Theres a great little site somewhere, and the guy (I think hes in USA) builds his own generators for wind power using scrap.
Stators made from brake drums and potted coils/magnets on each side if the housing, it's the power conditioning the other side that's more difficult without some sort of intelligent controller. These things are more available now so it's easier I guese
So many cool ideas I wish I had an acre to build something on!
Stators made from brake drums and potted coils/magnets on each side if the housing, it's the power conditioning the other side that's more difficult without some sort of intelligent controller. These things are more available now so it's easier I guese
So many cool ideas I wish I had an acre to build something on!
Assuming you are not being ironic, you are the first person I hear of who also likes the looks of wind turbines.
When I look at an 18-century Dutch windmill, I see an impressive technical construction with hardly any decorations. When I look at a 21-century windmill/windturbine, I also see an impressive technical construction with hardly any decorations. Still, when someone wants to place new mills, they get accused of spoiling the view, and when someone wants to remove antique windmills, they get accused of the very same.
I am not an engineer, and know nothing about how to actually run a modern power generating substation. But sometimes this is an advantage; when you're too close, "You can't see the forest for the trees". In other words, not being within nose-touching distance of a generator makes it easier to see the big picture.
What's the big picture? I look at it this way: if you put up one square metre of "thingy" (some device) to collect energy from nature, what is the maximum amount of power you could get? What is the potential bang for the buck, dictated purely by raw physics, without distortion by politics, popularity, greenwashing, hype, advertising, or all the other silly things we humans use to confuse ourselves into coming to the wrong conclusions?
In more technical terms, what is the areal energy density of wind, solar, microturbine, etc?
The energy available to extract in a moving fluid depends on the density of the fluid, and on its velocity cubed. Air has a very low density, about 1.225 kilograms per cubic metre, and this means the energy available per square metre of windmill is rather pathetically small.
To put some numbers to it, if you had a magical 100% efficient windmill with one square metre of blade area in a wind of 3 metres/sec (about 11 km/hr, or 7mph, at the strong end of the "light breeze" category), and it was connected to a magical 100% efficient alternator or generator, you would generate approximately 33 watts of electric power. (i.e., the areal energy density of an 11 km/hr wind is 33 watts per square metre.)
A practical (very well engineered) windmill is unlikely to exceed 80% efficiency, and the generator attached to it is unlikely to exceed 90% efficiency. Put together, that's a 72% efficiency, so our hypothetical 33 watts/m^2 is reduced to a practical 24 watts per square metre of windmill. Expect DIY wind power to be half that efficient.
How about solar panels? One square metre of direct sun on the surface of the earth at the equator has an areal energy density of about 1000 watts per square metre. That's about thirty times more energy than you can get from a light breeze.
Affordable solar panels only have about 15% efficiency, so a single square metre of solar panels will spit out about 150 watts of power at the equator. This is poor compared to the potential harvest of 1000 watts, but even so, 150 watts is about six times as much power as the very well engineered windmill of the same area!
And moving water? Water has a density nearly a thousand times greater than air, so if it moves at the same speed, there is a thousand times more energy per square metre waiting to be extracted. But this is a technical problem which has not been cracked yet; there have been many, many attempts to put a "windmill" underwater, in a moving current of water, and so generate energy, but none of them has successfully been commercialized. Too many problems with the ungodly combination of electricity, moving machinery, and water.
Interestingly, traditional hydroelectric generators extract energy from moving water. As we've seen, there is a lot of energy in moving waer, so it's no wonder that hydroelectric power generation has been well established for a long time. British Columbia, where I now live, is lucky enough to have lots of rivers, and much of our power is hydro power.
So, stripped of politics and BS, the fact is that moving water packs far more energy than the other recently popular power sources. And solar panels are far better bang for the buck than windmills. There's much more energy to be harvested per square metre, there are no moving parts that constantly need repair and maintenance, and the expected lifetime is very long, unlike the fragile mechanical parts of a windmill rotor.
Windmills are really only worth bothering with if they're very large, and you have strong winds in the area. They are expensive to manufacture, expensive to erect, and expensive to maintain. But they can make power at night, when solar panels are as useful as a spaghetti vaulting-pole.
Solar panels used to be ridiculously expensive, which is how windmills got their start. The equation has changed now, as solar panel prices have fallen drastically in the last ten years, and as we saw, sunlight has thirty times the areal energy density of a light breeze. Now solar makes a heck of a lot more sense - as long as you're in a location with lots of sun for much of the year.
Nuclear? IMO, it's beyond utterly ridiculous, it's actually utterly idiotic. It makes toxic waste that remains toxic for tens of thousand of years, which we cannot neutralize, and which we cannot get rid off. That's longer than the entire period since the ice-sheets retreated and human civilization as we know it became possible. How humanity can be stupid enough to think that polluting the planet with 100,000 year poison is a good idea, is beyond me.
-Gnobuddy
That 1000 W/m^2 is a standardized figure for solar panel measurements, but even on the equator with no clouds the real number is a bit lower. On the other hand, you can't extract more than 16/27 of the kinetic energy of the wind to keep the air from accumulating behind the mill, see
Betz's law - Wikipedia
Nonetheless, you might be interested in this:
Ampyx Power B.V
Betz's law - Wikipedia
Nonetheless, you might be interested in this:
Ampyx Power B.V
I have one down the road from me. It's called Aldington Converter Station. It runs a bi-directional line under the English Channel to France. The main converter consists of three stacks of SCR switches controlled via opto-isolators. The room with this in is about 100ft high and stinks of ozone. Conversion is between 400kV AC and +/-270kV DC at 2000MW.
HVDC Cross-Channel - Wikipedia
Graham H
I actually thought about the impossibility of having zero exit air velocity behind the turbine, but I had never heard of Betz's law. Thanks!
Thanks again! That image triggered a memory - I read a Popular Science article about this concept (and several other similar ones) about five years ago. Google found it: The Quest To Harness Wind Energy At 2,000 Feet | Popular Science
According to the article, Ampyx' flying generator was supposed to be operational in 2017. So they're approaching three years behind schedule at the moment. Why am I not surprised?
Ampyx Power's gigantic-kite-gone-mad reminded me of, well, actual childhood kites gone mad, whirling like demented dervishes before plunging nose-first into the ground and shattering themselves to pieces. Having witnessed that firsthand, and having cried little-boy tears at my now ruined kite, I would imagine the liability insurance alone for operating an Ampyx glider would cost as much as installing a new solar farm of equivalent power generation ability! 🙂
My guess is that the loosely similar Altaeros Buoyant Air Turbine is about likely to succeed as the proverbial lead zeppelin - but it would make a fantastic CGI image for a B-grade science fiction movie! 😀
-Gnobuddy
Ampyx uses tethered glider aircraft with electric motors rather than kites, as they found kites to be too uncontrollable - which matches your childhood experience. Normally the motors are off, but when the aircraft needs to land, it can do so on the motors if needed. They have working prototypes, but they are not suitable yet for flying continuously in rough weather.
Gnobuddy,
The Bigger picture, energy density per cubic metre of air etc, well that....that is looking at the whole picture from a theoretical view, imho.
As far as generator efficiencies go, you're way off....most have been achieving >95% for decades....
It's the prime movers, GTAs, Steam Turbines and the boilers, combustion cycle that are the main losses inefficiency. I.e. your car alternator is almost 2 or 3 times more efficient that the petrol or diesel engine driving it...
Water is of course a 'better' way, provided you're lucky to have the topological features to accommodate a dam, lake, and all. In the states and Canada along with some areas in Europe there is room for hydro.
Just as in Iceland, geothermal generation is practical, where in other locations, it isnt viable.
We have tidal, wave, wind and solar potential generation in the UK.
Its only a pity we dont have rain powered generation.
I guess Greenwashing is a derogatory term. That is anything but putting politics aside and that is needless really, it's a shame more credence is paid to opinions that reinforce our own, rather than challenge our selves and belief systems.
The Bigger picture, energy density per cubic metre of air etc, well that....that is looking at the whole picture from a theoretical view, imho.
As far as generator efficiencies go, you're way off....most have been achieving >95% for decades....
It's the prime movers, GTAs, Steam Turbines and the boilers, combustion cycle that are the main losses inefficiency. I.e. your car alternator is almost 2 or 3 times more efficient that the petrol or diesel engine driving it...
Water is of course a 'better' way, provided you're lucky to have the topological features to accommodate a dam, lake, and all. In the states and Canada along with some areas in Europe there is room for hydro.
Just as in Iceland, geothermal generation is practical, where in other locations, it isnt viable.
We have tidal, wave, wind and solar potential generation in the UK.
Its only a pity we dont have rain powered generation.
I guess Greenwashing is a derogatory term. That is anything but putting politics aside and that is needless really, it's a shame more credence is paid to opinions that reinforce our own, rather than challenge our selves and belief systems.
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I think I read somewhere that if you try to extract more than 30% of the energy in the wind then you start to modify the local weather.
Onshore wind farms can be a navigation hazard for birds and planes, and may confuse radar. They also may disrupt TV and radio reception for those in their shadow. Offshore wind farms can complicate intruder detection.
Onshore wind farms can be a navigation hazard for birds and planes, and may confuse radar. They also may disrupt TV and radio reception for those in their shadow. Offshore wind farms can complicate intruder detection.
Hello,
This is a goofy question.
In the us we use 3 phase 100KV plus distribution systems. High volts means (pun) smaller conductor size per megawatt. In the neighborhoods the voltage is stepped down to 3 phase 12KV. In the older residential neighborhoods there may be a step down transformer to 230VAC on a pole in the back yard. Two phases of the 3 phases are run out to the individual homes. That is 2 phases of 3 or 230VAC from A Phase to B phase, 230VAC between phases. That is not 110VAC supplied. Water heaters, cooking ranges, and HVAC equipment are all 230VAC. At the residence service panel there is a ground where the green safety ground and grounded current carrying neutral conductors are all tied together. Phase A or phase B each with a current carrying grounded neutral conductor make 115VAC (at my house it is 127VAC) branch circuits that serve lighting and small appliances.
So no US homes do not have 110 volt mains.
Larger buildings requiring more power get all 3 phases at 480VAC or higher.
Why does my cell phone require a USB-C cord and my wifes’s requires a USB-B cord?
Thanks DT
“Y” and “Delta” 3 phase another day
According to Betz's law, the maximum of mechanical power that can be extracted from moving air is 16/27 of the mechanical wind power. That is somewhat lower than 60 % and is independent of the wind turbine design. The reason behind is that you can't stop the wind completely from moving behind the turbine, as the flow and subsequently the turbine also would stop. The turbine itself extracts not more than 80 % of this maximum, even if it's design is state of the art, and transfers that power to it's shaft. So the mechanical power that is present at the generator shaft is alway less than 48 % of the wind power.
Best regards!
It certainly is. And if you understand what the word "theory" means in science, this top-level theoretical view is the most important thing of all: it sets the cap, the upper bound, the maximum you can possibly do if all engineering was magically perfect. You cannot do better than this, under any circumstances, with any technology.
And it turns out that while the media wave around the words "solar" and "wind" as if they were equal contenders, in fact, one of them is capable of roughly 15 watts per square metre, while the other is capable of ten times as much. Rather significant, that!
It's not that I'm opposed to windmills, or any other form of clean energy generation. I'm just pointing out that they are not all equivalent, as the general public has been misinformed into believing. The fact is that some are far better bang-for-the-buck than others.
Just to be clear, you and I are not arguing opposite viewpoints at all. They say a drowning person will clutch at a straw, and it's not surprising that we on our overheated and slowly dying planet are also starting to clutch at straws. I'm just pointing out that some straws are bigger, fatter, and float better than others. 😀
I wrote, and I quote, "the generator attached to it is unlikely to exceed 90% efficiency." Five percent is "way off"? It's the second decimal place, for crying out loud!
This is almost a perfect example of not seeing the forest for the trees. You're pointing out a 5% difference in electrical machine efficiency, versus the 3000% difference I pointed out in areal energy density between a 11kmph breeze and direct sunlight at the equator!
Yes indeed. I used to fly electric-powered model aircraft, and this was one of the great equalizers between internal-combustion powered models, and the newer wave of electrics. Those one-cylinder two-stroke model engines probably didn't break 10% - 15% efficiency, while cheap electric motors could reach 75% - 85% at optimum load.
That, and the fact that if you knew what you were doing, you could get better efficiency out of a lower-rpm propeller on an electric motor, made the electric models first match, and then surpass, the performance of IC engined models over quite a wide range of sizes. (IC engines were cheaper when it came to the largest and heaviest models.)
I often traded a bit of motor efficiency for considerably more propeller efficiency in my powertrain designs; the small prop in an electric RC model is by far the least efficient part of the powertrain, and often, trading off 5% motor efficiency by going to a lower-Kv motor could gain you 15% propeller efficiency due to the fact that you could now use a larger propeller.
Everyone seems to know about Iceland, but Costa Rica is thoroughly ignored for some inexplicable reason, though it has achieved spectacular results. Almost 100% of the country's electrical generation is from renewables in recent years, mostly hydro, but also windmills, solar, and yes, geothermal.
They also burn biomass instead of coal in some otherwise more-or-less conventional power stations.
Here in North America, it is a term sometimes used to describe complete BS publicized as "saving the planet", when science and engineering both say the opposite.
One example, this one pushed by the petroleum corporations, manufacturers of internal combustion engines, and ignorant politicians:
"We're going to save the planet by using electricity to separate water into hydrogen and oxygen (losing energy in the process). Then we'll store vast quantities of hydrogen and oxygen using some magic technology that we haven't invented yet (losing more energy in the process.) Then we'll burn them in a 25% efficient internal combustion engine (losing 75% of the remaining energy.) Now your car will run on water, and the world will be saved! Yay!"
The obvious question is "Why don't we just feed that electricity straight into a battery (a very efficient process), and then use those batteries to run electric motors (also very efficient) to drive my car? We'll waste far less energy, won't we?"
But the press and the public never seem to ask that question. I'm sure plenty of engineers and scientists do, though, behind the scenes, while tearing their hair out and banging their heads against the nearest wall.
Not at all. The whole point is that politics is largely fact-free. We have to ruthlessly apply scientific scepticism before buying into anything trotted out by politicians, the media, and frequently, by ill-informed engineers.
-Gnobuddy
The arguement I always had against electric transport for the masses, was resources.
All the lithium, neodymium and probably difficult or costly to mine and refine, and vast quantities, for maybe 1 billion cars? Really?
Add to that, the other rare earth metals used in magnets in permanent magnet wind turbine generators.
Are there enough resources? What's the harm to the environment by mining all these things? What's the price to it all? Because, I think, one way or another there is always a cost to someone.
All the lithium, neodymium and probably difficult or costly to mine and refine, and vast quantities, for maybe 1 billion cars? Really?
Add to that, the other rare earth metals used in magnets in permanent magnet wind turbine generators.
Are there enough resources? What's the harm to the environment by mining all these things? What's the price to it all? Because, I think, one way or another there is always a cost to someone.
Electric trains are far more practical than cars (electric or not), at least in densely populated areas.
Marcel,
Totally. The trains here are a joke, a bad joke.
Almost every other nation in the EU I've visited has had a reliable timely, comfortable train service. Not here.
Totally. The trains here are a joke, a bad joke.
Almost every other nation in the EU I've visited has had a reliable timely, comfortable train service. Not here.
I agree with you fully.
The thing is, we have built a house of cards so high that we no longer even remember when it started.
A quick rewind: plants need nitrogen to grow. Most plants can't extract it from the air, but depend on lightning in the earth's atmosphere to oxidize it to soluble nitrates, which wash down into the soil with the rain.
Somewhere about the late 1700s or early 1800s, all the lightning on planet earth could no longer produce enough nitrates to grow enough food to feed all the humans on planet earth. We had reached the carrying capacity of the planet, but we didn't know it. This was more than 200 years ago, mind you.
So people added manure - fertilizer, with nitrates from animal bodies - to their farmlands. Trouble is, there wasn't enough manure, and famines started to become a very real problem all over the world.
This led to the "Guano wars", in which powerful nations (Spain, Peru, Chile) battled one another for the mountains of bird-poop (guano) on the Chincha islands. Bring home the bird-poop, or your population goes hungry.
Thousands of years worth of guano was quickly used up in a few decades by desperate governments struggling to feed their populations. By the mid 1800s, the guano was running out, and so was the money Peru was making from its sales.
At about that time, naturally occurring nitrate deposits were discovered in the soil of the Atacama Desert. Bolivia, Peru, and Chile fought murderous battles for ownership and control of the precious nitrate-rich soil. And we weren't out of the 1800s yet.
We (humans) had by now multiplied to the point where our need for food had only exceeded the ability of all the world's lightning to provide it for us; we had also managed to use up most of the world's known large resources of nitrates. We were in deep trouble, and our population (somewhere between 1.2 billion and 1.6 billion) would have been flattened and then dragged down due to deaths by starvation, as happens with almost every other animal species on the planet.
Fortunately or unfortunately, depending on your point of view, several brilliant chemists had been attempting to synthesize nitrogen-rich ammonia. By the early 1900s, what is now known as the Fritz Haber process for manufacturing synthetic ammonia in large quantities became practical. Artificial fertilizers were soon invented, and the human population, instead of starving to a manageable size, continued to grow.
Now, in 2019, there are about 7.7 billion of us, with that number increasing by about 200,000 every single day - roughly 300,000 daily births less 100,000 daily deaths ( World Population Clock: 7.7 Billion People (2019) - Worldometers ).
In other words, there are now more than five times as many humans now as there were in the late 1800s, when the nitrate crisis was near its peak, and we had demonstrably already considerably exceeded the earth's carrying capacity.
We've got this far at a tremendous cost. We've used up millions of years worth of fossil fuels in less than two centuries, destroyed most of the worlds forests, despoiled most of the worlds seas, and used up most of the worlds fresh water. We've been incredibly clever and ingenious at staving off disaster, by building our house of cards taller, and taller, and taller.
And now we want billions of cars for the billions of people standing on top of the already-very-tall house of cards.
How do you think the story will end?
How does every story involving a very-very-tall house of cards end? 🙁
-Gnobuddy
I beg to differ about the microscopic part... for personal experience In the underground coal mining industry, picking up a de-energized piece of cable by the conductor contacts (good grip pints) that feeds a load center or piece of equipment, without first safely shunting the cable, can be deadly. Maybe microscopic in terms of overall capacity... but still plenty of available stored energy due to capacitance. FWIW dragging such cables can induce one hell of a stored static charge, again enough to ruin your day.
For those curious... 480/575 3-phase is the most common working voltage for the majority of mobile equipment. 12,470 (or much higher, up to 21.6 KV) is usually distributed throughout the mine and stepped down as need by smaller load centers.
Mines with trolly wire (bare and at head level, eye level or lower in most places) is 400-600 VDC and essentially not current or fault protected, as such protection would trip as heavy track equipment is energized to move heavy loads. Always super fun to get into with the back of your neck or ear.
The difference between the real world and underground coal mine power distribution is safety due to the confined space, proximity, and many other variables. Very complex cables, shields, fault monitors, etc.
Anyway... just figure some of you may find that useless info interesting.
Exactly! 🙂
The trouble is the total absence of a definition for "plenty".
50 joules is about the energy used per jolt in initial attempts to re-start a human heart with a defibrillator. That's a huge kick for a human being. But its only enough to power a 100-watt bulb for one half a second, so it's a negligible amount of energy compared to what your kitchen uses in one day.
So is 50 joules, plenty, or not?
It's a meaningless question, until we ask "Compared to what?" (Mathematically, we need a dimensionless ratio; a ratio of one energy to another, which means all the dimensions and units cancel out, and we're left with just a pure (dimensionless) number.)
And that is exactly what I did: I compared stored energy in the line to the power being transmitted by the power line. And the result is, as we are all now agreed, that the power stored in the line is negligible compared to the power transmitted by the same line. 🙂
Had I instead chosen to compare the stored energy in the line to the energy used to light a high-efficiency LED for one second, the answer would be very different. But this comparison doesn't really make much sense - it's mathematically valid, but meaningless as a relevant comparison when it comes to the claim I was trying to address: that the stored energy in the line acted as a reservoir to absorb fluctuations in the power output of solar, wind, and other clean power sources.
Comparing the stored energy in the line with the amount of energy needed to shock a human, or light an LED for a while, may be quite relevant in other contexts (if we're studying electric shock hazards to humans, say.) But not in this context. It would be as though we were trying to choose an animal to pull our carriage, and we decided to compare the power output of a horse to the power output of a fruit-fly. Surely it would make a lot more sense from a practical perspective to compare the power output of the horse to the power output of something else that might pull our carriage: a human perhaps (as in a rickshaw), or a donkey, or a bullock, or a water-buffalo?
-Gnobuddy
The solution is to become even more clever and ingenious - we need a new wave of real invention and not just cheaper faster computers and more data capacity on the cell phone network. A faster internet won’t do much in the grand scheme of things for long term survival - other than keeping people’s heads in the sand watching videos. The choices are quite clear - either figure out how to make what we need out of what we have, or die off. If what’s available close to home (stored on earth) isn’t enough, humanity must look elsewhere.
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