Since many of the Haliade’s components will be located in the tower, the Cherbourg factory will assemble towers rather than fabricate them. ‘Where the metallic part of the tower will be made, we don’t know,’ Hendrick says, ‘but because of the internals in the tower, assembly is sensitive from a quality point of view.’

Alstom says that once it is scaled up to full production the St Nazaire facility will produce about 15 machines per year, with approximately 20 days spent on producing each machine. The temporary plant is expected to produce roughly 40 turbines before serial production begins at a permanent facility.

Employees work in two shifts. The 3000 m2 work space is divided into 15 stations manned by six people per station – no more, explains Girault, because of safety regulations. Currently 12 people work in the St Nazaire factory; by March 2013 a staff of 40-50 (half of which will be assembly workers, the other half engineers and technicians) is planned, and by 2014 the facility is expected to have a staff of 100.

Assembly

The Haliade’s nacelle is put together along an assembly line, in a dynamic construction process akin to the way automobiles are made. Girault explains that it takes 2.5 days to manufacture one nacelle.

Production takes place on a transport platform. A ‘multi-wheeler’ wagon moves the entire assemblage from one station to the next. The generator is moved with a hydraulic crane and is eventually bolted onto the nacelle.

Assembly begins with the turbine’s central block, which forms the interface between tower and nacelle. The central block contains the direction drive system, including a direction bearing. The central block also includes the helipad.

Next the intermediate block is fitted to the permanent magnet generator. The two blocks are then fitted together, ready to receive the rotor, and then the blades are fitted to the rotor.

At the end of the production process, parts are placed in a storage and logistics area before shipping. Blades, towers, nacelles and other parts sit to wait for installation close to the site.

A ‘self-improving system’

Girault terms his production process a ‘self-improving system’ and a ‘never-ending improvement loop’. His goal is a process akin to Toyota’s ‘lean system’ for auto manufacturing (also known as Toyotism). Lean manufacturing focuses on generating value for the end customer while requiring as little work as possible from the employees. Its principles are increasing efficiency, decreasing waste, and using empirical methods to decide what matters, rather than uncritically accepting pre-existing ideas. Lean manufacturing is widely viewed as building on earlier efficiency systems, such as Fordism, and taking them forward.

Girault believes in empirically testing his production process. Turbine assembly is broken down into discrete tasks which are timed, and then timed again to see if their duration can be reduced. The workers keep track of timing on a large wall chart which records how long it takes the assigned number of workers to do a particular job and is updated after each task is completed.

Girault conducts weekly audits on safety, quality, activity and logistics in order to streamline the process; employees are also encouraged to suggest areas for improvement and awards are given for workable ideas. For example, one employee suggestion that was adopted was integrating an ‘octopus’ tracking intelligence module, which monitors machines and processes, into the workshop; another suggestion was to fix mirrors to the underside of the generator in order to see whether there are workers near it.

Alstom’s engineering and R& D centre in Barcelona has designed detailed documentation for training purposes, which Girault hopes will make assembling a wind turbine ‘as easy as putting together furniture from Ikea’.

Rules and procedures applicable to serial production have been applied from the first unit produced in St Nazaire; Girault believes this will make subsequent commercial production easier to implement. In this way the current production facility is also a testing facility: it is constantly testing and refining the manufacturing process in which it is engaged.

Eventually Girault hopes that Alstom’s four French factories, planned to initially manufacture the 240 Haliade turbines to be installed from 2016 onwards as part of the French tender, will all benefit from the lessons learned at St Nazaire.

A big future

Hendrick believes that the Haliade 150 will be ‘the turbine for the coming decade’. He doesn’t believe that offshore turbines will get much larger because of limits linked to the size of installation vessels. And rotational speed is key: higher tip speeds can result in blade erosion in a saline offshore environment. Also, if rotational speed is reduced in order to get more power, ‘you’ll have enormous torque’, explains Hendrick. So will there be 15 MW-20 MW turbines? ‘I don’t believe it,’ he says. But the Energy Research Centre of the Netherlands’ 2011 Upwind: Design Limits and Solutions for Very Large Wind Turbines report found that 20 MW turbine designs should be achievable if some key innovations can be developed, and GE Global Research has already begun work on developing a generator for 10 MW-15 MW turbines. If turbines grow ever larger, innovation in manufacturing, assembly and transport will be increasingly necessary.

Tildy Bayar is Associate Editor of Renewable Energy World magazine.