Wind Turbines of Crookwell - Clean, Green, International Partnership Machines

Australia's first grid connected wind farm represents the way of the future in more than just electricity generation, it shows the way for successful international partnerships in emerging industries. The wind farm at Crookwell, near Goulburn in the NSW Southern Highlands, contributes five megawatts to the national electricity grid, generated by eight of the largest wind turbines yet installed in Australia.

Commissioned by Pacific Power and Great Southern Energy as a pioneering exercise in commercially viable, sustainable electricity generation, the wind farm was an international exercise from beginning to end. Danish specialist Vestas Wind Systems, manufactured the turbine units and contracted Australian Defence Industries (ADI) in Bendigo to supply the two piece, 45 metre steel towers on which they are mounted.

When commissioned, the Crookwell installation became not only the first such installation to be connected to the grid, but easily the largest wind farm in Australia to date.

At 600 kW, each of the eight turbines equals the size of the single Vestas Wind Systems unit installed at Newcastle in 1997. Previous Vestas Wind Systems installations included two 225 kW units installed on Thursday Island in 1997 and nine 225 kW units at Esperance, WA, four years earlier, producing less than half the total output of the Crookwell farm.

The Crookwell site was chosen for its good average wind, its general accessibility and its proximity to the main electricity grid. Vestas Wind Systems estimates the installation will save around 8,000 tonnes of carbon dioxide emissions per year compared with the output of a coal fired power station. The farm's total output of 5 megawatts is enough to serve around 3500 average homes. Its energy is fed into the Great Southern Energy grid for distribution to customers who choose the "earthsaver" option for their power. The wind turbines are connected via underground 11 kilovolt cables to a substation which steps up the voltage for connection to the local 66 kilovolt grid.

Successful partnership

A key element in the project was the successful partnership between Vestas Wind Systems and ADI, which was built on their previous collaboration on the Esperance wind farm. ADI manager Robert Scott and Vestas Wind Systems project manager Bjarne Iversen knew each other from the earlier joint project, and worked closely on the Crookwell project

Bjarne Iversen believes a good working relationship is vital in this type of project, where components from opposite sides of the world need to be married precisely on site. "Building the tower is not complicated but you have to pay attention to the details to make it all fit together properly. When you are on site with a 200 tonne crane and up to 10 people to erect it, you don't want to find anything that doesn't fit," he said.

In the case of Crookwell, it took just three and a half days to erect the eight towers and their turbines on their prepared foundations. In Vestas Wind Systems' experience, which runs to more than 500 installations in an average year, things rarely go wrong, but when they do the result can be time delays which are very much out of character for the Danish company. "At Vestas Wind Systems we like to be on time, whatever it takes. With ADI everything was right on time, well ahead of Pacific Power's requirements," Mr Iversen recalled.

Robert Scott says the main challenge was logistical; ensuring everything was ready and on site on time. Each tower comprised two sections of 20 and 25 metres weighing a total of 36 tonnes and tapering from three metres diameter at the base to 2.1 metres at the top. The steel is protected by a sprayed coating of aluminium and zinc mix and finished with a top coat of two pack epoxy paint.

In a nacelle mounted atop each tower is a Vestas Wind Systems V44 turbine, along with its related gearing and control mechanisms, fitted with a 44-metre diameter, three blade fibreglass rotor. With the turbine assembly weighing 21 tonnes and the rotor itself 8.5 tonnes, each tower supports a total of 29.5 tonnes 45 metres above the ground with the rotor tip reaching 67 metres high at the top of its arc.

World leadership

Wind turbines are Denmark's third largest export, making it easily the world leader with several manufacturers together holding more than 60 per cent of the global market. Vestas Wind Systems, the largest of the three, accounts for a quarter of the world market on its own. To date it has built almost 7,000 units around the world, producing more than 1.5 million kilowatts.

Mr Iversen explains this Danish dominance of the wind turbine business as the result of a series of historical events. "During the Middle East oil crisis we were badly hurt because we were almost entirely dependent on oil fired power stations. Therefore a lot of our power stations were converted to coal and we also got seriously involved in renewable energy including wind turbines," he said.

"In the late 1980s, when tax incentives in California created a boom time for wind power, Denmark had the lead. This experience was important, because it's not that simple to make an effective wind turbine. American and Japanese companies have tried making huge units without success. But in Denmark we started with small, 30 kilowatt units and we grew in small steps, so now our largest units installed so far have reached 1,650 kilowatts".

"In Denmark the aim of the government is to have 10 per cent of electricity generated by wind turbines, at present it is about five per cent. The biggest outright number of installed megawatts in Europe is in Germany, but the highest percentage is in Denmark."

By contrast, Australia is yet to emerge as a major market for wind turbines, but Vestas Wind Systems intends to be in the box seat when the time comes. Bjarne Iversen said the partnership with ADI was a natural part of establishing the Vestas Wind Systems presence here. "You need to be well represented locally for these projects to work," he said. "Because this was for a new client, and also, our first big installation in Australia, it was important that we did it correctly. We knew that Pacific Power favoured having a local partner, so we chose ADI because we had known them for a long time."

Component exports

For ADI, Crookwell was an opportunity to strengthen a valued partnership. Although the company still derives significant income from defence industry projects, other types of work are increasingly important. As with the supply of towers for Vestas Wind Systems, Robert Scott said a major on-going job at Bendigo was the supply of major components for GE in the USA.

"Initially we won an order for 23 production bases for GE marine engines," he said. "We learnt from that job 13 years ago, and we've been doing it ever since. More recently we have supplied ducts and shafts for the LM2500 gas turbine marine engine which GE builds for vessels such as frigates and destroyers. For example, our Anzac frigates generally run on a diesel engine, but they also have one of the 32,000 horsepower units if they want to get somewhere in a hurry".

"We really need these partnering agreements to ensure on-going work. Vestas Wind Systems seems keen to establish its name in this market where there is plenty of potential. Also, BlueScope Steel has given its support and expertise to ensure our success. I think BlueScope Steel sees it as a future green market."

The underlying theme of international collaboration can be found in many aspects of the Crookwell project, not least in the relationships established between the key people involved. Once the order was placed with Vestas Wind Systems in November 1997, work began in earnest both in Australia and Denmark. Before that, Robert Scott prepared for his role as "the local presence and go-between" by visiting the Vestas Wind Systems factory in Denmark, where towers are made for the home market, Scandinavia and northern Germany.

While Robert Scott was busy with the towers in Bendigo, Bjarne Iversen was based at Crookwell "from the first day of making the first foundations in January until the commissioning in June." Normally he would manage European projects where he could visit the site for a week or two at a time.

For an intercontinental project such as this, Bjarne Iversen said the personal relationships were more significant than usual. "Robert Scott and I got on well from the start, and that is important when you are working in such different time zones and sometimes you have to call very late at night," he said. "Communication is always important, and about 80 per cent of our turnover is in overseas markets".

Good relationships and clear communication come to the fore in ensuring that specifications drawn up for Denmark translate properly into the requirements of an overseas market. This includes adapting the design to suit local grades of steel, and in this respect the partners found the support of BlueScope Steel in one instance vitally important. Vestas Wind Systems routinely employs local engineering consultants to check the original specifications against local standards, and it was in this process that Bjarne Iversen found a technical detail that needed clarification.

Robert Scott recalls that it was a small mix-up with the specification of the flanges, related to the through-thickness mechanical properties of the plate. Although not a major issue in itself, he said it was crucial to the performance and safety of the towers that the issue be resolved. "BlueScope Steel helped out with technical data assembled from experience over the years," he said. "They presented a paper to Vestas Wind Systems which demonstrated the required performance to proceed with the project. This was just as important as BlueScope Steel's competitive supply package for the steel."

Future potential

Throughout the project there has been a spirit of investment in the future, and Bjarne Iversen believes that Australia could eventually become a significant wind turbine user and to a large degree a producer as well.

"It is some way off yet, but it will come," he said. "Australia does have some very good locations for wind in some areas, and somehow you will have to meet your carbon dioxide commitments. Although a wind farm can only just compete with a big thermal power plant in outright cost terms, when you take everything into account in the longer term, renewable energy wins out."

"As the demand increases, there is potential for more local manufacturing of towers - we are in the business of selling wind turbines, not towers. And once there is a groundswell of demand for more, we could do local manufacturing of other components. This is what we have done in the Netherlands and Spain, and ultimately a very big proportion can be localised. Not that we would want to localise absolutely everything, but this has the potential to be an important local industry in the years to come."

Anatomy of a Wind Turbine

The Vestas Wind Systems V44 wind turbines installed at Crookwell represent the current state of the art in wind-driven electricity generation.
Blades - rotating at 28 rpm, the fibreglass blades are designed for maximum efficiency and minimum noise.
Hub - cast iron hub connects blades to the main shaft - hub and blades combined weigh 8.5 tonnes.
Gearbox - increases rotation speed from 28 rpm up to 1500 rpm to drive the generator.
Generator - produces 3-phase, 690 volts.
Nacelle - casing for gearbox and generator, rotates through 360° to face the wind - nacelle assembly weighs 19 tonnes.
Weather instruments - at the back of the nacelle, a three-cup anemometer measures wind speed and a wind vane records direction.
Yaw motors - ensure that the rotor always faces into the wind as recorded by the wind vane.
Parking brake - stops the blades rotating in gale force winds or for maintenance - similar to a car disc brake.
Hydraulic power pack - operates parking and yaw brakes.
Vital statistics - for observers of the Crookwell wind turbines, an overwhelming impression is of their sheer size and scale:

• Output per turbine 600 kW
• Hub height from ground 45 m
• Blade diameter 44 m
• Rotational speed 28 rpm
• Blade tip speed (approx) 200 km/h
• Start-up wind speed 15 km/h
• Wind speed for maximum power 54 km/h
• Cut-out wind speed 72 km/h
• Directional nacelle movement range 360°
• Concrete foundation volume 105 m3
• Weight of steel tower 36 t
• Weight of nacelle, hub and blades 27.5 t
• Generator voltage 690 v (3-phase)
• Underground cable voltage 11,000 v
• Grid transmission line voltage 66,000 v
• Length of buried power cable 3300 m