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Wednesday, July 28, 2010

Enabling Wind Farms

submitted to the New Zealand government in 2010 in response to a request for submissions on her energy policy

Enabling Wind Farm

Because of the nature of our (New
Zealand's) existing electrical generating infrastructure, the addition of wind turbines is more effective in New Zealand than for most other countries of the world. However, the construction of wind farms is being blocked at every turn by concerned citizens. Some of their concerns are pure Nimbiism and dislike of change but some of their concern may be justified. The government needs to honestly and thoroughly investigate such concerns associated with existing wind farms and then prepare and disseminate a paper on their findings in clear, easily understood language. If some of the concerns are genuine, the government must then help with the necessary research to solve these problems. Such an approach will ease the introduction of wind farms which are so essential for the future well being of New Zealand.

Much is made by many commentators of the need for more research into ways of producing renewable energy. There is of course truth in their assertion. However, it draws attention away from the fact that one of the best forms of renewable energy, namely wind turbines, is already well up the technological learning curve. Wind energy is already very competitive, cost wise, with other energy sources. As you look to the future with the steady increase in the cost of fossil fuel and our Kyoto
commitment, wind generated electricity will rapidly become the most viable option. As with many of the problems which face us today such as population increase, water degradation, green house gases and so forth, the problems are not ones of technology but of vested interests. The technological solutions are obvious.

Wind farms, because of their intermittent generating characteristics need huge storage batteries to balance their output. New Zealand is rich in such batteries. They are called hydro-electric dams. Every KWh produced by wind leaves water in the dams to be instantly used when the wind decreases. Here in New Zealand, because of the availability of already developed hydro power, wind turbines are more economically viable than for most other countries in the world. This is especially so since the generation capacity of our hydro generators is well above the sustainable energy generation capacity (determined by the amount of water flowing into the dam). This means that a dam can be drawn down, producing energy at a far greater rate than it's sustainable rate when necessary, and allowed to accumulate energy (water) when the wind is blowing strongly. This balances a similar, though not identical characteristic of wind turbines.

A one MW wind turbine is not expected to generate one megawatt continually throughout the year. Sites are rated for the availability of wind (capacity factor) and at a 30% site, over the year or years, you would expect to generate on average 0.3MW of power. However, this means that when the wind is at the optimum speed, a full MW is being generated for every nominal (nameplate) MW of generating equipment. Under these conditions, water (energy) can be left to accumulate behind the hydro dams. I repeat, a MW of wind generating capacity in New Zealand is worth more than the same capacity in almost any other country of the world.

Despite the obvious benefits of wind farms, at every turn there are fanatical objectors. The objections fall into a number of categories. These are

*Aesthetic. While some people, such as myself, find wind turbines things of beauty both for their elegant form and for what they represent, others do not.

*Shadow Flicker. This is the effect when the sun is directly behind a wind turbine from the point of view of an observer.

*Glint. Glint refers to the reflection of sunlight off the blades of a turbine and may occur when the sun is to the side or behind the observer.

*Noise. This includes audible noise transmitted through the air and low frequency sub-audible noise, primarily transmitted through the ground.

Lets have a look at each of these and then see what the government could do to ease the introduction of wind turbines.

The solution

There is not a lot that can be done about this problem. In Europe, where electricity is expensive where the cost of electricity is subject to fossil fuel price fluctuations , where there are many potentially dangerous nuclear power plants and where air pollution is far worse than in New Zealand, many people see wind farms, at the very least, as the lesser of a number of evils and at best, things of beauty. We are somewhat spoiled in New Zealand.
(See appendix 2)

Shadow Flicker

Shadow flicker occurs when you, the wind turbine and the sun are perfectly lined up. Unless you are very close to the wind turbine, a situation that is avoided by wind farms, the change in the intensity of light is very small and occurs for at most a few minutes on a few days per year. What the government can do in this regard is to publish as part of a paper on wind turbines, a well thought out explanation with suitable diagrams explaining the absurdity of worrying about shadow flicker. (see Appendix 1)


Glint can occur as different parts of the wind turbine reflect the sun to the observer. It is virtually eliminated by using matte paints on the turbine blades and by using light absorbing colors. Having the wind turbines a reasonable distance away from the observer also reduces any significant glint. Here the government must check out any reports of glint, determine if they actually exist, measure their intensity and duration and publish the results. If glint is indeed discovered from some wind turbines, a small research effort could be mounted to find an appropriate paint which will solve the problem.


The air born noise of a modern wind turbine which are constructed with acoustic isolation of the internal machinery from the nacelle and acoustic isolation of the generator from the blades along with the correct shaping of the blades makes it virtually impossible to separate air born turbine noise from the sound of wind through the trees at anything beyond a kilometer. In most instances you must be well within a km to hear a wind turbine. The effects of low frequency sound which propagate through the ground must be taken more seriously.

If an individual turbine does indeed produce low frequency sound and if it transmits the sound to the ground, such vibrations can propagate. Depending on the geology of the area, these vibrations can be propagated in unexpected ways. It is within the realm of possibility (just) that these vibrations could come up under a house, for instance, to the annoyance of the occupants. So what must the government do to address this problem.

All reported cases of low frequency sound from existing turbines should be investigated. This would involve
a) scanning the frequencies, if any, which are being transmitted from a turbine to the adjacent ground,
b)making measurements at the site of the complainant to see if any of these frequencies are showing up at the location in question,
c) stopping one or more turbines to see if that stops the vibrations (the same frequencies could be from a different source) and
d) applying dampers to any offending turbines and going back to "a".


What is needed is for the government to sponsor a small research project that examines any reported cases of annoyance from wind turbines and determines if they are justified. If any of these complaints prove to be justified, the government should lend a hand to find solutions.

(Appendix 1) Shadow flicker
Shadow flicker is a red herring. If you are any distance at all from the turbine, shadow flicker is virtually nonexistent. I will use the example of my house here in Waipara which is 5000m from the Mt Cass ridge to the East. The diameter swept out by a 3mw wind turbine is typically 90m. 90m at a range of 5000m makes an angle of 1.03 degrees of arc. From the observers point of view, looking at the horizon, the sun comes up at a different place each day. The amount it moves each day is 1/4 degree. Therefore, each wind turbine you can see from your house will have the sun behind it for 4 days as the sun 'travels' south and 4 days as it travels North. A total of 8 days per visible wind turbine.

The sun rises at 15minutes of arc(1/4 degree) per minute of time. If there was any flicker from a wind turbine at that range, it would last for just over 4 minutes. In my case, that would be 4 minutes just as the sun comes over the horizon early in the morning. However, as you will see in the next paragraph, there is practically no shadow flicker at that range.

A wind turbine blade for a 3mw turbine is typically 3.5m wide at its widest part. If the sun was a point source at an infinite distance, it would send a solid shadow 3.5 meters wide to Waipara. The sun is not a point source. It has a width of 32minutes (half a degree) of arc. Light from the edges of the sun fills in the shadow such that a full shadow (umbra) extends 350m beyond a 3.5m wide blade and by that distance the width of the full shadow is zero. At a distance of 5000m beyond the wind turbine, the shadow of the blade has spread out over 46m. Stated another way, the sun intensity will vary for the above mentioned 8 days of the year for 4 minutes in the early morning on those 8 days from full strength to 93% strength. Unless you are very close to a wind turbine, shadow flicker is virtually non existent and even if you are close, it will occur only for the short time that you, the turbine and the sun are perfectly lined up. Some simple graphics in the proposed government paper would explain this to the layman.

(Appendix 2) Aesthetics
One legitimate aspect of the aesthetic fear is the belief that if a wind turbine is visible from a property then the value of that property will decrease. The government should carry out a detailed survey both here and abroad to see if such properties have decreased or increased more or less than other properties in the same area that do not have a view of wind turbines. This would form part of the government report. An item on National Radio a couple of years ago indicated that the price of properties with a view of a wind turbine had actually increased more than the average in Europe.

William Hughes-Games

Mining Royalties and Renewable Energy

Mining Royalties and Renewable Energy

Revenue from mining is a one off. Minerals are not renewable and once gone they can not be mined again. There is no justification whatsoever for mining our family jewels if we plan to waste this money on current consumption. All the revenue from mining must be used to set up infrastructure which will benefit future generations of Kiwis. These minerals belong to them, just as much as they belong to us. A very good sector in which to invest this money is renewable energy. The benefits of having New Zealand totally independent from overseas energy are too obvious to warrant listing yet again and the benefit of energy independence extends far into the future.

One thing must be guarded against. Mining revenue must not be used to displace money from other sources which otherwise would have been put into renewable energy. This is creative accounting at its worst. Mining revenue must be added to the funds that would have been spent anyway to add to our already high proportion of renewably generated energy. Such funds can be invested directly, in, for instance a State Owned Windfarm (SOE) or instead, can be leveraged by providing research funds or incentives which tip the viability of a renewable energy source towards economic feasibility.

Mining royalties have been reported as 1% of the sales value of the mineral sold. If this is the "whole story" then there is no justification for selling off our family jewels for such a poor return. I note the intention mentioned in the New Zealand Energy Strategy to review the royalty situation, presumably the way the Australian Rudd government recently attempted. This is good. Once sorted out, these increased royalties should be paid into the Mine Revenue Account for use in development which creates long term benefits. However, the bare royalty payment is not the whole story.

Does a mine pay income tax in addition to its royalty payment? If so, the tax must be credited to the Mine Revenue Account. Without the mine, this stream of revenue would not come to the government. Next, every employee of the mine pays income tax. This is a revenue stream to the government which would not exist if the mine was not operating. Into the Mine Revenue Account also. Every purchase by the mine and its employees of everything from a new vehicle to a roll of toilet paper attracts GST at 12.5% (soon to rise). Into the mine revenue account. And then there are the downstream effects of, for instance, a mine employee buying his food at a local super market which pays taxes and whose employees pay taxes. Give this one to your resident math boffin. It is an infinite converging series with a finite sum. If you have a good mathematician on board, he will be able to work out how much more of the tax take should go into the
Mine Revenue Account.

Looking at the above, it turns out that the revenue from a mine to the government goes far beyond the bare royalties and all this revenue should be used for development that benefits future generations. (in addition to funds that would have been spent on this if the mine didn't exist)

The next question is what we do with the minerals we have mined. Let's use iron sands as an example. Are we going to sell off the raw mineral with just the gangue (waste) removed the way Australia does. This is like selling off a Faberge egg for the price of the gold it contains. At the very least we should be selling refined ingots of steel but let's get more ambitious. How about selling railway lines, machine tools and even car parts. How about selling our own electric car with a difference.

We are fixated on the idea that we could never compete with the big boys overseas. We could never, for instance compete with Hollywood, could we? Well we could and we did. Lets not sell New Zealand short. By adding value to our mineral resources, far more money will go into the Mine Revenue Account to be used for renewable energy infrastructure. If, at present, we are not able to beneficiate our mineral resources and sell value added products, let's leave them in the ground until we have achieved the necessary level of sophistication. They are only going to be more and more valuable as the years go by and other countries use up their non-renewable resources.

However we use our minerals, let us use this windfall, one off source of revenue to benefit future generations. We couldn't do better than to use this revenue to ensure New Zealand's energy independence.

Electric Cars in New Zealand

Electric cars in New Zealand

The uptake of electric cars will benefit New Zealand by:

a) improving our balance of payments as it reduces the amount of fossil fuel we import

b) reducing our financial obligation under Kyoto due to our reduced production of CO

c) making our existing sources of renewable energy (hydro, geothermal) and future sources of renewable energy (marine, wind, solar) more economically viable.   

Electric cars can be charged, to a large extent, when power is available rather than on demand. If you can sell hydro power, rather than allowing surplus water to go over the spillway, the hydro dam is more economic. Demand-balancing, instead of the present Supply-balancing of our grids is the key to the more efficient use of our electrical generation capacity and electric cars fit perfectly into this new paradigm.

d) Improving health due to reduced pollution by p10 carbon particles and  oxides of sulphur and nitrogen (from burning diesel and petrol). Improved health means lower health care bills

e) reducing road maintenance since i) electric cars tend to be lighter than petrol driven cars and therefore create less damage to roads and ii) electric cars do not drip petroleum products on to asphalt. Leaking petrol and oil degrade asphalt.

f) helping with supply balancing of our grids since electric cars which are not being used can be set to take electricity from the grid when electricity is cheap and available and feed it back for peak shaving. Despite inevitable energy losses, there is an economic gain both to the country and to the car owner from the adoption of this strategy due to not needing to build more power stations which only operate for peak shaving.

It is therefore very much in our interest to encourage the uptake of electric cars. The government could subsidize electric cars the way she subsidizes KiwiSaver but subsidies should be very low on the governments list of available tools. Far better to simply set up the framework so that the uptake of electric cars happens by itself with no output of money from the government. Government at its best doesn't do things but rather sets up the framework so that other people do things. 

Measures that the government could take include:

a) ensure there are no import charges for electric cars. We do not have an electric car industry (yet?) to protect so there is no justification for tariffs of any kind. (and "it is very much in our interest to encourage the uptake of electric cars")

b) wave GST on the purchase of electric cars. There is no revenue at present from the purchase of electric cars and if removing GST is the measure which tips the private financial calculation towards the purchase of an electric car, the government looses nothing. Without this measure, people won't buy electric cars and no revenue will come to the government anyway. (I see the holes in this argument but remember that "it is very much in our interest to encourage the.......................")

c) wave road taxes on electric cars for at least 20 years from the date of first purchase in New Zealand. (Remember that "it is very much .................")

d) Switch government employees who are entitled to have a car to electric cars and reticulate government parking lots with charging points. Bargain with the car companies for very good prices based on the large number of cars you will be purchasing and based on the fact that with the government buying cars, this initiates the infrastructure which will make it possible for private citizens to buy electric cars. You give electric car manufacturers an 'in' to the New Zealand market by buying cars for government employees. (get a pharmac exec. on this)

e) Encourage Shell (which now belongs to us) to put in at least one battery exchange station in each major city in New Zealand right now before there are significant numbers of electric cars in our fleet. Following this, as electric car numbers increase, encourage them to put further battery exchange stations* at strategic locations so that one can travel from city to city.  Put these next to restaurants or areas of great scenic beauty so that people will have something to do for the half hour that it takes to charge up the car to about 80%.

*Since writing this, it would appear that battery exchange for electric cars is a dead end.  Instead, we should be installing charging points as widely as possible. Hence:

f) encourage our power companies to give every possible support to  car charging locations.Charging stations need greater electrical supplies than ordinary businesses and many of our electrical companies are government companies*. They are therefore amenable to government 'encouragement'.

*Since the writing of this blog, a little under half of each of our power companies have been sold off to private concerns.  We therefore have much less leverage with them.

g) encourage between-town restaurants, business car parks, city parking meter sites and so forth to set up card swipe charging points.

Set this all up now before the government becomes dependent on a new source of revenue

Sunday, July 18, 2010

Wind turbine Effects

Some of the detrimental effects reported for wind turbines are hugely exaggerated and misrepresented while some may have some truth in them. Lets have a look at a few of them.

Visual Pollution
I suspect there are more of us that like the look of wind turbines, both for their elegant shape and for what they represent than the contrary. Certainly a lot of people in the crowded areas of the world with air pollution, heat waves and a fear of their coastal cities being flooded by rising sea level, look with great favor on wind turbines. Here in New Zealand, we are somewhat spoiled. We sometimes seem to believe that we are immune from the effects of climate change and that overpopulation will never darken our shores.  Good luck to us.

Shadow Flicker

Shadow Flicker is seen when the sun, the wind turbine and the observer are in a direct line and the sun is interrupted as the blades turn. I'll use my own situation here in Waipara, New Zealand as an example. You can apply the principles to your own area. There are plans to build a multi-turbine wind farm on the ridge to the East of Waipara. The ridge is 5000 meters from the town. We are located at 45degrees south and, as the year advances, the sun rises over the ridge at different locations. In the summer it rises roughly 25degrees south of a direct line to the ridge and in the winter at about 25 degrees north of a direct line to the ridge. Throughout the year, then, there will be days when my house is exactly lined up with the sun and one of the wind turbines early in the morning when the sun rises. Here we come to the first point.

The sun 'moves' a quarter of a degree per day south  between the summer solstice and the winter solstice and a quarter of a degree North each day, between the winter solstice and the summer solstice. With a wing span of 90m at a range of 5000m, the wing span of the turbine, from where I see them, is just over 1 degree. If there is any shadow flicker it will occur for 4 days as the sun moves south and 4 days as the sun moves north. A total of 8 days per year for each wind turbine which is visible from my house.

As mentioned, the arc of a 3mw turbine is just over 1 degree. The sun rises 15 degrees per hour or 15arc minutes per minute of time. Since the sun travels 15minutes of arc per minute of time, the flicker will last, where I live, for just over 4 minutes starting a few minutes after my apparent dawn and will only occur on those days when I am perfectly lined up with the sun and the turbine in question. Sofar, we  have a possibility of shadow flicker for 4 minutes at dawn for 8 days of the year for each wind turbine I can see from my house.

Lastly, what about the intensity of the shadow. If the sun was a point source and ignoring refractive edge effects, there would be a hard shadow cast at my house. However, the sun subtends 32 arc minutes(just over half a degree). As you move away from an object that shades the sun, there is a cone of darkness behind the object (umbra). When you get to a distance such that the object in question subtends 32 arc minutes, the object will just cover the sun. Further away, you will be able to see more and more of the sun on either side of the object. Stated another way, light from the opposite sides of the sun fills in the shadow behind the object. If you are familiar with eclipses here we are talking about the umbra and preumbra. Doing the same calculation that we used above, it turns out that a 3.5m wide blade (width of a typical blade of a 3mw generator at its root) will just cover the sun at 364m. Using the same calculation to see over what distance the shadow of the blade will be spread at my house, it turns out to be 46m. A 3.5m shadow is dispersed over 46m. Doing a little more math, we see that the intensity of the sun will decrease and increase 7%.

In short, there will be a 7% change in light intensity which will occur on those 8 days during the year when I am perfectly lined up with a turbine. It will last for 4 minutes and will occur at my apparent dawn. lets see if the rest of the arguments against wind turbines have a little more substance.

Glint occurs when the light from the sun, which is behind or to the side of the observer, is reflected off a blade into the eyes of the observer. If glint actually occurs, it should be relatively easily solved by using matte paint of a dark color.

Noise is the only one of the objections that seems to have the possibility of some validity.

The two bladed Gebes Pass turbine was noisy initially. Apparently the blades were broadcasting generator noise like a loud speaker. The solution was to put a sound absorbing coupling in the drive shaft. Most of the noise disappeared . Tonal noises have also being observed in early wind turbines. Bias cut gears (taken from automotive gear shifts) and isolation of the generator from the nacel solved this problem.

Blades swish as they travel through the air. This problem has been addressed by making sure that the trailing edge of the blades is sharp and that wind turbines are built with the blades upwind of the tower. Further work will undoubtedly further reduce this source of noise. If a house is close enough to a wind turbine to hear air born noise, one solution which has been found to be effective is to double glaze windows. Such retrofits should, of course, be undertaken by the wind farm.  It has been noted that when the wind is blowing, the swish of the wind through the trees to a large extent masks any swish from the blades.

A further decrease in noise is connected with the number of blades. Three bladed turbines are quieter than 2 bladed turbines.

Low frequency noise is another question. Frequencies below the 20cps detectable by the human ear can be disruptive to animals and if intense enough, can disturb humans. Such frequencies are hard to exclude from a building as they are not absorbed by conventional sound deadening materials and they can propagate through the ground. For instance, it has recently been found that Elephants communicate over long distances using 'infra sound' which they detect with their feet. Sound waves in the ground travel in peculiar ways. For instance, an earthquake, which in simply high intensity low frequency sound, can leave a nearby town unscathed and destroy one further away from the epicentre. There exists the possibility, however remote, that a dwelling could be effected by vibration from a wind turbine. Fortunately the solution is not difficult.

The first stage is detection. Instruments exist that can detect sound below the auditory frequency range of humans. First a reading is taken on the foundation of each turbine as it is commissioned to see which, if any, frequencies it is generating. Then at the location where it is believed that these vibrations are occurring, similar readings are taken. If there is any indication that vibrations are being transmitted from the wind farm to the location, all the turbines can be feathered to see if this stops the vibrations. Then the turbines can be started up one by one, to detect the offending unit or units.

Assume for the sake of the argument, that one or more turbines are found to be sending vibrations to a house. There are at least two possible solutions. The first solution is to determine where on the offending supporting tower the inter-nodes are located. Dampers are than attached at this (these) locations.

Alternately, the same sort of devices which are used to isolate buildings from earth quake vibrations can be used to isolate a tower from the ground. These consist of lead filled rubber pads.

The bottom line of all this is that humanity in general and New Zealand in particular is desperately in need of cutting its dependence on fossil fuel to the absolute minimum. That doesn't mean that people must put up with annoyance from sources of renewable energy including wind turbines. If legitimate problems arise from the installation of wind turbines, they must be addressed and solved. However, they must be genuine problems and not nimbiism.

What is needed here is a thorough, honest research effort by government to examine complaints adjacent to existing wind farms. Let the chips fall where they may. This must not be a cover up but a genuine examination to see if there are legitimate reasons for complaint. If it is found that, for instance, infra sound is being transmitted to a nearby house, work needs to be done to determine how to mitigate the annoyance. Once the work has been done, it must be widely published and used by wind farm developers. If it has been found that wind turbines cause legitimate annoyance, they must take the measures which have been found to mitigate the annoyance.

The uptake of wind farms is far too important for the future well being of New Zealand to allow Nimbiism to halt their development.  They are far too important to allow genuine concerns go unsolved.