Bright and breezy for wind turbines

Wind farms are getting bigger, as are turbine capacities. In the near future 6 MW turbines will be a common sight, requiring larger and faster cranes to erect them. Euan Youdale reports.

Figures from the World Wind Energy Association (WWEA) show new wind energy capacity increased by 19.696 GW in 2007, bringing the total global capacity to 93.849 GW.

The added capacity equals a growth rate of 26.6%, up from 25.6% in 2006. It is responsible for 1.3% of electricity consumption globally, but in some countries that figure stands at 40%.

Based on the accelerated development, WWEA has increased its forecast for 2010 and now estimates some 170 GWs will be installed by the end of that year. However, in the majority of the top 40 wind markets the increase in the deployment of wind energy slowed down in 2007.

Dr Anil Kane, WWEA president says, "Another concern is that most of the developing countries are far behind the development of the leading wind energy countries. With today the emerging countries India and China among the top five wind markets, there should be sufficient motivation for the governments, as well as for international donor organizations, to launch effective and substantial international deployment programmes."

Putting the concerns aside, most rental companies involved with wind turbine erection, especially those in northern Europe, are reaping the benefits of new projects demanding heavier lifts.

Narrow chassis

UK crawler crane rental company Weldex is setting its sights on offshore wind farm and port handling-related projects. One of them involves lifting 300 tonne foundation poles at Workington, north England, for MT Højgaard.

Weldex is also working for Siemens Wind Power in Moston, north England. So far the company has offloaded four ship loads of components from Denmark and is preparing to set out the blades and towers.

For heavy wind turbine work Brian Hyde, Weldex technical services manager, says the 600 tonne Terex Demag CC2800-1 NT has become a tried and tested workhorse of the industry. With a chassis width of 5 m, the NT version transforms the crane into a specialist unit for erecting turbines at wind farms, along with other multiple heavy lift contracts.

Its narrow chassis width can deal with the roads built specifically for transporting wind turbine components and the unit can travel with long booms and counterweights in place, says Terex Demag.

While crawlers are the crane of choice, Weldex is bucking its own trend by taking delivery of a Liebherr LG1550 lattice boom mobile crane, for the first time, in March.

Hyde says the 550 tonne capacity machine is aimed at the 2 to 3 MW on land wind turbines. The benefits include 100 tonnes capacity from a 91 m boom with a 6 m jib.

For high end work, the company has a second 400 tonne Liebherr LR1400/2 crawler crane on order. These machines complement the four 600 tonne capacity Kobelco SL6000s ordered at Bauma 2007.

Bigger vessels

Hyde says there has been renewed growth in the renewable energy market. "It's no secret that there are half a dozen [wind energy] projects coming up on the east coast in the next two years. The onshore market seems to be keeping pace too."

At the moment 2 to 3 MW is the standard capacity, but that will increase to 5 and 6 MW machines in the future. Although, Hyde notes, that these higher capacities will not be the norm until about 2013.

The Seimens Wind Power project consists of 3.6 MW windmills, which have cells weighing 135 tonnes and blades weighing 60 tonnes. This type of work is carried out by jack-up barges carrying crawler cranes. But for large-scale 5 to 6 MW windmill erection, new and larger vessels will have to be developed, comments Hyde. "Not so much for handling and assembling in the yard, but we have to think hard about offshore installation."

On land, in the UK, it is easier to get planning permission to build smaller capacity windmills, adds Hyde, which is another reason why 2 to 2.5 MW turbines are still popular.

While wind energy is providing massive potential for crane companies, the reality is not always so certain. Hyde says it is very difficult to plan for the future when large-scale offshore wind projects are working their way through planning and the contract is not secure. For this reason Weldex buys crawlers that can be used for other types of work. "We have to buy them with general construction in mind. We have spent a lot of time developing narrow track cranes but we have still got to have them working when wind farms dry up," Hyde adds.

Industry first

Peter Libert, area sales manager at Sarens, says the "experimental" offshore 5 to 6 MW, and even 7 MW, market will grow 400% over the next five to 10 years. The Thornton Bank project, in the North Sea, is an example (see Offshore Giants box story).

"So far wind turbine manufacturers have installed test sites with one or two turbines at the same location. The Thornton Bank is the first real offshore wind park where Sarens has installed the first six of a total of 60 turbines," says Libert.

Today, wind energy projects account for 10 % of the work carried out by Sarens. "Wind is growing fast, but as the main markets of the Sarens Group - petrochemical, energy and civil - are also growing very fast, we feel that the 10% will stay as it is."

Other work carried out by Sarens includes the installation of the first offshore 5 MW wind turbine for Bard in Hooksiel, close to Wilhelmshaven, Germany.

Sarens is also due to install the world's biggest onshore wind park to be made up of 6 MW Enercon wind turbines. The Estinnes project in Belgium consists of 11 wind turbines each. Up until now sites incorporating the 6 MW turbines have only included one or two units.

Secret specifications

The rotor weighs 365 tonnes and is lifted to a height of 135 m. Total height, including blades is 198 m. The testing and experimental phase is complete and the first turbine will be installed at end of 2008 or the beginning of 2009. The project will be finished around the end of 2009.

For this lift Sarens' product developing department created a new crane in cooperation with Terex Demag: the CC 9800. The specifications remain a secret but delivery is expected at the end of 2008.

However, for day-to-day wind work, with turbines ranging from 1 to 2.5 MW, a flexible and fast-working crane is a necessity. Libert adds that they must be able "to lift heavy weights at a small radius but great heights. And be erected and dismantled easily between wind turbine sites, in a timely and cost saving way. This is important if you want to install two or more turbines per week in a wind park with only one crane."

Christian Prangl, at German rental company Prangl, says synergy between different machines is vital. "With our Terex Demag TC 2800 and CC 2800 - both compatible with our S7-kit - we can offer our customers the same machine either on wheels or on crawler tracks. Another issue, of course, is the need for the quickest and most feasible way of mobilizing and demobilizing the cranes."

Key factor

Serving and maintenance of windmills represents a considerable amount of Sarens' wind business turnover, says Libert. "Erection is a singular operation, while servicing lasts eternally, and secondly servicing represents 15 % of our wind business turnover and is still growing."

At Prangl the servicing of windmills is a business strand that is slowly developing. "The turbines are still very young. But the prospects are sound. Once again, mobilization is one of the key factors together with the possibilities of using man baskets," says Prangl.

Overall, Prangl is benefiting from the wind energy market as much as its counterparts in the crane industry. In 2007, the company took stock of a Terex Demag CC 2800, which has been working in a number of wind parks in Germany. "We are currently negotiating another wind energy crane," adds Prangl.

Commenting about the future of the wind turbine market Prangl says: "I see an ongoing trend for the next couple of years. I think the regional growth depends very much on the legislative situation in each country. But I am absolutely positive that we will see a wind energy boom in a lot of countries all over the world. I do not think that there are certain areas of highest priority. Alternative energy will be needed everywhere.

"Thus we will see new crane types for this field. Nevertheless I believe that the bottleneck in the future will not only be the crane capacity but the limitations to transporting the turbine components on the road."