The global wind energy sector is an expanding market for cranes

Without wind energy-related applications these tough economic times would feel a lot worse for manufacturers and operators alike.

Most crane service companies planning to expand their fleets are looking to invest in the latest technology with reduced rigging times, says Neil Partridge, Ainscough managing director. The UK-based rental giant has a range of models, including TC 2800-1 lattice boom truck crane, CC 2800-1, CC 2500-1 lattice crawlers and AC 1000 all terrains from Terex, as well as a Liebherr LGD 1550 and an LR 1300 crawler.

In the UK, Partridge cites Scotland and Wales as having great potential with huge expanses of hills and moorland. He also pointed out the advantages of higher capacity telescopic cranes, 1,000 to 1,200 tonnes, with long booms, up to 100 m, as well as lattice boom cranes with special wind boom kits for greater capacities at minimum radius.

"As turbines continue to increase in size and weight the [1,000 tonne capacity] Terex AC 1000 will become a useful tool, along with narrow track crawler cranes," says Partridge. "Much emphasis is being based on the speed of erection and dismantling, as one of the critical costs for the turbine erection companies is the cost of moving between the working platforms," adds Partridge.

Terex sees wind turbine capacity growing worldwide. "As a trend we see increasing capacities and increasing tower heights. New installations start with 80 to 100 m towers, while years ago they started with 60 to 80 m towers," says Guntram Jakobs, product marketing manager for the lattice boom crawler cranes.

Globally, growth is still strong and increasing, although the USA has seen an unexpected reduction in wind energy-related work since the beginning of this year. Rick Nichols, Terex Cranes, president confirmed this at the manufacturer's Customer Days event in October. He cited reduced oil prices as one reason. It has also been suggested the USA national grid network is not comprehensive enough.

Moving on to related models, Terex launched its 1,600 tonne capacity CC 9800 lattice boom crawler crane in 2009. It can lift 350 tonne nacelles to 150 m tower heights (see picture story). The newest addition from Terex is the Powerlift 8000, a 360 tonne capacity crawler crane manufactured in China for the Asian market. It has a specially developed main boom and fixed jib for wind turbine erection. In addition the crane has a variable crawler system allowing it to retract crawlers for travelling.

Liebherr has also been busy designing cranes for the wind energy sector. Its 1,200 tonne capacity LTM 11200-9.1 wheeled telescopic and LR 1600/2 crawler were introduced in 2008, with both of them being used mainly in the wind energy sector. In 2009 the LTR 11200 tracked version of the LTM 11200-9.1 and the LR 1600/2-W followed. Both have narrow-track crawler chassis, and, again, the main applications are wind farms.

"Another feature which is especially suitable for wind power erection, is the hydraulically adjustable jib of our telescopic cranes, with this, very sensitive luffing at high hook heights is possible," adds Wolfgang Beringer.

The trend is for taller and higher capacity wind turbines, confirms Beringer, "Not only in steel, but also as hybrid towers - concrete and steel. High load capacities are required for the concrete segments as well. So the jobs for the new generations of windmills get more challenging and sophisticated."

Onshore, this means 3 to 4 megawatt turbines installed on towers reaching 120 to 150 m tall. "We think the crane population for wind power will increase at the same speed as in recent years. And the demand will always be for larger cranes," concludes Beringer.

As mentioned, adaptations and developments of existing cranes for wind energy have become common, for example the LTR 11200 mentioned above, and the CC 9800, borne out of the existing CC 8800-1. Kobelco offers another example with its new heavy fixed jib for the 550 tonne capacity SL6000 crawler, presented at Bauma 2010. It is designed specifically for wind energy applications and is aimed at 2.5 MW nacelles with 80 m towers. According to Bruce Yanagido, product planning department manager, the company will soon introduce a heavy fixed jib for the 400 tonne capacity SL4500 crawler, aimed at 1.5 MW towers in Asia and the maintenance of 80 m towers in Western countries.

"Wind energy construction requires height, therefore 'strong' and 'light weight' features are needed on the boom and jib section. These incompatible factors make it a challenge." Yanagido adds that as onshore and offshore turbines increase in height and capacity, customer liaison will become ever more important to get "more accreted information and requirements for what the crane needs to be - capability for turbines and erection time are paramount."

Along with Europe and the USA, Yanagido identifies China as a key market as wind energy growth is exceeding any other country in the world. An example of how Chinese manufacturers are exploiting this growth is the highlight on Fuwa's Bauma China 2010 stand. The new 750 tonne crawler crane has been developed for the wind power market. According to Di Xiangdong, Fuwa CEO, it has significant advantages over machines currently on the market for this application.

"There are specific requirements for the installation of wind turbines. Normally you need a 750 tonne crane with a superlift attachment. That gives you enough capacity, but it's not very convenient to transport.

"This crane will have a 96 m main boom, with a special a special boom head. It also has what we call a 'super lift mast', but without the extra counterweight. That allows it to lift 3 MW turbines. We have done some special developments in the turning bed with the slewing bearings to improve them," adds Xiangdong.

Such developments and adaptations are key to success in wind turbine lifting. Christian Prangl, Prangl managing director, explains, "Of course the lifting capacity is the decisive factor. Supported by heavy boom systems, for example, Terex S1 or S7 Kit, the machines become even more powerful. Since we have these types of cranes in our fleet already, these extra boom kits can be exchanged among the various mobile cranes."

Opportunities lie across the European countries, Prangl adds, "Due to better profitability and increased wind utilisation, boom systems for lifting heights of 130 to 160 m will be the future. In addition, wind turbines will increase in size. Therefore, measurements and weights will rise accordingly." Prangl continues, "We believe that being able to offer complete packages - logistics, cranes, etcetera, will be the trend in the future."

Christian Jacques Vernazza, Mediaco-Lifting president, agrees that height and capacity of turbines will be crucial in the future, with 3 MW capacity and above turbines emerging, along with an expanding offshore market.

As cranes become more compact with taller booms, however, there is a greater risk from wind impact. Vernazza, who is also president of the European Association for Heavy Haulage, Transport and Mobile Cranes (ESTA) explains, "ESTA is working with the manufacturer and the FEM association, on the working at height safety problem. Wind forces are underestimated when the lifts are performed above 60 m, with big rotor and three blades that represent a kind of weight like a Boeing 737 hanging up.

"ESTA is recommending to the manufacturers that clients using the largest cranes in windmill operations at a big height have to pay more attention to wind impact. It is why ESTA and FEM recommends not lifting more than one blade a time - not the three blades with rotor - to avoid accidents."