United Kingdom

United Kingdom

Lean blades for tomorrow's world

Tomorrow's blades will be made from raw materials in a sophisticated and highly integrated process close to the site of wind turbine installation

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At a compound growth rate of 30% a year, the wind energy industry grows by an order of magnitude about every eight years. What are the drivers that will shape it? Established members of the energy industry Shell and BP are turning to welcome wind and to add their expertise in the management of large projects and in working offshore. BP now says its initials stand for "Beyond Petroleum." Others, such as ABB, have come in with a much more integrated view of the electricity generation and transmission system, suggesting considerable simplification and weight reduction at the wind turbine end -- rare earth, permanent magnet, direct drive generators -- and a much streamlined transmission system using high voltage DC to interconnect the turbines. What other changes are out there?

Wind energy is an interesting bringing together of the electricity supply industry and aero-mechanical systems. All conventional electricity generation involves thermo-mechanical systems and thus much of the technology involves the performance of materials at high temperatures carrying very high energy intensities (steam turbines and gas turbines for instance). Wind energy begins with a low intensity source of energy -- the air -- and so it involves very large aerodynamically shaped structures, designed to transfer that energy into (slow) rotary motion and thence into electricity. Wind turbine blades are now a serious part of the world composites industry. How does that industry view things in wind power?

A look at how that industry views other things might give us some clues. Two composite firms, American Corning, who make glass fibres, and British Structural Polymer Systems, who make epoxy resins, recently announced a collaborative agreement to work together on the development of production processes for automotive body parts as part of the general effort to make car bodies lighter. Part of the requirement is to make body parts at the rate necessary for automotive production, and at automotive prices. Both these requirements demand a lean process, with the minimum number of manufacturing moves from the raw material to the finished product. Here there is much going on that will affect the wind turbine industry.

Composites are moving towards highly integrated "PFD" processes: Place, Fuse, Deliver. The first step involves placing both fibres and resin at very high speed in exactly the right thickness and orientation directly into the moulds. This is a serious advance on fabric manufacturing technology; it is focused on direct generation of the end product, not on the generation of an intermediate product (cloth). Another British company, JDR Composite Solutions (the "J" is Jeff Vane, who developed the whole concept of stitched fabrics which transformed the composites industry in the 1990s), is developing advanced fibre placement techniques for just these kinds of processes, with both the automotive and wind industries in mind.

The "Fuse" step involves careful integration of mould and process design, using heat and pressure in a precisely controlled cycle to fuse the fibres and resin into the finished structure in the shortest possible time. Structural Polymer Systems are very involved here.

The "Deliver" step then simply sums up the leanness of the process. You begin with raw materials. Nothing goes into the mould which is not part of the final product and all the elements are so integrated that the product emerges complete. Not only is it complete, it is in the right place. The PFD machine is set up where the product is needed and you deliver the raw materials to it. It does the rest.

In seven years nobody is going to be transporting wind turbine blades by road. The aerodynamic compromise to get a 60 metre blade under a bridge is unacceptable. Barges work offshore, but what about using the new airships being developed in Germany? (You think that's crazy? Take a look at projections of the wind turbine production rate in seven years). The automotive industry is steadily progressing towards very integrated ways of operating. When wind turbines were small it was possible to think of blades as components, bought from a factory. Today they are a sophisticated product. Tomorrow's lean wind turbine is a rotor, a direct drive generator and a tower, assembled from the raw materials in a sophisticated process close to site. Think process. Think lean.

NOTE: A boat sailing into the wind is hard pressed against the elements and so are its crew. Once off the wind, however, the boat levels out, the battering of the relative wind is banished, the temperature soars and the crew, no longer clinging to a sharply inclined vessel, relax and unwind. Conversation turns to the lighter side of life and whimsical musings. That's just what this new column is for: musings about wind power in general, by Helmsman. You're welcome to contribute, under that pseudonym or using your own name.

Contact: editorial@windpower-monthly.com.

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