Staying close to original is not always outdated

WORLDWIDE: At a recent automotive seminar on lightweight, high-strength materials for innovative vehicle design one presenter introduced a low-weight electric city bus project, demonstrating a major conceptual rethinking with clever design solutions -- producing an unusual design.

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He explained that by trying to stay within the confines of the original design - because many firms prefer a gradual evolution of technology - and leaning towards conservative technology, optimal results are not achieved.

Two historic images highlighted the transformation of a horse carriage into an early car model, starting with removing the horses and all the pulling-gear attached to them. The next step was fitting an engine and modifying the front-axle steering with a handlebar, finalised by an artificial horse head attached to the carriage-car body in front. This artefact was perceived a necessary precaution to prevent panic in the horses of the horse-carriages that passed by the new vehicle.

One of the key design objectives of vehicle-mass reduction by Ford was to cut the lifecycle CO2-emission footprint, explained a Ford research expert. He referred to a quote by Henry Ford of 1923: "Fat men cannot run as fast as thin men, but we build most of our vehicles as though dead-weight fat increased speed! Saving even a few pounds of a vehicle's weight ... could mean that they would also go faster and consume less fuel. Reducing weight involves reducing materials, which, in turn, means reducing cost as well."

A century's worth of advancement in the automotive industry cannot be compared with only about 35 years of modern wind-industry development, but there are interesting parallels in a need for lower mass, costs and environmental impact, and for public acceptance.

Visual acceptance

American wind expert Paul Gipe wrote that many contemporary US turbine designers had distinct technology preferences for basic lightweight structures and integrated drivetrain solutions. Danish turbine designers, noted Gipe, had already realised the importance of harmonious, visually pleasing turbine designs as critical for public acceptance.

I experienced the importance of turbine visual aspects when I visited eastern Germany in 2002 to see Enercon's prototype 4.5MW E-112 wind turbine. Beforehand, I could not imagine what to expect, or how such a giant turbine would dominate its surroundings. But while passing groups of Enercon turbines all with characteristic eggbeater nacelle, it was only when I was very close that I was able to distinguish it from smaller models.

Some argue that with turbines developed for offshore use the visual design aspects, including the choice of two or three blades, are insignificant for market acceptance, giving almost unlimited freedom to product designers in the race to produce larger turbines with a parallel main objective to curb head mass.

One example of a radical design is the Aerogenerator X, an unusual 10MW vertical-axis offshore turbine development led by UK-based Wind Power Limited. It features a V-shape two-blade Darrieus-type rotor with 270-metre diameter and double-sided tip winglets.

Spoke-type generator

Last year Norwegian company Sway Turbine introduced a 10MW horizontal-axis ST10 offshore turbine with an unusual 25-metre spoke-type direct-drive permanent magnet generator. Innovative is the integration of generator and three rotor-blade supports, eliminating a traditional rotor hub and a main enabler towards limiting head mass at around 625 tonnes or less.

Dutch engineering consultancy Mecal launched its 12MW offshore concept turbine with a 200-metre rotor diameter this year. The product reference was a state-of-the-art 6MW offshore turbine, adding a 155-metre rotor diameter. Despite doubling the rated capacity and an initial 1,050-tonne head mass and massive overall dimensions, the turbine's shape largely resembles the appearance of smaller turbines developed decades ago.

Mecal indicated that besides asking the right questions regarding methods, materials and constraints, a maximum of two main technology innovations in such a new product development has proven to be key in curbing project risk. Many comments I heard around the industry showed an easier acceptance of the likelihood of production for this model than for those of more unusual designs.

Wind industry expert opinions further suggest that Mecal's overall strategy could, for the moment, offer an optimal balance between the industry's wish to continue innovating while curbing technical, bankability and other risks. Trying to stay close to the original could prove a successful basis for continued product advancement.

Eize de Vries is Windpower Monthly's technology and market trends consultant.

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