Introduction - Wind Power Integration: Connection and System Operational Aspects - page 18

The role of energy storage in the operational integration of wind power is
considered further in Chapter 5.
The variable sources of renewable energy, such as wind, are likely to
benefit from load management, although there are potential benefits for all
technologies. The potential benefits for wind have been examined (Econnect
Ltd, 1996), but such arrangements will be dependent on the agreement of
the supplier.

1.8 Future developments

1.8.1 Technology
Wind turbine technology has now come full circle since the days of the early
government-funded programmes, which spawned a number of MW-size machines
around 30 years ago. Although few of those machines were economic, the industry
learned a lot and is now, once again, building machines of similar size - or bigger.
As this progression towards larger sizes shows little signs of slowing, the question
is often asked whether there is any technical or economic limit. Roughly speaking,
rotor weights increase as the cube of the size, whereas energy yield increases as the
square. Perhaps more importantly, there will eventually come a point at which
gravitational bending forces start to dominate the design process and beyond this
point weights increase with the fifth power of the diameter. However, a simplified
analysis of the crucial design drivers has suggested that this crossover point is
unlikely to be reached until rotor diameters of about 200 m (Milborrow, 1986).
Even then, the use of strong, lightweight materials such as CFRP may raise the
limit higher.
The use of these lightweight materials is also likely to bring about further
weight and cost savings in the large machines now being developed. More
advanced control techniques and electrical innovation are also likely to improve
energy yields and further improve the attractions of wind turbines to electricity
network operators.
Several manufacturers are now marketing machines specifically for the offshore
market, with ratings up to 6 MW. In addition, it is possible that the removal of some
of the onshore constraints may lead to significant changes in design. The use of faster
rotational speeds and of two bladed machines are two options which would result in
significant weight reductions. The use of CFRP for the blades also results in
significant weight reduction. Although CFRP is presently too expensive, it is possi-
ble that an increased demand for the product would lead to cost reductions.

1.8.2 Future price trends
World wind energy capacity seems likely to continue doubling every three years or
so, accompanied each time, assuming recent trends continue, by a 10-15% reduc-
tion in production costs. During 2005, however, there was a marked upturn in
the installed costs of wind plant, primarily due to increases in the price of wind
turbines. This, in turn, was due to increases in the prices of steel, copper and