The Wind Power Variability Myth Gets Debunked, Again

Wind unpredictability and variability are preventing wider and more ambitious adoption of the clean power source, or so the thinking goes in some circles. But is that true?

Not according to a new review on wind power, Managing Variability, commissioned by Greenpeace and carried out by energy consultant David Milborrow.

Just because winds do not blow constantly, does not mean the power produced by them cannot be constant, the energy consultant writes. In fact:

"There are no significant barriers to the introduction of wind energy due to its variability."

Though the UK was the focus of the study, the results are relevant worldwide, as characteristics of wind are broadly similar everywhere.

Across the windswept UK, wind energy provides just one half of one percent of electricity needs right now. According to Milborrow, increasing that to 40 percent can be technically managed by Britain's existing power system with modest — and even declining — costs.

In fact, British utility National Grid went so far as to conclude that that there is no 'ceiling' on the amount of wind-generated electricity that can be accommodated. It wrote in its Seven Year Statement last year:

"Based on recent analysis of the incidence and variation of wind speed the expected intermittency of the national wind portfolio would not appear to pose a technical ceiling on the amount of wind generation that may be accommodated and adequately managed."

The reason is simple. Contrary to popular perception, wind energy is not totally random and unpredictable. For one, the wind very rarely stops blowing everywhere at once. As Milborrow points out,

"Nothing will happen when the wind stops blowing, simply because it never stops blowing, suddenly, over the whole of the British Isles."

Truth is, no generation is 100 percent reliable. And energy from wind gusts is actually more manageable than most other options. The report finds that relative to dirtier conventional sources, fluctuations from the power output of wind installations are mild. More wind may even improve grid resilience.

"Thermal plant outputs, such as nuclear, coal and gas-fired power plants are truly 'intermittent,' in as much as they can disappear without warning when components fail, posing a greater threat to the stability of electricity networks than the relatively benign fluctuations of power output from wind installations."

For evidence, the study examined Western Denmark, where wind power made up 26 percent of electricity generation in 2007. Specifically, it looked at the changes in demand that had to be managed as the region boosted its wind share.

If there had been no wind power in 2007, the maximum one-hour increase in system demand would have been 675 MW. What happened with 26 percent wind? Turns out, not a whole lot.

"Sometimes the wind fluctuations augmented the demand fluctuations, sometimes they reduced them. The maximum increase in demand that the System Operator had to deal with went up from 675 MW to 900 MW. In that hour, there was an increase in demand at the same time as the output from the wind plant fell.

"However, the number of times that the net demand increased by more than 600 MW in an hour only went up from 55 (consumer demands only) to 63 (consumer demand net of wind production)."

In Britain, projections look similar. As reported in Recharge, calculations made by Oxford University Environmental Change Institute show that between 1970-2003, low wind speeds — those too slow to generate energy — occurred one hour per year on average across the UK.

All these numbers add up to a simple fact: Assimilation of wind is not a serious problem, anywhere. As Milborrow wrote: