Another take on wind turbines

[Alan S]

Whilock,

Jillian Ambrose, the Guardian's energy correspondent said:

"The breezy conditions at the site on the River Thames will help generate enough clean electricity to power 23 homes."

Alpa-311 say on their website:

" One A311 Vertical Axis Wind Turbine can generate as much power as 24 solar panels. 24 solar panels measuring 1m2 will produce 6KW per day"

Do you think this is good science or is it nonsense?

 

[JumbleDuck]

Jillian Ambrose, the Guardian's energy correspondent ...

 

[Mistroma]

You lot are very unkind. From the Alpha 311 website -
"Electric vehicles will turn our turbines and which will power more electric vehicles, in a beautiful never-ending cycle."
Yay!!! They've invented perpetual motion.

I suppose they'd argue that the turbine is just reducing wastage by recovering some energy. However, I also said in #7 that the turbine itself was probably a perpetual motion machine as the output figures may well be more than the energy in the wind moving past the device. I didn't do any calcs. for that part but suspect you'd need a hurricane to achieve the levels they mention.

EV vehicle probably have a bad habit of designing them to have low drag coefficients and local authorities tend to prefer reducing average speed in built-up areas. Alpha 311 have designed something with inherently low efficiency, mounted on lamposts that are mainly close together in low speed traffic areas used by many fairly aerodynamic vehicles.

I think perpetual motion is probably a pre-requisite for the idea to succeed. The mark II will probably use the energy produced to initial cold fusion with an even greater step change in output. I wonder if they are already improving on earlier work by Fleischmann and Pons.

 

[JumbleDuck]

I suppose they'd argue that the turbine is just reducing wastage by recovering some energy. However, I also said in #7 that the turbine itself was probably a perpetual motion machine as the output figures may well be more than the energy in the wind moving past the device. I didn't do any calcs. for that part but suspect you'd need a hurricane to achieve the levels they mention.

Their figures are utterly, total ridiculous. By a happy coincidence I currently have a wind tunnel set up to measure the wakes created by cars, but you don't need to go to that trouble to show that it's nonsense. Stand by a roadside on a calm day, hold up a newpaper and see how much passing cars disturb it.

 

[Sealong]

I suppose they'd argue that the turbine is just reducing wastage by recovering some energy.

No, the energy generated by this wind turbine is entirely parasitic and not wastage. The energy is obtained from the fuel (electric or otherwise) used to overcome aerodynamic drag of the vehicles driving by. It is the same fatuous proposition as mounting a wind turbine on the roof of a car, to generate electricity to help power it.

 

[Mistroma]

No, the energy generated by this wind turbine is entirely parasitic and not wastage. The energy is obtained from the fuel (electric or otherwise) used to overcome aerodynamic drag of the vehicles driving by. It is the same fatuous proposition as mounting a wind turbine on the roof of a car, to generate electricity to help power it.

It is of course fatuous. My point was that they would probably make such a claim, given the other claims. My point was that it sounds reasonable to claim that if no turbines are fitted the air moved by cars simply dissipates, serves no useful purpose and is therefore wasted. Harnessing it with a turbine generates energy from the moving air instead of simply allowing it to dissipate. They blew their case a bit with the output figures almost requiring a perpetual motion machine to work.

I can see their unique selling point.
"Fit turbines made from recycled materials to existing poles already connected to the grid and situated close to air being wastefully moved around by vehicles."

Green energy, reduce wasted energy, make it from re-cycled materials and utilise existing infra-structure. Sounds great, especially when you hint that the power output is going to be large. What's not to like (lots actually) and I don't expect them to give details of extensive trials.

 

[Hoist]

just knock down the 02 arena and put a couple of real turbines up. it's not like anybody will be visiting soon anyway

Been in the offshore turbine game now for 10 years. the advances in that short time is unbelieveable

1 offshore turbine powers 12,000 homes... job done

 

[Mistroma]

Their figures are utterly, total ridiculous. By a happy coincidence I currently have a wind tunnel set up to measure the wakes created by cars, but you don't need to go to that trouble to show that it's nonsense. Stand by a roadside on a calm day, hold up a newpaper and see how much passing cars disturb it.

I think EV manufacturers are really missing a trick here. They could make big boxy vehicles, perhaps even bring back HUGE tailfins from the 1950s but designed to maximise turbulence. Vehicles built in this way would generate much more drag and hence more wind available for roadside turbines.

Might have to quadruple battery capacity to get any decent range. But think of all the free energy you'd be getting from turbines.

 

[Kelpie]

No, the energy generated by this wind turbine is entirely parasitic and not wastage. The energy is obtained from the fuel (electric or otherwise) used to overcome aerodynamic drag of the vehicles driving by. It is the same fatuous proposition as mounting a wind turbine on the roof of a car, to generate electricity to help power it.

So I presume this means we should avoid planting trees beside roads, because their leaves and branches waving in the turbulence from passing vehicles robs energy from the vehicles.

 

[Sealong]

So I presume this means we should avoid planting trees beside roads, because their leaves and branches waving in the turbulence from passing vehicles robs energy from the vehicles.

Well you cannot ignore the physics. Just like a boat with a weedy hull requires greater energy, than a smooth hull to move it through the water, so it is the same for trees adjacent to a road. Although most of the branches are well above the height of the vehicles so not much energy is being used to shake them around.

 

[Hot Property]

I visit many schools and maybe 10 years ago it was all the rage to install windmills to generate electricity to reduce the schools overall consumption.

In the last 5 years I haven't seen one as they have all been dismantled!!

Servicing costs were £600 at one school which was 3 times the amount of electricity it produced.

A complete waste of taxpayers money, school leaders were blinded by the "science" and didn't do a back of fat packet payback calculation as it was against the green agenda....

It continues with solar panels today. Without your neighbour paying a subsidy to you, they are generally uneconomic except in off grid locations.

 

[JumbleDuck]

Well you cannot ignore the physics. Just like a boat with a weedy hull requires greater energy, than a smooth hull to move it through the water, so it is the same for trees adjacent to a road. Although most of the branches are well above the height of the vehicles so not much energy is being used to shake them around.

The energy dissipated in wake turbulence is far, far, far more than any energy which might usefully turn a turbine, or even shake a tree. Ever been blown off your feet by a bus passing? No, me neither.

 

[Sealong]

The energy dissipated in wake turbulence is far, far, far more than any energy which might usefully turn a turbine, or even shake a tree. Ever been blown off your feet by a bus passing? No, me neither.

I am not sure what point you are trying to make and I think you are confused; the energy (skin friction or form drag) has to come from somewhere. Energy from a wake can be used to drive a turbine and will certainly shake a tree. The force is proportional to the rate of change of momentum, so the energy (rate of change of (mass * velocity) * distance) varies with the square of the speed. I have not been blown off my feet by a passing bus, but buses travel at a relatively slow speed. If you have ever had the misfortune to stand on the hard shoulder of a motorway with large lorries travelling at 70 mph, then you certainly do feel it.

 

[crewman]

As buses create much more turbulence than cars is that the reason that governments are encouraging us to travel on buses?

 

[JumbleDuck]

I am not sure what point you are trying to make and I think you are confused; the energy (skin friction or form drag) has to come from somewhere. Energy from a wake can be used to drive a turbine and will certainly shake a tree.

Of course the energy comes from somewhere. However, most of it it goes into wake turbulence and is dissipated as heat. Only a tiny amount of the work done by the engine for a car/bus/lorry goes into any bulk movement of the air, and even that is over too short a timescale to be of any conceivable use for power generation.

The force is proportional to the rate of change of momentum, so the energy (rate of change of (mass * velocity) * distance) varies with the square of the speed. I have not been blown off my feet by a passing bus, but buses travel at a relatively slow speed. If you have ever had the misfortune to stand on the hard shoulder of a motorway with large lorries travelling at 70 mph, then you certainly do feel it.

You feel a bit, but nothing like the consistent flow you'd need to have meaningful power. For the output figures this company is claiming you'd need a fairly constant F10 along the hard shoulder.

 

[sgr143]

If you have ever had the misfortune to stand on the hard shoulder of a motorway with large lorries travelling at 70 mph, then you certainly do feel it.

I think what you feel in that situation is the "Whoomph" (technical term awaited) of the large vehicle displacing air. This would be a hit of compression, followed by a more or less equal hit of rarefaction, as Eddie Stobart's finest hammers past. So a rotary turbine would be flipped first one way, then the other. To get steady rotation, the vehicles would have to drag air with them as they proceed; they may do that to some extent, but I'd think it would be much less then the + and then - "whoomph" (technical term still awaited).
I stress that this is speculation (though I think reasonable speculation) .... I guess I could put it to the test by standing on the hard shoulder of any motorway not yet "smartened", on a still-air day, holding a flag in one hand and an anemometer in the other; but (1) I have better things to do; (2) the police might also suggest I have better things to do.

 

[Alan S]

I mentioned in an earlier post that I had been in touch with the turbine manufacrurers hinting that I would like to invest and asking for confirmation of their figures. Very brief reply so I have asked for some more complete test data....


"Thank you for getting in touch.

You asked: "Is it true, as reported in New breed of mini wind turbines installed at O2 arena
that "...The installation of 10 of the 68cm vertical turbines could generate up to an estimated 87,600 kilowatt hours (kWhs) a year – enough electricity to power 23 homes...."?

It is indeed true.

Regards,
.................."

 

[Mistroma]

I mentioned in an earlier post that I had been in touch with the turbine manufacrurers hinting that I would like to invest and asking for confirmation of their figures. Very brief reply so I have asked for some more complete test data....


"Thank you for getting in touch.

You asked: "Is it true, as reported in New breed of mini wind turbines installed at O2 arena
that "...The installation of 10 of the 68cm vertical turbines could generate up to an estimated 87,600 kilowatt hours (kWhs) a year – enough electricity to power 23 homes...."?

It is indeed true.

Regards,
.................."

Wow, a miracle. Glad you reported back, I must rush out and buy one for my house. Perhaps they'd consider making a 1/10th scale version for my boat (6.8cm tall and easy to mount).

I don't have dimensions apart from height quoted as 68cm and they don't look very wide, certainly less than 30cm. Being generous, the "useful part" is taking up approx. 0.1 m2 (.68 x .3 /2 m2 ).

My Rutland 913 has a swept area of 0.65m2 and that includes the hub. Let's assume the "useful part" is about 0.5m2. That means their turbine is sitting in about 20% of the air passing my 913 blades.

The 913 did once generate about 1.8kW hours in a day but that was anchored in a constant wind of around 30knots. To be honest, daily summer output averages out at 130Wh.

They are claiming a daily output of 24 kWh per turbine vs. my max. ever of 1.8kWh for a larger wind-gen and vertical axis units are usually less efficient.
Again, wow. That is a very exaggerated claim (probably at least 2 orders of magnitude but I'm not tempted to work it out ).

87,600 kWh from 10 turbines per annum is 8,760/365 kWh per day and that's 24 kWh per day.

I'm certain Jumble Duck will be along soon to correct my rough fag-packet calculations and point out an obvious flaw. I might be forgetting something obvious regarding synergistic effects in proximity to an Einstein-Rosenberg bridge. Then again, JD might have fallen over laughing at their claim and be unable to type.

 

[Neeves]

I'm very pleased that the thread has provided so much entertainment and education

However I wish we could stick more accurately to what was originally said

'The breezy conditions at the site on the River Thames will help generate enough clean electricity to power 23 homes.'

I have not read the whole article again but assuming the rest is the same as this sentence, or part of a sentence, then you are barking up the wrong tree and chastising the journo unfairly.

I interpret this section of the article as saying the 10 turbines will contribute a PART of the power needed to service 23 homes. There is no suggestion that this part will be 100% of the power required. Though AlanS enquiry appears to suggest it is a very large part. It seems the journo hedged their bets, which seems professional - the argument appears to be with the turbine manufacturer not the accuracy of the journo.

I'm not sure why they chose 23 homes - seems a very odd measure of power production, it cannot be considered a metric nor an imperial measure ......maybe something to do with horses, perhaps.....



Jonathan

 

[Neeves]

It seems fashionable to develop wind turbines (and for the Guardian to keep us up to date).

Coincidentally here is another to get you teeth into

Good vibrations: bladeless turbines could bring wind power to your home

It all makes a refreshing change from anchors

Jonathan