Wind Farms

[viewer]

Don't know much about windfarms or changes in pressures around them (beyond exploding bats), but, about 40 years ago the then water authority and waterways board monitored the effects of forestation and deforestation in mid Wales on micro-climate, micro-wind patterns and local rain fall. There were significant changes in the patterns which affected local streams and hence the flood patterns in high rainfall periods. I'd expect something similar near very large windfarms but don't know of any active research.

 

[bernardgreen]

With a water wheel the water flow rate is limited by the miller controlling how much water passes through the wheel when there is an excess of water. The unused water backs up in the mill pond before and above the wheel until it over flows and bypasses the wheel in the relief channel. That is only true if there is more flow than the wheel needs. Many mills did not have enough flow so the miller allowed the mill pond to fill with the sluice controlling flow to the wheel closed. When the mill pond was high the sluice was opened to feed the wheel. As the level in the pond dropped the sluice had to be gradually opened more to get the same flow at the lower pressure ( head ) from the pond.

 

[ericmark]

Does the wheel slow the flow of the water?

have you not come across the phrase "as still as a mill pond"? The water will approach the watermill's wheel at a fair rate of knots, but once it has passed the wheel (and had the energy extracted), there's often virtually no movement/flow at all.

Kind Regards, John

Mill ponds where I live are before the wheel not after it. They are to store water to ensure a continuous flow.

I do remember something about Romans and camping where the lea side of the hill had more turbulence than side facing the wind.

Height is of course important. Trees have damped the winds effects for 1000's of years and wind farms at tree height are really no different. However as a radio ham I have been surprised how low isotropic propagation takes place. TV masts are often over the inversion which means loss of TV signal. If the wind mill is mixing the two different temperature airs together then clearly there could be a dramatic effect on the weather and also of course radio signals.

 

[bernardgreen]

Some of the energy extracted from the wind due to the cooling of the air as it passes the blade. As I recall ( from a talk some years ago ) the blades have an aerofoil shape as in an aircraft wing. In the aircraft the wing creates lift to keep the aircraft airborne. In the turbine the "lift" pulls the blade to rotate the turbine. In aircraft the energy used to create the lift cools the air, in extreme cases enough to cause icing even when the ambient temperature is above freezing.

Edit this is a near copy of the talk.

Wind Turbine Blade Aerodynamics - Gurit
http://tinyurl.com/ocdctmw


Ice does form on wind turbine blades in cool and not necessarily freezing weather. Ice throw being one of the hazards for people, animals and property within a few hundred yards of an operating turbine.

 

[SimonH2]

IMO, apart from the aesthetics, the biggest problem with wind power is how the politicians have been taken in by the "solution to our power problems" snake oil lie and used it as an excuse to kick the difficult questions (nuclear) out past the next election.

Reading my union rag, I recall an announcement that some members were facing redundancy at a gas power station which was closing due to being uneconomic. Meanwhile, the windmills hoover up demand when the wind is blowing (depriving other operators of the income) but expect other operators to ramp up and down to compensate for changes in wind (thus increasing their variable costs - rapidly changing power levels cause huge thermal stress cycling issues in a turbine). The result is inevitable - on top of the objectionably high subsidies given to the ROC-generator farms, they increase costs for other operators which don't get included in their figures.

Then a couple of days ago I looked, and wind was down to just 197MW our of an installed capacity of over 7GW - or less than 3% of it's rated output. Thats OK at this time of year, but when such static air masses happen during the depths of winter (Dec 2010 anyone ?) then demand will be high and wind about as much use as a chocolate teapot.

So now to "fix" this entirely foreseeable problem, we are spending billions more on installing smart meters whose primary function is to ration demand. Yes, I believe "ration" is about the right word, since the intention is to restrict consumption - whether by coercion by punitive per-unit costs, or if that fails, by physically turning off the supply.

At work, one of our customers is involved in wind power. Lets just say I try not to have contact with them as I (along with a couple of others) could very easily make our feelings known - which might not go down too well. And their boss drives a Pious as well.

 

[westie101]

At work, one of our customers is involved in wind power.

I can possibly guess who that is

 

[JBR]

I very much agree with Simon. This country is being mismanaged, and not only with respect to wind turbines. The powers that be cannot seem to realise that we cannot afford to rely on Russia for gas or Poland for coal. What's more, they are determined to remove all fossil fuel-based electricity generation as soon as they can in favour of unproven and pie-in-the-sky 'green' solutions.

Anyone with any sense would have expanded our nuclear power capability long ago, but no, just because some sandal-wearing, brown rice-eating hippies are frightened that it is unsafe we have been fobbed off with completely impractical windmills.

 

[ban-all-sheds]

Anyone with any sense would have expanded our nuclear power capability long ago, but no, just because some sandal-wearing, brown rice-eating hippies are frightened that it is unsafe we have been fobbed off with completely impractical windmills.

Many accidents at or involving nuclear power plants have shown that it is not safe. The problem is not so much that there is intrinsically a high risk of an incident, I don't believe there is, but when something major goes wrong the consequences can be catastrophic.

And when you look at the whole life-cycle of nuclear power plants, including mining, refining and transporting fuel, decommissioning the plants and dealing with the waste, nuclear is not a low-carbon power source.

But then burning fossil fuels can cause deaths too:

Although it caused major disruption due to the effect on visibility, and even penetrated indoor areas, it was not thought to be a significant event at the time, with London having experienced many smog events in the past, so called "pea soupers". However, government medical reports in the following weeks estimated that up until 8th December 4,000 people had died prematurely and 100,000 more were made ill because of the smog's effects on the human respiratory tract. More recent research suggests that the total number of fatalities was considerably greater at about 12,000

How long before the economics reach the point where people start thinking about restarting underground coal mining in the UK?

 

[bernardgreen]

Over wide picture.

Chernobyl was not an accident, it was the result of a test too far and human error, failing and politically hindered management.

It is also possibly that severe reluctance to admit thing were getting out of control and seek advice meant by the time the control room admitted they had created a dangerous situation it was too late to prevent the in-evitable.

 

[Aragorn84]

I dont think the test itself was the issue?

The problem occured because the grid controller decided at the last minute that they wanted the plant to stay online for a longer period than planned, then instead of cancelling the test, they went ahead with it anyway much later than intended, with staff who didnt really know what they were doing.

Human error and management error certainly.

http://en.wikipedia.org/wiki/Chernobyl_disaster#Conditions_prior_to_the_accident

When they fked up and had it at its near-shutdown state, they should have aborted the test and left it alone, but no, they tried to bring the poisoned reactor back online, overriding all the safety systems. Clever.

 

[ban-all-sheds]

It's a bit like saying that if you drive too fast and fall off the road on a bend that it wasn't an accident.

And some of the problems at Fukushima were also due to human error, management failings etc.

These things happen, and they happen everywhere. When they do they are often hidden, people lie and cover up rather than learning, or teaching others. It is not unique to the nuclear industry, but the nuclear industry has a rare capacity to produce a catastrophe orders of magnitude greater than nearly all others.

Thorium-based reactors are not without their risks, but they do seem to be a lot lower than Uranium or Plutonium based ones.

 

[Norcon]

There is a hill near (about 30 acres) me where the farmer is chopping down the remaining clump off 150 year old beech trees and using them for firewood.

Now he is considering renting out a plot for a turbine. The guy was out the other day and he reckons its a good site.

It sits above a lake and will be sited in the flight path of swans so I'm hoping the environmental agency will turn it down.

Is this the future? Chopping down all the tree's and leaving a barren landscape dotted with turbines so we can keep our computers running?

 

[ban-all-sheds]

It could be, until they stop the madness of paying people who make a bit of electricity (by any means) more for it than it is worth.

 

[OtleySpark]

Despite 'new discoveries' of fossil fuel sources, they are finite and WILL run out. Then what?
If we can make fossil fuels go further by taking some of the demand up using wind, solar, whatever, that surely has to make the most long term sense.
The obsession about price/profit is nuts in the long term. What use is money in the bank if there's no energy left?
Governments can subsidize/fix prices if they choose - and they should because in the long term the only thing that matters is that we have sustainable energy resources (and have not destroyed the planet on the way).

 

[ban-all-sheds]

If we can make fossil fuels go further by taking some of the demand up using wind, solar, whatever, that surely has to make the most long term sense.

If between then they cannot take up all of the demand, then maybe it makes no sense? Maybe the investment should go into systems which mean that when the hydrocarbons run out, electricity does not.

Governments can subsidize/fix prices if they choose - and they should because in the long term the only thing that matters is that we have sustainable energy resources (and have not destroyed the planet on the way).

But they should not do it by lining the pockets of landowners and homeowners who have their own roofs to bribe them into installing small-scale generating capacity which does SFA to reduce our need for fossil fuels.

They should end FITs etc now, just chop them off - cancel all existing agreements. If they can take money away from disabled people and drive them into destitution, if they can leave newly unemployed people with no means to live for a week, if they can force people out of the homes they've lived in for years, then they can ******* well put up with a bit of whining from people who put solar panels on their roofs.