The early days saw quite independent development on two different fronts with research and development concentrated on big machines and largely ignoring the smaller scale, market driven activity. An important point was reached when the two routes converged in the late 1980s, meeting at about 200-300 kW rated capacity. The practical, commercial experience of the smaller scale came together with more abstract work on the larger machines. In parallel with the manufacturing industry the understanding of the technology has improved in enormous strides. The full importance of the scientific knowledge gathered by the research community -- and that which continues to be gathered -- is still not applied in real life to the extent that it should be. The gap between the research community and the manufacturing community is wider than is either healthy or necessary.
Real progress is only made by a combination of theoretical, experimental and practical experience. In the old days "build and bust" was possible and perhaps even economically sensible. With megawatt scale machines such an approach is folly. In the design process there is no substitute for careful analysis, monitoring and hence understanding of the behaviour of machines.
Mass reduction or mass production
Danish style wind turbines have reached maturity. Is there a new generation of wind turbines being secretly developed behind the scenes in Jutland, or is it simply more of the same? Probably not. Bigger and better, yes, but essentially the same. That is not a route through which we can expect a leap in cost benefits and efficiency. Reductions in the costs of these machines are going to be derived through mass production and possibly through an increase in size. A market for existing machines must continue to be encouraged. Cost reductions will result, quite simply, from sheer volume -- mass production.
The movement towards larger machines -- initiated in the European Union and then repeated in the US and elsewhere -- is certainly a development in the technology, but it may not be optimisation. It may be happening instead of rather than in parallel to a reduction in the costs of existing machine sizes. Is it possible to make a 500 kW machine which is, say, 25% cheaper than the existing commercial machines simply through a proper understanding of its behaviour?
There is a severe danger attached to neglecting the scope for cost reduction through improvement in the technology and understanding and simply relying on size and volume. The real potential of wind energy will only be realised if both the minimum cost machines are introduced and they are mass produced -- mass reduction and mass production.
Listen to the market
There are likely to be two separate markets which develop over the next few years. Those in which very large machines are possible and those in which they are not. There is some suggestion that large machines will be most economic. To force development down that route when it may be that the market does not want such a development can be dangerous. The market may not be able to sustain such developments as a result of two quite separate considerations which have nothing to do with costs: access and dominance. Access will be a problem for the remoter areas of both Europe and the rest of the world; the machinery may simply be too big. Dominance of wind turbines is likely to be a problem in the more populated areas. It is likely that there will be a market for machines in the 400-800 kW range for a long time to come. There is little evidence, at present, that the optimum solution in this range has been produced or even deduced.
Within these two markets there are also variations. Differing environmental conditions of high wind, high salt content or weak grids, for example. Most of these variations may be accommodated by variations in the machine design rather than radical changes to the machine concept. The large stand alone, or "village power" market remains largely ignored by wind turbine manufacturers. It calls for smaller machines which could now benefit from the lessons learned as the grid connected machines have increased in size. What would a new 50 kW turbine look like if it were designed with the hindsight that is now available to several leading manufacturers?
No room for complacency
The considerable achievements of this tiny industry during the last decade in reducing the costs of its technology to be comparable to those of conventional electricity sources must not allow it to become complacent. Although the present generation of commercial machines has reached a high level of reliability and maturity, the technology as a whole is still immature. There is clear scope for further cost reduction through both increases in volume of production and technological improvement. The long term solution is both -- they are not alternatives. The key to technological improvement is the understanding of the machines and the transfer of that understanding to the manufacturing industry. Simple pursuit of larger machines may reduce the market size and frustrate development of the optimum solutions.
Andrew Garrad, of independent wind energy consultants Garrad Hassan & Partners of the UK, has worked in wind energy for the past 15 years. His company, started in 1985, is also celebrating ten years in the wind business.