The winds of change

Wind power should no longer be dismissed. It is a force to be reckoned with, providing huge potential for a rewarding career. Dr. William Nuttall reports.

Only a few months ago wind power came across as small scale, intermittent, low-tech and harmless. It was one of those ‘renewables’ that environmentalists loved to celebrate, but that seemed almost irrelevant to the serious business of the electricity industry.

However, the technology has changed and many people’s vision of a row of 10m turbines atop a range of hills, with blades turning quickly and constructed in the face of fierce local opposition, is outdated.

The modern reality is quite different. The future of wind power is at sea, ideally 30km out. There are good technical, political and environmental reasons for such offshore locations, but surely it is no coincidence that the turbines are far out at sea where they cannot spoil the view.

One criticism of wind turbines has been that ridiculously large numbers would be needed for the technology to make a meaningful contribution to electricity supply. While such criticism may have been deserved when turbines were a few metres tall and generated a few hundred kilowatts, it is badly out of date now that state-of-the-art turbines are nearly 200m tall, each generating 4.2MW. The hub heights of the latest designs are 80m above the surface of the sea and the blade sweep is about 110m in diameter.

These structures are so large that engineers must be transferred to the hub nacelle by helicopter. As wind power has become a serious technology its developers have had to get involved with new stakeholders. For instance, the MoD raised objections about turning turbine blades possibly disrupting the radars used for UK air defence. Its arguments succeeded in blocking developments at Shell Flat, Lancashire, and Southport. but three large sites acceptable to the MoD have now been found.

Another serious stakeholder is the Health and Safety Executive. Conscious of the possible hazards to engineers, it has now included offshore wind installations in its regulations established under the Health and Safety at Work Act 1974.

Maintenance engineers for offshore wind power will assume the risks of their profession voluntarily and with professional understanding of the issues. As such societal acceptance of these risks is likely.

However, wind turbines as a hazard to shipping would be less likely to be tolerated by the public and media. The best sites for offshore wind are usually away from shipping routes, in shallow waters. But wind power developers would be wise to remember the 70,000-tonne car transporter Tricolor, which sank in the Channel last December. Though it was well marked and its location widely reported, two vessels collided with within weeks.

One axiom of wind power has been that it is good for the climate. However, work at Carnegie Mellon University suggests that kinetic energy removed from the wind for electricity can have a significant effect on regional climate downwind. Importantly, no impact on global temperature is predicted, but it is interesting to consider whether large-scale wind developments off the west coast of the UK might have negative impacts on agriculture.

It is frequently asserted that wind power will be so intermittent that it will make life impossible for the national grid. This view is looking increasingly incorrect. Operators are likely to set their turbines so that the blades turn at a lower speed than the maximum possible from the wind available. Such operation reduces wear on the machinery while allowing, via blade pitch adjustment, constant electricity output in the face of fluctuating wind speeds.

Furthermore, the balancing market of the New Electricity Trading Arrangements has its ‘gate closure’ time only one hour before the electricity is required. Such a short time between sale and delivery is well suited to wind power, even in a country with unreliable weather.

While these aspects of NETA are helpful, others have hit renewables hard. For instance, a purely wind-based generator would be unwise to enter a NETA-style bilateral long-term winter contract despite the high prices on offer. This is because cold spells often coincide with high barometric pressure and very low wind speeds. A wind generator forced to buy in the balancing market to fulfil its contract could be in serious trouble. However, a post-NETA market in which a greater fraction of supply runs through a spot market would suit wind much better.

Now that wind power is serious, it is likely to excite our best young engineers and potential engineers. The skills needed include ocean engineering, fluid dynamics, materials, mechanical engineering and control. The challenges and the promise of large-scale wind power are not to be underestimated. And a career at the cutting edge of an emerging technology, while not for the faint-hearted, will be rewarding.

William Nuttall is director of the MPhil in technology policy at Cambridge University.