Wind has proven itself to be the most
viable and successful form of renewable energy to date, having a current renewable energy market share
of 11% (August 2003) in Australia and is expect to grow to 41% by 2020. However like many renewable energies,
while Wind Power is zero emission, it is not capable of supplying base loads, i.e if the wind stops, so does
the power. Wind power at suitable
sites in Australia has a 80-85% availability. Due to the size of the turbines, typically greater than 60
meters in diameter and siting on towers 70-100 meters tall, Wind turbines can lend themself to greater
visual "pollution" than other forms of renewable generation.
One solution is to place the large turbines out at sea which has been done for many years in other
countries. However while there is better wind speeds out at sea due to the flatter surface (less resistance),
there is a large cost penalty caused by sea based electricity grids, wind tower foundations, construction costs
and the life of plant. Denmark and other such countries already operating sea based wind farms have electricity
prices much greater than Australia, in the case of Denmark as much as three times (Source : Electricity Supply
Association of Australia 2003). As Australia has the second cheapest electricity of any major developed nation
(second only to South Africa), it is considered sea based wind farms are just not yet currently viable in Australia.
The concept of wind is not new for South Australia. Wind energy was first studied by ETSA in the
1950’s with a Wind Energy Committee set up in 1984. The first wind monitoring units were established
on the Fleurieu Peninsula in mid 1985 with a total of 30 sites monitored around SA by 1988. A
single 150kW Nordex Wind Turbine was installed in Cooper
Pedy and was commissioned on the 15th March 1991.
Operational South Australian Wind Farms :
However South Australia only comissioned its first large scale plant in July 2003. Being developed
by Tarong Energy (A Queensland Government owned electricity generator), the $65 million dollar project is
situated north of Cape Jervis with a total of 13 NEG Micon 1.5 MW NM64C/1500
wind turbines generating 34.5MW. This is enough energy to power approximately 18,000 South Australian homes.
The farm connects to the ETSA Utilities’ Yankalilla Substation via a 66KV High Voltage Transmission Line.
South Australian Wind Farms under Construction :
Proposed South Australian Wind Farms :
Another farm in construction is Babcock & Brown WindPower Pty Ltd’s Lake Bonney Stage One, an 80.5MW Wind Farm costing more than $100 Million. Work has begun on the first of 46 foundations and 76 metre towers to support the Vestas 1.75MW Wind Generators having blades 66 meters in diameter. The farm was under threat in 2001 when "outstanding issues associated with the connection of the wind farms to the high voltage grid system" was hindering the farm’s commercial viability according to a Spokesman for Babcock & Brown Windpower. It appears many farms are having trouble with monopoly ElectraNet S.A. in connecting to the H.V. transmission grid at reasonable prices.
No doubt you will notice Wind farms are having a few publicity problems at the present. This appears to have stemmed from a minority of residents who have legitimate concerns about a farm being built nearby and the possibility of visual pollution. Coupled with the media who really doesn’t care if it is fact or fiction, provided it makes a good story, the problem has escalated from myth to myth.
Here are the normal myths circulating at present:
- Wind power is not base load and we will need to build extra generation to supplement wind power when the wind is not blowing. Typically availability is quoted 30%.
- The energy payback time for a wind farm is too great.
- Wind Farms and the power they generate are expensive.
- Wind Farms cause visual pollution.
- Wind Farms are noisy.
- Wind Farms kill birds.
Myth #1 Wind power is not base load and has an availability of 30%.
Wind farms are the most successful form of renewable energy to date. As a result it carries the weight of some far-fetched ideas that wind farms will one-day replace fossil fuel power stations. It’s probably easy to guess why someone would jump to this conclusion. After all the growth of wind farms have been quite significant in the past couple of years.
However if some how it was possible, so called experts would point out wind is intermittent form of energy and wind only blows 30% of the time. Well the statement is not entirely correct but what they are talking about is the capacity factor (CF). There is no hidden secret. The capacity factor of a wind farm is approximately 30%. What is capacity factor?
"So ask yourself the question: If South Australia was stupid enough to go for wind, how would you run air-conditioners or, indeed, hospitals and industry for the other 244 days of the year? " - David Bellamy
Wind farms, have an availability figure of around 96-98%. This indicates the turbine will be ready to generate energy say 98% of the time. During the other two percent, the turbine or grid may be undergoing maintenance, the distribution grid may be down due to fault or for bush fire prevention etc.
Then there is a wind availability figure. At most good sites within Australia this is approximately 80%. This indicates that 80% of the time, the wind is fast blowing enough to generate power, or less than the cut-off wind speed at which the turbine shuts down and turns out of the wind. This is done to protect the turbine from damage in very strong winds.
Last there is a turbine power curve which plots power output against speed. It shows at what wind speed the output of the generator will peak. Multiply all these figures together with the wind speeds at the site and you get a capacity figure as a percentage. This means if you have an 18.2MW wind farm you could expect an output of approximately 47.8GWh/year (18.2MW/h x 24hours x 365days x 30%).
Pacific Hydro which has built both the Codrington Farm and more recently Australia’s Largest Wind Farm, Chalicium Hills, quotes Capacity Factor on the fact sheets for its farms. Codrington (18.2MW) was expected to be about 32%. In the 2002/03 Annual Report, Codrington generated 47.8GWh of clean renewable energy. That’s a 29.98% capacity factor which is not bad for the first couple of years when the farm is still being fine tuned and serviced under the manufacturers warrantee.
So the media is right. A 18.2MW wind farm really only generates 30% of the name plate capacity. This then requires scheduled generation when the wind is not blowing. This is not a significant problem as gas fired peaking plants or hydro can be brought on line quickly. So what does the media (the people in the know) suggest as alternatives? Solar? Yep. Wave? sure do.
Unlike wind, the sun doesn’t shine 80-85% of the time. At worst case from sunset to sunrise, you would be really scratching at a maximum of 14 hours or 58%. Then you have cloudy days, which can see the output drop 5-20%, and maximum power output at certain conditions no different to wind. Most solar panels don’t track the sun, and they are less efficient at higher temperatures.
The North Terrace Power Station (PV Solar), has an installed capacity of 19.8KW. Each year it generates 25,950kW/hrs so we can conclude it has a capacity factor of 14.9% (19.8KW x 24 hours x 365 days = 173,448kW / 25,950). Gee, that’s poor. The North Terrace Power Station was commissioned in November 2002, Codrington was in November 2001 so both use about that same era of technology. To be fair, the Redding Report states CF figures for Solar at a slightly higher 18%.
Unfortunately we are still a few months of seeing the first prototype wave power plants being installed in Australia and there is no comprehensive wave studies in Australia. Economics has been the main reason why wave has not let taken off. While I prefer to work on actual production data, we will have to base our wave capacity on research.
Like wind, Wave power is said to have an approximate availability of 80% in Australia. However in a report from the Australian Greenhouse Office, it is suggested Wave power has a capacity factor of 7% upwards to 25% based on the device used.
"The efficient use of every form of energy is a must. In your sunburnt country, surely solar power can bridge the gap until wave power begins to provide real base load power to solve the problem. " - David Bellamy.
So David Bellamy, if we adopt solar power how do we run our air-conditioners or, indeed, hospitals and industry for the other 310 days of the year?
It has never been suggested Intermittent Renewable Energy such as Wind would replace fossil fuels. Most renewable technologies simple do not scale up well. However they are designed to supplement power generation, and we must start somewhere. We can’t keep putting of construction hoping for some miracle solution to come along.
It is hard to understand how Wind could ever overtake fossil fuels without some significant shift in Federal Government Policy. The Mandatary Renewable Energy Target calls for 9,500 GWh of renewable energy by 2010, or about 1.5% of electricity to come from renewable sources. At present Wind makes up 11% of renewable energy and is expect to grow to 40% by 2020. Therefore Wind would be predicted to make up approximately 0.6% of generation. Any further generation would have no REC’s to support it. Even if MRET was increased to 10%, Wind would only ever make up 4% of total generation. AusWEA suggests that up to 20% of electricity could be generated by Wind before it would cause problems.
Myth #2 The energy payback time for a wind farm is too great.
The energy payback time is the time taken to repay all the energy used to manufacture, install, operate and decommission the plant. The payback time for wind is in the order of a couple of months, typically anywhere from 3 to 8 months depending upon the wind speed at the location.
In comparison solar cells have a payback time of around 1 to 4 years depending upon the technology. It’s typically around 4 years for today’s multicrystalline-silicon cells and 3 years for thin-film modules.
It can be expected both will continue to decrease as technologies get better. Only two years ago it was common to use 1.3MW wind turbines, today they are using 1.75MW turbines economically.
Myth #3 Wind Farms and the power they generate are expensive.
The comparison of capital costs for various forms of generation is normally expressed as cost to install 1kW of name plate generation. It is not a true comparison, as Capacity Factor will effect viability of the project.
|Type||Capital Cost||Power Cost|
|PV Solar||$10,000/kW||>$300 MW/h|
|Solar Tower||$4000/kW||$180 MW/h|
While Australia is a good location for Solar Power it’s price still makes it prohibitive on a large scale. Wave is predicted to be better, but would still be many years away.
Myth #4 Wind Farms cause visual pollution.
Two Turbines from Pacfic Hydro’s Codrington Farm (Victoria)
Extract from Adelaide’s NewsPapers : Picture of decade old wind
farms which the media love to recycle. These photos originate from overseas. No one needs to worry about a farm
ending up like this. Being so old and inefficient, its simply not economically viable to build such a monstrosity.
This is true to some extent. However it is highly dramatised by the media. Early farms overseas used smaller
turbines and consequently many more of them. They were all placed on top of each other in a small density
polluted farm. The media has these first images and have never let go from them. In reality turbines today
are much larger and placed much further apart.
The other myth is the speed of the blades. People visualise ‘fans’ spinning around. In fact the speed of the
blades spin around at a typical speed of 15 to 17 revolutions per minute, or 3 and a half seconds to do a
single revolution. I can remember approaching my first farm from a distance and actually thought they were
aseptically pleasing to watch.
Wind farms normally have all cables buried underground. Therefore if I was given the option to have a wind
farm across the road or a couple of gas/coal turbines complete with rusting chimney stack and high voltage
switch yard or an open cut coal mine, I think I would take the first option.
Myth #5 Wind farms are noisy.
Another myth about wind farms is its noise. Really, some misinformed people must turn on their fans and
really visualise the turbines are just as noisy!
The most you can hear directly standing under a turbine is the swishing of air as the tip of each turbine
cuts through the air at 15RPM. Even this is insignificant. At 400 meters which is the closest a turbine can
be built to a house, the noise level is 40dB. This is the equivalent to a library. You can easily hold a
conversation under a Wind Turbine, which is said to be 60dB.
For the sake of economics you would expect the farm to be built in a location known for high winds. In this
case you are more likely to hear the wind blowing, than you would the swishing noise.
Australian Wind Energy Association Fact Sheet on Noise
People having a conversation under a Turbine from Pacific
Hydro’s Challicum Hills Farm
Myth #6 Wind farms kill birds.
Yes, it’s a given that the turbines can and will kill birds. However it’s important to get it in proportion.
Motor Vehicles, Buildings & Windows, Power Lines, Communication Towers, Global Warming and even Domestic Cats
will kill many times more. An Australian Study suggested mortality rates of 0.23 birds per year per turbine,
quite insignificant when compared to mortality rates caused by domestic cats or motor vehicles. The study
showed after a farm was installed, birds would change their flight a couple hundred meters before approaching
the blades and actually fly over it, as they would other obstacles.
Australian Wind Energy Association Fact Sheet on Birds