) or compressed air (around 60% efficient) as opposed to hydrogen electrolysis which is fairly inefficient (I believe around 30%).

Subject: RE: BS: Wind turbine efficiency
From: MaineDog
Date: 04 Dec 06 - 05:14 PM

A major problem with heat pumps is that you must not freeze the heat source exchanger. This will happen if you try to get too much heat out of it: You'll get a nice insulating sheath of ice around it, and then, no more heat will flow!
MD

Subject: RE: BS: Wind turbine efficiency
From: GUEST
Date: 04 Dec 06 - 05:06 PM

I've long fancied building a vertical wind turbine, which is a 44gal/200l drum split vertically, offset and mounted on a shaft. They work like the Castrol signs did, whirling around in any wind at all, and not directional. Rig a 12v car generator to that, and it might produce enough power to charge a battery of batteries.

Subject: RE: BS: Wind turbine efficiency
From: Bunnahabhain
Date: 04 Dec 06 - 12:23 PM

There is considerable scope for medium scale Hydro-power schemes. Germany does it, and we could, using the same kind of sites. The sites used a few centuries ago, to grind cereals, run forges, etc.

They are costly at the moment, but they would become much cheaper if they were more common. The small ponds assciated with this don't displace people, and are positivly good for the enviroment in their own right. Mill ponds are prettier than turbines as well.

Subject: RE: BS: Wind turbine efficiency
From: Donuel
Date: 04 Dec 06 - 12:03 PM

But on a dark windless frigid day you need a wood stove.

Some of those wood furnaces you put outside look mighty nice.

meanwhile r&d is right about insulation.

Subject: RE: BS: Wind turbine efficiency
From: Donuel
Date: 04 Dec 06 - 11:57 AM

A wind turbine is super if used only to run a heat pump (two Saline heat exchanger tanks) that is buried 20 ft. down where it is always 52 degrees F.

That way you gets lots of heat in the winter when it is always fairly windy.

Add a solar panel to the system and it all flows together to make a nice off the grid Heating and AC unit.

It is my design but I have never built it. It seems elegant enough on paper.

Subject: RE: BS: Wind turbine efficiency
From: Gervase
Date: 04 Dec 06 - 11:47 AM

Townies? *snort* Try telling that to my sheep!
An here in West Wales there are still rather bitter memories about flooding valleys.

Subject: RE: BS: Wind turbine efficiency
From: Paul Burke
Date: 04 Dec 06 - 11:24 AM

Is it a coincidence that a windmill was a big part of the plot in Animal Farm?

He's rumbled us! The alternative energy eco-fascist-commies, suburbanites and townies, whose only plan is to dominate the world by installing wind turbines and thus destroying rurally idyllic Archerland!

Why not water? Because to get significant generation from hydroelectricity, you need massive amounts of water. Dams, which swallow up millions of tones of concrete, destroy whole ecosystems not to mention communities (Ladybower near me), and oops need access roads.

We had a look at one for our village. A nice little brook, good head but not much volume. Estimated cost £8000. Estimated output 160W.

Come and live up in't country wi' us northern folk, where we either heat our homes and feel bad, or don't heat our homes and feel good, or don't heat our homes and feel bad. Ever seen a Yokshireman smile?

Subject: RE: BS: Wind turbine efficiency
From: GUEST,Jim and the whippets
Date: 04 Dec 06 - 10:44 AM

The ecological damage isn't confined to bird strike. Wind farms need access roads and these also need drainage. Putting in new roads and drains on moorland is disruptive (proof: a local estate was prosecuted by the EA and heavily fined for putting in new moorland roads for shooting purposes).

Most of the people who profess a liking for large wind turbines sound like suburbanites who want to keep the heating on and feel good at the same time. Their idea of environment is the small shrubbery at the entrance to their local Tesco. Those of us who live and work in the hill country are daily affronted by the steady encroachment of these unsightly and usustainable contraptions.

Is it a coincidence that a windmill was a big part of the plot in Animal Farm?

As someone said earlier here, why don't people look at water? There's lots of it in our hills and it drove the first industrial revolution. Nottingham Trent Uni has done some great work with re-used and modified AC motors to create small cheap and truly sustainable power generators.

Subject: RE: BS: Wind turbine efficiency
From: Bunnahabhain
Date: 04 Dec 06 - 10:26 AM

Bird strikes vary vastly, within in a small area. SNH ( Scottish Natural Heritage, the Govt busibodies with noses in this area) have been collecting data, and have opposed several schemes as their siting would cause excess bird strikes, and proposed acceptable alternatives, often only half a mile or so away.

This is a body renowed for paying very little attention to the wishes of people, especially locals.

Subject: RE: BS: Wind turbine efficiency
From: Gervase
Date: 04 Dec 06 - 09:39 AM

I've got three quite near me, and when I first read the claims about bird carnage I thought I'd go and have a look. I've now been several times at various times of the day and seasons of the year.
Believe me, when those blades hit a bird they must do a darned good job, because I was unable to find a feather, let alone any recogniseable part of a mangled fowl.
Or do you think perhaps someone was scaremongering.
It's the same with the noise. I read a letter in a newspaper from someone saying that the low frequency noise made by the turbines was intrusive.
I think I must be deaf. Standing within 50 metres I only heard a mild sussuration as the blades went round, but no low frequency hums.
Or was it scaremongering again?

As these arguments are routinely trotted out by people opposed to wind turbines and are demonstrably wrong, it does make me suspect the other arguments they use.

Subject: RE: BS: Wind turbine efficiency
From: Paul Burke
Date: 04 Dec 06 - 09:17 AM

Large wind turbines can make a worthwhile contribution. The generating power increases with the square of the blade length, and the wind speed is also higher further from the ground. Also the electrical and mechanical efficiency increase with size.

I personally don't find them visually unpleasant, and their effect on migrating birds has been exaggerated. After all, birds learned to live with windmills from the middle ages to the nineteenth century.

Subject: RE: BS: Wind turbine efficiency
From: Mr Yellow
Date: 04 Dec 06 - 08:03 AM

Under soil heat collection -

Apparently, at the depth of water supply pipes the temperature remains fairly constant at 6 deg C in the UK. Hence the depth of supply pipes - never freezes.

I would have thought summer cooling would be more efficient winter heat collection but I have seen TV programmes where they install the garden pipes.

Mind you sub-soil windage is not that great...............

Subject: RE: BS: Wind turbine efficiency
From: GUEST,Jim and the whippets
Date: 04 Dec 06 - 04:07 AM

If you live in UK uplands outside national park boundaries (as we do) watch out for mass landscape despoilation by ugly useless and subsidised (by you and me) wind turbines. This feelgood nonsense is very likely to happen in the near future under tory or labour governments, and will ruin the aesthetic and ecological value of huge tracts of land.

You've been warned. Fight now or lose it all.

Jim and the whippets

Subject: RE: BS: Wind turbine efficiency
From: s&r
Date: 04 Dec 06 - 03:36 AM

We've just had cavity wall insulation installed for £200 and reinsulated the loft with 200mm insulation. The difference (subjectively till we've had time to compare figures from last year) is phenomenal. The house heats in a fraction of the time it used to, and the timer is set to not turn on a.m. because the house remains warm.

we use mostly low energy bulbs but I'm not convinced they make much difference in energy usage because the wasted energy in producing heat of the incandescent lamp is just added to the house heating. Street lamps I suppose are all low energy.

I think there's still room for reducing our consumption before we go down the road of Wind Turbines and PV panels.

Stu

Subject: RE: BS: Wind turbine efficiency
From: The Fooles Troupe
Date: 03 Dec 06 - 07:26 PM

With winter temps of 20 deg C to nealy 30 deg C in daytime in some parts of Australia, there's no need to heat the external air...

Subject: RE: BS: Wind turbine efficiency
From: GUEST
Date: 03 Dec 06 - 12:41 PM

In the US, at least, fossil fuel costs are still so low that solar or wind energy approaches aren't economically feasible---unless they're subsidised by the government.
In New Jersey, f'rinstance, about half the cost of a photovoltaic installation is provided by the state government, and the local power companies (who don't want to have to build more generating capacity) have agreed to buy any excess generated at the current maeket price. This provides a roughly 9-10 year payback, which would be drastically reduced if fuel prices rose during that period.

Heat pump water heaters work, but they draw their heat from air which may have to be heated by other, less efficient means. Ground- or water-sourced heat pumps are an excellent solution if a)you live in a temperate climate and b) if you can live with a rather high initial cost. one of their major benefits is the low operating cost for either heating or cooling.

Subject: RE: BS: Wind turbine efficiency
From: The Fooles Troupe
Date: 02 Dec 06 - 08:01 PM

You can buy in Australia hot water heaters that are 'energy pump' devices that extract heat from the surrounding air to heat the water. they have a small electric pump that uses far less energy than heating the water with electricity.

I remember a big fuss many years ago about 'thermal pump' air-conditioners that sourced/sinked heat from a huge web of pipes buried in the earth nearby.

Subject: RE: BS: Wind turbine efficiency
From: GUEST,windy miller
Date: 02 Dec 06 - 05:36 PM

I think wind turbines are amazingly efficient - have you not noticed how windy it gets when they are all switched on?

Subject: RE: BS: Wind turbine efficiency
From: Grab
Date: 02 Dec 06 - 05:13 PM

Fair point on the quibble. I was thinking more in terms of efficiency as energy produced versus energy to make the thing in the first place.

Sadly photovoltaic is only a worthwhile option in places with lots of guaranteed sunlight. The Mediterranean or southwest US might quality - the UK certainly doesn't. "Which?" magazine calculated a 20-year payback term on photovoltaic in the UK, assuming that it runs for 20 years without needing any servicing.

Solar heating is a much better bet though. You just need to be somewhere where installing it doesn't mess anyone else up. Detached houses in the country and most US houses (again mostly detached) are fair game. Houses in cities or on estates might be more of a problem.

Graham.

Subject: RE: BS: Wind turbine efficiency
From: Schantieman
Date: 02 Dec 06 - 05:01 PM

As far as reducing carbon dioxide concentration is concerned, what we ought to do is make things - houses, furniture, ships - out of wood. This will stop (or at least greatly delay) it decaying and its carbon being respired by the decomposing microorganisms.

Or even just grow a lot more of it and then store it somewhere it won't rot. Like shrink-wrapped in plastic, down an empty coal mine.   

Has nobody thought of this?

S

Subject: RE: BS: Wind turbine efficiency
From: Bert
Date: 02 Dec 06 - 01:12 PM

The turby wind mill looks much like a double helix.

Oh Gawd! do you think they'll come to life and take over???

Subject: RE: BS: Wind turbine efficiency
From: Donuel
Date: 02 Dec 06 - 12:57 PM

The turby wind mill looks much like a double helix.

Subject: RE: BS: Wind turbine efficiency
From: Mr Red
Date: 02 Dec 06 - 12:51 PM

Well folks - wind power has one big advantage - it is available wherever the windmill is. If that is on a narrowboat then at least you get to top-up the battery and probably cover the residual on the TV or satellite reciever. Which could be switched off rather than hitting the remote but then non-techies mostly wouldn't.

The other top-ups are going to be mains (longgggggggggggggggg leads?) or engine. It is not a case of overall CO2 budget always, availability is sometimes paramount.

Repair instead of replace is a cheaper CO2 solution.

But if you really want to ballance the books think on this. All energy is solar (including wind) except nuclear! And if we insist on spending millions of years of insolation trapped in fossil fuels in a few hundred years, we is going to exhaust the bank ballance.

If solar energy falling on the earth NOW (of whatever kind) cannot supply all our needs then we, as a world, are most definitely raiding limited reserves. 50 years of oil is a mere blink in the history of just Homo Sapiens. It ain't rocket science - but it is communal responsibility - and we ain't got that much that these days.